Quantitative Estimation of Right Ventricular Hypertrophy using ECG Criteria in Patients with Pulmonary Hypertension: A Comparison with Cardiac MRI

Abstract

In patients with pulmonary arterial hypertension (PAH), right ventricular mass (RVM) correlates linearly with pulmonary artery pressure, and decreases with successful treatment. Accurate measurement of RVM currently requires cardiovascular magnetic resonance (CMR) imaging. We therefore tested the relationship between RVM and a simple, 12 lead ECG-derived value, the Butler-Leggett (BL) score. This has previously been validated in patients with RV hypertrophy (RVH) due to mitral stenosis. We also tested the diagnostic accuracy of the BL score in detecting RVH. The Scottish Pulmonary Vascular Unit database was reviewed retrospectively. Twenty-eight patients with PAH were identified, in whom CMR and ECG data had been recorded no more than 28 days apart. All had completed a comprehensive clinical assessment, including right heart catheterization. CMR-derived absolute RVM and RV mass index (RVMI=RV mass/LV mass) were correlated against BL score. The ability of this score to detect RVH was tested using 2 x 2 contingency tables. RVM and RVMI correlated with BL score (r=0.77, P<0.001 and r=0.78, P<0.001, respectively). A BL score >0.7 mV proved a highly specific but insensitive indicator of RVH, based on either absolute RVM (sensitivity 74%, specificity 100%) or a high RVMI (sensitivity 61%, specificity 100%). The BL score, which can be defined using a standard 12-lead ECG, correlates with RVM and RVMI in patients with PAH. A score >0.7 mV was a highly specific but insensitive indicator of RVH in these patients.

Changes in Right Ventricular Function Measured by Cardiac Magnetic Resonance Imaging in Patients Receiving Pulmonary Arterial Hypertension–Targeted Therapy

“…CMRI is superior to radionuclide imaging because it does not require ionizing radiation and superior to electrocardiography because it is more sensitive. 39 There is also some evidence to suggest that N-terminal B-type natriuretic peptide measurements reflect changes in CMRI-determined RV structure and function in patients with PH, 33,39 but the potential of this noninvasive marker as a surrogate for outcome remains to be demonstrated. 40 The study had some limitations.…”

Validity of the Surface Electrocardiogram Criteria for Right Ventricular Hypertrophy

“…59 Uniformly, in much smaller groups of patients (ranging from n=23 to n=38) than our study, various criteria for RVH have been examined, including the AHA recommended criteria. Similar to prior published work, these studies were in patients with known RVH 56–58 or, based on clinical risk factors, were at high risk for pulmonary hypertension. 59 Investigators found low sensitivity and insufficient specificity to be clearly useful in identifying RVH.…”

“…16 A more recent study compared this same criterion to the gold standard of cMRI in 28 patients known pulmonary arterial hypertension and confirmed high specificity but with similarly low sensitivities of 64–71%, depending on the definition of RVH used. 56 …”

“…Several recent studies have aimed to examine the usefulness of ECG in the diagnosis of RVH as measured by cMRI 56–58 or elevated pulmonary arterial pressures. 59 Uniformly, in much smaller groups of patients (ranging from n=23 to n=38) than our study, various criteria for RVH have been examined, including the AHA recommended criteria.…”

The comparative relationships between locations of the papillary muscles and electrophysiologic QRS axis in patients with atrioventricular septal defect and common as opposed to separate orifices in the valve guarding the common atrioventricular junction

“…It was shown previously that isolated right ventricular pressure overload, due to pulmonary hypertension, alters the balance of QRS forces and causes right axis deviation. 7 With only the right ventricular volume overload produced by the so-called "ostium secundum" atrial septal defect, however, there is well-documented absence of right axis deviation. 8,9 Only the patients with defects permitting ventricular shunting, therefore, would be expected to have the increase in right ventricular wall tension that would affect its ventricular gradient sufficiently to alter both its depolarisation and repolarisation.…”