Is the atherosclerotic risk of extreme dipping in youth partly explained by exaggerated morning surge?

Is the Atherosclerotic Risk of Extreme Dipping in Youth Partly Explained by Exaggerated Morning Surge? To the Editor: I have read the article by Viera et al demonstrating that disrupted circadian rhythm of blood pressure (BP) in youth was a predictor of coronary calcium levels in younger adults. The study is of great interest because, although an association between normotensive nondippers and advanced target organ damage is expected, the risk of extreme dipping was unexpected in younger subjects. In 1999, we first demonstrated a U curve-shaped association between nocturnal BP dipping and silent cerebrovascular disease (silent cerebral infarcts and advanced deep white matter lesions) detected by brain MRI in elderly hypertensive patients, indicating that both types of circadian BP rhythm disruption (ie, nondipping/ rising and extreme dipping) predispose individuals for future cardiovascular disease. In the prospective Jichi Medical University Ambulatory Blood Pressure Monitoring Study, extreme dipping was associated with an increased risk of clinical stroke events compared with that in dippers. Extreme dippers with exaggerated BP dipping during sleep are likely to exhibit an exaggerated BP increase in the morning relative to their lowest BP level during sleep. In our previous studies, extreme dipping also showed a close association with orthostatic hypertension and exaggerated morning BP surge. Exaggerated morning surge in BP and orthostatic hypertension could be considered an early marker of sympathetic activation and an early marker of prehypertension before an increase in BP levels in youth. In fact, in the previous report of the Coronary Artery Risk Development in Young Adults Study, orthostatic hypertension was associated with future hypertension. Thus, I speculate that the risk of coronary calcium found in extreme dippers of the Coronary Artery Risk Development in Young Adults Study may be partly explained by the risk of exaggerated morning surge. The extreme dipping, orthostatic hypertension, and exaggerated morning surge are partly associated with each other, and together they increase BP variability and the risk of future hypertension, target organ damage, and cardiovascular disease (Figure).