Nighttime systolic BP associated with cardiac events in heart failure
Patients with heart failure who had a median systolic blood pressure (BP) of 100 mm Hg overnight had a higher incidence of cardiac events than those with a median of 117 mm Hg or 136 mm Hg.
Low nighttime systolic blood pressure (SBP) was associated with an increased cardiac event rate in patients with heart failure (HF), a Japanese study found.
To determine the prognostic impact of nighttime SBP in patients with HF, researchers conducted continuous nighttime SBP measurements noninvasively using pulse transit time in patients with HF and followed up for cardiac events of HF hospitalization or cardiac death. The study included 366 patients with HF who had undergone overnight sleep studies along with pulse transit time (PTT)-based BP monitoring from April 2018 to March 2022. Patients were divided into tertiles based on average values of nighttime pulse transit time-based SBP, with 122 in the high- SBP group (median SBP, 136 mm Hg), 122 in the middle- SBP group (median SBP, 117 mm Hg), and 122 in the low-SBP group (median SBP, 100 mm Hg). Results were published July 21 by the Journal of the American Heart Association.
During a median follow- up of 1,083 days after nighttime PTT-based SBP measurement, 71 patients experienced a cardiac event. The highest incidence of cardiac events occurred in the low-SBP group; the lowest SBP tertile was associated with a significantly higher risk of cardiac events compared with the highest SBP tertile (hazard ratio, 2.100 [95% CI, 1.121 to 3.933]; P=0.021). In analyses dividing patients into tertiles based on nighttime diastolic BP, there was a tendency for poorer prognosis in the low diastolic BP group, but no significant difference was observed.
The researchers noted that a 10-mm Hg decrease in nighttime SBP was associated with an increased risk of both cardiac events and HF hospitalization in patients with HF and that PTT-based BP measurements are superior to ambulatory BP monitoring because they do not require a cuff, thereby reducing patient discomfort and allowing for nighttime measurements without disturbing sleep.
The study identified factors associated with low BP, such as low cardiac function as exhibited by left ventricular end-systolic volume, stroke volume, and left ventricular ejection fraction determined by echocardiography, the authors noted.
An accompanying editorial cautioned that nighttime BP dipping is a natural part of circadian rhythm and sleep.
“While the study opens the door to a better understanding of the nighttime BP in HF, more studies are necessary to clarify the link and, if a link exists, the directionality of such a link,” the editorial stated. “Such knowledge may help us identify the optimal nighttime BP goal in HF. After all, this study does remind us that nighttime BP matters in HF.”