Significance of T-loop change in vectorcardiographic diagnosis of left ventricular hypertrophy

Sex Differences in the Relationships Between Electrocardiographic Abnormalities and the Extent of Left Ventricular Hypertrophy by Echocardiography

BACKGROUND

Several criteria have been proposed for the electrocardiographic diagnosis of left ventricular hypertrophy (LVH). However, their diagnostic accuracy is questionable. Furthermore, the diagnostic accuracy of abnormalities in ST-T patterns for LVH is known to be uncertain, especially in women. We examined the relationship between electrocardiographic abnormalities and the extent of LVH.

METHODS

We studied 76 men and 48 women who satisfied electrocardiographic voltage criteria for LVH (RV(5) or RV(6)> or = 2.6 mV, SV(1) + RV(5) or SV(1) + RV(6)> or = 3.5 mV). They were classified into three groups based on ST-T pattern: normal, early strain, and strain. We defined echocardiographic evidence of LVH as an LV wall thickness > or = 12 mm.

RESULTS

LVH was identified by echocardiography in 55.3% of men and in 47.9% of women. In strain and early strain groups, the prevalence of echocardiographic LVH was significantly higher in men than in women (strain group: 100 vs 75%, P < 0.05, early strain group: 81.8 vs 42.1%, P < 0.05), it did not differ significantly between men and women in normal group. In men, QRS voltage values were significantly correlated with echocardiographic indices. In group strain of men, significant good correlations were observed between QRS voltage values and echocardiographic indices. However, in women, there were no significant correlation between QRS voltage values and echocardiographic indices even in strain group.

CONCLUSIONS

The combined criteria of both QRS voltage and ST-T classification could provide a greater accuracy in diagnosing LVH compared to the criteria using QRS voltage alone in men rather than in women.

Evaluation of electrocardiographic criteria for left ventricular hypertrophy based on anatomical comparison

The reliability of precordial electrocardiographic criteria for left ventricular hypertrophy (LVH) was evaluated by comparing it with the anatomical findings of 421 postmortem hearts examined by the chamber dissection technique. Of these 421 postmortem hearts, 136 without cardiovascular disease served as normal controls. The weights of the left ventricular free wall with interventricular septum (LV + S) and of the whole heart in normal controls were 153 +/- 36 grams (mean +/- SD) and 289 +/- 67 grams, respectively. Correlation coefficients between LV + S and whole heart were 0.89 for men and 0.90 for women. Anatomical LVH was defined as the weight of LV + S exceeding the average plus one standard deviation of that of a normal control heart. Anatomically established LVH was found in 99 (28%) of 353 cases having precordial electrocardiograms available for evaluation. The sensitivity, specificity, and predictive accuracy of electrocardiographic criteria for LVH were as follows: SV1 + RV5 greater than 3.5 mV, 56.6%, 76.0% and 47.9%; SV1 + RV5 greater than 4.0 mV, 45.5%, 87.4% and 58.4%; SV1 + RV5 greater than 5.0 mV, 21.2%, 94.5% and 60.0%; SV1 + RV5 greater than 3.5 mV with strain type ST-T, 35.4%, 93.3% and 67.3%; SV1 + RV5 greater than 4.0 mV with strain type ST-T, 29.3%, 94.9% and 69.0%; SV1 + RV5 greater than 5.0 mV with strain type ST-T, 14.1%, 98.0% and 73.7%; strain type ST-T, 36.4%, 92.5% and 65.5%; nonspecific ST-T, 26.3%, 76.4% and 30.2%; SV1 + RV5 greater than 3.5 mV with nonspecific ST-T, 12.1%, 93.3% and 41.4%; and right anteriorly directed T vector, 39.4%, 89.4% and 59.1%.(ABSTRACT TRUNCATED AT 250 WORDS)

Vectorcardiographic diagnosis of left ventricular hypertrophy

The vectorcardiographic diagnosis of left ventricular hypertrophy, using the Frank lead system, was evaluated in 93 autopsied male patients (70 with hypertrophy of the left ventricle and 23 without such hypertrophy). The criterion of the maximal QRS magnitude in the transverse plane greater than 2.2 mv below the age of 50 years and 1.8 mv at the age of 50 or more was positive in 61% of hypertrophied hearts and negative for all the nonhypertrophied hearts. The criterion of the T loop vector greater than H°-70° in the transverse plane was positive in 82% of 49 hypertrophied hearts and positive in one (7%) of 15 normal hearts for which the T loop was available.

The maximal QRS magnitudes in the frontal and sagittal planes had too low a sensitivity to be of value while the angles of the maximal QRS vector in the transverse and sagittal planes was too nonspecific to be useful.

By combining the QRS magnitude and the T loop vector in the transverse plane, the diagnosis of left ventricular hypertrophy was made in 90% of 49 hypertrophied hearts for which the T loop was available.