Monday, June 11, 2007

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.



Anonymous said...

Dr Fisher:

This meeting took place almost a year ago (July 2006), did I read that right?

Is it typical for the results of such a meeting to be published so long after it occurs? Have there been other developments since then?
LIke with MTWA screening?

I know you've been ambushed by MTWA advocates after other related posts, and are probably skeptical about this comment because of that, but I do find your ongoing thoughts about MTWA testing to be helpful

Thanks for a great blog.

DrWes said...

Anony 07:00-

The delays in publishing are likely multifactorial - perhaps the paper was submitted elsewhere and not accepted, perhaps the peer-review process took longer than usual - I do not know. What is clear is that there was a cogent discussion of the pros and cons of MTWA testing (and other tests like EP study) by others beside myself who noted both the strengths and weaknesses of the approach. I need not reinterate their discussion since it is now publically available. Part II of meeting's discussion (published in the same issue) discusses what would be needed to obtain a suitable screening test. I would encourage all to read both articles. What does seem clear is that based on these articles, it is hard for me to see how Medicare will require MTWA testing to determine who should and should not receive a defibrillator until better outcome data are forthcoming.