OBJECTIVE. Although the electrocardiogram is commonly obtained in the evaluation of patients with pulmonary hypertension, its value as a screening test for right ventricular hypertrophy or pulmonary hypertension is unclear. Therefore, we sought to determine the value of an electrocardiogram in the diagnosis of right ventricular hypertrophy using echocardiography as the gold standard.
METHODS. We identified children without congenital heart disease who underwent evaluation for suspected pulmonary hypertension that included both an electrocardiogram and echocardiography within a specified time frame.
RESULTS. A total of 76 echocardiography-electrocardiogram pairs for pulmonary hypertension were identified. Although there was a significant relationship between electrocardiogram and echocardiography evidence of right ventricular hypertrophy, the sensitivity of an electrocardiogram in diagnosing echocardiography-documented right ventricular hypertrophy was only 69%, and the positive predictive value was 67%. There was no relationship between electrocardiogram changes and Doppler tricuspid regurgitation gradient.
CONCLUSION. Despite a statistically significant relationship between an electrocardiogram and echocardiography in the diagnosis of right ventricular hypertrophy, an electrocardiogram has limited value as a screening tool for right ventricular hypertrophy because of its relatively low sensitivity and positive predictive value.
Patients with pulmonary hypertension represent a diverse group for whom management is often dictated by the presence of right ventricular (RV) hypertrophy (RVH). Electrocardiography (ECG) and echocardiography are tests used to noninvasively assess RVH. The ECG is a common screening test in patients with suspected or known pulmonary hypertension, because ECG criteria for RVH have been established and used for decades.1,2 Despite the frequent use of ECG, its value as a screening test is unknown. Echocardiography, on the other hand, has been shown to correlate well with RVH when compared with autopsy and MRI.3–5 In addition, the Doppler tricuspid regurgitation (TR) velocity is useful for the estimation of RV and pulmonary artery systolic pressure.6,7 Therefore, we sought to determine the value of ECG in the diagnosis of RVH using echocardiography as the gold standard.
The institutional review board of the University of Utah School of Medicine approved this retrospective study. The echocardiography database was used to identify all of the patients undergoing echocardiography specifically ordered for suspected pulmonary hypertension between 2002 and 2004. Criteria for inclusion were: (1) 6 months old to 18 years, and (2) echocardiograms matched with ECGs within a 2-month interval for patients <18 months of age and within 4 months in patients >18 months. When >1 echocardiography-ECG pair was available for a given patient, only the first pair was used. Exclusion criteria at presentation were the presence of congenital heart disease and presence of a bundle branch block pattern of ECG. The medical charts were reviewed for patient age, weight, and body surface area at the time of the echocardiography and dates of echocardiography and ECG.
ECGs had been performed and then stored using the Marquette MUSE database. Criteria for RVH were modified from Davignon et al.1 Fulfillment of ≥1 of the following criteria resulted in an ECG diagnosis of RVH: (1) R-wave in V1 or V3r > 98th percentile for age; (2) S-wave in V6 > 98th percentile for age; (3) upright T-wave in V1 (patients <10 years); (4) rSR′ pattern in V1 or V3r (R′ >15 mm if <1 year or >10 mm if >1 year); and (5) qR pattern in V1 or V3r.
Two-dimensional and Doppler echocardiography were performed using an Acuson Sequoia (Acuson, Mountain View, CA) or a Hewlett Packard Sonos 5500 system (Agilent, Andover, MA) with images recorded on 0.5-in videotape. Echocardiographs were reviewed, and optimal images were selected for offline measurements. The RV diastolic anterior wall thickness was measured from subcostal imaging and compared with established normals for assessment of RVH (Fig 1). 5,8 RV systolic pressure was calculated from the Doppler TR gradient in the apical 4-chamber view using the Bernoulli equation, and 5 mmHg was added as an estimate of central venous pressure for calculation of the systolic pulmonary artery pressure. Pulmonary hypertension was defined in this study as RV systolic pressure ≥40 mmHg. This value was chosen based on the criteria established by the World Health Organization Symposium on Primary Pulmonary Hypertension (1998), which defines mild pulmonary hypertension as a systolic pulmonary artery pressure of 40 to 50 mmHg.
