Objective: To determine whether survival after cardiac resynchronization therapy (CRT) is related to improvement in clinical or echocardiographic parameters.
Background: In clinical trials, CRT improved symptoms, left ventricular (LV) structure, function, and survival. In clinical practice, response to CRT is highly variable and whether survival benefit is confined to those patients who experience improvement in clinical status or cardiac structure and function is unclear.
Methods: This is a single-center study of patients receiving clinically indicated CRT between January 2002 and December 2004.
Results: Of 309 patients (age 68 ± 11 years, 83% male) receiving CRT at our institution during the study period, 174 returned for follow-up and 127 had repeat echocardiography. Baseline clinical characteristics and survival were similar among those who did or did not return for follow-up. In paired analyses, New York Heart Association (NYHA) class (−0.56 ± 0.07, p < 0.0001), ejection fraction (EF, 6.3 ± 0.7%, P < 0.0001), LV dimension (−2.7 ± 0.6 mm, P < 0.0001), pulmonary artery systolic pressure (PASP, −4.6 ± 1.3 mm Hg, P = 0.0007), and MR severity grade (−0.20 ± 0.05, P = 0.0002) improved after CRT. Survival after CRT was associated with decrease in NYHA class (risk ratio [RR]= 0.43, P = 0.0004), increase in EF (RR = 0.94, P = 0.02), and decrease in PASP (RR = 0.96, P = 0.03). Change in EF and NYHA class were correlated (r =−0.46, P < 0.0001) and, adjusting for this covariance, change in NYHA (P = 0.04) but not EF (P = 0.12) was associated with improved survival.
Conclusion: Patients who experience improved symptoms, ventricular function, and/or hemodynamics have better survival after CRT. These data enhance understanding of the relationship between CRT clinical response and survival benefit in clinical practice.