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Scoring System Simplifies Risk Assessment for Sudden Cardiac Death After NSTE ACS

By L.A. McKeown


About one-third of patients who die within 1 year after an acute coronary syndrome do so from sudden cardiac death, but investigators say using a risk calculator may help pinpoint those most at risk. 

Using data from four large trials of NSTE ACS patients—APPRAISE-2, PLATO, TRACER, and TRILOGY ACS—researchers found that the risk for sudden cardiac death was quite variable and that having a recurrent MI or needing to be rehospitalized after the initial NSTE ACS greatly increased the likelihood of dying.

“With certain clinical risk factors associated with [sudden cardiac death], the development of a comprehensive risk-stratification tool that accounts for [sudden cardiac death]-associated clinical characteristics and produces a user-friendly risk score may be helpful in NSTE ACS clinical care and research,” write investigators led by Paul L. Hess, MD (Veterans Affairs Eastern Colorado and Health Care System, Denver, CO).

Risk Factors Identified

Among the 37,555 patients studied, 1,640 died of a cardiovascular cause within 12 months. Of these, sudden cardiac death accounted for 31.3%. Importantly, Hess and colleagues found that risk of sudden cardiac death does not plateau with longer time from the NSTE ACS, but is instead “significantly influenced by events that occur after the initial hospitalization.”

The study, published online March 16, 2016, in JAMA Cardiology, identified 10 variables associated with increased risk of sudden cardiac death after NSTE ACS: reduced left ventricular ejection fraction (LVEF), older age, diabetes, lower estimated glomerular filtration rate, higher heart rate, prior MI, peripheral artery disease, Asian race, male sex, and high Killip class.

The final model was then used to create a calculator that assigns points to each variable, thereby simplifying individual risk assessment by providing a score.

Lastly, Hess and colleagues looked at the risk of sudden cardiac death in relation to recurrent clinical events following NSTE ACS and found that both MI and rehospitalization for any reason more than doubled risk.

Conversely, the risk of sudden cardiac death was reduced among patients who had undergone coronary revascularization (HR 0.75; 95%CI 0.58-0.98).

Practical Tool for Assessment

The study authors say the risk calculator can be useful in two ways: as a tool to support the treatment and counseling of individual patients, and to help select patients who may benefit from preventive devices like implantable cardioverter defibrillators (ICDs) or wearable defibrillators.

“Prevention of events downstream from the index hospitalization may be as important as considering ICDs for these patients,” they write. “More data regarding the additive prognostic significance of clinical events after hospitalization and their implications for treatment are needed.”

In an email, senior author Pierluigi Tricoci, MD, PhD (Duke Clinical Research Institute, Durham, NC), said from a practical perspective, the risk model is “simple and informative” and can be used to assess risk of sudden cardiac death prior to discharge in patients with NSTE ACS.

“We clearly need more data on how a tool like this can be integrated in the decision making process, which is true also for other risk stratification tools we have available. For example, we need more studies to understand if patients who are classified at high risk of sudden death may benefit from specific intervention to prevent sudden cardiac death, especially those who don’t currently qualify for an ICD for primary prevention because they are in the early period after an MI or do not meet the [ejection fraction] criteria,” Tricoci said. “From this regard, the model we provide can be used in the design of interventional studies aimed at reducing [sudden cardiac death] risk in situations where an ICD is not currently indicated.”

Considerations for the Future

Tricoci said to his knowledge, no previous studies have shown a link between Asian race and sudden cardiac death. However, since Asian patients have been underrepresented in many of those studies, further assessment is needed to validate that association.

Eric R. Bates, MD (University of Michigan Medical Center, Ann Arbor, MI), who was not involved in the study, called it “well done,” and said the biggest message is the low event rate seen with contemporary therapy compared with historical controls.

“The major limitation is that it is not clear that the sudden death rate is any different in patients without ACS who have the same risk factors,” Bates said in an email. “It would be interesting to measure the risk of sudden death and test the risk calculator in a population with stable ischemic heart disease.”

Source:

  • Hess PL, Wojdyla DM, Al-Khatib SM, et al. Sudden cardiac death after non–ST-segment elevation acute coronary syndrome. JAMA Cardiol. 2016;Epub ahead of print. 

Disclosures:

  • Hess reports honorarium from Sanofi. 
  • Tricoci reports consultant agreement fees and research grants from Merck. 
  • Bates reports consultant/honoraria/speakers fees from AstraZeneca. 

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