Predictors of response to cardiac resynchronization therapy in chronic heart failure patients

Cardiac resynchronization therapy (CRT) is established in the management patients with moderate to severe symptoms due to left ventricular systolic dysfunction who present with signs of electrical dyssynchrony. There is wide variability in the clinical response and improvement in LVEF with CRT. Prediction of response to CRT is an important goal in order to tailor this therapy to patients most apt to derive benefit. Aim: The aim of the study was to assess and identify the best predictors of CRT response. Patients and methods: The study included 170 consecutive heart failure (HF) patients in New York Heart Association (NYHA) functional class III or IV and LVEF ⩽ 35%. Routine device and clinical follow-up, as well as CRT optimization, were performed at baseline and at 3-month intervals. Responders were defined as having an absolute reduction in left ventricular end-systolic diameter >15% and an improvement in LVEF >10%. Results: 170 patients were included [71.1% men; mean age 68.8 ± 9.7 years; 159 patients NYHA class III, 11 patients ambulatory NYHA class IV; 91 patients had non-ischemic cardiomyopathy (ICM) - 79 patients had ICM; 55.3% of patients had LBBB; mean QRS duration 145 ± 25 ms; left ventricular ejection fraction 28.38 ± 7.2]. CRT-P was implanted in 65 patients and CRT-D was implanted in 105 patients. CRT response was achieved in 114 patients (67.1%). Mean LVEF improved from 28.38 ± 7.2% to 35.46 ± 9.3% (p = 0.001), mean LV end-diastolic diameter reduced from 67.91 ± 8.7 to 64.95 ± 8.9 mm (p < 0.001), and mean LV end-systolic diameter reduced from 57.02 ± 8.8 to 52.42 ± 9.9 mm (p < 0.001). Responders had significantly wider baseline QRS duration, lower BMI, lower baseline serum creatinine level, smaller baseline RV diastolic dimension and significantly greater tricuspid annular peak systolic excursion (TAPSE) value. In multi-nominal regression analysis to identify the pre-implantation predictors of response, QRS duration >150 ms, non-ICM, TAPSE >15 mm, sinus rhythm, the absence of COPD and the absence of renal disease were the independent predictors of CRT response. We generated a new CRT score to predict responders to CRT. The score consists of maximum 9 points. The CRT response rate has been markedly different according to the CRT score: CRT response rate was 97.5% patients with CRT score >6 vs 40.7% if CRT score <6, p < 0.001. Conclusion: Only some of the commonly used response criteria predict outcome in patients undergoing CRT. The newly generated CRT score may be used to improve the appropriate use of CRT, to increase the CRT response rate. This score needs to be validated on another population of patients.