Right ventricular apical pacing-induced left ventricular dyssynchrony is associated with a subsequent decline in ejection fraction

BACKGROUND In patients with normal left ventricular (LV) ejection fraction (EF), the interposition of chronic, high-dose right ventricular apical (RVA) pacing may produce late EF decline. OBJECTIVE To test the hypothesis that LV dyssynchrony, defined echocardiographically and apparent early after interposition of pacing, would be greater in patients who subsequently demonstrated EF decline. METHODS Ninety-one patients with normal prepacing EF who underwent atrioventricular node ablation and subsequent high-dose RVA pacing were studied. Transthoracic echocardiograms were performed early (median 4 months) and late (median 28 months) after interposition of pacing, with a significant decline in EF between these studies defined as >= 5%. Speckle-tracking longitudinal strain analysis of the early echocardiogram was performed to quantify dyssynchrony. In addition to standard dyssynchrony indices, a novel index of apex-to-base mechanical propagation delay (MPD) was used. RESULTS Multivariable analysis determined that MPD of the septum correlated with a significant decline in EF, independent of all other dyssynchrony, clinical, or pacing variables. A septa MPD value exceeding 50 ms was associated with EF decline at 81% sensitivity and 88% specificity. CONCLUSIONS Dyssynchrony, in particular septal MPD, measured early after interposition of high-dose RVA pacing predicted a significant late decline in EF in patients who had normal prepacing EF.