Clinical Outcome of Patients With Inducible Capillary Blood Flow Abnormalities During Demand Stress in the Presence or Absence of Angiographic Coronary Disease

BACKGROUND: Our aim was to determine the cardiovascular outcome of patients with capillary blood flow (CBF) abnormalities detected during demand stress in the absence of obstructive coronary artery disease. METHODS AND RESULTS: We identified 380 consecutive patients referred for coronary angiography (CA) after dobutamine or exercise stress echocardiography (SE) between 2008 and 2013 performed with real-time perfusion imaging to examine myocardial CBF with a continuous ultrasound contrast infusion. Patients with left ventricular ejection fraction <40% were excluded. There were 3 groups based on results: positive SE/negative CA, patients who had abnormal regional CBF but no significant angiographic disease; positive SE/positive CA, those with abnormal CBF and significant disease on subsequent CA; and negative SE/negative CA, patients with normal CBF and negative CA. Event-free survival examining death and nonfatal myocardial infarction was compared. Median follow-up was 4 years. There were 91 positive SE/negative CA, 189 positive SE/positive CA, and 100 negative SE/negative CA patients over the study period. The positive SE/negative CA patients were more frequently women and had a lower prevalence of hypertension and hyperlipidemia (all P<0.001). Analysis of event-free survival with Cox regression demonstrated that death/nonfatal myocardial infarction rates were higher in the positive SE/positive CA (hazard ratio, 2.10; CI, 1.02-4.29) and positive SE/negative CA (hazard ratio, 2.02; CI, 0.99-4.31) groups when compared with negative SE/negative CA groups. CONCLUSIONS: Patients with inducible CBF abnormalities in the absence of significant obstructive disease at CA still have similar death/nonfatal myocardial infarction rates as those with significant disease at CA.