Cardiac Resynchronization Therapy Is Associated with Reductions in Left Atrial Volume and Inappropriate ICD Therapy in MADIT-CRT

Heart rhythm: the official journal of the Heart Rhythm Society (Impact Factor: 4.92). 06/2014; 11(6). DOI: 10.1016/j.hrthm.2014.01.033

ABSTRACT Background
There are no prior studies assessing the relationship between left atrial volume and inappropriate ICD therapy following treatment with cardiac resynchronization therapy.

We hypothesized that patients randomized to CRT-D in the MADIT-CRT trial who had significant left atrial volume (LAV) reductions would have reduced risks of inappropriate ICD therapy.

Cardiac resynchronization remodeling was assessed by measuring LAV change between baseline and 12-month echocardiograms in 751 CRT-D treated patients. Patients were stratified into quartiles based on percent reduction of LAV change: High LAV responders were those in the highest three quartiles of LAV reduction (LAV reduction >21%) and low LAV responders were those in the lowest quartile of LAV reduction (LAV reduction <21%). Clinical factors associated with >21% reduction in LAV were evaluated by linear regression analysis.

In Cox proportional-hazards regression analyses, high LAV responders had a 39% reduction in the risk of inappropriate therapy (hazard ratio 0.61, p=0.04) and LBBB patients exhibited an even greater risk reduction in inappropriate therapy (hazard ratio 0.51, p=0.02) compared to low LAV responders during follow-up extending up to 3 years after the 12-month echocardiogram. High LAV responders also had a significantly lower risk of heart failure or death during follow-up than low LAV responders.

A ≥21% reduction in LAV with cardiac resynchronization therapy is associated with significant reductions in inappropriate ICD therapy and in heart failure or death during a 3-year follow-up.