July 1st, 2013
Selections from Richard Lehman’s Literature Review: July 1st
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 26 June 2013 Vol 309
Personalized Medicine vs. Guideline-Based Medicine (pg. 2559): Another Viewpoint piece has the tempting title “Personalised Medicine vs Guideline-Based Medicine” and discusses the uses and abuses of subgroup analysis. I think we may need more of this, once statistical science has developed sufficiently to meet the challenge of massive individual patient data sharing. This piece dwells on the counter-intuitive findings of trials of implantable cardioverter-defibrillators: they have no mortality benefit in the months of highest risk after myocardial infarction, but only show benefit much later on—perhaps as much as two years later.
JAMA Intern Med 24 June 2013 Vol 173
Aggressive Fluid and Sodium Restriction in Acute Decompensated HF (pg. 1058): Emergency rooms are dangerous places for people with heart failure. In some cases (I know from an unpublished study) the doctor is likely to put up a litre of saline and give you inhaled beta stimulants and corticosteroids before doing anything else: in many other places, your fluid intake will be restricted while you are rendered thirsty, hypovolaemic, and hypotensive with loop diuretics, and then given inotropes to bring you round and/or kill you. To try to bring some science (and humanity) into this situation, patients admitted with acute decompensated systolic HF in this trial were randomized to fluid and sodium restriction or none. “Aggressive fluid and sodium restriction has no effect on weight loss or clinical stability at three days and is associated with a significant increase in perceived thirst. We conclude that sodium and water restriction in patients admitted for ADHF are unnecessary.”
Yield of Routine Provocative Cardiac Testing Among Patients in an Emergency Department–Based Chest Pain Unit (pg. 1128): Coming to hospital with non-cardiac chest pain is also extremely perilous, especially in the USA. Guidelines there mandate that you are offered an appointment with a cardiologist within three days, irrespective of the likelihood of your chest pain being cardiac. The cardiologist will then order a treadmill test, just to be on the safe side (and to earn money); and as you will know from reading Sackett et al, the false positive yield of stress tests depends on the pre-test probability, which in some of these patients will be close to zero. False positive treadmill means angiography (another nice little earner) and maybe the detection of some atheroma, sitting quietly and doing nothing. In goes the stent: the patient is grateful: she thinks her life may have been saved, and she has a label of ischaemic heart disease so every future chest twinge gets similar attention. Or, as this study observes, “In an emergency department–based chest pain unit, routine provocative cardiac testing generated a small therapeutic yield, new diagnoses of coronary artery disease were uncommon, and false-positive results were common.” But as my example demonstrates, this is only the half of it: detecting atheroma in the coronary arteries is not the same as establishing it as the cause of the chest pain. Why don’t people get this? Here is the distinguished Pat Crosskerry writing in the first article of this week’s New England Journal: “When a patient undergoes analytic assessment for chest pain in a cardiac clinic that culminates in angiography, the conclusion is invariably correct.” Oh boy.