Vindicated

Sorry, but after all the trash-talk I received from members of a certain financial board regarding my decision not to purchase Cambridge Heart's T-wave alternans test previously, I'm feeling a bit vindicated right now.

Current Data on Risk Stratification for Sudden Cardiac Death

Some interesting results of an industry-sponsored expert conference on risk stratification of sudden death appeared in this month's American Heart Journal. The experts reviewed left ventricular ejection fraction (LVEF), New York Heart Association Class, the presence of nonsustained ventricular tachycardia, microwave T wave alternans, measures of cardiac autonomic modilation (like heart rate variability), QT interval variability, signal averaged EKG, electrophysiology study, genetic testing, imaging studies and serum markers (like brain naturetic peptide or c-reactive protein).

Their take? Only ejection fraction seems worthy for risk stratification so far.

Here's what they said about ejection fraction:

The LVEF has been recognized as a predictor of all-cause mortality in patients with coronary artery disease (CAD) for >30 years. One early study by the Multicenter Postinfarction Research Group showed in 866 post–myocardial infarction (MI) patients that the strongest predictor of 1-year cardiac mortality was the LVEF. This finding has withstood the test of time. In the VALIANT (trial), a randomized comparison of captopril, valsartan, and their combination in post-MI patients (n = 14 609) with left ventricular dysfunction, CHF, or both, LVEF was a strong predictor of SCD or cardiac arrest. The risk of SCD or cardiac arrest increased by 21% for every 5% decrease in LVEF.

Left ventricular ejection fraction is also a strong predictor of all-cause mortality in patients with nonischemic cardiomyopathy. The MACAS (trial) was a prospective cohort study of 343 patients with nonischemic cardiomyopathy and an LVEF ≤45% who were followed for a mean of 52 months. Left ventricular ejection fraction was the only significant predictor of major arrhythmic events with a relative risk (RR) of 2.3 per 10% decrease in LVEF (95% CI 1.5-3.3, P < .0001) in patients with sinus rhythm and 4.5 per 10% decrease in LVEF (95% CI 1.5-13.2, P = .0008) in patients with atrial fibrillation.

Participants at the meeting were as follows:

Participants from the Academia: Sana M Al-Khatib, MD, MHS (co-Director), J Thomas Bigger, MD, Alfred Buxton, MD, Robert M Califf, MD, Anne Curtis, MD, Jeptha Curtis, MD, Bernard J. Gersh, MB, ChB, DPhil, Michael R. Gold, MD, PhD, Jeff Goldberger, MD, Stephen C. Hammill, MD, Jeff Healey, MD, MS, Mark Hlatky, MD, Stefan Hohnloser, MD, Raymond J Kim, MD, Kerry Lee, PhD, Daniel Mark, MD, MPH, L. Brent Mitchell, MD, Eric Prystowsky, MD, Gillian Sanders, PhD (co-Director), and Wojciech Zareba, MD, PhD

Participants from the Centers for Medicare and Medicaid Services: Steve Phurrough, MD, MPA

Participants from the US Food and Drug Administration: Norman Stockbridge, MD, PhD, Robert Temple, MD, Bram Zuckerman, MD

Participant from the National Institutes of Health: Robin Boineau, MD, Michael Domanski, MD

Participant from Agency for Healthcare Research and Quality: Elise Berliner, PhD

Participant from the Heart Rhythm Society staff: Joel Harder

Participants from Industry: Mark Carlson, MD, Eric Fain, MD, Ali Haghighi-Mood, PhD, Steve Ketchum, PhD, Steve McQuillan MS, Marcus Mianulli MA, Philip Sager, MD, Dan Schaber, PharmD, Robert Shalwitz, MD, Joseph Smith, MD, PhD, Michael A Stein, MD, David Steinhaus, MD

Coordinating Staff: Marelle Molbert and Cass Finley from the Duke Clinical Research Institute.

The conference was funded by AstraZeneca, Bayer, Boston Scientific, Cambridge Heart Inc, Medtronic, Reliant Pharmaceuticals, St Jude Medical.

-Wes

Procedural Darwinism

New procedures in medicine do not always stay – they must survive.

I have been interested to see Procedural Darwinism at work in my daily practice. Charles Darwin introduced his theory of natural selection of species to the scientific community at the turn of the 20th century. But his work, I have found, is not limited to all creatures great and small – it is related to medical procedures as well. You see, some procedures that heath care professionals perform provide good value to the medical community and the doctors themselves, while other procedures are too time-consuming and too economically under-reimbursed to survive in the ever-frenetic pace of medicine today.

Take the stethoscope, for instance. It is rapidly succumbing to Procedural Darwinism. If it weren’t for the stethoscopes ability to hear breath sounds, it would have been extinct long ago. The echocardiogram is far superior to “hear” heart sounds, and adds procedural survival protection by providing additional size, structure, and functional information regarding the heart with little pain or toxicity to the patient. The echo also reimburses well. The echo will clearly and directly survive Procedural Darwinism.

Although it may be on the “Endangered Procedures” list because it reimburses nothing to the physician, the stethoscope still clings to Procedural Life by providing important value to the physician in a different venue: there is no faster way to detect the early onset of congestive heart failure or pneumonia. Stethoscopes survive, then, by providing indirect economic value to the physician (by making him improve outcomes and therefore referrals). Therefore, by indirect economics, the stethoscope is likely to survive Procedural Darwinism.

But some new procedures may not survive Procedural Darwinism. One such procedure is T-wave alternans testing for the evaluation of patient considered to be at risk for sudden death. For those not familiar with this test – it is like a treadmill test, but much more time-consuming to perform. It uses special (and relatively expensive) electrodes configured in a non-familiar way (to people who do these test for a living), and detects information that cannot be seen by the naked eye (therefore it’s hard to believe/understand/verify by those who do treadmills for a living). It also requires remarkable fortitude to assure reliable data are collected (have to hold the heart rate in a narrow range for a pre-specified amount of time). Worse still, the economics of reimbursement are poor: the “special” electrodes cost $74 a set while the entire inpatient reimbursement is under $150 for a test that takes at least 45-60 minutes per patient to perform in the inpatient setting. While the costs in the outpatient setting are a bit more favorable ($300 reimbursement), there are Medicare coding rules that are complicated to perfect, and therefore – at least in Illinois - difficult to assure collection of any reimbursement in the first place. This procedure, as it stands now, is destined for Procedural Extinction unless something changes.

St. Jude’s recent resuscitation of Cambridge Heart (the maker of the only approved T-wave alternans machine to date) flies against the forces of Procedural Darwinism. St Jude feels they have an answer to counteract their declining defibrillator sales: that the indirect value of T-wave alternans testing in terms of increased referrals for defibrillator implants will justify the hours spent performing the test (and revenues/time lost). If internists are to perform the test, unless they receive a kickback for such a referral to cardiac electrophysiologists, there will be little economic reason to perform this test due to its difficult procedural requirements in terms of time and reimbursement.

T-wave alternans testing will only survive if environmental conditions change: that is, a mandate by Medicare to require the testing for people with weak heart muscles and no prior arrhythmia or heart failure. Even then, the application of this test, when other better reimbursing tests exist (like EP testing), keeps this test likely for extinction.

-Wes