[Primary heart arrest during dynamic ECG in the myocardial infarct patient during convalescence. Contribution of 4 cases].

Four cases of cardiac arrest occurred during Holter monitoring are described. All patients had sustained an acute myocardial infarction thirteen-fourteen days prior to recording and were fully mobilized. In all of them the fatal arrhythmic event was ventricular fibrillation (VF). ECG analysis revealed an increase in heart rate before initiation of VF in one patient only. Warning ventricular arrhythmias were present in two patients. Transient ST segment changes during monitoring were noted in all patients. In three cases the arrhythmia was initiated by an ectopic ventricular beat (EVB) with R-on-T phenomenon; in two of them the EVB occurred after a sinus beat following a long post-ectopic pause. The different electrical events able to induce VF showed a variable and unpredictable pattern of occurrence and association in different patients and at different times in the same patient. Therefore, no specific "trigger" of the fatal arrhythmia could be identified.