Electrocardiographic identification of left ventricular hypertrophy: test performance in relation to definition of hypertrophy and presence of obesity.

OBJECTIVES: This study sought to assess a test performance of the electrocardiogram (ECG) in relation to 1) varying definitions of left ventricular hypertrophy based on different methods of adjusting left ventricular mass for body size, and 2) the presence or absence of obesity.
BACKGROUND: Although left ventricular mass is most commonly indexed for body surface area or height when defining left ventricular hypertrophy, recent work suggests that normalization for height to the power of 2.7 (height2.7) may decrease variability among normal subjects and correctly identify the impact of obesity on hypertrophy.
METHODS: The product of Cornell voltage and QRS duration (Cornell product) and Framingham-adjusted Cornell voltage were determined from 12-lead ECGs in 212 patients. Left ventricular hypertrophy was defined on the basis of left ventricular mass indexed to body surface area, height and height2.7.
RESULTS: Using partitions with matched specificity of 95%, the sensitivity of ECG criteria varied with the definition of hypertrophy, ranging from 39% to 52% for the Cornell product and from 24% to 33% for adjusted Cornell voltage. When left ventricular mass was indexed to body surface area or to height2.7, the 52% and 39% sensitivities of the Cornell product were significantly greater than the 24% (p < 0.001) and 29% (p < 0.05) sensitivities of adjusted Cornell voltage, with a similar trend when left ventricular mass was indexed to height (43% vs. 33%, p = 0.10). Comparison of receiver operating characteristic curves confirmed the superior overall performance of the Cornell product relative to adjusted Cornell voltage for hypertrophy defined by body surface area and height2.7 and demonstrated greater reproducibility of overall performance, as measured by the coefficient of variability, for the Cornell product (1.7%) than for adjusted Cornell voltage (5.8%). Sensitivity of adjusted Cornell voltage was significantly greater in obese than in nonobese subjects (50% to 59% vs. 18% to 24%, p < 0.01), but the Cornell product had only minimally higher sensitivity in nonobese than in obese subjects (40% to 54% vs. 32% to 44%, p = NS).
CONCLUSIONS: The ability of ECG criteria to detect left ventricular hypertrophy differs depending on the method of indexing left ventricular mass for body size and with the presence or absence of obesity. Further, the Cornell product provides the best combination of overall accuracy and low variability of performance between definitions of hypertrophy. These findings have important implications for the clinical and epidemiologic use of 12-lead ECG criteria for the detection of left ventricular hypertrophy.