Association between early post-resuscitation heart rate and survival with neurological recovery in a pig model of cardiac arrest

Heart rate (HR), a readily available clinical parameter, has proven prognostic value in cardiovascular disease and may provide similar insights following cardiac arrest. This study investigated whether post-resuscitation HR might predict functional recovery in a preclinical porcine model of cardiac arrest and cardiopulmonary resuscitation (CPR). Retrospective analyses were conducted in data from earlier prospective animal studies. Ninety-six pigs successfully resuscitated after 8 to 12 min of ischemically induced ventricular fibrillation, followed by 5 min of CPR prior to defibrillation attempt, were included in the study. HR, arterial and central venous pressures were continuously monitored for 4 hrs after resuscitation. Survival with neurological function was assessed up to 96 hrs post-resuscitation by the optimal performance category (OPC) score, with 1-2 considered as good outcome and 3-5 as poor outcome. Fifty-four animals (56%) presented a 96-hr good outcome, while 42 (44%) had a poor outcome. Animals with favourable neurological outcome showed significantly lower HR during the 4-hr post-resuscitation period compared with those with poor outcome (p<0.01). Lower HR, shorter no-flow and low-flow durations, higher diastolic, mean, and coronary perfusion pressures were associated with good outcome. However, only HR was an independent predictor of good neurological recovery (OR 0.971 [0.947-0.995] per 1 bpm increase); a HR > 135 bpm predicted poor outcome with 80% sensitivity and 70% specificity. In this model, lower post-resuscitation HR was independently associated with survival with favourable neurological recovery.