Assessment of blood pressure variability in patients with coronary microvascular dysfunction

Background Recent research suggests that patients with ischemia and no obstructive coronary arteries (INOCA) are at a higher risk for cardiovascular (CV) events. Additionally, there is growing evidence that elevated blood pressure variability (BPV) and nocturnal blood pressure (BP) dipping is linked to increased CV disease risk.This study aims to assess whether patients with coronary microvascular dysfunction (CMD) exhibit different day-to-night BPV compared to individuals without CMD. Purpose This study aims to assess whether patients with coronary microvascular dysfunction (CMD) exhibit different day-to-night BPV compared to individuals without CMD. Methods All participants underwent functional coronary angiography with coronary circulation physiology assessment. Coronary flow reserve (CFR) and index of microvascular resistance(IMR) were measured. CMD patients were classified into 2 subgroups, structural and functional endotype(CFR <2.5 & IMR ≥25 were considered abnormal). In addition, in all participants, BPV was assessed using cuff-based 24h-Ambulatory Blood Pressure Monitoring (ABPM). We analyzed all outcomes using multivariable linear mixed models, adjusted for age, sex, optic disc size, axial length, and BP parameters. Results We included 94 patients in total. 48 patients without CMD, control group [female, 57%, mean age: 62.9±7.3 years] and 46 patients with CMD, CMD group (female, 67%, mean age: 59.7±9.3 years). In CMD group, 37% had a normal value of IMR, indicating functional CMD endotype, while 63% had an abnormal IMR, indicating structural endotype. The lower difference between daytime and nighttime DBP was significantly correlated with CMD (6.4± 5.7 vs 10.1±.7 mmHg, p=0.11). Besides, CMD group was characterized by higher pulse pressure index (PPi) and increased difference between day and night PPi were independent predictor of CMD. Besides, there was a trend towards statistical significance for the nocturnal non-dipping pattern for CMD group (p=0.54). After adjustment of all covariants, the day to nighttime DBP difference was always significantly associated with CMD. There was no statistical difference in 24-hour, day and night blood pressure SDs between CMD & control groups. Conclusion Patients with CMD are characterized by differences in BPV and increased pulse pressure index compared with controls independently of demographic, clinical and hemodynamic confounders. Moreover, there was a high prevalence of non-dipping patterns among CMD patients as well as less pronounced nocturnal DBP drop, compared to SBP drop. These novel observations help to clarify aspects of CMD and, thus, to develop new evidence-based risk assessment tools and effective therapeutic strategies for this rapidly growing patient population. Pharmacologic therapies targeting interventions to prevent alterations in nighttime BP profile may prove invaluable in the management of these patients.