The impact of left ventricular size on response to cardiac resynchronization therapy

• Published in: The American heart journal Vol. 162; no. 4; pp. 646 - 653
• Main Authors: Rickard, John, Brennan, Danielle M., Martin, David O., Hsich, Eileen, Tang, W.H. Wilson, Lindsay, Bruce D., Starling, Randall C., Wilkoff, Bruce L., Grimm, Richard A.
• Format: Journal Article
• Language: English
• Published: New York, NY Mosby, Inc 01.10.2011; Mosby; Elsevier Limited
• Subjects: Aged; Biological and medical sciences; Cardiac Resynchronization Therapy; Cardiology. Vascular system; Cardiomyopathy; Cardiomyopathy, Dilated - mortality; Cardiomyopathy, Dilated - pathology; Cardiomyopathy, Dilated - physiopathology; Cardiomyopathy, Dilated - therapy; Cardiovascular; Chronic obstructive pulmonary disease; Clinical trials; Drug therapy; Female; Gender; Heart attacks; Heart failure; Heart Ventricles - pathology; Humans; Male; Medical sciences; Middle Aged; Mortality; Organ Size; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Regression analysis; Retrospective Studies; Society; Stroke Volume; Survival Rate; Variables; Response; Cardiac resynchronization; Instrumental stimulation; Size; Instrumentation therapy; Cardiovascular disease; Circulatory system; Cardiology; Left ventricle
• ISSN: 0002-8703; 1097-6744; 1097-6744
• DOI: 10.1016/j.ahj.2011.07.008

Patients with nondilated (NDCM) or severely dilated cardiomyopathies (SDCM) have been underrepresented in clinical trials of cardiac resynchronization therapy (CRT). We examined changes in left ventricular ejection fraction (LVEF) and survival in patients with NDCM or SDCM compared with those with traditionally studied moderately dilated cardiomyopathy. We evaluated 800 consecutive patients undergoing the original implantation of a biventricular pacemaker between January 2004 and August 2007. For inclusion, patients had a baseline and pre-CRT echocardiogram, an LVEF ≤40%, a US social security number, and New York Heart Association class II to IV symptoms on standard medical therapy. Patients with a follow-up echocardiogram >2 months after device implantation were included in an analysis of remodeling. Using multivariate models, the impact of baseline left ventricular end-diastolic diameter (LVEDD) on change in LVEF and all-cause mortality was assessed. A total of 668 patients met inclusion criteria and were included in the assessment of mortality. Four hundred seventy-one had an appropriately timed follow-up echocardiogram and were included in the analysis of remodeling. Patients in all 3 groups realized improvements in LVEF (%) after CRT as follows: NDCM (n = 137; LVEDD ≤5.5 cm) 10.0 ± 12.7, P < .001; moderately dilated cardiomyopathy (n = 233; LVEDD 5.6-6.9 cm) 8.2 ± 11.3, P < .001; and SDCM (n = 101; LVEDD ≥7.0 cm) 5.4 ± 9.4, P < .001. In multivariate analysis, baseline LVEDD was inversely associated with change in LVEF (parameter estimate −3.13 ± 0.56, P < .001) and directly associated with increased all-cause mortality (hazard ratio 1.25 [1.05-1.47] P = .01). Patients with NDCM and SDCM experience significant improvements in LVEF after CRT. The degree of baseline left ventricular dilatation before CRT is an important predictor of subsequent changes in LVEF and survival.