The Role of the Electrocardiogram in Pregnant Individuals with Chronic Hypertension

OBJECTIVE: The American College of Obstetricians and Gynecologists suggests that an electrocardiogram is an acceptable first-line test. We sought to examine whether an electrocardiogram is a sufficient screening tool to identify echocardiogram-diagnosed left ventricular hypertrophy. We also sought to determine risk factors associated with left ventricular hypertrophy. STUDY DESIGN: This was a retrospective cohort study of pregnant individuals with chronic hypertension who delivered at 20 weeks' gestation or greater at a tertiary care center. Analyses were limited to individuals who had both electrocardiogram and echocardiogram during pregnancy. Left ventricular hypertrophy was diagnosed using the American Society of Echocardiography guidelines. Maternal demographics and electrocardiogram results were compared between individuals with left ventricular hypertrophy and those without left ventricular hypertrophy. The sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of the electrocardiogram to identify left ventricular hypertrophy were also calculated. Adjusted odds ratios (aORs) with 95% confidence intervals (95% CIs) were calculated, controlling for covariates. RESULTS: Of 172 individuals, 60 (34.9%) had left ventricular hypertrophy. The sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of the electrocardiogram to identify echocardiogram-diagnosed left ventricular hypertrophy was 18.3% (95% CI: 9.5-30.4), 91.1% (95% CI: 84.2-95.6), 2.05 (95% CI: 0.93-4.56), and 0.90 (95% CI: 0.78-1.02), respectively. Compared with individuals without left ventricular hypertrophy, those with left ventricular hypertrophy were more likely to have hypertension of 4 years' duration or longer (aOR = 4.01; 95% CI: 1.71-9.42), unknown duration of hypertension (aOR = 4.66; 95% CI: 1.28-17.04), and higher body mass index (aOR = 1.04; 95% CI: 1.01-1.07). After adjusting for covariates, left ventricular hypertrophy by electrocardiogram was not associated with actual left ventricular hypertrophy (aOR = 2.59; 95% CI: 0.94-7.10). CONCLUSION: Electrocardiogram was not a sufficient test for identifying left ventricular hypertrophy in pregnant individuals with chronic hypertension. We suggest an echocardiogram evaluation for all individuals with chronic hypertension. KEY POINTS: · The first-line test for cardiac evaluation is an electrocardiogram.. · In our cohort, the rate of left ventricular hypertrophy was 35%.. · The electrocardiogram was not sensitive to detect left ventricular hypertrophy..