The absolute cumulative probability of death at 12 months was 5 percent lower for patients who received routine invasive coronary angiography and revascularization as indicated during an unstable angina admission compared to those who did not. The survival benefit persisted when angiography was delayed up to 2 months after the first unstable angina episode. Results of a comparative effectiveness analysis are published in Annals of Internal Medicine.
Non-ST-segment elevation acute coronary syndromes consist of non-ST-segment elevation myocardial infarction (MI) and unstable angina. Reported rates of unstable angina have declined with the introduction of high-sensitivity troponin testing, which identifies patients with non-ST-segment elevation MI, yet patients with unstable angina still account for one-quarter to one-half of all those with acute coronary syndromes who present to the hospital. In general, current guidelines recommend routine invasive coronary angiography for patients with non-ST-segment elevation MI, but not for those with unstable angina. Meta-analyses of previous trials have shown conflicting results with regard to routine invasive management of unstable angina, potentially due to the high crossover from control to intervention groups in the randomized controlled trials.
Researchers at St. Vincent's Hospital, University of Melbourne, Victoria, Australia used hospital discharge data to assess the effect of angiography on mortality in 33,901 patients admitted to the hospital with an initial episode of unstable angina. The investigators compared outcomes of patients who had angiography during their first hospitalization with those of other patients by using advanced statistical methods to adjust for differences in individual patient characteristics and to account for crossovers from control to intervention groups. The data showed that routine angiography, with or without subsequent revascularization, was associated with a 52 percent relative decrease in 12-month mortality. Revascularization offered no additional statistical mortality benefit compared with diagnostic angiography alone. The authors conclude that routine invasive diagnostic angiography up to 2 months after an emergent admission for unstable angina in association with optimum medical therapy might prevent up to 5 deaths per 100 hospital admissions for unstable angina during the 12 months after hospitalization for the initial episode.
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