Abstract 12782: Effect of Cardiac Resynchronization Therapy on Phasic Coronary Flow Pattern and Microvascular Resistance of Left Anterior Descending Coronary Artery and Left Circumflex Coronary Artery in Patients With Non-Ischemic Cardiomyopathy
Background: Left bundle branch block (LBBB) and permanent right ventricular pacing induces mechanical dyssynchrony, which leads to deterioration of coronary flow dynamics. This study sought to examine the effect of cardiac resynchronization therapy (CRT) on coronary circulation of left anterior descending coronary artery (LAD) and left circumflex coronary artery (LCx).
Methods: 16 patients with non-ischemic cardiomyopathy (67.7±9.7 years old, 14 males, NHYA class 3.1±0.3, QRS duration 175±22ms and EF 30.5±9.7%, LBBB in 7 and complete AV block(CAVB) in 9) were enrolled. One week after CRT device implantation, coronary flow velocity and pressure in LAD and LCx were measured invasively, before and after adenosine triphosphate administration, during 2 programming modes: atrial pacing in patients with LBBB or sequential atrial and right ventricular pacing in patients with CAVB (Control), and sequential atrial and biventricular pacing (BiV). We measured hyperemic microvascular resistance index (HMR, coronary pressure divided by hyperemic average peak velocity (APV)) and phasic coronary flow pattern.
Result: Baseline APV in LAD were significantly higher at BiV compared with Control (26.4±8.8 cm/s vs.23.1±6.4 cm/s ; P =0.01). And HMR was lower at BiV compared with Control in both LAD and LCx (LAD: 1.59±0.47 vs.1.86±0.45; P=0.008, LCx: 1.74±0.30 vs.1.94±0.43; P=0.03). Phasic coronary flow parameters in LAD were significantly higher at BiV compared with Control (33.0±12.0 cm/s vs.27.3±7.5 cm/s for diastolic velocity, 19.4±6.8 cm/s vs.15.9±3.7 cm/s for diastolic VTI, 20.4±9.9 cm/s vs.14.8±9.4 cm/s for acceleration; P<0.05 for both), but not in LCx. No significant changes were observed in systolic velocity, systolic VTI, systolic time, diastolic time, and deceleration in LAD and all parameters except for systolic time in LCx.
Conclusion: CRT has a beneficial effect on coronary flow circulation through reduction in microvascular resistance.
- © 2011 by American Heart Association, Inc.