Background With improved life expectancy and advances in medical care, the number of pacemakers implanted in people 226580 years of age has been steadily increasing. Current pacing guidelines favour implantation of dual-chamber pacemakers for brady-arrhythmias including sinus node disease and higher degree atrioventricular (AV) block except in patients with chronic atrial fibrillation (AF).1,2 Dual-chamber pacing resembles more closely to the normal cardiac physiology and maintains the AV synchrony. Therefore, dual-chamber pacemaker is thought to be potentially more advantageous in older adults who have increased contribution of atrial contraction to ventricular filling with their haemodynamic changes of ageing.3,4 However, there is still a significant proportion of single-chamber pacemakers being implanted in the octogenarian and nonagenarian patients perhaps because of the paucity of data and evidence specifically addressing this in the very elderly group.5-7 In clinical practice, the specific determinants of pacing mode selection in patients remain unspecified even if there are guidelines to assist the implanting physicians. The objective of this study was to assess our local practice of dual-chamber pacemakers vs single-chamber ventricular pacemakers implantation rate in octogenarian and nonagenarian patients at Auckland City Hospital. We aimed to assess whether the current cardiac pacing guideline is adhered in this population and aimed to identify whether there are any variables between the two groups that affected the decision of pacing mode selection. We also aimed to assess whether there were any differences in their clinical outcome and complication rate. Methods This is a retrospective observation study involving octogenarian and nonagenarian patients who required pacemaker implantation. We identified patients aged 80 years or older, who received their first pacemaker at Auckland City Hospital (ACH) for a conventional reason for long-term pacing for the three-year period (July 2010 to June 2013) from a centralised ACH pacing database. We identified the patient demographics, medical co-morbidities, indications for pacing, type of pacemaker implanted, acute (within 24 hours of implant), early (from >24 hours to two weeks) and late (from two weeks to three months after pacemaker implantation) complications and patients discharge destinations from the local hospital electronic medical records. Most octogenarian and nonagenarian patients are expected to have some degree of valvular heart disease and chronic kidney disease. For the purpose of our review we included only severe symptomatic valvular heart disease that will be otherwise considered for surgery or patients with post valve surgery as medical co-morbidity. For chronic kidney disease, only stage 4 or more advanced kidney disease were included as their medical co-morbidity. Statistical Analysis Statistical comparisons for continuous data were performed using ANOVAs single factor, unpaired t-tests and chi-squared tests, and Fishers exact test were used for categorical data. Continuous variables are presented as mean 00b1 SD, and categorical data as counts or percentages. Ethics approval was obtained from the Auckland DHB Research Review Committee. Results A total of 357 patients 226580 years of age who received their first pacemaker implantation were identified for the study period. We excluded one patient who had an atrial pacemaker (AAI) and left with 356 patients for the analysis. Figure 1 showed the number of dual and single-chamber pacemakers implanted in these populations throughout the study period. Only 50 patients 226580 years of age received dual-chamber pacemakers. Mean age of the patients at the time of first implant was 86.100b14.3 years (range 80 to 99 years) and 82.600b12.9 years (range 80 to 90 years) for single and dual-chamber pacemakers respectively (p<0.05). 54% of the patients were male. Figure 1: Number of dual and single-chamber pacemakers implanted in those 226580 years of age for three-year period. The indication for pacemaker implantation was showed in Table 1. The most common indication for pacing was high-grade AV block (43.5%) followed by AF/flutter with slow ventricular rate/pauses (35.9%). Table 1: Indications for pacemaker implantation. Indications Number Atrioventricular (AV) Block 155 (43.5%) Sinus node disease 28 (8%) Mixed AV block and sinus node disease 41 (11.5%) Atrial fibrillation (AF)/flutter with slow ventricular response 128 (35.9%) Ventricular tachycardia and empiric pacing for recurrent syncope 4 (1%) Table 2 showed the demographic data of the patients who received single and dual-chamber pacemakers. Those who received single-chamber pacemaker were