Effect of cardiac resynchronization therapy on left ventricular diastolic filling pattern in responder and nonresponder patients.

BACKGROUND: The aim of this study was to investigate the short- and long-term effects of cardiac resynchronization therapy (CRT) on left ventricular (LV) diastolic filling pattern and the relation between the diastolic filling pattern and the response to CRT.

METHODS: Twenty-three patients with systolic heart failure and complete left bundle-branch block underwent implantation of biventricular pacemaker devices. In order to follow the changes in diastolic function, mitral inflow, pulmonary venous flow, and LV flow propagation (Vp) velocities were measured with pulsed-wave and color M-mode Doppler echocardiography 1 week before and 1 and 6 months after pacemaker implantation. At the 6-month follow-up, patients were divided into two groups according to their response to CRT defined as a relative increase in LV ejection fraction (LVEF) > or =25% versus baseline.

RESULTS: After biventricular pacemaker implantation, significant clinical improvement was observed in all patients. Compared to baseline, the ratio of early-to-late peak velocities (E/A) decreased significantly at the 6th month (E/A ratio: from 1.5 +/- 0.9 to 0.8 +/- 0.5 at the 6th month (P = 0.02)). Pulmonary systolic flow to diastolic flow ratio (PVs/PVd) increased with CRT after 6 months (PVs/PVd ratio: from 0.9 +/- 0.4 to 1.3 +/- 0.7 at the 6th month (P = 0.02)). E/Vp ratio decreased significantly at the 1st and 6th month (E/Vp ratio: from 2.7 +/- 0.8 to 2 +/- 0.8 at the 1st (P < 0.002) and to 1.9 +/- 0.7 at the 6th month (P < 0.02)). In responders (n: 17, 74%), E wave and PVra velocity decreased, E-wave deceleration time increased, and E/Vp ratio improved significantly, whereas in nonresponders, changes in LV diastolic parameters remained insignificant. However, diastolic filling pattern improved significantly at the 1st and 6th month of CRT in both responders and nonresponders.

CONCLUSION: CRT enhances diastolic filling patterns in both responder and nonresponder patients. This may be related to improvement in symptoms even in nonresponders who have a relative increase in LVEF <25%.