PREVENT-SCD trial, presented at the American Heart Association Scientific Sessions in Orlando, Florida, reinforce the value of the Microvolt T-wave Alternans (MTWA) test in identifying patients at risk of sudden cardiac death (SCD).

PREVENT-SCD (PRospective EValuation of VENtricular Tachyarrhythmic Events and Sudden Cardiac Death in Patients with Left Ventricular Dysfunction), a prospective multi-center study of patients with cardiomyopathy and ejection fraction of 40% or lower, enrolled a total of 453 patients from 38 institutions in Japan. Two hundred eighty (280) patients underwent non-invasive MTWA testing using the analytic spectral method and were followed for up to three years.

At a median follow-up time of 36 months, patients with an abnormal MTWA test were 4.4 times more likely to experience a life-threatening arrhythmia or SCD than those with a normal test. The 3-year negative predictive value was reported to be 97.0%, indicating that patients with a normal or negative MTWA test are at low risk for experiencing sudden death.

"MTWA has a very high negative predictive value for lethal arrhythmias in this population,” said Dr. Satoshi Shizuta, Kyoto University Hospital, Kyoto, Japan, lead author of the study. In PREVENT-SCD, 29% of patients eligible for the test had a negative MTWA result. He noted that these patients are at very low risk for SCD in the next three years.

This trial further confirms the predictive value of MTWA in patients with LV dysfunction (EF£40%).  Patients with an abnormal MTWA result were 4.4 times more likely to experience a lethal ventricular tachyarrhythmia, while patients with a normal MTWA test were at very low risk (97% NPV at 3 years).

 

Additional details that were included in the poster but not the abstract:

 

·      The NPV at one-year was 100%; at two years, 98.6%.

·      Unlike MASTER, a small percentage of patients had an ICD (25%) and the majority of endpoint events were SCD or resuscitated VF (not ICD shocks).

·      Of 280 patients tested, 29% were negative for MTWA – very similar to the breakout for other studies like Bloomfield, Chow and ALPHA.  

·      Interestingly, the patients who were ineligible for the MTWA test were also at higher risk.  Most of these were due to atrial fibrillation, but others were due to inability to exercise or being pacemaker dependent.  In the real world, some of these patients could have been tested via pharmacologic testing or AV sequential pacing thereby reducing the number of truly ineligible patients, but those methodologies were not used in this study.

 

These results are an important confirmation of the value of MTWA testing and further demonstrate that, in trials not dominated by ICD shocks as the endpoint, the data supports the predictive value of MTWA for SCD.  The authors are pursuing publication and we should see the full paper out early next year.