Objectives: Our purpose was to study whether the in-hospital prognosis of anterior acute myocardial infarction (AMI) is influenced by preexistent collateral circulation to the infarct-related artery.
Background: Collateral circulation exerts beneficial influences on the clinical course after AMI, but demonstration of improved survival is lacking.
Methods: We studied 238 consecutive patients with anterior AMI treated by primary angioplasty within the first 6 h of the onset of symptoms. Fifty-eight patients with basal Thrombolysis in Myocardial Infarction (TIMI) flow >1 in the infarct-related artery or with inadequate documentation of collateral circulation were excluded. Collateral channels to the infarct-related artery before angioplasty were angiographically assessed, establishing two groups: 115 patients (64%) without collateral vessels (group A) and 65 patients (36%) with collateral vessels (group B).
Results: There were no differences in baseline characteristics between groups A and B, except for the greater prevalence of previous angina in group B (15% vs. 34%, p = 0.003). During the hospital stay, 26 patients (23%) in group A and 5 (8%) in group B died (p = 0.01). Cardiogenic shock accounted for 74% of deaths. Cardiogenic shock developed in 30 patients (26%) in group A and in 4 (6%) in group B (p = 0.001). The absence of collateral circulation appeared to be an independent predictor of in-hospital death (odds ratio 3.4, 95% confidence interval 1.2 to 9.6, p = 0.02) and cardiogenic shock (odds ratio 5.6, 95% confidence interval 1.9 to 17, p = 0.002).
Conclusions: Preexistent collateral circulation decreases in-hospital death from anterior AMI by reducing the incidence of cardiogenic shock.