LBOS 01-02 CLUSTERING OF SILENT HYPOTENSIVE EPISODES IN THE MORNING/LATE-MORNING HOURS IN SUBJECTS TREATED FOR HYPERTENSION.

OBJECTIVE: We have previously noted morning/late-morning hypotension (M/LM) in some hypertensive subjects. Here we intended to establish its prevalence in relation to daytime blood pressure (BP) in general.

DESIGN AND METHOD: Daytime hypotension was defined as systolic BP<110mmHg or ≥25% lower than the mean 3 first awake recordings provided that it was also < 85% of the mean 24 h systolic-BP. We evaluated 781 ABPM (Spacelabs 90207/902017A) recordings from 179 subjects with normal BP and 602 hypertensive subjects.

RESULTS: Daytime hypotension (mean systolic pressure [SP] during hypotension 101+/-1 mmHg) was more common in subjects receiving antihypertensive drugs than in untreated hypertensive subjects [158/336 (43%) vs. 76/266 (29%); p < 0.05]. In treated hypertensive subjects hypotensive episodes tended to cluster in the M/LM hours [08:00-12:00]: in nearly 50% (76/158) of treated patients with daytime [06:00-23:00] hypotension, hypotensive episodes were detected in the M/LM, as compared to 19/79 (24%;) in untreated hypertensive subjects (p < 0.05). Clustering analysis revealed that M/LM hypotension was more prevalent, compared to other daytime hours in treated, but not in untreated hypertensive subjects (OR- 1.69 and 0.87, respectively; p < 0.0005). Among treated hypertensive subjects, M/LM clustering was seen in the uncontrolled subjects (p < 0.0005) but not in controlled patients. However, daytime SP was higher in treated subjects free of daytime hypotension compared to those with falls in BP (136 ± 14 vs. 130 ± 14; t-test, p < 0.0001). SP during M/LM falls was lower in controlled than in uncontrolled hypertensive subjects (93+/-7 vs. 103+/-12mmHg; p < 0. 0001). Age (68 ± 1.7 vs. 64 ± 1; p < 0.0001) was higher among treated subjects with M/LM falls compared with treated subjects without M/LM falls.

CONCLUSIONS: Daytime hypotensive episodes are common and tend to cluster in the M/LM hours in treated older hypertensive subjects, particularly in the setting of uncontrolled hypertension. Age, dosing time and circadian decline in hormones affecting blood pressure may play a role in this phenomenon.