For angina patients without obstructive coronary artery disease (CAD), adjunctive testing of coronary vascular function during coronary angiography followed by medical therapy targeted to the findings improved angina outcomes, according to the CorMicA trial. In the study published in the Journal of the American College of Cardiology, a tiered approach for assessment for microvascular and/or vasospastic angina among patients with stable angina and no evidence of significant epicardial disease was deemed superior to usual care.
Angina without obstructive epicardial coronary artery disease (CAD) is a common problem with distinct underlying causes. Coronary angiography often fails to identify patients with vasospastic and/or microvascular angina as the angiogram does not reveal the small network of myocardial microvessels, which are drivers of myocardial blood flow. The goal of the trial was to test the hypothesis that stratified medical therapy guided by an interventional diagnostic procedure (IDP) improves patient outcomes among those with angina without evidence of obstructive coronary artery disease (CAD). Moreover, this would also help patients receive a definitive diagnosis on whether the normal/diseased state of their coronary arteries.
A randomized, controlled, blinded clinical trial of stratified medical therapy versus standard care was conducted in 151 patients with angina. Patients without obstructive CAD were immediately randomized 1:1 to the intervention group (stratified medical therapy) or the control group (standard care, IDP sham procedure). In the active assessment arm, patients were treated with beta-blockers and lifestyle modification if they had evidence of microvascular angina, calcium channel blockers, and lifestyle modification if they had evidence of vasospastic angina, and if neither was present, then antianginal therapies were stopped. Vasoreactivity testing was performed by infusing incremental concentrations of acetylcholine (ACh) followed by a bolus vasospasm provocation (<100μg). The primary endpoint was the mean difference in angina severity at 6 months (assessed by the Seattle Angina Questionnaire summary score). The duration of follow-up was 6 months. For the study, the interventional cardiologist recorded the diagnosis and management strategy at baseline (before angiography), after angiography but before randomization, and then after randomization when they either received the results from the additional testing or remained blinded to it. “We implemented a stratified medical therapy strategy encompassing an interventional diagnostic procedure with linked therapy as a routine adjunct to elective invasive coronary angiography in patients with known or suspected angina,” Ford and his colleagues wrote.
“We believe that a person-centered approach to care is key. Avoiding unnecessary medicines and optimizing therapy to a specific diagnosis will benefit patients and healthcare providers. Furthermore, stratifying this group of undifferentiated patients in the clinic will pave the way for new insights into mechanisms and disease-modifying therapy.”- Dr. Tom Ford, M.D.
The primary endpoint, change in Seattle Angina Questionnaire (summary score at 6 months was 11.7 units higher in the arm that underwent active assessment compared with control; 95% confidence interval 5-18.4, p = 0.01), reported Tom Ford, MBChB, of Golden Jubilee National Hospital in Clydebank, Scotland, at the Transcatheter Cardiovascular Therapeutics meeting and online in the Journal of the American College of Cardiology. These results were driven by an improvement in physical limitation: 14.5 U, p < 0.001 and in angina frequency: 9.3 U, p < 0.001. There were no differences in major adverse cardiac events (MACE) at the 6 month follow up (2.6% controls v 2.6% intervention; p =1.00). The intervention nearly doubled the likelihood of a diagnosis of a disorder of coronary function (66 vs 35 cases, relative risk 1.91, P<0.001). There was a 4.49-fold increase in certainty of that diagnosis (62 vs 14 cases, P<0.001) and a change in diagnosis from yes to no or vice versa in 39 intervention cases.
The results of this trial indicated that a tiered approach for assessment for microvascular and/or vasospastic angina among patients with stable angina and no evidence of significant epicardial disease was superior to usual care. This approach allowed for a change in diagnosis in more than half of the patients, and there was diagnostic certainty regarding microvascular/vasospastic angina in >80% of patients. In an undifferentiated population of patients without obstructive coronary artery disease at angiography, adjunctive coronary function testing with the application of stratified medical therapy to guide treatment was feasible, safe and associated with improvements in angina, quality of life and treatment satisfaction scores. Emphasizing his beliefs regarding this approach, the primary investigator, Dr. Tom Ford stated, “We believe that a person-centered approach to care is key. Avoiding unnecessary medicines and optimizing therapy to a specific diagnosis will benefit patients and healthcare providers. Furthermore, stratifying this group of undifferentiated patients in the clinic will pave the way for new insights into mechanisms and disease-modifying therapy.”
To view the interview with Dr. C. Michael Gibson, click here.
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