Ambulatory electrocardiographic recordings at the time of fatal cardiac arrest.

The relation between arrhythmias at cardiac arrest and the outcome of arrest is poorly understood. The Holter monitor tracings of 13 patients were reviewed after they sustained an in-hospital cardiac arrest during ambulatory electrocardiographic monitoring. All had a prior cardiac arrest or cardiac syncope. Twelve patients had ventricular tachycardia (VT) as their initial arrest arrhythmia and 1 patient had bradycardia followed by ventricular fibrillation (VF). VT degenerated to VF in 10 of 12 patients after a mean interval of 96 +/- 31 seconds (+/- standard error of the mean). The number of VT runs increased significantly during the hour immediately preceding arrest (p = 0.004). Despite prompt resuscitation efforts in 12 patients, only 6 survived. The 6 survivors and 6 nonsurvivors were not different with regard to age, ejection fraction, extent of coronary artery narrowing and time to first defibrillation. However, degeneration to VF within 30 seconds of arrest (5 of 6 nonsurvivors and 1 of 6 survivors, p = 0.04) and a slower rate of VT at the onset of arrest (166 beats/min in nonsurvivors and 227 beats/min in survivors, p = 0.02) were associated with unsuccessful resuscitation.