Identification of the substrate of cardiac arrest

Approximately 40% of out-of-hospital cardiac arrest victims have the underlying substrate of acute myocardial infarction.4The issue of whether or not to give thrombolysis to these patients if they have received prolonged cardiopulmonary resuscitation (CPR) is a difficult one. Trials provide conflicting information about the incidence of serious haemorrhagic complications.5-8 Cited complications include haemothorax, and hepatic and retroperitoneal haemorrhage. The incidence of major bleeding is reportedly as high as 19%, although most studies cite much lower figures. It is reasonable to consider thrombolysis if there is a clear history of chest discomfort preceding collapse, and there is no indication that the patient has suffered head trauma or a primary intracerebral haemorrhage. A computed tomographic head scan may be required to clarify this. Thrombolysis is contraindicated if significant thoracic trauma has occurred, so it is sensible to examine a chestx ray before proceeding. As the benefits of thrombolysis may be partly offset by an increased risk of major haemorrhage after prolonged CPR, it should probably be reserved for patients with a widespread infarct territory (usually patients with anterior infarction), or infarction associated with haemodynamic compromise.8 If there is concern about the safety of thrombolysis, then primary angioplasty can be considered. Primary angioplasty and …