Calculator Estimates Spontaneous MI Risk in Medically Managed NSTE ACS Patients

Spontaneous MI occurs in about one out of every 10 medically managed NSTE ACS patients in the 2-and-a-half-year period following the event, and it can be predicted with good accuracy by a risk calculator incorporating baseline characteristics, an analysis of the TRILOGY ACS trial shows. That might have implications for both clinical practice and research.

Spontaneous MI was predicted most strongly by age, type of index event, diabetes, use of angiography, and creatinine level, although the Excel-based risk calculator takes into account 17 baseline variables, report Renato Lopes, MD, PhD (Duke Clinical Research Institute, Durham, NC), and colleagues.

“The proposed calculator, primarily intended for practicing clinicians, provides real-time and individualized time-varying risk estimates (with error estimates)” and could increase awareness of spontaneous MI risk, they note. “This enhanced awareness of MI risk could reinforce the importance of provision of, and adherence to, evidence-based secondary prevention medications and lifestyle changes.”

The tool could also be used to identify at-risk patients, thereby streamlining the development of future clinical trials, they add.

The findings were reported in a study published in the March 22, 2016, issue of the Journal of the American College of Cardiology.

Although revascularization has become increasingly common for NSTE ACS, up to about one-third of patients are still managed with medications alone, according to the authors. These patients have a high risk of spontaneous MI, which itself carries a greater risk of mortality compared with procedural MI.

“These observations highlight the importance of being able to identify patients at risk for a spontaneous MI event with an accurate risk prediction tool,” Lopes and colleagues write.

To develop one, the researchers turned to the TRILOGY ACS trial, which randomized 9,326 patients with NSTE ACS to be treated with prasugrel or clopidogrel on a background of aspirin without planned revascularization. Outcomes in the trial were similar with both P2Y12 inhibitors.

Over 30 months of follow-up, there were 695 spontaneous MIs. The accumulated rate was 10.7%.

The five strongest predictors of spontaneous MI were older age, NSTEMI rather than unstable angina as the index event, diabetes, a lack of prerandomization angiography, and higher baseline creatinine.

The model developed from 17 variables had a “good” predictive ability to distinguish patients with and without spontaneous MI, as indicated by a Harrell’s c-index of 0.732, and good calibration, particularly in patients with a low-to-intermediate predicted risk.

In an accompanying editorial, Gennaro Sardella, MD, and Massimo Mancone, MD, PhD (Sapienza University of Rome, Italy), say that the ease of the risk calculation “should encourage utilization by all operators.”

They also note that there is a disparity across countries in terms of access to angiography, with rates ranging in TRILOGY ACS from as high as 84% in North America to as low as 21% in Central or Eastern Europe.

Because of that, “this predictive model could play a different important role in different regions,” they say. “Where an invasive coronary evaluation is not widespread and easily achievable, it can confirm the necessity of a coronary angiography and give patients who are not planned for angiography and revascularization a ‘second chance’; in the countries with a high rate of coronary invasive evaluation, it will be very useful to identify ACS patients who are not suitable for revascularization and are at high risk for a new myocardial event to optimize secondary prevention.”

The major concern, they note, is whether operators will actually use the calculator. Existing scores, they add, are underused.

• Lopes RD, Leonardi S, Neely B, et al. Spontaneous MI after non-ST-segment elevation acute coronary syndrome managed without revascularization: the TRILOGY ACS trial. J Am Coll Cardiol. 2016;67:1289-1297.
• Sardella G, Mancone M. Save the unlucky unrevascularized acute coronary syndrome patient. J Am Coll Cardiol. 2016;67:1298-1299.

Related Stories:

• Procedural, Spontaneous MI Carry Different Prognostic Weights
• Comparable Long-Term Safety, Efficacy with Prasugrel, Clopidogrel in ACS
• TRILOGY ACS Substudy: Angiography Prior to Prasugrel Therapy Reduces CV Events