Assessment of response criteria to cardiac resynchronization therapy (CRT) and prediction of response.

Aims: Approximately 30% of patients treated with cardiac resynchronization therapy (CRT) do not respond. We evaluated response to CRT at six and 12 months, tested a novel response criterion and evaluated different clinical and echocardiographic predictors of response.

Methods And Results: Eighty one patients were enrolled. A definition of response to CRT was predefined as a combination of 1) a reduction of LV end-systolic volume of ≥10% and 2) either an improvement in NYHA class by ≥1 or an increase in peak oxygen consumption of ≥1 ml/kg/min. Pre-and postoperatively at six and 12 months we also evaluated the most commonly employed definitions of response in our material: NYHA class, quality of life, left ventricular (LV) performance and functional capacity. After six and 12 months of CRT, 42 (52%) and 48 patients (59%) were responders, respectively. Employing different criteria, response ranged from 33-96% and 31-94% at six and 12 months, respectively. In our material a large pre-operative interventricular motion delay (IVMD) was a predictor of response to CRT (p<0.05).

Conclusions: Fifty two percent and 59% were responders to CRT at six months and one year given a predefined novel endpoint. Different response criteria to CRT gave response rates ranging from 33-96% and 31-94% at six and 12 months, respectively. A large IVMD predicts response to CRT at six and 12 months.