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Coronary artery disease in men—the role of the Y chromosomeMen are more commonly affected with coronary artery disease
than women. This study explores the role of the Y chromosome in coronary artery
disease in the context of this sexual inequity.
The researchers genotyped 11 markers of the male-specific
region of the Y chromosome in 3233 biologically unrelated British men from three
cohorts. Each Y chromosome was tracked back into one of the 13 ancient lineages
defined as haplogroups. Of nine haplogroups identified, two (R1b1b2 and I)
accounted for roughly 90% of the Y chromosome variants among British men.
Carriers of haplogroup I had about a 50% higher age-adjusted risk of coronary
artery disease than did men with other Y chromosome lineages. They speculate
that this haplogroup interconnects with common genes related to inflammation and
immunity which have a strong relevance to atherosclerosis and may explain the
higher incidence of coronary artery disease in this cohort.
Lancet
2012;379:915–22.
Does cannabis use by drivers increase the risk of a motor vehicle collision?Apparently simulated laboratory studies suggest a
dose–response relationship between cannabis use and reduced driving
skills. This study is a meta-analysis of nine studies which compare accident
rates between cannabis users and non-users. Cannabis use was documented by
toxicology or self reporting. Only motor vehicle collisions resulting in serious
injury or death were included. The authors report an almost two-fold (odds ratio
1.92) increase in the risk of serious accident in the cannabis users. They note
that they had insufficient toxicological data to measure any dose–response
effect. They speculate that cannabis may also be relevant in minor
collisions.
BMJ 2012;344:e536.
Proton pump inhibitors (PPIs) and the risk of postmenopausal hip fractureThe US Food and Drug Administration warned of this
possibility in 2010. Hence this report which prospectively examined 79,899
postmenopausal women enrolled in the US Nurse’s Health Study who provided
data on the use of PPIs and other risk factors biennially since 2000 and were
followed through to 1 June 2008.
During the follow-up there were 893 hip fractures with an
absolute risk of 2.2 events per thousand person years amongst the PPI users
compared with 1.51 events in non-users. It is of note that cigarette smoking is
involved in the equation and non-smoking PPI users did not have an increased
risk of fracture.
BMJ 2012;344:e372.
Cardiovascular magnetic resonance (CMR) versus single-photon emission computed tomography (SPECT) in the diagnosis of coronary heart diseaseIn this prospective trial, patients with suspected angina
pectoris and at least one cardiovascular risk factor were scheduled for CMR,
SPECT, and invasive X-ray coronary angiography.
39% of 752 patients had significant coronary disease
identified by angiography. For CMR the sensitivity was 86.5%, and 66.5% for
SPECT, a significant difference. Currently SPECT is the most widely used test
for the assessment of myocardial ischaemia but this report strongly suggests
that CMR is better. It also does not expose patients to ionising radiation. On
the other hand, CMR has limitations—cost, patient claustrophobia, some
patients will have incompatible cardiac devices (pacemakers) and some with renal
impairment may not tolerate this gadolinium used as a CMR image enhancer.
Lancet
2012;379:453–60.
Oral rivaroxaban for pulmonary embolismThe authors of this study note that a fixed-dose regimen of
rivaroxaban, an oral factor Xa inhibitor, has been shown to be as effective as
standard anticoagulant therapy for the treatment of deep-vein thrombosis,
without the need for laboratory monitoring.
They speculate that such a regimen may be equally effective
in the management of pulmonary embolism and have conducted an appropriate
randomised study. They randomised 4832 patients who had acute pulmonary embolism
with or without deep vein thrombosis to either rivaroxaban (15 mg twice daily
for 3 weeks, followed by 20 mg once daily) or standard therapy with enoxaparin
followed by an adjusted-dose vitamin K antagonist for 3, 6, or 12 months.
Rivaroxaban proved to be non-inferior to the standard
treatment for efficacy. There was less bleeding seen in the rivaroxaban cohort.
It is noted that with no need for therapeutic injections or monitoring of
laboratory results there may well be economic benefits as well.
N Eng J Med
2012;366:1287–97.
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