Management and Outcomes of Non-ST Elevation Acute Coronary Syndromes in Relation to Previous Use of Antianginal Therapies (from the Canadian Global Registry of Acute Coronary Events [GRACE] and Canadian Registry of Acute Coronary Events [CANRACE])

Study Questions:

What are temporal changes in the chronic use of antianginal therapy among patients presenting to the hospital with non–ST-segment elevation myocardial infarction (NSTEMI) or unstable angina (UA), and is pretreatment with antianginal therapy associated with differences in the clinical presentation, management, and outcomes of non–ST-segment elevation acute coronary syndrome (NSTE-ACS)?

Methods:

This was a retrospective analysis of 10,019 Canadian patients in the GRACE/GRACE2/CANRACE database who had a final diagnosis of NSTE-ACS between 1999 and 2008, and for whom information regarding previous treatment with antianginal therapy was available and complete. The authors compared in-hospital outcomes among patients who did and did not receive chronic antianginal therapy before hospitalization.

Results:

Overall, 54.5% of patients were being treated with ≥1 antianginal medication. The rates of beta-blocker use were 39.3%; nitrate use, 24.4%; and calcium antagonist use, 23.6%. There was a significant decline in the chronic use of nitrates over time. Chronic antianginal use with a single agent or multiple agents was not a significant predictor for in-hospital mortality (adjusted odds ratio [OR], 0.70; 95% confidence interval [CI], 0.35-1.37; p = 0.30 for use of one antianginal agent and adjusted OR, 0.60; 95% CI, 0.29-1.25; p = 0.17 for ≥2 antianginal agents). Compared with patients not on any antianginal therapy before presentation, those on treatment were less likely to present with positive biomarkers (p < 0.001). In particular, NSTEMI and UA were the final diagnosis in 72.5% and 27.5%, respectively, of patients not treated with chronic antianginal agents; of those on chronic antianginal therapy, 57.5% presented with NSTEMI and 42.5% with UA (p < 0.001). Any previous antianginal use was a negative predictor of cardiac catheterization (adjusted OR, 0.83; 95% CI, 0.70-0.98; p = 0.03).

Conclusions:

Over the preceding decade, there have been multiple temporal trends in the chronic use of antianginal therapy among patients presenting to the hospital with NSTEMI and UA. In particular, beta-blockers remain the most commonly used antianginal agents before presentation for ACS; the chronic use of nitrates has declined over time; ACS patients on chronic antianginal therapy were less likely to have NSTEMI in the hospital and were less likely to undergo in-hospital coronary angiography; and there was no independent association between previous use of antianginal therapy and in-hospital mortality.

Perspective:

Although not capable of establishing the efficacy of chronic antianginal therapy in this population of patients presenting to the hospital with NSTE-ACS, this observational retrospective study does suggest some temporal patterns about the prescription of antianginal medications, illuminates real-world practice patterns, and draws attention to the potential underutilization of select secondary prevention therapies after ACS.

Clinical Topics: Acute Coronary Syndromes, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, ACS and Cardiac Biomarkers, Interventions and ACS, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: Myocardial Infarction, Acute Coronary Syndrome, Hospital Mortality, Biological Markers, Coronary Angiography, Cardiac Catheterization, Nitrates, Canada, Hospitalization


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