White-Coat Hypertension Versus Sustained Hypertension in Japan

Hypertension in Japan To the Editor: Khattar and associates recently described the extent of target organ damage and the cardiovascular prognosis of white-coat hypertension in a middle-aged adult population.1 Pickering, who introduced the concept of “white coat hypertension” in clinical practice, provided editorial comments.2 The major conclusion of the study was that white-coat hypertension is relatively benign in hypertensive adult patients. There is some debate on the extent of target organ damage in white-coat hypertension. Some reports have concluded that target organ damage is advanced in whitecoat hypertension compared with normotension, but others have not found any differences. There are important difference in the demographics of hypertensive target organ damage. In Japan, coronary artery disease is much less common and cerebrovascular disease more common than in Western countries. In our cross-sectional study using ambulatory blood pressure (BP) monitoring, silent lacunar infarction, a strong predictor of clinically overt stroke, was detected by brain MRI in 26% of elderly subjects with white-coat hypertension (mean [95% CI] age 72 [69–74] years; 34% male), whereas it was found in 52% of subjects with sustained hypertension.3 Thus, we believe that the benefits of antihypertensive treatment in Japanese to prevent stroke would be low in whitecoat hypertension. We appreciate the comment of Dr Pickering that the use of ambulatory BP monitoring to distinguish whitecoat hypertension from sustained hypertension is clinically important. In addition, the prognosis of white-coat hypertension would be determined by coexisting target organ damage, especially in an older population. Recently, we identified 236 white-coat hypertensives by a cutoff value for ambulatory BP of 130/80 mm Hg (mean [SD] age 71 [12] years; 34% male) in 821 older hypertensive Japanese patients. In the follow-up period of 43 (14) months [mean (SD)], 5 had a clinically overt stroke (3 cerebral infarction and 2 cerebral hemorrhage). Left ventricular hypertrophy was found in 60% (3 patients) of those who had a stroke, whereas it was detected only in 5.2% (12) of the remaining 231 subjects with white-coat hypertension. In addition, in 5 whitecoat hypertensives who had a stroke, silent lacunar infarction had been detected by brain MRI before the event in all 4 subjects, and 3 of the 4 had multiple infarctions (3 or more lacunae per person). We have previously described patients with white-coat hypertension who developed sustained hypertension that required antihypertensive treatment after the acute major stress of the Hanshin-Awaji earthquake.4 Those cases all had target organ damage (microalbuminuria). Thus, in high-risk elderly subjects with white-coat hypertension who already have silent target organ damage, we should pay attention to the possibility that sustained hypertension or cardiovascular morbidity might be triggered by additional stressful events.