Survival benefit of early intervention in non-STEMI patients is independent of other factors

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Sameer Arora (Division of Cardiology, University of North Carolina at Chapel Hill, Chapel Hill, USA) and others report in Catheterizations and Cardiovascular Interventions that early percutaneous coronary intervention (PCI) in patients with non-ST-segment elevation myocardial infarction (NSTEMI) significantly increases 28-day survival. They add that this finding is independent of factors such as demographics and comorbidities.

Current US guidelines, Arora et al write, recommend early PCI for initially stabilised high-risk NSTEMI patients. However, they note that the evidence for early PCI is “largely driven by a lower incidence of refractory of ischaemia or new myocardial infarction rather than survival”. “This is likely due to limitations recruiting a large enough sample with sufficient power to analyse mortality alone, especially in the light of the low mortality following PCI,” the authors add. Therefore, the aim of the present study was to analyse real-world effectiveness of early vs. late PCI for reduction of mortality.

Using data from 21 hospitals in four US communities in the Atherosclerosis Risk in Communities (ARIC) surveillance study, Arora et al identified 4,419 NSTEMI patients who underwent PCI between 1987 and 2012. Of these patients, 55% were classified as low risk and 65% were revascularised late. The authors report, “we considered revascularisation performed <24 hours after symptom onset to be ‘early’ and revascularisations ≥24 hours to be ‘late’”, adding: “The proportion of revascularisations occurring within 24 hours of symptom onset decreased from 1987 to 1996 but then increased with calendar year, reaching a high of 46% by 2012.”

At 28 days, early intervention was associated with a 58% risk of lower mortality in the overall cohort and a 57% lower risk for patients at high risk. This finding was after adjustment for demographics, thrombolysis in myocardial infarction (TIMI) score, comorbidities, aspirin use, weekend admission, and transfer status. Additionally, also after adjustment for cofounding factors, early intervention in patients admitted within six hours of symptom onset was associated with 68% lower 28-day mortality (67% lower mortality for patients admitted within 24 hours). Arora et al state: “The higher 28-day mortality observed with delayed PCI is likely due to the prolonged ischaemic time prior to revascularisation, leading to myocardial necrosis and poor subsequent outcomes.”

However, by one year, there were no significant differences in mortality between those who had undergone early intervention and those who had undergone late intervention. According to the authors, this may be because of adherence to guideline-based recommendations for acute coronary syndrome. They observe: “In particular, antithrombotic and cardioprotective medications have led to a reduction in post-hospitalisation mortality for NSTEMI patients, irrespective of timing of revascularisation.”

Last year, a study presented at the 2016 Scientific Session American College of Cardiology (and published in The Lancet) indicated that delaying stenting in STEMI patients did not improve overall outcomes compared with immediate stenting and was associated with a significant increase in unplanned revascularisation of the target vessel.

Arora told Cardiovascular News: “Early PCI was associated with improved survival in patients with NSTEMI and a high risk of clinical events.”

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