Interlead distance and left ventricular lead electrical delay predict reverse remodeling during cardiac resynchronization therapy.

BACKGROUND: Both anatomic interlead separation and left ventricle lead electrical delay (LVLED) have been associated with outcomes following cardiac resynchronization therapy (CRT). However, the relationship between interlead distance and electrical delay in predicting CRT outcomes has not been defined. METHODS: We studied 61 consecutive patients undergoing CRT for standard clinical indications. All patients underwent intraprocedural measurement of LVLED. Interlead distances in the horizontal (HD), vertical (VD), and direct (DD) dimensions were measured from postprocedure chest radiographs (CXR). Remodeling indices [percent change in left ventricle (LV) ejection fraction, end-diastolic, end-systolic dimensions] were assessed by transthoracic echocardiogram. RESULTS: There was a positive correlation between corrected LVLED and HD on lateral CXR (r = 0.361, P = 0.004) and a negative correlation between LVLED and VD on posteroanterior (PA) CXR (r =-0.281, P = 0.028). To account for this inverse relationship, we developed a composite anatomic distance (defined as: lateral HD-PA VD), which correlated most closely with LVLED (r = 0.404, P = 0.001). Follow-up was available for 48 patients. At a mean of 4.1 +/- 3.2 months, patients with optimal values for both corrected LVLED (>or=75%) and composite anatomic distance (>or=15 cm) demonstrated greater reverse LV remodeling than patients with either one or neither of these optimized values. CONCLUSIONS: We identified a significant correlation between LV-right ventricular interlead distance and LVLED; additionally, both parameters act synergistically in predicting LV anatomic reverse remodeling. Efforts to optimize both interlead distance and electrical delay may improve CRT outcomes.

Usefulness of cardiac resynchronization therapy in the management of Doxorubicin-induced cardiomyopathy.

Doxorubicin is a widely used antineoplastic agent that may cause irreversible dilated cardiomyopathy. Doxorubicin-induced cardiomyopathy (DIC) can occur several years after exposure and carries a poor prognosis. Although cardiac resynchronization therapy (CRT) is a useful intervention in end-stage heart failure unresponsive to optimal medical therapies, its efficacy in DIC remains unknown. Four consecutive patients receiving CRT for DIC were evaluated before and after CRT. CRT resulted in improvements in the mean left ventricular ejection fraction at 1 month from 21+/-4.7% to 34+/-5% (p=0.03) and at 6 months (to 46+/-7.5%, p=0.01). CRT-induced reverse remodeling was observed, with a mean reduction in left ventricular internal diameter at end-diastole from 54.75+/-3.7 to 52.5+/-1.9 mm at 1 month (p=0.06) and further to 47+/-2.3 mm at 6 months (p=0.03). All patients experienced reductions in heart failure symptoms and improvements in New York Heart Association functional class (p<0.05). The impact of CRT was sustained over a follow-up of 18.5+/-3.5 months. In conclusion, this study suggests that patients with DIC, refractory to optimal pharmacologic therapy and meeting criteria for resynchronization device implantation, may achieve sustained benefit from CRT.