March 11th, 2013
Selections from Richard Lehman’s Literature Review: March 11th
CardioExchange is pleased to reprint selections 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 6 Mar 2013 Vol 309
Antiplatelet Therapy to Prevent CV Events and Mortality in Patients With Intermittent Claudication (pg. 926): We’ve become accustomed to giving low dose aspirin to people at higher cardiovascular risk, and clearly people with intermittent claudication count as that. Most of them have smoked and all of them have narrowed leg arteries. This clinical review confirms that all anti-platelet therapies do indeed reduce adverse cardiovascular events in people with leg claudication. Clopidogrel may be more effective than aspirin. So should all patients with peripheral vascular disease be given a platelet inhibitor? Until the last few weeks, I’d have said of course. But people who have smoked are at highest risk of macular degeneration, and we now know that aspirin doubles that risk. We don’t know if clopidogrel does the same. So we really don’t know how to advise our patients about the balance between the risk of a heart attack and the risk of blindness.
It may take months or years before anyone gives us the answer, but it is literally at our fingertips. Anyone who has access to a good enough database such as the UK CPRD can feed in search terms such as aspirin, clopidogrel, claudication, PVD, myocardial infarction, and macular degeneration and get the figures. Put them through suitable statistical software and the observational data could be on line within hours. Anyone with the right skills, sitting in an office in Cardiff or Azerbaijan, could provide this information in real time to clinicians across the world. It is high time somebody set up this service.
NEJM 7 Mar 2013 Vol 368
Endovascular Therapy After Intravenous t-PA vs. t-PA Alone for Stroke (pg. 893): Cut off from oxygenated blood, brain cells die very quickly. The wonder is not that thrombolysis makes so little difference in ischaemic stroke but that it makes any difference at all. The alternative to dissolving the clot is removing it using some type of endovascular procedure, but this takes even longer to organise because it requires a specialised unit with rapid access angiographic facilities. “Current endovascular approaches include endovascular pharmacologic thrombolysis, manipulation of the clot with the use of a guidewire or microcatheter, mechanical and aspiration thrombectomy, and most recently, stent-retriever technology.” Don’t ask me what the last item means.
This paper reports the results of a large stroke trial in which initial treatment with intravenous t-PA was followed by endovascular treatment of any kind preferred by the operator, in the hope of getting early lysis followed a little while after by vessel clearance. It was stopped early because of futility after 656 participants had undergone randomisation. Removing the clot after the damage has been done is not a recipe for success.
Endovascular Treatment for Acute Ischemic Stroke (pg. 904): So how do the two strategies compare if deployed as early as possible in a head-on randomised trial? The answer is that they are equally bad. This Italian trial was much smaller than the previous one and again there was operator discretion when it came to the actual technique used for endovascular clot disruption/removal.
There are various signs of over-pragmatism in this trial—patients were treated within a maximum of 2.5 hours but randomised within 4.5 hours, and on the vexed question of consent during an evolving stroke, we are told that “competent patients gave written informed consent before enrollment; otherwise, a witnessed waiver of consent was possible.” Just so you know: if I have a big stroke, the intravenous treatment I would prefer is a soluble anaesthetic followed by a large slug of potassium chloride.
Imaging Selection and Endovascular Treatment for Ischemic Stroke (pg. 914): But it might still be argued that there is a place for endovascular stroke treatment if only we know how to select the right patients. Pleading from subgroups and “judicious selection” is always the last refuge of a failing intervention, and so it proves here. The patients who should benefit from mechanical clot removal are those with a “favourable penumbral pattern” on imaging—meaning a small core infarct surrounded by a lot of salvageable brain tissue.
So this trial was set up to compare endovascular treatment with usual care within a generous time frame (8 hours) and to stratify patients according to a favourable or unfavourable penumbral pattern. It ended up demonstrating that “neuroimaging did not identify patients who would differentially benefit from endovascular therapy for acute ischemic stroke, nor was embolectomy shown to be superior to standard care.”
Judging from these three trials, embolectomy seems yet another blind alley in the treatment of acute ischaemic stroke. Use t-PA in suitable patients caught within an hour or so: otherwise let nature take its often brutal course, because there is nothing you can do about it.
Lancet 9 Mar 2013 Vol 381
Safety and Performance of the Drug-Eluting Absorbable Metal Scaffold (DREAMS) in Patients with De-Novo Coronary Lesions (pg. 836): From the sublime to the ridiculous. Here’s the interpretation of this study: “Our results show feasibility, a good safety profile, and promising clinical and angiographic performance results up to 12 months for DREAMS. Our promising clinical results show that absorbable metal scaffolds might be an alternative to polymeric absorbable scaffolds.” What? Since when did “promising” and “might” amount to a clinically significant result? Has this even been edited for its English (“promising” in two successive sentences)? And who does the “our” refer to? Step up Biotronik, who made and named the DREAMS stent, paid for the study, and “had roles in study design; monitoring; and data collection, analysis, and interpretation.” Would they by any chance be interested in buying up a few reprints from Elsevier?
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