猝死的危险分层
The EP show: Risk stratification for sudden death
Eric Prystowsky MD Director, Clinical Electrophysiology Laboratory St Vincent Hospital Indianapolis, IN
Arthur Moss MD Professor of Medicine and Cardiology University of Rochester Rochester, NY
Michael Gold MD Chief, Division of Cardiology
Medical University South Carolina
Charleston, SC
Risk stratification for sudden death
Historical look at early markers
Began during the mid-1980s with a prospective study of about 1000 postinfarction patients
Measured 24-hour Holter recordings for ventricular premature beat frequency
Determined ejection fraction
Ascertained several other routine clinical parameters
Moss
Historical look at early markers
Found inverse relationship between the ejection fraction and total mortality as well as sudden death
Cut point between 30% and 40%
Recent studies, including MADIT I and II, grew out of this early
work
Moss
Serial electrophysiology testing
Mechanistically driven
Sudden death in postinfarction patients predominately due to ventricular tachycardia
If you could induce ventricular tachycardia and introduce a
drug that suppresses this
ability, you could monitor
efficacy
Gold
Reviewing CAST
Cardiac Arrhythmia Suppression Trial (CAST)
Large randomized trial that looked at whether suppressing ventricular ectopy after MI reduces sudden death
Trial stopped because antiarrhythmic agents associated with increased mortality
Reviewing CAST
"This set the stage for moving from antiarrhythmic agents to device therapy."
Moss
Reviewing CAST
Could these results be related to the drugs selected?
Subsequent trials confirmed that this was not the case
Prystowsky
MADIT I
Would an ICD or conventional therapy improve survival in this high-risk population?
Randomly assigned 196 patients with prior MI and:
NYHA functional class 1, 2, or 3
A left ventricular ejection fraction <35%
An episode of asymptomatic unsustained ventricular tachycardia
Inducible, nonsuppressible ventricular tachyarrhythmia on electrophysiologic study
MADIT I findings
MADIT I
In high-risk patients with prior MI, prophylactic therapy with an ICD leads to improved survival compared with conventional medical therapy
MUSTT
Multicenter Unsustained Tachycardia Trial (MUSTT), a randomized controlled trial
Can electrophysiologically guided antiarrhythmic therapy reduce the risk of sudden death?
Looked at coronary artery disease patients with a left ventricular ejection fraction <40% and asymptomatic unsustained ventricular tachycardia
MUSTT
MUSTT
Therapy with implantable defibrillators, but not with antiarrhythmic drugs, reduces the risk of sudden death in high-risk patients with coronary disease
Unsustained VT
"I think it's a relatively weak risk stratifier. And as you point out, it was both frustrating and cumbersome."
Gold
MADIT II
Randomized trial evaluating the effect of an implantable defibrillator on survival
1232 patients with prior MI and a left ventricular ejection fraction of <30%
Patients randomly assigned in a 3:2 ratio to receive ICD or conventional medical therapy
MADIT mortality rates
MADIT II
"This really introduced a simplified stratification approach."
Moss
MADIT II and CMS
"They took a conservative position and said that they were going to reimburse only for MADIT II patients who had a QRS duration >120 milliseconds and that they would revisit this when SCD-HeFT data were presented."
Moss
SCD-HeFT
Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT)
Largest of the trials involving ICD therapy with a longer patient follow-up than previous studies
SCD-HeFT
Compared all-cause mortality in >2500 patients
With NYHA class 2 to 3 HF
LVEF <35%
Patients randomized to receive ICD, amiodarone, or placebo on top of standard medical therapy
SCD-HeFT all-cause mortality
SCD-HeFT
ICD cuts all-cause mortality by 23% in NYHA class 2 to 3 heart failure
What's a payer to do?
"The trials were designed specifically to answer the major question of defibrillators and their role to reduce total mortality. I think the trials, as you point out, are concordant in that regard, and I think that it would be reasonable that that would be an indication
for paying."
Gold
What's a payer to do?
"Getting into subsets when it's not really prespecified that's what you're looking for is potentially very treacherous and can be misleading."
Moss
The future
Many have become cynical as noninvasive test after noninvasive test failed to live up to its expectations
But I remain optimistic
Gold
Question
Are there patients in MADIT II who are:
"Too healthy" to benefit from an ICD?
"Too sick" for one?
Prystowsky
Latest look at MADIT II
The benefit from ICD was entirely in the patients who carried one or more risk factors
The 20% of the population that carried no risk factors achieved no benefit whatsoever
Moss
Summary
Several decades of research have put risk stratifiers to the test
Ejection fraction remains supreme as a noninvasive test
We've identified the benefactors of ICD therapy
And realized that antiarrhythmic drugs to prevent sudden death are not as important as once thought
In conclusion
Despite?so many noninvasive tests failing to live up to?expectations,?many still show promise
Hot off the press! New soon-to-be-published data will show that combinations of risk stratifiers may help pinpoint patients who will
derive the most and least
benefit from an ICD
Prystowsky