Multiple standardized clinic blood pressures may predict left ventricular mass as well as ambulatory monitoring: A metaanalysis of comparative studies

It is generally recognized that the relation between left ventricular mass (index) and blood pressure measured in the clinic is weak. Several investigators have studied whether ambulatory blood pressure outside the hospital environment can explain more of the variance of left ventricular mass than does clinic pressure. In a metaanalysis of such comparative studies, the weighted correlation coefficient averaged 0.35 (95% confidence limits: 0.30 to 0.40) for systolic clinic pressure and was significantly (P< .001) higher for the 24-h pressure (r = 0.50; range 0.45 to 0.54). In several studies, however, the methodology and conditions of the clinic pressure measurements were poorly described or standardized, whereas multiple meticulously obtained measurements were present in other reports. The ambulatory pressure monitoring was usually performed with great care and reported in detail. In some studies in which clinic blood pressure consisted of multiple readings in well-standardized conditions in the resting subject, clinic pressure seemed to predict left ventricular mass as well as ambulatory monitoring. We suggest that the strength of the relationship of left ventricular mass with ambulatory pressure may not differ from that with clinic pressure when an adequate number of blood pressures are measured in well-standardized conditions in the clinic.