Effect of Pacing‐Induced Ventricular Dyssynchrony on Right Ventricular Function

BACKGROUND: Asynchronous electrical activation induced by right ventricular (RV) pacing can cause several abnormalities in left ventricular (LV) function. However, the effect of ventricular pacing on RV function has not been well established. We evaluated RV function in patients undergoing long-term RV pacing. METHODS: Eighty-five patients and 24 healthy controls were included. After pacemaker implantation, conventional echocardiography and strain imaging were used to analyze RV function. Strain imaging measurements included peak systolic strain and strain rate. LV function and ventricular dyssynchrony by tissue Doppler imaging (TDI) were assessed. Intra- and interobserver variabilities of TDI parameters were tested on 15 randomly selected cases. RESULTS: All patients were in New York Heart Association functional class I or II and percentage of ventricular pacing was 96 ± 4%. RV apical induced interventricular dyssynchrony in 49 patients (60%). LV dyssynchrony was found in 51 patients (60%), when the parameter examined was the standard deviation of the time to peak myocardial systolic velocity of all 12 segments greater than 34 ms. Likewise, septal-to-lateral delay ≥ 65 ms was found in 31 patients (36%). All echocardiographic indexes of RV function were similar between patients and controls (strain: -22.8 ± 5.8% vs -22.1 ± 5.6%, P = 0.630; strain rate: -1.47 ± 0.91 s(-1) vs -1.42 ± 0.39 s(-1) , P = 0.702). Intra- and interobserver variability for RV strain was 3.1% and 5.3%, and strain rate was 1.3% and 2.1%, respectively. CONCLUSIONS: In patients with standard pacing indications, RV apical pacing did not seem to affect RV systolic function, despite induction of electromechanical dyssynchrony.