Predictors of Acute Response to Cardiac Resynchronization Therapy in Cardiomyopathy Patients

Background: Usefulness of echocardiogram-associated markers for prediction of the response of the patients with cardiomyopathy to Cardiac Resynchronization Therapy (CRT) is under debate. Method: In a cross sectional retrospective design, we analyzed data from 69 cardiomyopathy patients (mean age = 57.59 ± 11.17 years, 69.6% male) with New-York-Heart-Association class ≥ III, left ventricular ejection fraction (LVEF) ≤ 35%, and QRS duration > 120 ms who underwent CRT. Transthoracic echocardiography and tissue Doppler imaging were performed before CRT and transthoracic echocardiography was repeated after CRT. More than 5% increase in the LVEF within 48 hours post CRT was considered as acute response. Results: After CRT, 36 (52.2%) patients were acute responders. Before CRT, responders had a remarkably higher frequency of diabetes mellitus (36.1% vs.15.2%, p = 0.048), lower left ventricular end systolic volume (125.82 ± 179.73 vs. 179.73 ± 77.51 ml, p = 0.002) and end diastolic volume (165.03 ± 67.09 vs. 236.06 ± 93.24 ml, p < 0.001) compared to none responders. Other echocardiography characteristics were not significantly different. In multivariable analysis, left ventricular end systolic volume remained the sole independent predictor of acute response. A cut-off of 135 ml for left ventricular end systolic volume had a good sensitivity (67.65%) and specificity (72.73%) to distinguish responders from non-responders. Conclusion: More than half of the cardiomyopathy patients had improvement ≥ 5% in LVEF within 48 hours after CRT. No relationship was found between formerly defined pre-CRT echocardiographic dyssynchrony markers and acute response. Left ventricular end systolic volume was the sole independent predictor of acute response and a threshold of 135 ml could discriminate acute responders to CRT.