O0008: Right Atrial Enlargement on ECG. Does It Matter?

Background: Right atrial enlargement (RAE) criteria on ECG have been established. This is defined as a p wave amplitude greater than 2.5mm in any lead, usually on lead II. These criteria have been shown to poorly correlate with RAE on echocardiogram in adults. However, no studies have been done to evaluate these criteria in pediatrics.

Methods: We performed a single center retrospective review of pediatric patients with 1) ECGs that were read as RAE by a pediatric cardiologist and 2) had echocardiograms obtained within 90 days of the ECG. Patients with known congenital heart disease (CHD), heart transplant, cardiomyopathy and critical/chronic illness were excluded. ECGs were reviewed by an electrophysiologist to confirm RAE and determine which leads met criteria. The echocardiograms were then reviewed and RA measurements with Z-scores obtained. A Z-score >2 for right atrial volume, area, long axis length or short axis length was considered positive for RAE by echocardiogram. Numeric variables were compared via Mann-Whitney U test and categorical variables were tested via Fisher’s Exact test.

Results: A total of 162 patients were included in the study (Table 1). The median age was 10.8 years (0.6-15.4). A total of 23 patients were positive for RAE by echocardiogram. This gives an overall positive predictive value (PPV) of 14% for RAE on ECG. However, 65% of the patients in the positive group were less than 1 year of age, making the PPV in this population 33%. Above the age of 1 year, only 7% were found to have RAE. In the positive group, patients were more likely to meet criteria for RAE in the anterior precordial leads (V1-V3) compared to the negative group (48% vs 5%, p< 0.001) and more likely to meet criteria for right ventricular hypertrophy (RVH) (22% versus 6%, p=0.023).
A total of 30 patients (19%) were newly diagnosed with CHD. Of these, 17 patients (57%) were positive for RAE on echo, 12 (71%) < 1 year of age. The CHD group was also more likely to meet criteria for RAE in the anterior precordial leads (42% vs 14%, p< 0.001) and to have RVH (29% vs 7%, p value=0.015) compared to those without. In patients >1 year with isolated RAE on ECG, the PPV for detecting CHD is 4%.

Conclusion: This study demonstrates that RAE on ECG in patients < 1 year of age is more likely to be associated with true RAE on echocardiogram. These findings suggest that an echocardiogram should be performed in patients < 1 year of age with RAE in any lead or for pediatric patients >1 year with RAE in the anterior precordial leads and associated RVH. Above 1 year of age, isolated RAE on ECG has a low PPV for detecting CHD.