LONDON – Patients with stable angina pectoris who are found to have no obstructive coronary artery disease upon diagnostic coronary angiography actually have significantly lower rates of all-cause mortality and acute MI over the next 7 years than the age- and gender-matched general population, according to a large Danish registry study.
“This is a novel finding that’s never been reported before,” Dr. Kris K. Olesen noted in presenting the results at the annual congress of the European Society of Cardiology.
His retrospective, population-based cohort study of patients in the Western Denmark Heart Registry who were referred for diagnostic coronary angiography during 2003-2012 included nearly 40,000 individuals with stable angina pectoris who were found on elective coronary angiography to have no obstructive CAD, meaning no lesions involving 50% or greater luminal narrowing. They were compared to the age- and gender-matched general western Danish population without a history of ischemic heart disease.
The upshot: Individuals without angiographic obstructive CAD had an absolute 1.61% lower rate of all-cause mortality, compared with the general western Danish population, during a median 3.9 and maximum 7 years of follow-up. They also had an absolute 0.41% lower risk of acute MI. After adjustment for comorbid conditions, this translated to a 39% relative risk reduction in all-cause mortality and a 41% reduction in MI risk, with both results being statistically significant with P values of less than 0.0001, reported Dr. Olesen of Aahus (Denmark) University.
One possible explanation for these surprising results, he said, is that patients with stable angina who elect to undergo diagnostic angiography are more health-aware than the general population and take better care of themselves. Another factor is that the general population with no history of ischemic heart disease probably includes individuals with significant CAD and chest pain who have never sought medical attention; they would drive up rates of MI and all-cause mortality in the comparison group.
Discussant Dr. Elmir Omerovic of the University of Goteborg (Sweden) offered up another possibility: Patients without obstructive CAD avoid percutaneous coronary intervention and are thereby spared the risks associated with an invasive procedure, including the hazard of serious bleeding events due to dual antiplatelet therapy.
Dr. Olesen reported having no financial conflicts with regard to this study, conducted with institutional funds.