Determinants of coronary blood flow after thrombolytic administration

OBJECTIVES: This study evaluated the determinants of coronary blood flow fo llowing thrombolytic administration in a large cohort of patients. BACKGROUND: Tighter residual stenoses following thrombolysis have been asso ciated with slower coronary blood how, but the independent contribution of other variables to delayed flow has not been fully explored. METHODS: The univariate and multivariate correlates of coronary blood flow at 90 min after thrombolytic administration were examined in a total of 2,1 95 patients from the Thrombolysis in Myocardial Infarction (TIMI) 4, 10A, 1 0B and 14 trials. The cineframes needed for dye to first reach distal landm arks (corrected TIMI frame count, CTFC) were counted as an index of coronar y blood flow. RESULTS: The following were validated as univariate predictors of delayed 9 0-min flow in two cohorts of patients: a greater percent diameter stenosis (p < 0.0001 for both cohorts), a decreased minimum lumen diameter (p = 0.00 03, p = 0.0008), a greater percent of the culprit artery distal to the sten osis (p = 0.03, p = 0.02) and the presence of any of the following: delayed achievement of patency (i.e., between 60 and 90 min) (p < 0.0001 for both cohorts), a culprit location in the left coronary circulation (left anterio r descending or circumflex) (p = 0.02, p < 0.0001), pulsatile flow (i.e., r eversal of flow in systole, a marker of heightened microvascular resistance , p = 0.0003, p < 0.0001) and thrombus (p = 0.002, p = 0.03). Despite a min imal 16.4% residual stenosis following stent placement, the mean post-stent CTFC (25.8 +/- 17.2, n = 181) remained significantly slower than normal(21 .0 +/- 3.1, n = 78, p = 0.02), and likewise 34% of patients did not achieve a CTFC within normal limits (i.e., <28 frames, the upper limit of the 95th percent confidence interval previously reported for normal flow). Those pa tients who failed to achieve normal CTFCs following stent placement had a h igher mortality than did those patients who achieved normal flow (6/62 or 9 .7% vs. 1/118 or 0.8%, p = 0.003). CONCLUSIONS: Lumen geometry is not the sole determinant of coronary blood f low at 90 min following thrombolytic administration. Other variables such a s the location of the culprit artery, the duration of patency, a pulsatile flow pattern and thrombus are also related to slower flow. Despite a minima l 16% residual stenosis, one-third of the patients treated with adjunctive stenting still have a persistent flow delay following thrombolysis, which c arries a poor prognosis. (C) 1999 by the American College of Cardiology.