Twenty-four hour ambulatory blood pressure in the Hypertension Optimal Treatment (HOT) study

Background and aims The Hypertension Optimal Treatment (HOT) study showed t hat when antihypertensive treatment reduces diastolic blood pressure well b elow 90 mmHg, there can be a further reduction of cardiovascular events, pa rticularly myocardial infarction, with no evidence of a J-shaped curve at l ower pressures. Office measurement however, gives no information about bloo d pressure outside the office. This paper describes a HOT substudy in which patients underwent both office measurement and 24 h ambulatory blood press ure monitoring. Methods The mean age of the substudy population was 62 +/- 7 years. Substud y patients were treated for a median period of 2 years. All received the di hydropyridine calcium antagonist felodipine, while some also received an AC E-inhibitor, a beta-blocker or a diuretic. Average 24 h, day and night ambu latory blood pressure values were computed at baseline (n = 277) and during treatment (n = 347): 112 patients had been randomized to a target office d iastolic blood pressure less than or equal to 90 mmHg, 117 to less than or equal to 85 mmHg and 118 to less than or equal to 80 mmHg. Additional analy ses included computation of: (1) trough-to-peak ratio and (2) the smoothnes s index (the ratio between the average of the 24 hourly blood pressure redu ctions after treatment and its standard deviation). Results Taking the subgroup as a whole, baseline 24 h average blood pressur es (146 +/- 18/90 +/- 10 mmHg) were significantly and markedly lower than o ffice blood pressures (170 +/- 14/105 +/- 3 mmHg, P <0.01). Office, 24 h, d ay and night blood pressures were all significantly reduced by treatment, b ut there was a smaller fall inambulatory, than in office pressures. The bet ween group differences in office blood pressure were smaller than those obs erved in the overall HOT sample. Between-group differences in 24 h blood pr essure were even smaller. Trough-to-peak ratios and smoothness indices were lowest in the highest blood pressure target group and highest in the lowes t blood pressure target group. Office and ambulatory blood pressures were s imilar in the groups randomized to placebo (n = 170) or acetylsalicylic aci d (n = 177). Conclusion In conclusion, in the HOT study, treatment reduced not only offi ce but also ambulatory blood pressure throughout the 24 h. The reduction wa s less marked for ambulatory than for office blood pressure. (C) 2001 Lippi ncott Williams & Wilkins.