older (86.1 vs 82.6 years, p<0.05), more likely to have valvular heart disease (p<0.05) and cognitive impairment (p<0.05). However, there were no differences in terms of the procedure-related complications or discharge status between the two groups. Table 2: Baseline characteristics of the patients who received single and dual-chamber pacemakers. Single-chamber (n=306) Dual-chamber (n=50) P Value Mean age Median age 86.1 00b1 4.3 86 82.6 00b1 2.9 82 <0.05 Gender Male (%) Female 161 145 32 18 0.13 Previous IHD 123 27 0.07 Valvular heart disease 35 13 <0.05 Congestive heart failure 58 10 0.86 Previous stroke 66 9 0.57 CKD 51 9 0.82 Active malignancy 21 2 0.44 Cognitive impairment/dementia 53 0 <0.05 Procedural complications Acute complications 16 3 0.82 Pneumothorax 8 0 0.25 Lead remanipulation 6 1 0.97 Early complications 10 4 0.12 Late complications 0 1 0.14 Discharge ctatus Death 4 0 1.0 Home 275 49 0.06 Residential care 27 1 1.0 Rest home 23 1 0.15 Private hospital 4 0 1.0 Abbreviation:IHD: ischaemic heart disease CKD: chronic kidney disease Within three months follow-up, a total of 9.5% of procedure-related complications occurred in 34 patients. Most common complications were lead-related problems (11/34) and pocket haematomas (11/34). Most patients were on at least one antiplatelet therapy due to co-existing ischaemic heart disease (IHD) or history of transient ischaemic attack (TIA)/stroke. Four patients with pocket haematomas were also taking warfarin with their international normalised ratio (INR) between 2 to 2.5. Another patient with moderate pocket haematoma had exacerbation of chronic idiopathic thrombocytopenia (ITP) and was re-admitted with platelet count <10 and was managed with prednisone and plasmapheresis. All the patients with haematoma were managed conservatively with pressure dressing. Less than 50% of all patients with complications required another procedure to manage their complications: 11 (3%) required lead re-manipulation and 4 (1%) patients required chest drain for pneumothorax. Complication rates between the two groups were comparable (Table 2). At the end of three-month follow up, four patients were deceased and there was no pacemaker-related death. At the time of implantation, 185 patients who received a single-chamber pacemaker were in sinus rhythm (52%). The baseline characteristics of these patients compared with those who received dual-chamber pacemakers were shown in Table 3. Patients who received single-chamber pacemaker tended to be older (86.2 +/- 4.3 years vs 82.6 +/- 2.9 years, p<0.05), more likely to have IHD (68 vs 27, p=0.02), significant valvular heart disease (22 vs 13, p=0.01) and cognitive impairment (34 vs 0, p=0.001). They were also more likely to be discharged to a long term residential care facility (17 vs 1, p<0.01). Table 3: Baseline characteristics of non-AF patients who received single-chamber pacemakers vs patients who received dual-chamber pacemakers. Non-AF single-chamber pacemakers patients (n=185) Dual-chamber pacemaker patients (n=50) Mean age Median age 86.200b14.3 86 82.600b12.9 82 <0.05 Gender Male Female 78 107 18 32 0.28 Previous IHD 68 27 0.02 Valvular heart disease 22 13 0.01 Congestive heart failure 27 10 0.35 Previous stroke 35 9 0.88 CKD 33 9 0.98 Active malignancy 16 2 0.27 Cognitive impairment/dementia 34 0 0.001 Complications Acute complications 9 3 0.72 Pneumothorax 4 0 0.58 Lead remanipulation 5 1 1.00 Early complications 4 4 0.07 Late complications 0 1 1.00 Discharge status Death 2 0 1.00 Home 166 49 0.06 Residential care 17 1 <0.01 Rest home 14 1 <0.05 Private hospital 3 0 1.00 Abbreviation:AF: Atrial fibrillation IHD: ischaemic heart disease CKD: chronic kidney disease Discussion Our study showed that utilisation of dual-chamber pacemakers in the octogenarian and nonagenarian populations remained low and did not comply with the current cardiac pacing guidelines. The important predictor that determines the choice of pacing mode was presence of cognitive impairment. Furthermore, those patients who received single-chamber pacemakers who were in sinus rhythm were older, more likely to have significant co-morbidities and more likely to be discharged to a residential care which might imply poorer baseline functional status before implantation. New Zealand, like many developed countries, has an ageing population and the number of people aged 85 years and over is expected to increase from 67,000 in 2009 to over a quarter of a million by 2051.8 Those who aged >85 years have been the most rapidly expanding segment of our population over the past decades and they will make up 22% of all New Zealanders aged 65 years and over, compared with 9% in 1996.8 To date, there is no published prospective