March 10th, 2014

Selections from Richard Lehman’s Literature Review: March 10th

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

JAMA Intern Med  Mar 2014

Cognitive Function and Brain Structure in Persons With Type 2 Diabetes Mellitus After Intensive Lowering of BP and Lipid Levels (pg. 324): There was a deathly silence when the NEJM first published the results of the ACCORD trial in June 2008. Nearly six years on, the diabetes community is still coming to terms with the demolition of its conceptual edifice based on ever tighter control of glucose and blood pressure. In the 40 months of the trial, we learn from this paper, people with longstanding diabetes in the tight BP control group showed more brain shrinkage on MRI than those on a laxer regimen. Cognitive function was the same in both groups. But these are just the sort of short-term data it’s best to ignore: we need much more than this to draw conclusions about specific treatments for type 2 diabetes. For more on that topic, read the excellent viewpoint by Kasia Lipska and Harlan Krumholz—Comparing Diabetes Medications: Where Do We Set the Bar?

Association of β-Blocker Therapy With Risks of Adverse Cardiovascular Events and Deaths in Patients With Ischemic Heart Disease Undergoing Noncardiac Surgery (pg. 336): One area of controversy I haven’t much commented on is the prescription of beta-blocking drugs prior to non-cardiac surgery. Mere GPs play little part in this saga, but out there in the exciting world of European cardiologists and surgeons, it’s been hotly debated, with accusations of needless deaths, bad trials, and non-evidence-based guidelines. To this fray, the Danes have now added some very useful observational evidence from their wonderful national registry. It seems that pre-op β-blockers only improve outcomes for two kinds of patients: those with heart failure and those who have had a recent myocardial infarction; i.e. those who should be on them anyway.

Warfarin Interactions With Antibiotics in the Ambulatory Care Setting (pg. 409): One of the commonest situations of risk for a drug interaction is the prescribing of antibiotics to patients on warfarin. I do it all the time, usually advising patients to reduce their warfarin dose slightly for the duration. A study from Kaiser Permanente shows that even this token effort is probably little needed. The investigators looked at over 11,000 patients with acute respiratory infections who were taking warfarin and who were or were not given antibiotics. “The proportion of patients experiencing an INR of 5.0 or more was 3.2%, 2.6%, and 1.2% for the antibiotic, sick, and stable groups, respectively…. Acute upper respiratory tract infection increases the risk of excessive anticoagulation independent of antibiotic use. Antibiotics also increase the risk; however, most patients with previously stable warfarin therapy will not experience clinically relevant increases in INR following antibiotic exposure or acute upper respiratory tract infection.”

JAMA  5 Mar 2014  Vol 311

Warfarin, Kidney Dysfunction, and Outcomes Following Acute Myocardial Infarction in Patients With Atrial Fibrillation (pg. 919): A Swedish registry study looks at what happened to people (median age 79) admitted to hospital with myocardial infarction who were discharged with atrial fibrillation. Only 22% of them went home on warfarin. The investigators were particularly interested to see if their kidney function seemed to make any difference to outcomes. It did not: “Warfarin treatment was associated with a lower 1-year risk for the composite outcome of death, MI, and ischemic stroke without a higher risk of bleeding in consecutive acute MI patients with atrial fibrillation. This association was not related to the severity of concurrent CKD.”

BMJ  8 Mar 2014  Vol 348

Removing the Hype from Hypertension: A splendid editorial has just appeared on the BMJ website dealing with the astonishing disparity between the early open trials of the Medtronic Symplicity renal denervation device, and the subsequent properly conducted randomized Symplicity 3 trial. You’ll remember that I was hoodwinked by the hype which surrounded the publication of the long-term follow up of the original Symplicity 1/2 trial in the Lancet three weeks ago, showing a 30mm Hg drop in systolic BP maintained into the third year. The Symplicity 3 trial of the same device subsequently failed to meet its prestated end-point of a 10mm Hg drop. This should already have been known to the Lancet, as it had been announced by Medtronic on the 9th January. It’s a startling illustration of the need for randomized, properly blinded trials of medical devices. And it’s scary to think how few of those there have been—of devices currently used by millions of people.



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