Clinical factors associated with slow flow in left main coronary artery-acute coronary syndrome without cardiogenic shock.

Since slow flow can be a fatal complication in left main coronary artery (LMCA)-acute coronary syndrome (ACS) patients, it should be important to anticipate and prepare slow flow during primary PCI for LMCA-ACS. We hypothesized that intravascular ultrasound (IVUS) findings would be useful to predict slow flow for LMCA-ACS patients without cardiogenic shock (CS). The purpose of this study was to investigate clinical factors associated with slow flow in LMCA-ACS patients without CS. We included 60 LMCA-ACS patients without CS, and divided into the slow flow group (n = 18) and the non-slow flow group (n = 42). Slow flow was defined as either transient or persistent TIMI flow grade ≤ 2. The prevalence of ST-segment elevation myocardial infarction (STEMI) was significantly higher in the slow flow group (55.6%) than in the non-slow flow group (11.9%) (p = 0.002). In the IVUS analysis, remodeling index was significantly greater in the slow flow group (1.15 ± 0.17) than in the non-slow flow group (0.99 ± 0.11) (p = 0.001). The multivariate logistic regression analyses in the IVUS factors revealed that remodeling index was significantly associated with slow flow (0.1 increase: OR 2.238, 95% CI 1.144-4.379, p = 0.019). In conclusion, remodeling index was significantly associated with slow flow. Our results suggest that the remodeling index determined by IVUS would be useful to find high-risk features of slow flow in LMCA-ACS patients without CS.