and randomised trial on the choice of pacing mode specifically assessing those octogenarian and nonagenarian patients. There is evidence of superiority of dual-chamber pacing over ventricular pacing alone in patients, especially in patients with sinus node disease. In 2000, The Canadian Trial of Physiologic Pacing (CTOPP) was the first large randomised study (N=2,568) to investigate the effects of dual-chamber versus single-chamber ventricular pacing on the risk of stroke or death due to cardiovascular causes.9 After a mean of three-year follow-up, there was no significant benefit of dual-chamber over single-chamber ventricular pacing in reducing stroke or cardiovascular death (4.9% vs 5.5%, p=0.33). The mean age of the patients in the CTOPP was 73+/-10 years and was much younger than our study population. There was no difference in the incidence of heart failure hospitalisation.9 However, the study showed a modest benefit of dual-chamber pacing on the development of AF and similarly, the Mode Selection Trial (MOST) in 2002 also demonstrated a beneficial effect of dual-chamber pacing on progression to chronic AF.10 In our study, 52% of the patients who received a single-chamber pacemaker were actually in sinus rhythm at the time of implantation. AF is a common arrhythmia in the elderly population.12 Having a dual-chamber pacemaker potentially can reduce the incidence of AF in this group. Because of the age and underlying comorbidities, these patients were preferentially given a single-chamber pacemaker despite the current cardiac pacing guidelines. There were more perioperative complications reported in CTOPP study, mainly lead-related problems.9 This was different from our study where there was no difference in the complication rates between the two groups. Although dual-chamber pacing does not provide survival benefit on published studies, the mortality endpoint is probably not the crucial determinant for mode selection in the majority of octogenarian and nonagenarian patients. Pacing is generally considered primarily as a means of improving quality of day-to-day life. Expectations, values and needs are different from patients who are younger. Small improvement in cardiac output and exercise tolerance with dual-chamber pacemakers may be a crucial factor in allowing continued independence and improving quality of life in our octogenarian and nonagenarian populations. Pacemaker syndrome consists of a constellation of signs and symptoms that occur in response to loss of AV synchrony and might have significant impact on older persons quality of life.14,15 Octogenarians and nonagenarians belong to a highly heterogeneous group with regards to the presence and severity of medical co-morbidities and functional capabilities. Older people with pacemaker syndrome might have recurrent presentations to general or geriatric service with vague and nonspecific illness and over time recurrent admissions might exert substantial increase on health care expenditure as well as negative impact on their quality of life until proper diagnosis is made. Interestingly in MOST study, there was high rate of crossover from single-chamber pacing to dual-chamber pacing due to pacemaker syndrome (18.3%).13 At the last follow-up, 313 patients (31.4%) assigned to ventricular pacing alone were receiving dual-chamber pacing. In the Pacemaker Selection in the Elderly (PASE) trial, the pacemaker syndrome occurred in 26% of patients during an average follow-up of 18 months.16 In contrast, CTOPP reported very low (2.7%) crossover rate.9 Currently there are no clear diagnostic criteria for pacemaker syndrome and different studies have different clinical thresholds for the diagnosis of such a subjective condition. In the CTOPP, re-operation was required to change from ventricular to dual-chamber pacing whereas only re-programming was necessary in the MOST and PASE trial so likely the two studies had lower threshold for the crossover.9,10,16 None of our patients were upgraded to physiological pacing during the study period for pacemaker syndrome and we acknowledge the limitation of our retrospective study and the need for upgrade to a dual-chamber system due to intolerable pacemaker syndrome must be weighed against the increased risk of complication and cost with dual-chamber pacemaker. At current stage we have no means of determining who will be more susceptible to pacemaker syndrome. Our review highlights the need for further research in this area. Risk stratification of octogenarian and nonagenarian patients meeting current pacing guidelines for dual-chamber pacemakers should be improved and standardised to achieve optimal patient outcome. At the start of the study, our hospital did have a