Left ventricular hypertrophy as a risk factor in arterial hypertension

Abstract

Data on the evolution and prognostic implications of left ventricular hypertrophy (LVH) determined by ECG, chest X-ray and echocardiogram in the Framingham Study are reviewed. Echocardiographic examination provides the most sensitive and specific measure of left ventricular hypertrophy, providing a quantitative evaluation of the anatomical condition. Chest X-ray evaluation is also more sensitive than the ECG, but less specific than the echocardiogram. When ECG-LVH is present, X-ray and echocardiographic LVH are often found; but, when negative, the ECG clearly does not exclude anatomical LVH. The incidence of each variety of LVH increases with age, weight and blood pressure. Although it may also appear following coronary heart disease (CHD), valvular deformity and congenital cardiac defects, the former are the major determinants of LVH in the general population. Each contributes independently to the occurrence of LVH. LVH has emerged as a powerful non-invasive indicator of increased vulnerability to the occurrence of major cardiovascular disease outcomes in hypertension. It appears that X-ray and echocardiographic LVH measure anatomical hypertrophy, whereas the ECG variety is also indicative of ischaemic myocardial involvement when repolarization abnormality is present. Hypertension clearly predisposes to both anatomical and ECG-LVH which cannot be taken as an incidental compensatory feature since at any blood pressure those with ECG-LVH, X-ray or echo LVH are distinctly more prone to cardiovascular sequelae. ECG-LVH carries a greater risk than anatomical (X-ray) LVH. ECG-LVH with repolarization abnormality is more dangerous than that with voltage alone. The latter appears to reflect chiefly the severity and duration of accompanying hypertension. There are no cardiovascular sequelae unique to either anatomical or ECG-LVH, but the ECG variety carries a substantially greater risk of cardiovascular events, particularly for coronary disease. Also, on cross-classification each is found to add to the risk of the other with ECG-L VH adding more to the risk than the concomitant anatomical hypertrophy. The combination confers the highest risk. Risk ratios associated with ECG-LVH are substantial and greatest for cardiac failure and stroke, but CHD is the commonest and most lethal sequela. ECG-LVH carries a risk as great as ECG-MI (ECG-myocardial infarction) and predisposes strongly to sudden death. Anatomical and ECG-LVH appear to make the myocardium more irritable, generating dangerous arrhythmias. Once an MI has occurred, ECG-LVH or X-ray LVH each independently contributes to recurrences or other adverse outcomes. LVH is reversible, the anatomical variety more so than the ECG, and the reversion of anatomical LVH appears to confer greater benefit than improvement of the ECG version.