New tool helps predict sudden death risk in ACS

By David Douglas

NEW YORK (Reuters Health) - A score based on factors such as left ventricular ejection fraction (LVEF) can help predict the risk of sudden cardiac death (SCD) in patients with non-ST-segment elevation acute coronary syndrome (NSTE ACS), according to new research.

Although the absolute SCD risk is relatively low, about 1% per year, Dr. Pierluigi Tricoci told Reuters Health by email, "sudden cardiac death accounts for one-third of all cardiovascular deaths. Moreover the risk is not the same for every patient and may go up to 20% at 2 years."

"Starting from simple clinical variables that are virtually available in every patient," he added, "we developed a tool to calculate the risk of sudden death in each patient following NSTE ACS."

For the study, online March 16 in JAMA Cardiology, Dr. Tricoci of Duke University Medical Center in Durham, North Carolina, and colleagues analyzed data on more than 37,000 NSTE ACS patients (median age, 65 years) from four clinical trials.

After a median follow-up of 12.1 months, there were 1,640 cardiovascular deaths, of which 31.3% were SCDs. Cumulative incidence estimates for SCD ranged from 0.79% at six months to 2.37% at 30 months.

The risk for SCD was assessed using components including LVEF, age, diabetes, estimated glomerular filtration rate, heart rate and myocardial infarction (MI).

A model developed to calculate the risk for SCD in the two trials in which LVEF was available had a C index of 0.77. A simplified integer-based score system (from zero to 50) yielded a calculated SCD probability ranging from 0.1% to 56.7% (C statistic, 0.75).

Thus, it "did not have a significant loss in accuracy compared with the full model," the researchers note.

In a multivariable model that included time-dependent clinical events after the initial hospitalization for ACS, SCD was associated with recurrent MI (hazard ratio, 2.95; p<0.001). This was also the case for any hospitalization (HR, 2.45; p<0.001). However, coronary revascularization had a negative relationship with SCD (HR, 0.75; p<0.03).

Dr. Tricoci said the risk calculator "can be used clinically to assess the risk of SCD prior to discharge in NSTE ACS."

However, he pointed out, "We clearly need more data on how this can be integrated into the decision-making process. 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 currently don't qualify for an implantable cardioverter defibrillator (ICD) for primary prevention because they are in the early period after an MI or do not meet the ejection fraction criteria."

He concluded, "The SCD risk stratification tool we provided could be used in the design of interventional study aimed at reducing SCD in high risk patients in situations where an ICD is not currently indicated."

Dr. Sumeet S. Chugh, who was not involved in the study, told Reuters Health by email that the new "findings highlight how far we have come in management of acute coronary disease, and provide some lessons on how we could do better. Once these patients reached the hospital, their risk of dying suddenly was quite low ... and could be decreased further by paying attention to subsequent clinical events."

"Now we need to work on risk models for those patients who have their sudden cardiac death in the field, without the opportunity to reach the hospital and enter the health care system," said Dr. Chugh, who is medical director of the Heart Rhythm Center at Cedars-Sinai, Los Angeles.

Merck & Co supported the study; Dr. Tricoci and a number of his coauthors reported financial ties to the company.

SOURCE: bit.ly/1RjCFUe

JAMA Cardiol 2016.

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