policy that all octogenarian and nonagenarian patients should receive only single-chamber pacemaker as the published data suggested no mortality benefit of dual-chamber pacing over single pacing. The local policy regarding our conservative approach to pacing in the elderly was not published anywhere and the final decision to implant type of pacemaker in this group of population has always been at operators discretion. Co-morbidities/frailty and cost were factors considered in our centre as well as the lack of resources to offer dual-chamber pacemaker for the growing population of octogenarians and nonagenarians. There were no national guidelines that we were aware at that point and there is none still at present. Given the large number of potential candidates (growing elderly populations) and the practical constraints of limited implanting specialist resource and funding in New Zealand, our local policy of implanting single-chamber pacemaker in octogenarian and nonagenarian represent a conservative but pragmatic prioritisation from the available trial evidence. We acknowledge this as one of the limitations of our study. With increasing availability of resources, the number of dual-chamber pacemaker implantation in the octogenarian and nonagenarian patients slowly increased but remained low as showed in Figure 1. This may be reviewed as part of clinical practice in the future. A number of clinical studies have shown that, unnecessary chronic right ventricular pacing can cause a variety of detrimental effects, including AF and heart failure.17-19 With the advance in the pacemaker technology, new pacing algorithms have influenced our clinical practice in implanting dual-chamber pacemakers to allow a more physiological pacemaker yet minimise ventricular pacing. Previously we may have put a single-chamber ventricular lead back-up (ie VVI) to minimise pacing in patients with sick sinus syndrome, but new dual-chamber pacing mode such as Managed Ventricular Pacing (MVP) allows a functional single-chamber atrial pacing (ie AAI) with ventricular monitoring and automatic switch from AAI to dual-chamber pacing (DDD) during episodes of AV block.18,19 Unfortunately, there is very limited data on the cost-effectiveness analysis of dual versus single ventricular pacemakers in this age group and further research is required in this area to help the clinicians to make informed decision. Multidisciplinary comprehensive geriatric assessment including assessment of cognition and frailty score prior to pacemaker implantation might assist in pacing mode selection by having more accurate information on their functional and cognitive status. Much work remains to be done with regard to the development of new algorithm. Limitations A number of limitations should be considered in interpreting the results of our study. Our study is a single-centre retrospective observational study, the selection of pacing mode, ie, device prescription is not randomised. The local policy regarding our conservative approach to pacing in the elderly might have influenced the operators decision on the choice of devices implanted. Information on patients frailty and functional status were not available. Patients with poor functional status and limited expected survival were likely to be implanted preferentially with single-chamber pacemakers. This opens the door for bias. Our study did not have cost-effective analysis; therefore, we do not know whether single vs dual-chamber pacemakers would potentially have any cost-saving in these populations. Our main strength is our results are a representation of 'real-world' practice. It provides a useful perspective for both clinicians and implanting physicians on the selection of pacing mode based on an individual patient clinical status. A multidisciplinary approach involving the geriatrician and implanting cardiologist to provide a comprehensive assessment prior to implantation should be considered. Conclusion Utility of dual-chamber PM in the octogenarian and nonagenarian populations remains below expectations and did not comply with current pacing guidelines. The presence of cognitive impairment was the strongest independent predictor for receiving single-chamber pacemaker. In addition, patients who received single-chamber pacemaker with sinus rhythm were noted to be older and more likely to have IHD, significant valvular heart disease and more likely to be discharged to residential care which might imply poorer baseline functional status. Those factors likely influenced the decision of type of device implanted. Balancing patients comorbidities and the potential for device-related complications against the potential benefit is recommended on a case-by-case basis.

