The effect of mild dynamic exercise on the electromechanical systole of heart in non-athlete, healthy first year medical students of Bengal as a predictive biomarker of arrhythmia

Introduction and Aim: Measurement of Systolic Time Intervals (STIs) is a non-invasive and convenient way of assessing left ventricular electro-mechanical activity. In this study, we assessed effect of mild dynamic exercise on QT, QS2, QT/QS2 ratio, QS2-Index among healthy young first year students at a government medical college of West Bengal, India and compared the same among girls and boys. Materials and Methods: IX-TA-220 multichannel recorder was used to record Electrocardiogram, Phonocardiogram and Carotid pulse tracing among 180 subjects before and after 1 minute of mild exercise with Harvard's Step of 30 cm height with metronome rhythm of 120 beats per minute. Results were analyzed by Microsoft Excel and comparison of each parameter between boys and girls were done using SPSS software in two hemodynamic states. P-value <0.05 was taken as statistically significant. Results: Post exercise mean QT and QS2 shortened and their ratio QT/QS2 increased. There was a statistically significant difference between pre-exercise and post-exercise mean QT, QT/QS2 ratio, QS2 index and significant differences were observed between mean values of the boys and girls. Conclusion: With hemodynamic changes as in exercise, due to sympathetic stimulation & catecholamine release, both QT andQS2 should reduce as all the phases of systole shorten but if QT does not reduce in comparison to QS2 it may lead to arrhythmia in future. Hence QT/QS2 can be a useful pro-arrhythmic biomarker and may complement ECG and Echocardiography in borderline cases.