Background: Chronic comorbidity is a prognostic determinant in ST-segment elevation myocardial infarction (STEMI). This study was aimed at determining to what extent this effect is independent or derives from adoption of different therapeutic strategies.
Methods: Seven hundred forty patients with STEMI hospitalized within 12 hours of symptom onset were enrolled in a population-based registry, in a health district comprising 1 teaching hospital with and 5 district hospitals without percutaneous coronary intervention (PCI) facilities. Three categories of increasing chronic comorbidity score (CS-1, n = 259; CS-2, n = 235; CS-3, n = 246) were identified from age-adjusted associations of comorbidities with 1-year survival.
Results: Higher CS was associated with lower direct admission or transferal rates to hospital with PCI. Coronary reperfusion therapy (PCI in 91.5% of 470 cases) was adopted less frequently (P < .001) in CS-3 (41.9%) than CS-2 (69.4%) or CS-1 (78.8%). Compared with conservative therapy (n = 270), reperfusion therapy reduced 1-year mortality in the whole series not significantly (P = .816) in CS-1 but significantly in CS-2 (P = .012) and CS-3 (P = .001). This trend persisted after adjusting for age, Killip class, and acute myocardial infarction location (hazard ratio [HR] = 0.63 [95% CI 0.14-2.80], HR = 0.62 [95% CI 0.31-1.25], and HR = 0.47 [95% CI 0.26-0.86] in CS-1, CS-2, and CS-3, respectively). By hypothesizing an extension of coronary reperfusion therapy utilization rate in CS-2 and CS-3 to that in CS-1, from 21 (crude analysis) to 20 (adjusted analysis) deaths were classified as potentially avoidable.
Conclusion: Increased mortality in patients with chronic comorbidity and STEMI derives, at least in part, from underutilization of coronary reperfusion therapy, and might be reduced with a more aggressive therapeutic approach.