Background: Cardiac resynchronization therapy (CRT) produces an early improvement in left ventricular (LV) function in patients with congestive heart failure (CHF), but little is known about its effects on right ventricular (RV) function.
Aim: To assess the early effects of CRT on RV function using myocardial strain analysis.
Methods: Fifty CHF patients (New York Heart Association class III/IV, left ventricular ejection fraction [LVEF] less than 35%, QRS greater than 120 ms) were studied before and three months after CRT. RV chamber dimension was quantified using tricuspid annulus diameter and RV short- and long-axis dimensions. RV function was assessed by tricuspid annulus plane systolic excursion and velocity (V(s)) and lateral wall strain. RV mechanical dyssynchrony was calculated using the difference in time-to-peak strain between septal and lateral wall.
Results: After three months, LVEF had increased significantly (from 22+/-6 to 27+/-9%; P<0.01) and LV end-diastolic volumes had decreased significantly (from 232+/-73 to 219+/-78 ml; P<0.05) in patients with LV mechanical dyssynchrony at baseline (n=35). RV dimensions did not change significantly, but there was an early improvement in RV function as demonstrated by an increase in V(s) (from 5.3+/-2.4 to 6.4+/-1.8 cm s(-1), P=0.001) and RV lateral wall basal and mid strain (from 23+/-9 to 28+/-9%, P=0.009 and from 20+/-7 to 25+/-8%, P=0.01, respectively). The improvement in RV strain occurred in patients with septal RV lead position and correlated with the magnitude of RV dyssynchrony at baseline (r=0.74; P<0.05).
Conclusion: After three months, CRT improved RV function significantly in CHF patients before any significant change in RV dimensions.