Subarachnoid hemorrhage (SAH) occurs primarily during early to mid-adulthood; approximately 30% of individuals with SAH die within 2 weeks, and mortality is 30% to 45%. SAH happens suddenly, without patients being aware of previous heart abnormalities. Here, we performed a pilot single cohort (historical) study to examine the hypothesis that early abnormal electrocardiographic (ECG) changes may reveal unknown but “silent” heart pathologies in SAH patients without previous heart disease (PHD). Data were collected retrospectively on 56 consecutive patients during the acute phase of SAH (29 men, 27 women; mean age 49.0 ± 6.2 years) with different degrees of neurologic deficit (Hunt-Hess scale assessment) in a 2-year period single-cohort study. Repolarization abnormalities were most frequent (p<0.05) and were independent of a history of PHD, although it corresponded to a higher risk for such abnormalities (odds ratio OR=3.21; CI95%=1.01–10.22). ECG changes in patients without PHD were similar to those in PHD patients, confirming the hypothesis that SAH is associated with previously “silent” heart pathology. The increased frequency of ECG changes in PHD patients and their high incidence in no-PHD patients suggested a neurogenic form of myocardial dysfunction following SAH. Notably, repolarization changes were more frequent in patients with less severe deficit (p<0.05), whereas rhythm and conductive abnormalities were more frequent in patients with more severe neurologic deficit.