COMPARISON BETWEEN THE FACTORS RELATED TO TWO TYPES OF MORNING SURGE IN KOREAN AMBULATORY BLOOD PRESSURE MONITORING REGISTRY

Abstract

Objective: Morning surge has been regarded as a strong prognostic indicator for cardiovascular events and a couple of hypothesis was generated for the pathophysiology of morning surge. Among them vascular stiffness and renal dysfunction or salt sensitivity were the very well-known factors. But in Korean subjects, there were few studies showing the factors related to two types of surges, i.e., surge from minimal nocturnal blood pressure and preawake blood pressure (BP).

Design and Method: For the Korean Ambulatory Blood Pressure Monitoring Registry data, two types of surge were calculated. Surge 1 was defined as BP for 2 hours after awake (postawake BP) – minimal nocturnal BP, which was defined as average of minimal nocturnal BP and its two nearest BPs. Surge 2 was defined as postawake BP – BP for 2 hours before awake (preawake BP). Among 3185subjects, 1518 subjects with available data were analyzed.

Results: The age was 55.4 ± 14.4 and the female was 29.0 %. Cholesterol level was 182.3 ± 41.6 mg/dL and eGFR was 88.3 ± 19.9 ml/min/1.72m2. Number of Mets was 2.5 ± 1.1 and prevalence of Mets was 49.4%. In multiple regression analysis, for surge 1, eGFR (beta = -0.0552, p = 0.034), cholesterol level (beta = 0.002523, p = 0.0119), and the number of Mets (beta = 1.19032, p = 0.004) were significant factors. For surge 2, age (beta = -0.1669, p = 0.0001) and the sex (beta = -3.77179, p = 0.0014) were significant factors. Interestingly, for BP difference between minimal nocturnal BP and preawake BP, age (beta = 0.15614, p = 0.0002) and sex (beta = 2.7149, p = 0.0157) were the significant factors.

Conclusions: Surge from the minimal nocturnal BP was significantly affected by the factors related to salt sensitivity except age. In contrast, surge from the preawake BP was largely dependent on the age or sex which suggest the association of the vascular aging or reactivity may be more important for the surge from the preawake BP.