the site and extent of intracranial blood on computed tomography scan, or the location of ruptured malformation, the extremely high incidence of cardiac arrhythmias, sometimes serious, in the acute period after subarachnoid haemorrhage and the absence of clinical and radiological predictors make systematic continuous ECG monitoring compulsory to improve the overall results of subarachnoid haemorrhage, irrespective of early or delayed surgical treatment.