High Prevalence of Clinically Important Echocardiographic Abnormalities in Patients with a Normal Electrocardiogram Referred for Transthoracic Echocardiography

Background: Normal electrocardiographic (ECG) results have been reported to be associated with a low prevalence of structural heart disease and thus may preclude the need for transthoracic echocardiographic (TTE) imaging. The goal of this study was to determine the prevalence of important TTE abnormalities in patients with a normal ECG referred for TTE imaging. Methods: Consecutive electrocardiograms over 6 months were reviewed. Patients with a normal ECG who underwent TTE imaging within 30 days formed the study group. TTE indication and appropriateness designation were determined. TTE findings were noted, including a composite, “major TTE abnormalities” (Maj TTE ABNs). Results: Of 26,254 electrocardiograms reviewed, 3,955 (15%) were normal, 522 with qualifying TTE studies. Maj TTE ABNs were common (27%). The most common TTE indication was signs or symptoms of congestive heart failure (17%), 35% of which had Maj TTE ABNs. Two echocardiographic indications were found to have significantly fewer of Maj TTE ABNs: palpitations (4%, P <.01) and preoperative evaluation before noncardiac surgery (6%, P <.01). A majority of TTE studies were appropriate (76%), with only 14% rarely appropriate. Maj TTE ABNs were less common in rarely appropriate compared with appropriate TTE studies (13% vs 30%, P <.01), with a very low prevalence of Maj TTE ABNs in outpatient rarely appropriate TTE studies (4%). Conclusions: Clinically important TTE abnormalities in patients with a normal ECG are common, suggesting that normal ECG results should not routinely preclude TTE imaging to identify structural heart disease. However, recognition of common clinical indications and application of the appropriate use criteria may identify patients with a normal ECG in whom TTE imaging is of very low yield.