3. Estimation of Coronary Flow Reserve Capacity Using Transthoracic Doppler Echocardiography and the Cold Pressor Test is Useful for Diagnosing Variant Angina

Abstract

Background

The cold pressor test (CPT) has been used to detect vasospastic angina, but its sensitivity for predicting vasospasm is low. The aim of this study was to determine if the estimation of coronary flow reserve capacity in the left anterior descending coronary artery using transthoracic Doppler echocardiography (TTE) and CPT can predict coronary artery spasm.

Methods

A provocation test of coronary artery spasm using acetylcholine (50 and 80 µg) was performed in 65 subjects (52±10yrs, M:F = 41:24) with chest pain and normal coronary angiograms. Before and during CPT, the peak (PDV) and mean diastolic flow velocity (MDV) of the distal left anterior descending coronary artery were estimated using high frequency TTE (Figure), and ECG, blood pressure, and symptoms were monitored every minute. CPT%PDV and CPT%MDV were defined as the % change of PDV and MDV during CPT, respectively. The subjects were divided into two groups??(Spasm+group, 31) and (Spasm-group, 34)]?? and compared.

Results

1. The CPT%PDV was 52.75±24% in the Spasm-group and 4.99±23.62% in the Spasm + group (p<0.001). 2. The CPT%MDV was 50.22±27.83% in the Spasm-group and 6.83±23.81 in the Spasm+group (p<0.001). 3. TheCPT%PDV<31.1% had a sensitivity of 93.5% and a specificity of 90% for predicting coronary artery spasm (95% CI:0.939-0.979, p<0.001). 4. The CPT%MDV<30.55% had a sensitivity of 90% and a specificity of 76.5% for predicting coronary artery spasm (95% CI:0.884-0.950, p<0.001).

Conclusion

Estimation of coronary flow reserve capacity using TTE and CPT is a promising noninvasive test for predicting variant angina.