Referral Bias in Coronary Micro vascular Dysfunction: a Retrospective Study

Obstructive coronary artery disease (CAD) is a well-defned condition and a signifcant cause of myocardial ischemia. Patients with angina typically undergo non-invasive cardiac investigations initially as a means of risk-stratifying. Coronary angiography is the diagnostic test of choice for patients with chest pain (angina) and signs of myocardial ischemia on noninvasive testing. Typically CAD is diagnosed based on the patency of the epicardial coronary arteries [1]. Approximately 30% of patients with angina have non-obstructive arteries on coronary angiogram and area diagnostic and management challenge for clinicians, contributing to signifcant social and economic burden [2]. They undergo multiple angiograms, experience a hospitalization rate 80% greater than patients with single vessel CAD and up to 50% have persistent symptoms leading to functional disability [3]. Historically, this population was given reassurance as long-term prognosis was believed to be benign [4]. We now know that a subset of these patients sui¬Â€er from coronary micro vascular dysfunction (MVD) [1] and are at increased risk for adverse cardiac events including congestive heart failure (CHF), myocardial infarction (MI), left ventricular (LV) dysfunction, and death [1,5]. The Cardiovascular Integrated Physiology (CVIP) program at Southlake Regional Health Centre (SRHC) investigates and manages patients with MVD. CVIP has received referrals for only a small fraction of patients with angina and non-obstructive angiograms at SRHC. It is unclear what factors promote referral. We hypothesized that referrals were not random and that the clinical characteristics of the referred patients dii¬Â€ered from the larger population of patients with angina and nonobstructive CAD. The primary objective of this study was to determine whether the patients referred to CVIP are an accurate representation of the overall population of patients with angina and non-obstructive coronary arteries.