The incremental value of right ventricular indices for predicting response to cardiac resynchronization therapy

Background: Right ventricular (RV) dysfunction in chronic heart failure (HF) is associated with poor prognosis. Cardiac resynchronization therapy (CRT) is an established method of improving prognosis in HF. However, the majority of known indices predictive of response to CRT are based on left ventricular (LV) assessment. The authors hypothesized that baseline RV function and tissue Doppler-derived dyssynchrony may have incremental value over LV dyssynchrony measures for predicting CRT response.

Methods: In this retrospective study, echocardiographic examinations were performed in 90 patients before pacemaker implantation and up to 18 months afterward. CRT results were evaluated using clinical criteria (death, hospitalization for decompensation, change in New York Heart Association class ≥1, and 10% decreases in both peak ventilatory oxygen uptake and 6-min walking distance) and reverse remodeling (>15% reduction in LV end-systolic volume).

Results: Baseline RV dyssynchrony during isovolumic contraction of 26 msec facilitated the segregation of responders from nonresponders with 85% sensitivity and 100% specificity, as well as synchrony in peak deformation of 54 msec, with 89% sensitivity and 67% specificity. The minor axis of the RV inflow tract predicted reverse remodeling after CRT with sensitivity of 73% and specificity of 58% with a cutoff value of 35 mm. According to the clinical criteria, LV indices (end-diastolic and end-systolic volumes) and interventricular delay gave an overall R(2) value of 0.20 (86.2% correctly classified patients; area under the curve, 0.80). The addition of RV dyssynchrony parameters (measured in peak strain and isovolumic contraction peak velocities) significantly increased the power of the model (R(2) = 0.86; 100% of patients correctly classified; area under the curve, 1; P for change in R(2) < .0001).

Conclusions: The value of baseline RV function analysis is incremental to LV indices for the prediction of clinical response to CRT but not reverse remodeling. RV synchronous longitudinal deformation and RV dyssynchronous isovolumic velocity are independent predictors of clinical response to CRT.