ISSN: 1223-1533

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RECEIVER  OPERATING CHARACTERISTIC ANALYSIS TO DETECT THE CUT-OFF VALUES OF ELECTROCARDIOGRAM VARIABLES FOR PREDICTION OF PATIENTS WITH LIKELIHOOD OF CARDIAC MEMORY AFTER VENTRICULAR EXTRASYSTOLES


Authors: Aly Hegazy, Mohamad Al-Kandary




 

Objective: Identify cut-off values of electrocardiogram-derived variables for prediction of likelihood of cardiac memory using of ROC curve analysis.

 

Methods: One hundred patients with ventricular extrasysoles were included and performed stress perfusion scintigraphy. ROC curve was performed for assessment electrocardiogram-derived variables, voltage of T wave, resolution time of T wave inversion, heart rate corrected QT interval, U wave, coupling interval and pause after PVC S.

 

Results: Predictive indices revealed that asymmetrical T wave inversion after PVC’S <5 seconds can be considered as indicator for prediction of cardiac memory as sensitivity was 80%, specificity =73% , accuracy =78% positive predictive value =83% and negative predictive value=69%.

ROC curve data revealed that cut-off value of voltage of T wave was <0.4 mV for prediction of likelihood of cardiac memory with sensitivity=87% , false positive =18% , the area under curve was 0.849, and probability of error was 30%, cut-off value of resolution of  T wave inversion was <5 sec with sensitivity =84% , false positive =19% , area under curve was 0.832 and probability of error was 40%, cut-off value of heart rate corrected QT interval was <460 sec with sensitivity=74% , false positive =28%, area under curve was 0.784 and probability of error was 48%. cut-off value of voltage of U wave was <0.3 with sensitivity=80% , false positive =28%, area under curve was 0.780 and probability of error was 50%, cut-off value of coupling interval was <80 msec with sensitivity=86% , false positive =30%, area under curve was 0.750 and and probability of error was 60%, cut-off value of sinus pause was <90 msec with sensitivity=75% , false positive =35%, area under curve was 0.719 and probability of error was 60%.

 

Conclusion: ROC analysis & ventricular repolarization-derived variables can be used to predict patients with cardiac memory after ventricular extrasystoles. Predictive indices revealed that rapid resolution of T wave inversion and shallow T wave inversion are considered as indicators for prediction of cardiac memory. Kappa coefficient value (K) indicated that there was a good agreement between rapid resolusion of T wave inversion , shallow T wave inversion and prolonged QT interval and normal perfusion scintigraphy (K=0.827, 0.793 & 0.765, respectively).