Two New JACC Studies Address Findings From the MADIT-CRT Study

Two recent studies in the Journal of the American College of Cardiology (JACC) look at findings from the MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy) Study. New data from MADIT-CRT study identifies who are the "super-responders," and a second paper finds a possible new effect of statins.

The first study looked at predictors of left ventricular ejection fraction (LVEF) super-response to cardiac resynchronization therapy with defibrillator (CRT-D) and whether super-response translated into improved, event-free survival in patients with mildly symptomatic heart failure (HF). Currently, few data exist on predictors of super-response to CRT-D and associated morbidity and mortality in mildly symptomatic HF populations.

Based on the findings from the study, researchers concluded that six baseline factors predict LVEF super-response in CRT-D–treated patients with mild HF. These factors are: female sex, no prior myocardial infarction, QRS duration of _150 ms, LBBB, BMI of _30 kg/m2, and smaller baseline LAVI. In addition, LVEF super-response at 12-month follow-up echocardiogram was associated with improved HF event-free survival after two years in CRT-D patients with mild HF symptoms, meaning that "LVEF superresponders may enjoy freedom from subsequent HF or all-cause death, even for those with mild HF symptoms at the time of CRT-D implantation."

The second study looked at whether time-dependent statin therapy reduced the risk of life-threatening ventricular tachyarrhythmias among patients with nonischemic cardiomyopathy (NICM). While some earlier studies have suggested that statin therapy exerts antiarrhythmic properties among patients with coronary artery disease, data regarding the effect of statins on arrhythmic risk among patients with NICM are limited.

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Researchers found that data from MADIT-CRT indicate treatment with statins was associated with a significantly lower reduction in the risk of ventricular arrhythmias for patients with NICM. In addition, they note the data suggest that statin treatment is associated with a slower cycle length at the time of the arrhythmia and with a lower incidence of VT/VF, regardless of the implanted device-type. More long-term studies are needed, however.

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