Abstract
AIMS: The CardioMEMS HF system is used to measure pulmonary artery (PA) pressures of patients with heart failure (HF). The goal of this study was to determine the impact of time in the daily PA pressure measurements, considering variance and influence of circadian rhythms on cardiovascular pathophysiology. METHODS AND RESULTS: The study included 10 patients with HF with reduced ejection fraction (LVEF < 40%; New York Heart Association class III). Individual daily PA pressures were obtained by CardioMEMS sensors, per protocol, measured up to six times throughout the day, for a period of 5 days. Differences between variation of morning versus evening PA pressures were compared with Wilcoxon signed-rank test. Mean PA pressures (mPAP) increased from a morning value of 19.1 ± 2 mm Hg (8 am; mean ± standard error of the mean [SEM]) to 21.3 ± 2 mm Hg late in the evening (11 pm; mean ± SEM). Over the course of 5 days, evening mPAP exhibited a significantly higher median coefficient of variation than morning mPAP (14.9 (interquartile range [IQR] 7.6-21.0) and 7.0 (IQR 5.0-12.8) respectively; p = 0.01). The same daily pattern of pressure variability was observed in diastolic (p = 0.01) and systolic (p = 0.04) pressures, with diastolic pressures being more variable than systolic at all time points. CONCLUSIONS: Morning PA pressure measurements yield more stable values for observing PA trends. Patients should thus be advised to consistently perform their daily PA pressure measurements early in the morning. This will improve reliability and interpretation of the CardioMEMS management, indicating true alterations in the patient's health status, rather than time-of-day-dependent variations.