PROGNOSTIC-SIGNIFICANCE OF CORONARY FLOW RESERVE ON LEFT-VENTRICULAR EJECTION FRACTION IN CARDIAC TRANSPLANT RECIPIENTS

Background Cardiac allograft vasculopathy is a common phenomenon in ep icardial and microvascular vessels., Intramyocardial vessel disease ma y lead to small, stellate infarcts, The present study tested the impac t of microvascular vasomotor function on changes in left ventricular s ystolic function in the long-term follow-up after cardiac transplantat ion. Methods. Seventeen consecutive cardiac transplant patients, 40+/- 21 months after cardiac transplantation, without angiographically visi ble cardiac allograft vasculopathy and without episodes of acute rejec tion were included in the study. Coronary microvascular reactivity was assessed by the endothelium-dependent stimulus acetylcholine (50 mu g i.c.) and by the endothelium-independent stimulus dipyridamole (0.56 mg/kg i.v.) utilizing an Doppler catheter, Radionuclide ventriculograp hy was performed at the time of coronary flow measurement and repeated 2 years later to correlate changes in left ventricular ejection fract ion with the coronary flow reserve measurement 2 years previously. Res ults, There was a statistically significant correlation between endoth elium-independent coronary flow reserve to dipyridamole and changes in ejection fraction at rest (r=0.59; P<0.01) and during exercise (r=0.4 8; P<0.05). Twenty-four months later, patients with a coronary flow re serve to dipyridamole <2.5 showed a significant decline in ejection fr action during exercise (-7+/-5%) compared to patients with a coronary flow reserve >2.5 (1.1+/-5%; P=0.003), Coronary flow reserve to acetyl choline was not correlated with a reduced ejection fraction during exe rcise. Conclusions. Endothelium-independent microvascular dysfunction has prognostic importance for deterioration of left ventricular functi on in cardiac transplant recipients without angiographically visible c oronary artery stenoses, These results reinforce the concept that micr ovascular and epicardial vessel disease after transplantation are two distinct entities with different functional consequences.