June 30th, 2014

Selections from Richard Lehman’s Literature Review: June 30th

CardioExchange is pleased to reprint this selection from Dr. Richard Lehman’s weekly journal review blog at BMJ.com. Selected summaries are relevant to our audience, but we encourage members to engage with the entire blog.

NEJM 26 Jun 2014 Vol 370

AF in Patients with Cryptogenic Stroke (pg. 2478):  Cryptogenic is a good word. It’s up there with “idiopathic” and “pleiotropic” and “diathesis” for covering gross ignorance with a smattering of Greek. “Cryptogenic” sounds as if it was first used to describe the odd symptoms that Superman experienced when exposed to kryptonite. However, its first use was recorded 30 years before the caped crusader first appeared in the skies above Metropolis in 1938. “Cryptogenic stroke” is a fairly recent term, covering 20-40% of incident stroke, and it challenges researchers to hunt around the garden looking for kryptonite hidden under stones. A patent foramen ovale! Ah yes, but it may be an innocent bystander. Atrial fibrillation (AF) then! Possibly, according to the EMBRACE study, but still unlikely to account for most unexplained ischaemic strokes. The Canadian researchers monitored 572 patients who had had an unexplained ischaemic stroke or transient ischaemic attack, half of them using standard 24 hour ECG, and half with a 30 day event monitor. Their mean age was 72, and the detection rate for AF was 3.2% versus 16.1% in the two groups.

Cryptogenic Stroke and Underlying Atrial Fibrillation (pg. 2478): In another study—a multinational trial funded by Medtronic—the longer the investigators looked for AF after an unexplained ischaemic stroke, the more they detected. Their cohort was considerably younger, with a mean age of 61.5. Here the comparison was between 24 hour ECGs done at one, six, and 12 months and continuous monitoring for a whole year using an implantable event detector. There was a cumulative difference through the year, at the end of which the detection rate was 2% versus 12.4%. These data lead the editorialist to conclude: “The results of two studies published in this issue of the NEJM indicate that prolonged monitoring of heart rhythm should now become part of the standard care of patients with cryptogenic stroke.”

JAMA 25 Jun 2014 Vol 311

Decline in Estimated Glomerular Filtration Rate and Subsequent Risk of End-Stage Renal Disease and Mortality (pg. 2518): “Chronic kidney disease (CKD) is a worldwide public health problem, with increasing prevalence, poor outcomes, and high treatment costs.” I don’t know if I believe a word of this. To me, the kidneys are complex appendages of the cardiovascular system, and most “CKD” is just an expression of cardiovascular disease. Its increasing prevalence is because people are living longer, and ditto its high costs. As the circulation fails, or diabetes gets into its final phase, people show a steep decline in glomerular filtration rate (GFR); this is not good news for these individuals, but it is hardly a public health problem. The more they are tinkered with, the higher their treatment costs become. Nobody likes to tell them how futile most of this treatment is, and how little renal physicians know about what works. I am sometimes called cynical for saying things like this, but am I missing something? This entirely nephrocentric paper paints a picture of gloom, based on the prognostic characteristics of a swiftly falling estimated GFR. We are indeed all doomed; but in my experience of generalist practice, to die of primary renal failure is actually quite rare.

JAMA Intern Med Jun 2014

Long-term Survival in Patients Undergoing Percutaneous Interventions With or Without Intracoronary Pressure Wire Guidance or Intracoronary Ultrasonographic Imaging (OL): A London registry lists 41 688 patients who had percutaneous coronary intervention (PCI) in NHS hospitals between 2004 and 2011. During this time, clever cardiologists in our centres of teaching and excellence increasingly adopted sophisticated techniques such as intracoronary ultrasound and intracoronary pressure wire measurement of fractional flow reserve. This long term survival study shows that they made no difference to outcomes compared with old fashioned angiography guided PCI. This paper does not bear the “Less is More” label, but it could.

Lancet 28 Jun 2014 Vol 383

Efficacy and Safety of Colchicine for Treatment of Multiple Recurrences of Pericarditis (pg. 2232): Forgive me if you have heard this before: colchicine is a good treatment for acute pericarditis and for preventing recurrences. Colchicums abound on the hills of Northern Italy, where this study was conducted. Don’t eat any part of them or you might die an unpleasant death. However, if you are an adult weighing more than 70kg and happen to have pericarditis, you may take 0.5mg twice daily for six months and this will halve your chance of having recurrences.

The BMJ 28 Jun 2014 Vol 348

Higher Potency Statins and the Risk of New Diabetes: The news that statins can “cause diabetes” broke about two years ago. This new Canadian study looks at several large primary care databases and discovers that: “In the first two years of regular statin use, we observed a significant increase in the risk of new onset diabetes with higher potency statins compared with lower potency agents (rate ratio 1.15, 95% confidence interval 1.05 to 1.26). The risk increase seemed to be highest in the first four months of use (rate ratio 1.26, 1.07 to 1.47).” So statins cause small elevations in blood glucose that correlate with their potency, i.e. their degree of LDL-C lowering. The usual reason to take a statin is not to lower LDL-C but to lower cardiovascular risk, and we do not really know whether risk lowering is directly linked with “potency”. We have only one individual patient data meta-analysis to go by, and its data are not available to researchers outside the Oxford Clinical Trials Support Unit. As for the “diabetes” bit, it should not matter to any individual whether they are classed as lying slightly below or slightly above the arbitrary definition line. What matters is the long term risk of harm associated with that particular level of blood sugar and their likelihood of benefit from treatment. And playing those odds, they would be better off staying on their statin, whichever it may be. But the choice is always a personal one.

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