Background With improved life expectancy and advances in medical care, the number of pacemakers implanted in people 226580 years of age has been steadily increasing. Current pacing guidelines favour implantation of dual-chamber pacemakers for brady-arrhythmias including sinus node disease and higher degree atrioventricular (AV) block except in patients with chronic atrial fibrillation (AF).1,2 Dual-chamber pacing resembles more closely to the normal cardiac physiology and maintains the AV synchrony. Therefore, dual-chamber pacemaker is thought to be potentially more advantageous in older adults who have increased contribution of atrial contraction to ventricular filling with their haemodynamic changes of ageing.3,4 However, there is still a significant proportion of single-chamber pacemakers being implanted in the octogenarian and nonagenarian patients perhaps because of the paucity of data and evidence specifically addressing this in the very elderly group.5-7 In clinical practice, the specific determinants of pacing mode selection in patients remain unspecified even if there are guidelines to assist the implanting physicians. The objective of this study was to assess our local practice of dual-chamber pacemakers vs single-chamber ventricular pacemakers implantation rate in octogenarian and nonagenarian patients at Auckland City Hospital. We aimed to assess whether the current cardiac pacing guideline is adhered in this population and aimed to identify whether there are any variables between the two groups that affected the decision of pacing mode selection. We also aimed to assess whether there were any differences in their clinical outcome and complication rate. Methods This is a retrospective observation study involving octogenarian and nonagenarian patients who required pacemaker implantation. We identified patients aged 80 years or older, who received their first pacemaker at Auckland City Hospital (ACH) for a conventional reason for long-term pacing for the three-year period (July 2010 to June 2013) from a centralised ACH pacing database. We identified the patient demographics, medical co-morbidities, indications for pacing, type of pacemaker implanted, acute (within 24 hours of implant), early (from >24 hours to two weeks) and late (from two weeks to three months after pacemaker implantation) complications and patients discharge destinations from the local hospital electronic medical records. Most octogenarian and nonagenarian patients are expected to have some degree of valvular heart disease and chronic kidney disease. For the purpose of our review we included only severe symptomatic valvular heart disease that will be otherwise considered for surgery or patients with post valve surgery as medical co-morbidity. For chronic kidney disease, only stage 4 or more advanced kidney disease were included as their medical co-morbidity. Statistical Analysis Statistical comparisons for continuous data were performed using ANOVAs single factor, unpaired t-tests and chi-squared tests, and Fishers exact test were used for categorical data. Continuous variables are presented as mean 00b1 SD, and categorical data as counts or percentages. Ethics approval was obtained from the Auckland DHB Research Review Committee. Results A total of 357 patients 226580 years of age who received their first pacemaker implantation were identified for the study period. We excluded one patient who had an atrial pacemaker (AAI) and left with 356 patients for the analysis. Figure 1 showed the number of dual and single-chamber pacemakers implanted in these populations throughout the study period. Only 50 patients 226580 years of age received dual-chamber pacemakers. Mean age of the patients at the time of first implant was 86.100b14.3 years (range 80 to 99 years) and 82.600b12.9 years (range 80 to 90 years) for single and dual-chamber pacemakers respectively (p<0.05). 54% of the patients were male. Figure 1: Number of dual and single-chamber pacemakers implanted in those 226580 years of age for three-year period. The indication for pacemaker implantation was showed in Table 1. The most common indication for pacing was high-grade AV block (43.5%) followed by AF/flutter with slow ventricular rate/pauses (35.9%). Table 1: Indications for pacemaker implantation. Indications Number Atrioventricular (AV) Block 155 (43.5%) Sinus node disease 28 (8%) Mixed AV block and sinus node disease 41 (11.5%) Atrial fibrillation (AF)/flutter with slow ventricular response 128 (35.9%) Ventricular tachycardia and empiric pacing for recurrent syncope 4 (1%) Table 2 showed the demographic data of the patients who received single and dual-chamber pacemakers. Those who received single-chamber pacemaker were