Relationship between ambulatory or exercise blood pressure and left ventricular structure: prognostic implications.

Left ventricular mass can be accurately measured by echocardiography, and this measurement has been shown to be a stronger predictor of cardiovascular morbid events or of death than blood pressure levels or all other conventional risk factors except age. Echocardiographic left ventricular mass is thus a useful 'bioassay' that can determine the effects on the heart of various measures of blood pressure. All available studies have shown a closer relationship between left ventricular mass or left ventricular wall thickness and blood pressure as measured by ambulatory monitoring over 24 h or during specific time periods, such as the working day, compared with casual pressure measurements. Similarly, blood pressure at the end of maximal or submaximal exercise predicted left ventricular mass better than causal pressures in each study of this topic. Thus there is a closer parallel between prognostically important measures of left ventricular structure and blood pressure during physical or mental activity than with clinic measurements of blood pressure. Although the mechanisms underlying these relationships are not fully understood, it has been proposed that the blood pressure levels measured during activity may be more closely related to left ventricular structure than conventional clinic measurements, that these levels appear to be free from any alerting reaction to the physician taking the measurement and that there may be a fundamental biological link between the stimuli to blood pressure levels during activity and cardiovascular hypertrophy.