Introduction: Transtelephonic electrocardiographic transmission is a diagnostic technique which has been systematically applied in recent years, mainly for the detection of arrhythmias or pacemaker malfunction. The purpose of this study was to assess the efficacy of this method in the recording and transmission of ST segment and T wave changes.
Method: A Bruce protocol exercise stress test was carried out in 47 consecutive patients (39 males, eight females, age 53.1 +/- 11.5 years) with suspected coronary artery disease (CAD). At the same time, a transtelephonic ECG system, with a 2-min memory and the capability for 16.5 days continuous recording, was used to transmit the ECG (modified leads II and V5).
Results: A positive ST segment shift was observed in 19 patients (40.4%) during the exercise test. The transtelephonic system recorded this change in 18 of these patients but missed the anteroseptal ST segment depression (V2-V4) in one patient (sensitivity 94.7%). All of the 23 patients with no ST segment changes during the exercise test had a negative transtelephonic ECG transmission (specificity 100%). The width of the ST depression recorded from modified lead II on the transtelephonic recording was not significantly different from that of the 12-lead ECG. The same was true for modified lead V5.
Conclusion: Transtelephonic ECG transmission in patients with suspected CAD can significantly contribute to the investigation of this problem, since the method has high sensitivity and specificity. The capacity for continuous recording and the memory of the device make possible the monitoring of high risk patients for a good length of time.