Body mass index, nocturnal fall in blood pressure and organ damage in untreated essential hypertensive patients.

Aim: We sought to investigate the relationship between body mass index (BMI) and parameters derived from 48-h ambulatory blood pressure monitoring (ABPM) as well as organ damage in human hypertension.

Methods: A total of 658 consecutive outpatients with grade 1 and 2 hypertension, never treated with antihypertensive medications underwent the following procedures: (i) routine examination, (ii) 24-h urine collection for microalbuminuria, (iii) ABPM over two 24-h periods within 4 weeks, (iv) echocardiography and (v) carotid ultrasonography. Each patient was classified as lean (BMI<25 kg/m2) or overweight/obese (> or =25 kg/m2) and according to the consistency of the dipping or nondipping status in the first and second ABPM period, as dipper (DD), nondipper and variable dipper.

Results: Mean 48-h, daytime and nighttime systolic BP or diastolic BP were superimposable in the lean (n=314) and overweight (n=344) group. Overweight patients had a reduced nocturnal BP drop compared with their lean counterparts; the prevalence of DD pattern, indeed, was 15% lower in the overweight group as a whole, with a 17% difference in men and 13% in women. The prevalence of left ventricular hypertrophy was higher in overweight than in lean patients (31.8 vs. 15.9% in men and 48.7 vs. 15.6% in women, P<0.01); this more pronounced cardiac involvement was associated with structural carotid alterations.

Conclusion: This study, the first to investigate the relationship between BMI and nocturnal BP patterns as assessed by two ABPM sessions, shows that overweight hypertensive patients are more likely to have a reduced nocturnal fall in BP and a greater cardiac and extracardiac organ damage as compared with their lean counterparts despite a similar overall BP load.