Importance of left ventricular mass as a predictor of cardiovascular morbidity in hypertension

Arterial hypertension is a powerful risk factor for cardiovascular disease, but the ability to use blood pressure measurements to predict complications in individual patients or small groups is limited. One possible approach to identifying hypertensive patients at high risk is based on the observation that the presence of electrocardiographic left ventricular hypertrophy (ECG-LVH) identifies individuals at severalfold higher risk than other individuals with similar blood pressure but no ECG-LVH. The suggestion that the increased risk associated with ECG-LVH is related to increased left ventricular (LV) mass has been supported by autopsy studies in which heart weight was found to be increased in patients dying of cardiovascular diseases. Unfortunately, the usefulness of LVH to predict prognosis in hypertension has been limited practically by the fact that ECG-LVH is present in only 3% to 8% of average hypertensive patients, and by the possibility that certain electrocardiographic patterns, particularly involving repolarization, might reflect undiagnosed coronary artery disease rather than myocardial hypertrophy. The development over the past dozen years of anatomically validated echocardiographic methods of measuring LV muscle mass has provided a probe that is more sensitive than electrocardiography for detection of hypertensive LVH. This method has now been utilized in studies which suggest that LV mass may be more important than blood pressure as a predictor and possible determinant of cardiovascular morbid events. It is the purpose of this review to evaluate critically these findings and other clinical and experimental evidence related to the prognostic significance and possible mechanisms of risk associated with increased LV mass.