Variability of coronary blood flow reserve assessed by Doppler catheter after successful thrombolysis in patients with acute myocardial infarction.

To establish whether abnormal function of small coronary vessels might limit the advantages of thrombolytic treatment, coronary flow reserve in the infarct-related artery was measured in nine patients with acute myocardial infarction early after successful coronary thrombolysis by using a Doppler catheter and intracoronary adenosine infusion. In each patient coronary flow reserve was calculated as the ratio between coronary blood flow velocity during the highest tolerated intracoronary dose of adenosine (0.5 mg/min in five patients and 1 mg/min in four patients) and baseline velocity. Coronary flow reserve ranged from 1 to 3 (mean 2 +/- 0.7). No correlation (r = 0.20; p = 0.58) was found between coronary flow reserve and the severity of residual coronary stenosis, which ranged between 23% and 76% (mean 47% +/- 17%). No correlation (r = 0.33; p = 0.39) was found between either coronary flow reserve and the interval between pain onset and administration of the thrombolytic treatment, which ranged between 2.2 and 6 hours (mean 4.2 +/- 1.4 hours). Thus, in patients with acute myocardial infarction, coronary flow reserve early after successful thrombolysis is strikingly variable and may be extremely low despite widely patent epicardial coronary arteries. This restriction of coronary blood flow, probably caused by abnormal function of small coronary vessels, might limit the potential benefit from successful coronary thrombolysis.