NEW YORK (Reuters Health) – Cardiac resynchronization therapy for a year improves cardiac size and performance in patients with mildly symptomatic heart failure, resulting in improved outcomes, according to findings from the Multicenter Automatic Defibrillator Implantation Trial: Cardiac Resynchronization Therapy.

“In MADIT-CRT we saw some of the most profound improvements in left ventricular size and function, coupled with improvements in left atrial size and right ventricular function, that we have seen with any heart failure therapies,” Dr. Scott D. Solomon told Reuters Health. “This benefit translated directly into improvement in outcomes in these patients.”

Dr. Solomon at Brigham and Women’s Hospital, Boston, Massachusetts and colleagues report their findings in the September 7 issue of Circulation published online August 23.

The study involved 1820 patients with NYHA class I or II heart failure, an ejection fraction of 30% or less, and a wide QRS complex. They were assigned to an implantable cardioverter defibrillator (ICD) with or without a cardiac resynchronization therapy (CRT) mode. This led to a 34% improvement in the occurrence of death of heart failure events in the CRT-plus-ICD group.

For the current study, the investigators assessed echocardiographic changes in the two treatment groups, in relation to outcomes.

“Compared with the ICD-only group, the CRT-plus-ICD group had greater improvement in left ventricular end-diastolic volume index (-26.2 versus -7.4 mL/m²), left ventricular end-systolic volume index (-28.7 versus -9.1 mL/m²), left ventricular ejection fraction (11% versus 3%), left atrial volume index (-11.9 versus -4.7 mL/m²), and right ventricular fractional area change (8% versus 5%; p<0.001 for all),” according to the report. Further analysis showed that for each 10% decrement in end-diastolic volume, the risk of subsequent death or heart failure event declined 40% (p<0.001). The results “suggest a compelling cardiac structural and functional mechanism by which CRT improves outcomes,” the authors conclude. Dr. Solomon added, “In properly selected patients — those with class I or II heart failure, low ejection fraction, wide QRS, and left bundle branch block — this therapy can be extremely beneficial.“ Reference:
Effect of Cardiac Resynchronization Therapy on Reverse Remodeling and Relation to Outcome. Multicenter Automatic Defibrillator Implantation Trial: Cardiac Resynchronization Therapyl

Circulation 2010;122:985-992.