Exercise treadmill testing (ETT) is validated to evaluate for flow-limiting coronary artery disease (CAD), however, little is known about its use for evaluating coronary microvascular disease (CMD).
Lopez et al sought to explore the diagnostic value of ETT in the diagnosis of this entity and found that ETT has limited sensitivity 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. These findings were recently published online in JACC Cardiovascular Imaging journal.
CMD refers to a subtype of nonobstructive CAD that affects the structure and function of the coronary microcirculation. The diagnosis of CMD requires direct interrogation (invasive or noninvasive) of coronary microvascular function. Little is known about the relative utility of ETT in the evaluation of patients with suspected CMD, and current approaches for the evaluation of CMD are based only on expert consensus.
In this study, Lopez et al sought to evaluate both the diagnostic and prognostic value of ETT in CMD.
They retrospectively studied 249 consecutive patients 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).
1.The sensitivity and specificity of a positive ETT to detect CMD were 34.7 and 64.9% respectively.
2. The specificity of a positive ETT to detect CMD increased to 86.8% when only classifying studies with ischemic electrocardiogram changes that lasted at least 1 minute into recovery were considered as positive.
3. In patients with CMD, ETT result was not associated with the composite endpoint.
Although exercise-induced ischemic ECG changes during angina-like chest pain have been traditionally considered an important feature in the diagnosis of CMD, this data suggests that this notion is outdated.
"The high specificity of a positive ETT caused by ischemic ECG changes that persist at least 1 minute into recovery in this population for the diagnosis of CMD is an important new finding from our study and parallels data from previous studies linking CMD and abnormalities on myocardial perfusion imaging and exercise testing", noted authors.
Future studies are needed to further determine the prognostic value of exercise testing in patients with CMD and its potential role in risk stratification.
Source: JACC Cardiovascular Imaging: DOI: 10.1016/j.jcmg.2021.07.013