Canada acute coronary syndrome risk score predicts no-/slow-reflow in ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention.

Background: The no-/slow-reflow phenomenon following primary percutaneous coronary intervention (PCI) in patients with ST-elevation myocardial infarction (STEMI)is associated with poor prognosis. The early identification of high-risk patients with no-/slow-reflow is critical. This study aimed to evaluate the predictive ability of the Canada Acute Coronary Syndrome (C-ACS) risk score for no-/slow-reflow in these patients.

Methods: Patients with STEMI who underwent primary PCI were consecutively enrolled and divided into three groups based on their C-ACS scores: 0, 1, and ≥2. The C-ACS score was computed using the four clinical variables evaluated at admission (one point for each): age ≥75 years, heart rate >100 beats/min, systolic blood pressure <100 mmHg, and Killip class >1. No-/slow-reflow was defined as thrombolysis in a myocardial infarction flow grade of 0-2 after primary PCI. The predictive ability of the C-ACS score for no-/slow-reflow was evaluated using a receiver operating characteristic curve.

Results: A total of 834 patients were enrolled, of whom 109 (13.1 %) developed no-/slow-reflow. The incidence of no-/slow-reflow increased from the C-ACS 0 group to the C-ACS ≥2 group (6.1 % vs 17.7 % vs 34.3 %, respectively,  < 0.001). After multivariable adjustment, the C-ACS score was an independent predictor of no-/slow-reflow (odd ratio 2.623, 95 % confidence interval 1.948-3.532,  < 0.001). Furthermore, the C-ACS score showed good discrimination for no-/slow-reflow (area under the curve 0.707, 95 % confidence interval 0.653-0.762,  < 0.001). Further subgroup analyses indicated a significant interaction between the C-ACS score and patient sex ( for interaction = 0.011). The independent association between the C-ACS score and no-/slow-reflow was only observed in male patients (odd ratio 3.061, 95 % confidence interval 1.931-4.852,  < 0.001). During a median follow-up duration of 4.3 years, the C-ACS score was independently associated with major adverse cardiovascular events independent of the occurrence of no-/slow-reflow ( for interaction = 0.212).

Conclusion: The C-ACS risk score could independently predict the no-/slow-reflow in patients with STEMI undergoing primary PCI, particularly in male patients.