Determine if the presence of coronary collateral circulation (CCC) during an ACS is associated with a reduction in mortality.Design and method:
We conducted a systematic search of studies using MEDLINE, EMBASE, ScienceDirect, Scopus, and Cochrane Central Register of Controlled Trials databases in all languages and examined reference lists of studies. The inclusion criteria for studies were 1) observational or randomized controlled trials; 2) population included adults > 19 years old with an ACS; 3) reported data on mortality in association with the presence or absence of CCC on angiography; and 4) if observational study, should have controlled for confounders by using logistic regression analysis. Studies identified were assessed for quality using the Newcastle-Ottawa Quality Assessment Scale for observational studies, and the Cochrane Tool for Assessing Risk of Bias for randomized trials. The outcome of interest was assessed using Mantel-Haenzel analysis of random effects to compute for relative risk.Results:
Pooled analysis from 12 identified trials showed that among patients with ACS who underwent coronary angiography, the presence of CCC showed a trend towards benefit in terms of mortality, but was not statistically different from those without CCC [RR 0.69, (95% CI 0.44 to 1.08), p < 0.0001, I2 = 73%]. In the secondary analysis, those patients with an ACS and CCC treated with PCI had a significant reduction in mortality versus those without CCC [RR 0.48, (95% CI 0.35 to 0.65), p < 0.00001, I2 = 0%].Conclusions:
The presence of CCC during ACS showed a trend towards mortality reduction. Among ACS patients treated with PCI, those with CCC had a significant reduction in mortality.