The Importance of the Electrocardiogram in TIA Evaluation
Background: Current guidelines recommend the use of the electrocardiogram (ECG) in the evaluation of patients with TIA, but data supporting its value in acute management are sparse. Methods: Patients who presented to one of 16 emergency departments in an HMO in Northern California and received a diagnosis of TIA March 1997 through February 1998 were enrolled. Patients were followed for 90 days after presentation with TIA. Clinical, demographic and outcome information were obtained from computerized databases and review of medical records. A cardiovascular event was defined as a hospitalization or death due to myocardial infarction, ventricular arrhythmia, congestive heart failure, or unstable angina. Stroke and recurrent TIA required neurologist confirmation. Analyses were performed with chi-square tests and multivariable logistic regression, adjusting for other clinical predictors with stepwise elimination of variables not contributing (p>0.10). Results: In a cohort of 1327 TIA patients with ECGs performed at presentation, there were 39 cardiovascular events, 145 strokes, 182 recurrent TIAs, and 34 deaths during 90-day follow-up. ECG revealed a new diagnosis of atrial fibrillation in 28 patients (2%). The risk of cardiovascular events was greater in those with any abnormal ECG findings (4.2% vs. 0.6%, p<0.001). The association remained significant after adjustment for medical history and signs (OR 6.8, 95% CI 1.6–28.5, p=0.009). Left ventricular hypertrophy, atrial fibrillation, and atrioventricular conduction abnormalities were each independently associated with more than doubling of risk of cardiovascular events. Abnormal ECG findings were not significantly associated with risk of stroke or death. Conclusions: Short-term cardiovascular morbidity is substantial after TIA. ECG reveals new atrial fibrillation in a significant portion of TIA patients, and can identify a group of patients that is at a substantially higher risk of short-term cardiovascular events. Urgent cardiac evaluation is probably indicated in TIA patients with abnormal ECGs.