Morning Surge in Blood Pressure and Cardiovascular Risk

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Hypertension is the most powerful risk factor for the cardiovascular diseases, including stroke, coronary artery disease, heart failure, chronic kidney disease, and aortic and peripheral arterial diseases. There is a significant variability in BP level among hypertensives; however, the diagnosis of hypertension and the therapeutic target of BP are based on the average of each BP measured. There is marked diurnal variation in the onset time of cardiovascular events, with the peak being exhibited in early morning. Blood pressure (BP) also exhibits a similar diurnal variation, with a decrease during sleep and a surge in the morning.1,2 In addition to the persistent pressor stress (averaged throughout a 24-hour period), dynamic diurnal variation in pressor stress from the nadir to the peak in the morning, that is, the morning surge in BP, would be expected to progress target organ damage and trigger cardiovascular events, particularly those occurring in the morning.3,4 Because my group first demonstrated that exaggerated morning surge in BP constitutes a risk for stroke independent of 24-hour BP,5 there has been a steady increase in cross-sectional and prospective evidence supporting the idea that morning BP surge is an independent risk factor for cardiovascular disease. Here I review the recent evidence and the remaining unresolved issues on this topic. ### Prospective Findings on Cardiovascular Events Normal morning BP surge is a physiological phenomenon, but an exaggerated morning BP surge is a cardiovascular risk. Thus, the association between the degree of morning BP surge and cardiovascular risk is not linear but rather has a threshold. There have been 6 prospective studies demonstrating that the morning surge in BP is a risk for cardiovascular events (Table 1).5–10 These studies have used 3 different definitions of the morning BP surge as follows (Figure 1): (1) a sleep-trough surge defined as the morning BP (2-hour …