Comparison of Risk Associated With STEMI vs NSTEMI

Within the first 90 days after discharge, older patients with ST-segment elevation myocardial infarction (STEMI) had worse outcomes compared with those with non–ST-segment elevation myocardial infarction (NSTEMI), according to research published in Circulation: Cardiovascular Quality Outcomes.

Amit N. Vora, MD, MPH, of Duke University Medical Center in Durham, North Carolina, and colleagues sought to determine if a time-dependent risk exists for mortality and/or nonfatal cardiovascular or cerebrovascular events in both NSTEMI and STEMI patients. As they noted, STEMI patients are typically prioritized for percutaneous coronary intervention (PCI) and coronary angiography compared with NSTEMI patients, so long-term outcomes are difficult to measure.

In their study, Dr Vora and colleagues evaluated a homogeneous group of older patients with STEMI and NSTEMI. They linked patients with acute MI and significant coronary artery disease included in the National Cardiovascular Data Registry ACTION Registry—Get With the Guidelines (GWTG) to Medicare claims data.

All-cause mortality, MI rehospitalization, stroke rehospitalization, and a composite end point of death, rehospitalization for MI, or rehospitalization for stroke were evaluated as postdischarge outcomes.

The researchers found single-vessel disease was more likely to be discovered in patients with STEMI during coronary angiography. On the other hand, patients with NSTEMI were more likely to have multivessel disease. PCI was more common in STEMI patients compared with NSTEMI patients who had either coronary artery bypass grafting or medical management.

At initial discharge, STEMI patients were more likely to receive secondary prevention medications (all evidence types) as well as lifestyle modification interventions compared with NSTEMI patients. However, in the first 90 days, STEMI patients were found to have an increased risk of mortality (hazard ratio [HR]: 1.52; 95% confidence interval [CI]: 1.38-1.68) and composite outcome (HR: 1.39; 95% CI: 1.29-1.50) compared with NSTEMI patients, after adjustment for differences in baseline clinical characteristics.

In unadjusted outcomes, STEMI patients had lower cumulative incidence rates for all outcomes, including mortality. A total of 2143 patients in the STEMI group died vs 4229 patients in the NSTEMI group (16% vs 19.8%; P <.001). Rehospitalization rates for MI and stroke as well as the composite end point between STEMI and NSTEMI patients were as follows: 6.1% vs 9.6% (P <.001), 2.7% vs 3.2% (P =.006), and 21.9% vs 27.9% (P <.001). The unadjusted rates of all end points were lower for STEMI patients compared with NSTEMI patients from 90 days to 2 years.

According to piece-wise analyses, mortality risk did increase from 90 days to 2 years (HR: 1.10; 95% CI: 1.02-1.18) in STEMI patients, but was attenuated compared with the first 90 days.

In addition to the impact on patients and providers, these findings may also affect payers and policymakers. As the authors explained, in the Bundled Payments for Care improvement initiative devised by the Center for Medicare and Medicaid Innovation, one-payment model involves “a bundled payment for an episode of care that includes the costs associated with the acute inpatient stay and ≤90 days of care after discharge.” However, based on the significant heterogeneity (ie, outcome differences by MI type and time to discharge) demonstrated in this study, those proposed bundled care payments may need to be extended beyond 90 days.

After multivariable adjustments, STEMI patients were at increased risk for events within the first 90 days of discharge, with attenuated risk from 90 days to 2 years; however, these results should still be considered “hypothesis generating,” the authors concluded.

Disclosures: Dr Wang received research funding from AstraZeneca, Daiichi Sankyo, Gilead Sciences, GlaxoSmithKline, Eli Lilly, Boston Scientific, and Regeneron and has consulted for AstraZeneca and Eli Lilly. Dr Roe received research funding from Eli Lilly, Sanofi-Aventis, Daiichi-Sankyo, Amgen, and the Familial Hypercholesterolemia Foundation. Dr Roe also developed educational activities or lectures for AstraZeneca and Bristol-Myers Squibb and has consulted for AstraZeneca, Eli Lilly, Merck, Janssen, Elsevier Publishers, and Bristol-Myers Squibb.

Reference

Vora AN, Wang TY, Hellkamp AS, et al. Older patients with ST-elevation vs non–ST-elevation myocardial infarction with angiographically proven coronary artery disease. Circ Cardiovasc Qual Outcomes. 2016;9. doi:10.1161/CIRCOUTCOMES.115.002312.