older (86.1 vs 82.6 years, p<0.05), more likely to have valvular heart disease (p<0.05) and cognitive impairment (p<0.05). However, there were no differences in terms of the procedure-related complications or discharge status between the two groups. Table 2: Baseline characteristics of the patients who received single and dual-chamber pacemakers. Single-chamber (n=306) Dual-chamber (n=50) P Value Mean age Median age 86.1 00b1 4.3 86 82.6 00b1 2.9 82 <0.05 Gender Male (%) Female 161 145 32 18 0.13 Previous IHD 123 27 0.07 Valvular heart disease 35 13 <0.05 Congestive heart failure 58 10 0.86 Previous stroke 66 9 0.57 CKD 51 9 0.82 Active malignancy 21 2 0.44 Cognitive impairment/dementia 53 0 <0.05 Procedural complications Acute complications 16 3 0.82 Pneumothorax 8 0 0.25 Lead remanipulation 6 1 0.97 Early complications 10 4 0.12 Late complications 0 1 0.14 Discharge ctatus Death 4 0 1.0 Home 275 49 0.06 Residential care 27 1 1.0 Rest home 23 1 0.15 Private hospital 4 0 1.0 Abbreviation:IHD: ischaemic heart disease CKD: chronic kidney disease Within three months follow-up, a total of 9.5% of procedure-related complications occurred in 34 patients. Most common complications were lead-related problems (11/34) and pocket haematomas (11/34). Most patients were on at least one antiplatelet therapy due to co-existing ischaemic heart disease (IHD) or history of transient ischaemic attack (TIA)/stroke. Four patients with pocket haematomas were also taking warfarin with their international normalised ratio (INR) between 2 to 2.5. Another patient with moderate pocket haematoma had exacerbation of chronic idiopathic thrombocytopenia (ITP) and was re-admitted with platelet count <10 and was managed with prednisone and plasmapheresis. All the patients with haematoma were managed conservatively with pressure dressing. Less than 50% of all patients with complications required another procedure to manage their complications: 11 (3%) required lead re-manipulation and 4 (1%) patients required chest drain for pneumothorax. Complication rates between the two groups were comparable (Table 2). At the end of three-month follow up, four patients were deceased and there was no pacemaker-related death. At the time of implantation, 185 patients who received a single-chamber pacemaker were in sinus rhythm (52%). The baseline characteristics of these patients compared with those who received dual-chamber pacemakers were shown in Table 3. Patients who received single-chamber pacemaker tended to be older (86.2 +/- 4.3 years vs 82.6 +/- 2.9 years, p<0.05), more likely to have IHD (68 vs 27, p=0.02), significant valvular heart disease (22 vs 13, p=0.01) and cognitive impairment (34 vs 0, p=0.001). They were also more likely to be discharged to a long term residential care facility (17 vs 1, p<0.01). Table 3: Baseline characteristics of non-AF patients who received single-chamber pacemakers vs patients who received dual-chamber pacemakers. Non-AF single-chamber pacemakers patients (n=185) Dual-chamber pacemaker patients (n=50) Mean age Median age 86.200b14.3 86 82.600b12.9 82 <0.05 Gender Male Female 78 107 18 32 0.28 Previous IHD 68 27 0.02 Valvular heart disease 22 13 0.01 Congestive heart failure 27 10 0.35 Previous stroke 35 9 0.88 CKD 33 9 0.98 Active malignancy 16 2 0.27 Cognitive impairment/dementia 34 0 0.001 Complications Acute complications 9 3 0.72 Pneumothorax 4 0 0.58 Lead remanipulation 5 1 1.00 Early complications 4 4 0.07 Late complications 0 1 1.00 Discharge status Death 2 0 1.00 Home 166 49 0.06 Residential care 17 1 <0.01 Rest home 14 1 <0.05 Private hospital 3 0 1.00 Abbreviation:AF: Atrial fibrillation IHD: ischaemic heart disease CKD: chronic kidney disease Discussion Our study showed that utilisation of dual-chamber pacemakers in the octogenarian and nonagenarian populations remained low and did not comply with the current cardiac pacing guidelines. The important predictor that determines the choice of pacing mode was presence of cognitive impairment. Furthermore, those patients who received single-chamber pacemakers who were in sinus rhythm were older, more likely to have significant co-morbidities and more likely to be discharged to a residential care which might imply poorer baseline functional status before implantation. New Zealand, like many developed countries, has an ageing population and the number of people aged 85 years and over is expected to increase from 67,000 in 2009 to over a quarter of a million by 2051.8 Those who aged >85 years have been the most rapidly expanding segment of our population over the past decades and they will make up 22% of all New Zealanders aged 65 years and over, compared with 9% in 1996.8 To date, there is no published prospective