Electrocardiographic waveform analysis for predicting the success of defibrillation.

A new electrocardiographic predictor of the likelihood that an electrical shock would restore a perfusing rhythm is described. The intent was to develop a prognosticator that would be displayed during precordial compression. We anticipated that such a predictor would allow more selective timing of electrical shocks and reduce electrical injury to the myocardium caused by repetitive shocks. In a porcine model of cardiac arrest because of ventricular fibrillation, electrocardiographic recordings of ventricular fibrillation wavelets were analyzed and transformed into an amplitude spectrum area (AMSA). An AMSA value of 21 mV x Hz predicted restoration of perfusing rhythm with a positive predictive value equivalent to that of coronary perfusion pressure. More important, the negative predictive value that a shock would fail to reestablish spontaneous circulation was 96%. AMSA, therefore, has the potential for guiding optimal timing of defibrillation.