Incremental diagnostic value of color M-mode propagation velocity of the descending thoracic aorta to exercise electrocardiography

OBJECTIVES
Exercise electrocardiography test (EET) has limited sensitivity and specificity. Recently, color M-mode-derived propagation velocity of the descending thoracic aorta (APV) has been shown to be associated with coronary artery disease (CAD). We evaluated the incremental value of APV for better prediction of CAD in EET-positive patients.

STUDY DESIGN
Color M-mode APV was measured in 342 patients undergoing EET for chest pain and an intermediate likelihood of CAD. Coronary angiography was performed in 199 patients having a positive EET.

RESULTS
The mean APV was 44.5±20.8 cm/sec in patients with a positive EET compared to 63.5±19.6 cm/sec in those with a normal test. Significant CAD was detected in 134 patients (67.3%), involving one vessel (n=41), two vessels (n=52), and three vessels (n=41). Patients with CAD had significantly lower APV values compared to patients with normal coronary arteries (33.8±13.2 vs. 66.6±15.6 cm/sec, p<0.001). An APV value of ≤41 cm/sec predicted CAD with 85.1% sensitivity and 93.8% specificity. An APV of >61 cm/sec had 94% specificity for the estimation of normal coronary arteries. A threshold of >41 cm/sec and a threshold of >61 cm/sec would have avoided unnecessary coronary angiography in 30.7% (61/199) and 21.6% (43/199) of patients with a positive EET but high APV values, with negative predictive values of 75.3% and 84.3%, respectively. In correlation analysis, APV was significantly correlated with Duke treadmill score (r=0.587, p<0.001) and the number of coronary vessels involved (r=-0.767, p<0.001), but not with any of the echocardiographic parameters.

CONCLUSION
Measurement of APV may improve diagnostic value of EET and may be specifically valuable to exclude false positive EET results, leading the physician to other noninvasive tests for further evaluation of CAD probability.