and randomised trial on the choice of pacing mode specifically assessing those octogenarian and nonagenarian patients. There is evidence of superiority of dual-chamber pacing over ventricular pacing alone in patients, especially in patients with sinus node disease. In 2000, The Canadian Trial of Physiologic Pacing (CTOPP) was the first large randomised study (N=2,568) to investigate the effects of dual-chamber versus single-chamber ventricular pacing on the risk of stroke or death due to cardiovascular causes.9 After a mean of three-year follow-up, there was no significant benefit of dual-chamber over single-chamber ventricular pacing in reducing stroke or cardiovascular death (4.9% vs 5.5%, p=0.33). The mean age of the patients in the CTOPP was 73+/-10 years and was much younger than our study population. There was no difference in the incidence of heart failure hospitalisation.9 However, the study showed a modest benefit of dual-chamber pacing on the development of AF and similarly, the Mode Selection Trial (MOST) in 2002 also demonstrated a beneficial effect of dual-chamber pacing on progression to chronic AF.10 In our study, 52% of the patients who received a single-chamber pacemaker were actually in sinus rhythm at the time of implantation. AF is a common arrhythmia in the elderly population.12 Having a dual-chamber pacemaker potentially can reduce the incidence of AF in this group. Because of the age and underlying comorbidities, these patients were preferentially given a single-chamber pacemaker despite the current cardiac pacing guidelines. There were more perioperative complications reported in CTOPP study, mainly lead-related problems.9 This was different from our study where there was no difference in the complication rates between the two groups. Although dual-chamber pacing does not provide survival benefit on published studies, the mortality endpoint is probably not the crucial determinant for mode selection in the majority of octogenarian and nonagenarian patients. Pacing is generally considered primarily as a means of improving quality of day-to-day life. Expectations, values and needs are different from patients who are younger. Small improvement in cardiac output and exercise tolerance with dual-chamber pacemakers may be a crucial factor in allowing continued independence and improving quality of life in our octogenarian and nonagenarian populations. Pacemaker syndrome consists of a constellation of signs and symptoms that occur in response to loss of AV synchrony and might have significant impact on older persons quality of life.14,15 Octogenarians and nonagenarians belong to a highly heterogeneous group with regards to the presence and severity of medical co-morbidities and functional capabilities. Older people with pacemaker syndrome might have recurrent presentations to general or geriatric service with vague and nonspecific illness and over time recurrent admissions might exert substantial increase on health care expenditure as well as negative impact on their quality of life until proper diagnosis is made. Interestingly in MOST study, there was high rate of crossover from single-chamber pacing to dual-chamber pacing due to pacemaker syndrome (18.3%).13 At the last follow-up, 313 patients (31.4%) assigned to ventricular pacing alone were receiving dual-chamber pacing. In the Pacemaker Selection in the Elderly (PASE) trial, the pacemaker syndrome occurred in 26% of patients during an average follow-up of 18 months.16 In contrast, CTOPP reported very low (2.7%) crossover rate.9 Currently there are no clear diagnostic criteria for pacemaker syndrome and different studies have different clinical thresholds for the diagnosis of such a subjective condition. In the CTOPP, re-operation was required to change from ventricular to dual-chamber pacing whereas only re-programming was necessary in the MOST and PASE trial so likely the two studies had lower threshold for the crossover.9,10,16 None of our patients were upgraded to physiological pacing during the study period for pacemaker syndrome and we acknowledge the limitation of our retrospective study and the need for upgrade to a dual-chamber system due to intolerable pacemaker syndrome must be weighed against the increased risk of complication and cost with dual-chamber pacemaker. At current stage we have no means of determining who will be more susceptible to pacemaker syndrome. Our review highlights the need for further research in this area. Risk stratification of octogenarian and nonagenarian patients meeting current pacing guidelines for dual-chamber pacemakers should be improved and standardised to achieve optimal patient outcome. At the start of the study, our hospital did have a