All of the values are expressed as mean ± SD. Statistical significance was inferred when P was < .05. Statistical analyses were performed using Minitab (Minitab Inc, State College, PA). Spearman rank correlation was used to compare Doppler TR gradient in patients with and without ECG and echocardiography evidence of RVH. A χ2 test was used to assess the relationship between ECG diagnosis of RVH and echocardiography diagnosis of RVH. Sensitivity, specificity, and positive and negative predictive values were calculated.
Of 625 echocardiographs performed for pulmonary hypertension during the study period, 228 were performed on patients between 6 months and 18 years, and 113 echocardiograms had an ECG within the specified time period. Of these 113 echocardiography-ECG pairs, 76 were performed on individual patients meeting inclusion criteria, and they formed the study group. Their ages ranged from 6 months to 17.6 years (5.7 ± 5.0 years), weight from 3.2 to 86.2 kg (22.2 ± 18.0), body surface are from 0.2 to 2.0 m2 (0.8 ± 0.4 m2), and 61% were boys.
There was a significant relationship between ECG and echocardiographic evidence of RVH (P < .0001). Of the 26 patients with echocardiographic evidence of RVH, 18 had RVH by ECG giving a sensitivity of 69%. Of 50 patients with no evidence of RVH by echocardiography, 41 had a normal ECG yielding a specificity of 82%. The positive predictive value of ECG for identifying echocardiographic RVH was 67% (18 of 27), and the negative predictive value was 84% (41 of 49; Table 1). For the 47 patients with measurable TR, there was no relationship between TR gradient and evidence of RVH diagnosed by ECG (Fig 2). However, there was a statistically significant relationship between TR gradient and echocardiographic evidence of RVH (P < .001).
Despite a statistically significant relationship between ECG and echocardiography in the diagnosis of RVH, ECG has limited value as a screening tool for RVH because of its relatively low sensitivity and positive predictive value. Pulmonary hypertension is a common cause of morbidity in childhood with occasional mortality.9 Recent history has shown improved survival with earlier diagnosis and more aggressive management strategies.10 Tailoring therapy depends on determining pulmonary artery pressure and its effect on the RV myocardium. As a result, ECG and echocardiography have become standard for the workup and assessment of pulmonary hypertension.2 Although cardiac catheterization may be necessary for an assessment of pulmonary vasoreactivity,11 ECG and echocardiography have the advantage of being noninvasive and readily available, allowing them to be used both for screening and for serial follow-up studies. Compared with ECG, however, echocardiography is expensive and may require the use of sedation. Therefore, ECG is often selected on the premise that it provides similar and reliable information.
Although our study showed a significant relationship between RVH identified by ECG and echocardiography, the positive predictive value of ECG changes for echocardiographic RVH was only 67% with a similarly low sensitivity of 69%. These findings are similar to other studies in patients with heart disease questioning the diagnostic value of ECG patterns of RVH.12,13 Furthermore, there was no relationship between Doppler-estimated RV pressure and the presence of RVH by ECG. Therefore, ECG does not provide similar information to echocardiography in the evaluation of patients with suspected pulmonary hypertension and must be used cautiously as a screening test. This study is limited by the retrospective design. Patients under 6 months were not studied, because their ECG parameters evolve during this time. Nineteen patients did not have TR, limiting the size of the sample used for assessing the role of ECG in evaluating pulmonary hypertension.
- Accepted April 3, 2006.
- Address correspondence to Michael D. Puchalski, MD, University of Utah, Primary Children's Medical Center, 100 N Medical Dr, Salt Lake City, UT 84113. E-mail:
The authors have indicated they have no financial relationships relevant to this article to disclose.
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- Prakash R. Determination of right ventricular wall thickness in systole and diastole. Echocardiographic and necropsy correlation in 32 patients. Br Heart J.1978;40 :1257– 1261
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- Copyright © 2006 by the American Academy of Pediatrics