EVALUATION OF ELECTROCARDIOGRAPHIC CRITERIA FOR RIGHT ATRIAL ENLARGEMENT BY QUANTITATIVE 2-DIMENSIONAL ECHOCARDIOGRAPHY

Objectives. This study was conducted to evaluate the sensitivity and s pecificity of traditional electrocardiographic (ECG) criteria for righ t atrial enlargement and identify improved criteria, using quantitativ e two dimensional echocardiography. Background. Traditional ECG criter ia for right atrial enlargement, such as P pulmonale, have been increa singly criticized as insensitive and nonspecific. Quantitative two dim ensional echo-cardiography has been shown to be a useful method for ev aluating atrial size. Methods. Hospitalized patients with mild, modera te and severe right atrial enlargement were selected from our laborato ry's data base and compared with age and gender correlated hospitalize d control subjects. After exclusions, 100 patients with right atrial e nlargement and 25 control patients remained. Planimetric measurement o f right atrial volumes was accomplished by two independent observers u sing the single-plane method of discs algorithm. Electrocardiograms we re independently evaluated for current and newly proposed right atrial enlargement criteria. Results. Fifty two patients (52%) were in sinus rhythm, 41 were in atrial fibrillation, 5 were in atrial flutter, and 2 were in ectopic atrial rhythm. All control subjects were in sinus r hythm. The right atrial volume for the control group was 35.0 +/- 7.4 ml (mean +/- SD), with a narrow, roughly normal distribution. The righ t atrial volume for the patient group was 147.6 +/- 69.1 ml (median 12 7.2) in a wide, skewed distribution. The difference of mean values was highly significant (p = 0.0001). Right ventricular enlargement was fo und to some degree in all patients with right atrial enlargement. The most powerful predictors of right atrial enlargement were a QRS axis > 90 degrees, a P wave height in lead V-2 >1.5 mm and an R/S ratio >1 in lead V-1 in the absence of complete right bundle branch block. The co mbined sensitivity of these three criteria was 49%, with preservation of 100% specificity. P pulmonale detected only 6% of patients with rig ht atrial enlargement. Conclusions. Using quantitative two-dimensional echocardiography, we found that most previously reported ECG criteria far right atrial enlargement have low predictive power. The best pred ictors of right atrial enlargement were a P wave height >1.5 mm in lea d V-2 and, as new criteria, a QRS axis >90 degrees and an R/S ratio >1 in lead V-1 in the absence of complete right bundle branch block. The combined sensitivity of these three criteria was 49%, with preservati on of 100% specificity. Further studies are needed to prospectively va lidate these findings.