Extreme Dipping: Always Means Nocturnal Hypotension?

Abstract

Although nocturnal hypotension is considered the key factor responsible for the increased cardiovascular risk associated with the extreme dipping (ED) pattern, no information is available on its prevalence in this setting. Therefore, we have assessed this topic in a cohort of patients referred to a single out-patient hypertension center. A large database of individual 24-hour ambulatory BP recordings from untreated individuals with a history of hypertension and treated individuals with hypertension was analyzed. A total of 339 of 7,074 patients (4.5%) exhibited an ED pattern (207 had a nighttime reduction in both systolic and diastolic BP ≥ 20% compared to daytime values and 132 a nighttime reduction in diastolic BP ≥ 20%). Among patients with ED, the prevalence of nocturnal hypotension varied from 9.1% to 45.0% depending on the criteria used (i.e., mean nighttime BP < 90/50 mm Hg or < 100/60 mm Hg), and the prevalence of nocturnal hypertension (i.e., mean nighttime BP ≥ 120/70 mm Hg) was 19.5%. Compared with untreated patients, those taking antihypertensive drugs were more likely to have nocturnal hypotension and less likely to have nocturnal hypertension. Our findings support the view that ED pattern is a condition not always associated with nocturnal hypotension because a large fraction of ED patients has normal or elevated mean BP nocturnal values.