Summary

Background: Electrocardiography has a very low sensitivity in detecting dobutamine-induced myocardial ischemia.

Objectives: To assess the added diagnostic value of a new cardiac performance index (dP/dt^ejc) measurement, based on brachial artery flow changes, as compared to standard 12-lead ECG, for detecting dobutamine-nduced myocardial ischemia, using Tc99m-Sestamibi single-photon emission computed tomography as the gold standard of comparison to assess the presence or absence of ischemia.

Methods: The study group comprised 40 patients undergoing Sestamibi-SPECT[1]/dobutamine stress test. Simultaneous measurements of ECG and brachial artery dP/dt^ejc were performed at each dobutamine level. In 19 of the 40 patients perfusion defects compatible with ischemia were detected on SPECT. The increase in dP/dt^ejc during infusion of dobutamine in this group was severely impaired as compared to the non-ischemic group. dP/dt^ejc outcome was combined with the ECG results, giving an ECG-enhanced value, and compared to ECG alone.

Results: The sensitivity improved dramatically from 16% to 79%, positive predictive value increased from 60% to 68% and negative predictive value from 54% to 78%, and specificity decreased from 90% to 67%.

Conclusions: If ECG alone is used for specificity, the combination with dP/dt^ejc improved the sensitivity of the test and could be a cost-savings alternative to cardiac imaging or perfusion studies to detect myocardial ischemia, especially in patients unable to exercise