At ACC 17
Washington (FRONTLINE MEDICAL NEWS) – Patients with spontaneous coronary artery dissection as their presentation of acute coronary syndrome have a markedly better long-term survival rate than do patients with ACS in its various other forms, Rahul Potluri, MD, reported at the annual meeting of the American College of Cardiology.
In his retrospective cohort study of 182 U.K. patients diagnosed with spontaneous coronary artery dissection (SCAD) as the cause of their ACS and 32,981 controls with ACS without SCAD, the 15-year all-cause mortality rate was 10.4% in the SCAD group vs. 32.1% in the controls.
Although SCAD was first described in 1931, half of the roughly 1,500 cases reported in the medical literature have been published within the past 5 years. That makes this series of 182 SCAD patients with 15-year outcome data unique in providing the longest follow-up to date reported in a sizable patient series, said Dr. Potluri of the University of Alberta, Edmonton, and Aston University in Birmingham, England.
For decades SCAD was thought to be rare, with an estimated prevalence of 0.1%-0.5% among patients presenting with ACS. But with increased use of high-resolution intracoronary imaging and growing physician awareness, more recent reports suggest that SCAD actually accounts for 2%-4% of all ACS cases. Moreover, among women with ACS before age 50, the prevalence of SCAD is now believed to be 20%-40%, Dr. Potluri noted.
SCAD is a rupture in a coronary artery wall not related to atherosclerotic heart disease, trauma, or iatrogenic causes. The dissection is thought to result from an intimal tear or medial hemorrhage from the vasa vasorum, with subsequent accumulation of blood in a false lumen.
It’s not entirely unexpected that patients with SCAD have a better long-term prognosis than do those with ACS without SCAD, Dr. Potluri said. After all, patients with SCAD tend to be considerably younger: In Dr. Potluri’s series, the average age was younger than 52 years, vs. 66 years in controls. Plus they had lower levels of cardiovascular risk factors, and by definition they were free of atherosclerotic heart disease. But SCAD often occurs in conjunction with fibromuscular dysplasia, and the long-term health implications of that combination have not been well studied.
In a multivariate logistic regression analysis adjusted for age, sex, ethnicity, and comorbid conditions, the likelihood of dying within 5 years was 89% greater in the non-SCAD group. During follow-up, the non-SCAD ACS group was 4.1-fold more likely to have another ACS and 32% more likely to be diagnosed with heart failure.
SCAD was typically managed conservatively in Dr. Potluri’s series: In the SCAD group, 11% underwent PCI and 2.7% had CABG, compared with 51% and 10.7%, respectively, of controls.
“Conservative treatment appears to be safe in the SCAD patient population,” he said.
The prevalence of SCAD in his series of more than 33,000 patients admitted for ACS to U.K. hospitals in 2000-2014 was 0.54%. Dr. Potluri said that low figure likely reflects considerable underreporting due to the fact that some data were from the early 2000s, when SCAD was still largely below physicians’ radar.
Dr. Potluri is an authority on big data analytics in medical research. He formed his 182-patient SCAD series using ACALM (Algorithm for Comorbidity, Associations, Length of Stay, and Mortality), an analytic tool he developed years ago as a medical student. At the time of his SCAD study, the ACALM registry included anonymous, deidentified data on 1.8 million U.K. patients. The ACALM methodology utilizes a form of artificial intelligence known as novel field derivation to analyze huge amalgamated data sets. This is made possible by the fact that all U.K. hospitals report patient data in an identical standardized way, which is not the case in the United States.
Dr. Potluri has previously applied the ACALM methodology to a variety of other health care issues, including studies of an association between hyperlipidemia and breast cancer, the relationship between cardiovascular disease and mental health, and the so-called weekend effect, whereby U.K. patients hospitalized for cardiovascular reasons on the weekend have higher mortality than do those admitted on weekdays.
THE ACALM registry now exceeds 4 million patients. Dr. Potluri said he plans to analyze this full group to develop a large, comprehensive SCAD patient registry. This will enable investigators to evaluate potential psychosocial risk factors for SCAD, the role of fibromuscular dysplasia and connective tissue diseases, and other practical questions.
He reported having no financial conflicts regarding his study.