policy that all octogenarian and nonagenarian patients should receive only single-chamber pacemaker as the published data suggested no mortality benefit of dual-chamber pacing over single pacing. The local policy regarding our conservative approach to pacing in the elderly was not published anywhere and the final decision to implant type of pacemaker in this group of population has always been at operators discretion. Co-morbidities/frailty and cost were factors considered in our centre as well as the lack of resources to offer dual-chamber pacemaker for the growing population of octogenarians and nonagenarians. There were no national guidelines that we were aware at that point and there is none still at present. Given the large number of potential candidates (growing elderly populations) and the practical constraints of limited implanting specialist resource and funding in New Zealand, our local policy of implanting single-chamber pacemaker in octogenarian and nonagenarian represent a conservative but pragmatic prioritisation from the available trial evidence. We acknowledge this as one of the limitations of our study. With increasing availability of resources, the number of dual-chamber pacemaker implantation in the octogenarian and nonagenarian patients slowly increased but remained low as showed in Figure 1. This may be reviewed as part of clinical practice in the future. A number of clinical studies have shown that, unnecessary chronic right ventricular pacing can cause a variety of detrimental effects, including AF and heart failure.17-19 With the advance in the pacemaker technology, new pacing algorithms have influenced our clinical practice in implanting dual-chamber pacemakers to allow a more physiological pacemaker yet minimise ventricular pacing. Previously we may have put a single-chamber ventricular lead back-up (ie VVI) to minimise pacing in patients with sick sinus syndrome, but new dual-chamber pacing mode such as Managed Ventricular Pacing (MVP) allows a functional single-chamber atrial pacing (ie AAI) with ventricular monitoring and automatic switch from AAI to dual-chamber pacing (DDD) during episodes of AV block.18,19 Unfortunately, there is very limited data on the cost-effectiveness analysis of dual versus single ventricular pacemakers in this age group and further research is required in this area to help the clinicians to make informed decision. Multidisciplinary comprehensive geriatric assessment including assessment of cognition and frailty score prior to pacemaker implantation might assist in pacing mode selection by having more accurate information on their functional and cognitive status. Much work remains to be done with regard to the development of new algorithm. Limitations A number of limitations should be considered in interpreting the results of our study. Our study is a single-centre retrospective observational study, the selection of pacing mode, ie, device prescription is not randomised. The local policy regarding our conservative approach to pacing in the elderly might have influenced the operators decision on the choice of devices implanted. Information on patients frailty and functional status were not available. Patients with poor functional status and limited expected survival were likely to be implanted preferentially with single-chamber pacemakers. This opens the door for bias. Our study did not have cost-effective analysis; therefore, we do not know whether single vs dual-chamber pacemakers would potentially have any cost-saving in these populations. Our main strength is our results are a representation of 'real-world' practice. It provides a useful perspective for both clinicians and implanting physicians on the selection of pacing mode based on an individual patient clinical status. A multidisciplinary approach involving the geriatrician and implanting cardiologist to provide a comprehensive assessment prior to implantation should be considered. Conclusion Utility of dual-chamber PM in the octogenarian and nonagenarian populations remains below expectations and did not comply with current pacing guidelines. The presence of cognitive impairment was the strongest independent predictor for receiving single-chamber pacemaker. In addition, patients who received single-chamber pacemaker with sinus rhythm were noted to be older and more likely to have IHD, significant valvular heart disease and more likely to be discharged to residential care which might imply poorer baseline functional status. Those factors likely influenced the decision of type of device implanted. Balancing patients comorbidities and the potential for device-related complications against the potential benefit is recommended on a case-by-case basis.