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Role of Exercise Treadmill Testing in the Assessment of Coronary Microvascular Disease
Diana M Lopez1, Sanjay Divakaran2, Ankur Gupta3
1Cardiovascular Imaging Program, Departments of Medicine and Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA. Electronic address: https://twitter.com/DMLopez5.
Insights
Exercise treadmill testing (ETT) shows limited sensitivity for diagnosing coronary microvascular disease (CMD). However, persistent ischemic changes on ETT after exercise suggest CMD in patients without obstructive coronary artery disease (CAD).
Area of Science:
- Cardiology
- Diagnostic Imaging
- Clinical Exercise Physiology
Background:
- Exercise treadmill testing (ETT) is established for diagnosing obstructive coronary artery disease (CAD).
- Its utility in diagnosing coronary microvascular disease (CMD) remains less understood.
- CMD is characterized by impaired coronary blood flow without significant epicardial CAD.
Purpose of the Study:
- To evaluate the diagnostic accuracy (sensitivity and specificity) of ETT for CMD.
- To assess the prognostic value of ETT findings in patients with CMD.
Main Methods:
- Retrospective study of 249 patients undergoing ETT and positron emission tomography.
- Exclusion of patients with obstructive CAD or left ventricular systolic dysfunction.
- CMD defined by coronary flow reserve < 2; follow-up for major adverse events.
Main Results:
- ETT demonstrated low sensitivity (34.7%) and moderate specificity (64.9%) for CMD.
- Specificity increased to 86.8% with persistent ischemic changes (>1 min recovery), but sensitivity decreased to 15.3%.
- ETT results were not significantly associated with adverse outcomes in patients with CMD.
Conclusions:
- ETT has limited sensitivity for detecting CMD.
- Persistent ischemic changes on ETT in the absence of obstructive CAD warrant suspicion for CMD due to high specificity.
- Larger studies are needed to confirm the prognostic implications of ETT in CMD patients.
Objectives:
The authors aimed to study the sensitivity and specificity of exercise treadmill testing (ETT) in the diagnosis of coronary microvascular disease (CMD), as well as the prognostic implications of ETT results in patients with CMD.
Background:
ETT is validated to evaluate for flow-limiting coronary artery disease (CAD), however, little is known about its use for evaluating CMD.
Methods:
We retrospectively studied 249 consecutive patients between 2006 and 2016 who underwent ETT and positron emission tomography within 12 months. Patients with obstructive CAD or left ventricular systolic dysfunction were excluded. CMD was defined as a coronary flow reserve <2. Patients were followed for the occurrence of a first major adverse event (composite of death or hospitalization for myocardial infarction or heart failure).
Results:
The sensitivity and specificity of a positive ETT to detect CMD were 34.7% (95% CI: 25.4%-45.0%) and 64.9% (95% CI: 56.7%-72.5%), respectively. The specificity of a positive ETT to detect CMD increased to 86.8% (95% CI: 80.3%-91.7%) when only classifying studies with ischemic electrocardiogram changes that lasted at least 1 minute into recovery as positive, although at a cost of lower sensitivity (15.3%; 95% CI: 8.8%-24.0%). Over a median follow-up of 6.9 years (IQR: 5.1-8.2 years), 30 (12.1%) patients met the composite endpoint, including 13 (13.3%) with CMD (n = 98). In patients with CMD, ETT result was not associated with the composite endpoint (P = 0.076).
Conclusions:
Our data suggest limited sensitivity of ETT to detect CMD. However, a positive ETT with ischemic changes that persist at least 1 minute into recovery in the absence of obstructive CAD should raise suspicion for the presence of CMD given a high specificity. Further study is needed with larger patient sample sizes to assess the association between ETT results and outcomes in patients with CMD.
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