February 24th, 2014
Selections from Richard Lehman’s Literature Review: February 24th
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.
JAMA 19 Feb 2014 Vol 311
Radiofrequency Ablation vs Antiarrhythmic Drugs as First-Line Treatment of Paroxysmal Atrial Fibrillation (pg. 692): As a would be designer of decision aids, I am always on the look out for situations of clinical equipoise. Take atrial fibrillation. The classic choices are between rate control or rhythm control, between various beta-blockers, or amiodarone or digoxin, or elective cardioversion; and between aspirin and warfarin or one of the fixed dose new anticoagulants. All very entertaining and ever changing. Now a trial comes along comparing drug therapy with radiofrequency ablation as first-line treatment for paroxysmal AF. The two work equally badly: recurrences are common. So is this a case of clinical equipoise? I don’t think so, because in this trial the rate of serious complications in the radiofrequency ablation group was 9%: an alarming 6% of the group had cardiac tamponade. Give me those pills please doc.
Lancet 22 Feb 2014 Vol 383
18F-fluoride positron emission tomography for identification of ruptured and high-risk coronary atherosclerotic plaques (pg. 705): The Holy Grail of cardiac imaging would be a technique for spotting the atheromatous plaques most likely to rupture as opposed to those merely causing the most stenosis. It’s just possible that it has now been found, but it’s far from clear to a mere onlooker what the clinical consequences might be. A team from Edinburgh used the radioactive tracer 18F-sodium fluoride to identify the kind of plaque that is most likely to cause trouble. In a complex exploratory study, they took newly harvested plaque from people who had just had carotid endarterectomy and showed that marked 18F-NaF uptake occurred at the site of all carotid plaque ruptures and was associated with histological evidence of active calcification, macrophage infiltration, apoptosis, and necrosis. Concurrently they used the tracer in 40 patients with recent myocardial infarction and in 40 with stable angina, and located its presence using PET-CT imaging of the coronary arteries. They also used intra-coronary ultrasound on these patients to pick up calcification and necrosis. In this way they were able to establish that the areas of highest 18F-NaF uptake are in plaques which show the most dangerous characteristics. This is clever stuff, and is bound to lead to a wave of new studies using this relatively cheap isotope and PET-CT hardware wherever it may be available. Perhaps the insights this generates will one day permeate into the world of real-life patient management: in the mean time it is nice to see some good old British investigational science of world class.
Symplicity HTN-1 and Symplicity HTN-3:
How I was misled by The Lancet last week:
In last week’s Lancet, three articles celebrated the success of renal denervation for “treatment-resistant” hypertension. There was a report of the Symplicity HTN-1 trial emphasizing huge sustained reductions in BP, though there was no control arm and very incomplete follow-up, as I noted. There was a laudatory editorial and a profile of the chief investigator, Henry Krum, pointing out that Australia was a good place to do clinical trials because of its permissive regulatory environment.
But it had escaped my attention that the Symplicity-1 trial had already been superseded by Symplicity-HTN-3. This well-powered randomized trial using a sham control failed to meet its primary end point, a 10mmHg reduction in systolic BP. This had been announced by Medtronic on 9 Jan. And in fact Darrel Francis and colleagues in the renal denervation field had already pointed out the inherent flaws in the design and execution of Symplicity HTN-1 in a paper just published in the International Journal of Cardiology, another Elsevier journal.
This had managed to get under my radar, which isn’t too surprising; but it is quite worrying that it managed to get under The Lancet‘s.