[Relationship of the duration of QT interval and corrected QT interval in patients with coronary heart disease and the cause of the bicycle ergometer test cessation].

AIM

To comparatively study Q-T interval duration in groups of patients with coronary heart disease (CHD) identified by the cause of exercise test cessation.

MATERIALS AND METHODS

Bicycle ergometric test (BET) was performed in 93 males with CHD (functional class II-III angina pectoris on exertion). During BET, ECG recorded in the leads, as described by Nebu. The QT interval was visually measured in one lead. This interval was determined as a distance between the onset of a Q wave and the end of a T wave (in mlsec). The mean value by 3 cardiac cycles was taken as an actual value of the QT interval. To compare the duration of the QT interval at different rates of cardiac rhythm, its corrected value (QTc) was calculated.

RESULTS AND CONCLUSION

In case of positive BET (anginal attack, 1-mm or more depressed ST segment at a distance of 0.8 cm from the joint J), the values of QT and QTc measured at rest and peak exercise were greater than those if the cause of test cessation was the submaximum heart rate or a patient's fatigue. The value of QTc was higher if the cause of BRT cessation was 1-mm or more depressed ST segment preceding an anginal attack or the only cause of test cessation.