Ischemic burden and cardiovascular mortality in 12 middle- and high-income European countries

Background Death rates from ischemic heart disease (IHD) are consistently higher in middle-income countries (MICs) than in high-income countries (HICs) in Europe, but the reasons are unknown. Purpose The main goal of this study was to disentangle the relation between patient-specific revascularization through percutaneous coronary intervention (PCI) and risk factor burden among European women and men from HICs and MICs Methods We enrolled 22,087 patients with myocardial infarction (MI) from 40 urban hospitals in 12 European countries (6 high-income and 6 middle-income countries; HICs and MICs, respectively) and quantified their traditional risk-factor burden (hypercholesterolemia, diabetes, current smoking and hypertension), the severity of their clinical presentation (incidence of ST-segment elevation MI [STEMI]) and their 30-day cardiovascular outcomes. We calculated women to men risk ratios (RRs) using inverse probability weighting models with estimates compared by interaction test on the log scale. Results Women and men from MICs were significantly (P<0.001) younger than those from HICs. Rates of hypertension and diabetes were significantly (P<0.001) higher in MICs compared to HICs for both women and men. By contrast, we did not find significant differences between country income levels, sex and rates of hypercholesterolemia. In line with these data the use of preventive medications was significantly (P<0.001) more common in MICs than in HICs and in women compared with men. Despite this, the rates of STEMI on hospital presentation were remarkably (P<0.001) higher in MICs than in HICs. (68.8% vs 57.7% in women and 71.0% vs 57.9% in men), and accordingly the case fatality rates for MI were consistently (P<0.001) higher in MICs than in HICs, with women having higher rates of mortality than men (10.3% vs 5.7%; RR: 1.90; 95% CI: 1.67-2.17 and 5.5%, vs 4.2%; RR: 1.31; 95% CI: 1.06-1.63; respectively; P interaction=0.002). Contrary to what was expected, MIC hospitals had higher rates of revascularization procedures than HIC hospitals both in women (72% vs 56%) and men (80% vs 61%). Although the rates of death were consistently lower in the population undergoing revascularization, still mortality remained significantly (P<0.001) higher in MICs than in HICs and in women than in men (6.9% vs 3.8% and 4.3% vs 2.3%; 10.3% vs 5.7%), but the relative RRs for the two country income groups did not significantly differ each other (P interaction=0.40). Conclusions Although the rates of revascularization procedures in MI were higher in MICs, the rates of death were substantially higher in MICs than in HICs. The high burden of risk factors in MICs appears to be the reason of a substantial increased baseline ischemic risk with higher rate of STEMI as MI clinical presentation. Better control of risk factors may mitigate the observed gap in mortality from MI between MICs and HICs, especially in women.