OBJECTIVE: Many previous studies have shown that electrocardiographic (ECG) changes occur patients with subarachnoid hemorrhage (SAH). This study was designed to identify the frequency, influencing factors, and outcome of clinically significant cardiac arrhythmias after SAH. METHODS: We retrospectively analyzed clinical data of 122 patients including ECG finding, age, sex, the Hunt-Hess grade, the Fisher's grade, the history of hypertension, peak blood pressure and heart rate, location of aneurysm, Glasgow Outcome Scale (GOS) score, the days of admission to the intensive care unit, the presence of symptomatic vasospasm. RESULTS: Of 122 SAH patients, 50% (n = 61) had a verified clinically significant arrhythmia. There were no statistically significant independent factors associated with clinically significant arrhythmia in multivariate analysis. Although adjustments for the effects of age, Hunt-Hess grade, and the presence of symptomatic vasospasm on death were made, clinically significant arrhythmias were still independently predictive of death (no arrhythmia versus arrhythmia, 11.5% versus 27.9%, adjusted odds ratio [OR] 3.524, 95% confidence interval [CI] 1.229-10.100, p = 0.019) and poor outcome (GOS < or = 2, 13.1% versus 29.5%, adjusted OR 3.202, 95% CI 1.174-8.732, p= 0.023). CONCLUSION: Clinically significant arrhythmias after SAH are associated with a high mortality rate, and serious cardiac and neurological comorbidity. Patients with an abnormal ECG on admission should undergo close cardiac monitoring, and the presence of rhythm disturbances should prompt aggressive measures to treat myocardial infarction (MI), maintain a normal cardiac rhythm, and minimize the presence of autonomic stress.