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People who suffer from high blood pressure while sleeping are more likely to have future cardiovascular diseases, especially heart failure, even if their daily blood pressure is in the normal range. This is based on new research published today in the American Heart Association’s flagship journal Circulation.
Healthcare professionals typically use office and daytime blood pressure measurements to determine a patient’s needs and dosage of high blood pressure medication. However, many patients may have undetected nocturnal hypertension – high blood pressure while sleeping.
“Nocturnal blood pressure is increasingly recognized as a predictor of cardiovascular risk,” said Dr. Kazuomi Kario, lead study author and professor of cardiovascular medicine at Jichi Medical University in Tochigi, Japan. “This study provides much more detailed information on the cardiovascular risk associated with high nocturnal blood pressure and various nocturnal blood pressure phenotypes than was previously reported.”
Between 2009 and 2017, 6,359 patients from all over Japan took part in the JAMP study (Japan Ambulatory Blood Pressure Monitoring Prospective) and measured day and night values with a portable ambulatory monitor at home. Blood pressure was measured during daily activities and slept for at least 24 hours, and device data was downloaded regularly at a health clinic. Almost half of the study participants were male and more than half were over 65 years of age. All patients had at least one cardiovascular risk factor, and three quarters of them were taking blood pressure medication, and none had symptomatic cardiovascular disease at baseline.
Study participants were instructed to rest or sleep at night and maintain their usual daytime activities. Their daily activities as well as sleeping and waking times were recorded in a diary. Almost every participant recorded 20 automated blood pressure measurements during the day and seven at night. To determine the night measurements, the patients reported themselves when they fell asleep and woke up. All other measured values were defined as the time of day.
Follow-up took place annually by telephone or a visit to the clinic, with the total follow-up being between two and seven years. The researchers analyzed the frequency of cardiovascular disease events, including heart attack, stroke, heart failure, and death, among participants. The occurrence and timing of cardiac events related to blood pressure fluctuations were analyzed to determine whether there were associations. Study participants experienced a total of 306 cardiovascular events, including 119 strokes, 99 diagnoses of coronary artery disease, and 88 diagnoses of heart failure.
The analysis shows:
Elevated levels during sleep – a systolic blood pressure of 20 mm Hg above a person’s daily systolic value – were significantly associated with the risk of atherosclerotic cardiovascular disease and heart failure.
Participants with an abnormal circadian pattern, that is, when their sleep blood pressure exceeds daily values, were at a particular risk of developing heart failure and a higher risk of developing cardiovascular disease.
Lowering blood pressure excessively during sleep can also be detrimental. Patients with well-controlled hypertension showed a significantly increased risk of stroke when the nightly systolic pressure dropped extremely sharply.
“The results show that nocturnal systolic blood pressure was a significant, independent risk factor for cardiovascular events,” said Kario. “The study underscores the importance of including nightly blood pressure monitoring in patient management strategies and will hopefully encourage clinicians to ensure that antihypertensive therapy is effective at lowering blood pressure throughout the 24-hour dosing period.”
The authors noted that the study was not without its limitations. Outpatient data were collected once at the start of the study, but no information was available on the contributions of subsequent changes in ambulatory blood pressure by the time a cardiac event was diagnosed. The study focused on systolic rather than diastolic measurements due to the older age of the participants. In addition, the study evaluations did not include echocardiograms, which prevented some degree of differentiation for types of heart failure.
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Kazuomi Kario et al., Nocturnal Blood Pressure Phenotype and Cardiovascular Prognosis: Practitioner-Based Nationwide JAMP Study, Circulation (2020). DOI: 10.1161 / CIRCULATIONAHA.120.049730 Provided by the American Heart Association
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