Resting Myocardial Contrast Echocardiography for the Evaluation of Coronary Microcirculation Dysfunction in Patients With Early Coronary Artery Disease.

Background: Coronary microcirculation dysfunction can occur in patients with chest pain suggestive of coronary artery disease (CAD). The present study aimed to determine the diagnostic value of resting myocardial contrast echocardiography (MCE) for early CAD with myocardial microcirculation dysfunction by evaluating the continuous imaging time, peak time, and peak intensity.

Hypothesis: Resting MCE is an effective and noninvasive method for evaluation of coronary microcirculation dysfunction in patients with early coronary artery disease.

Methods: The present study included 20 consecutive patients without obvious clinical evidence of early CAD and 20 healthy volunteers. Resting MCE was performed to evaluate the myocardial microcirculation perfusion, and the follow-up evaluation of myocardial microcirculation perfusion was performed with technetium 99 m 2-methoxy-isobutyl-isonitrile ((99m) Tc-MIBI) single-photon emission computed tomography (SPECT).

Results: Peak intensity was significantly lower in patients with high risk of CAD than in controls (P < 0.0001). The peak time and continuous imaging time were significantly higher in patients with high risk of CAD than in controls (P < 0.0001). None of the 40 subjects experienced discomfort, such as cough and chest tightness, during the resting MCE procedure, and the heart rate and blood pressure showed no abnormalities during the entire procedure. SPECT imaging showed reversible myocardial perfusion reduction in 80% (16/20) of the patients with high risk of CAD. Abnormalities of heart rate and blood pressure and adverse reactions were noted during the process of SPECT examination.

Conclusions: Resting MCE is an effective and noninvasive method for detecting abnormalities of coronary microcirculation and can help in the clinical analysis, risk assessment, and treatment of early occult CAD.