Background: Use of aggressive and invasive interventions is more common in the USA than in other countries. We have compared use of resources for patients with cardiogenic shock after myocardial infarction in the USA and in other countries, and assessed the association between use of resources and clinical outcomes.
Methods: We analysed data for patients with cardiogenic shock after myocardial infarction who were enrolled in the GUSTO-I trial (1891 treated in the USA, 1081 treated in other countries). Patients were randomly assigned combinations of streptokinase, heparin, and accelerated tissue-plasminogen activator (t-PA), then decisions about further interventions were left to the discretion of the attending physician. The interventions included in our analysis were: pulmonary-artery catheterisation, cardiac catheterisation, intravenous inotropic agents, ventilatory support, intra-aortic balloon counterpulsation (IABP), percutaneous transluminal coronary angioplasty (PTCA), and coronary bypass graft surgery (CABG). The primary outcome measure was death from any cause at 30 days of follow-up.
Findings: Patients who were treated in the USA were significantly younger than those treated elsewhere (median 68 [IQR 59-75] vs 70 [62-76], p < 0.001), a smaller proportion had anterior infarction (49 vs 53%, p < 0.001), and they had a shorter time to treatment (mean 3.1 vs 3.3 h, p < 0.001). Aggressive diagnostic and therapeutic procedures were used more commonly in the USA than in the other countries: cardiac catheterisation (58 vs 23%); IABP (35 vs 7%); right-heart catheterisation (57 vs 22%); and ventilatory support (54 vs 38%). 483 (26%) of the patients treated in the USA underwent PTCA, compared with 82 (8%) patients in other countries. Patients who underwent revascularisation had better survival in all countries. Adjusted 30-day mortality was significantly lower among patients treated in the USA than among those treated elsewhere (50 vs 66%, p < 0.001). The difference in mortality remained at 1 year-56% of patients treated in the USA died versus 70% of patients treated elsewhere (hazard ratio 0.69 [95% CI 0.63-0.75], p < 0.001).
Interpretation: 30-day and 1-year mortality was significantly lower among patients treated in the USA than among those treated in other countries. This difference in mortality may be due to the greater use of invasive diagnostic and therapeutic interventions in the USA.