A Possible Relationship of Nocturnal Blood Pressure Variability with Coronary Artery Disease in Diabetic Nephropathy

Abstract

Evidence suggests a relationship between short-term blood pressure (BP) variability and cardiovascular target-organ damage. Although a blunted nocturnal decrease in BP and reduced heart rate variability have been shown to be associated with cardiovascular morbidity in diabetic patients, little information is available on short-term BP variability. In this study, short-term BP variability was assessed in 36 subjects with type 2 diabetes and overt nephropathy who underwent ambulatory BP monitoring, and the factors that correlated with short-term BP variability were examined. The incidence of coronary artery disease (CAD) was significantly greater in the patients with increased 24-h systolic BP variability (67% versus 11%; p < 0.0005), while that of cerebrovascular disease was not significantly affected (61% versus 50%). Multiple stepwise regression analysis revealed that serum cholesterol (cholesterol) and plasma norepinephrine (p-NE) were significant and independent contributors to nighttime systolic BP variability (partial R2 = 0.490, p < 0.001; partial R2 = 0.470, p < 0.001) and demonstrated that body mass index and p-NE were primary determinants of nighttime diastolic BP variability (partial R2 = 0.539, p < 0.0005; partial R2 = 0.304, p < 0.05). Diabetic nephropathy patients with CAD had significantly increased daytime systolic (17.8 mmHg versus 13.1 mmHg, p < 0.0005), nighttime systolic (17.4 mmHg versus 10.5 mmHg, p < 0.0001), and nighttime diastolic (10.4 mmHg versus 7.2 mmHg, p < 0.05) BP variability. Furthermore, logistic regression analysis demonstrated that nighttime systolic BP variability was an independent risk factor for CAD (odds ratio 3.13 [95% CI 1.02-9.61]; p < 0.05). The increase in nighttime BP variability is associated with a proportional sympathetic activation in diabetic nephropathy. Elevated short-term BP variability combined with relative sympathetic prevalence during the night might represent an important risk factor for cardiovascular events in the diabetic population.

Effects of angiotensin II type 1 receptor blocker on ambulatory blood pressure variability in hypertensive patients with overt diabetic nephropathy

“…Several previous studies have reported that short-term BP variability estimated by noninvasive ambulatory BP monitoring is associated with cardiovascular disease in hypertensive patients. [8][9][10] The results of our previous cross-sectional study also showed that short-term BP variability was significantly increased in overt diabetic nephropathy patients with coronary artery disease, 26 and in particular, an increase in nighttime short-term BP variability was associated with the plasma concentration of noradrenaline, as well as with the prevalence of coronary artery disease in these diabetic nephropathy patients. 26 There is a well-established role for the renin-angiotensin system in promoting hypertension-and diabetes-related organ damage, including atherosclerosis and diabetic nephropathy.…”

“…of all HR values at 30-min intervals divided by mean HR. 8,9,26 Electrocardiogram and power spectral analysis of R-R intervals…”

“…Ambulatory BP and heart rates (HRs) were monitored every 30 min using a fully automated device (TM-2425, A&D, Tokyo, Japan), essentially as described previously. 26 The patients were instructed to fill out a diary to record the time of sleeping, rising and other daytime activities. Therefore, the term 'day' and 'night' hours used in this study reflect the average period during which the subjects were awake/upright and asleep/supine, respectively.…”

The coefficient variation of home blood pressure is a novel factor associated with macroalbuminuria in type 2 diabetes mellitus

“…20 Furthermore, previous human studies have also shown increases in ambulatory BP variability to be related to atherosclerosis, urinary protein excretion and cardiovascular disease in Japanese patients with type 2 diabetes. [21][22][23] It was postulated that the presence of advanced atherosclerosis and impaired baroreflex sensitivity, which was associated with diabetic neuropathy, could lead to increased variability in BP in diabetic patients.…”

Questionable link between normo- to microalbuminuria and home-measured blood pressure variability in hypertension

“…5,6 Short-term BP variability has also been suggested to be clinically relevant because hypertensive patients with similar mean 24 h BP values exhibit more severe organ damage when their short-term BP variability is greater. [7][8][9][10][11][12][13][14] With respect to home-measured BP, several clinical studies (both long-term followup surveys and cross-sectional studies) have provided an epidemiological basis for supporting the greater accuracy of home BP monitoring than clinic BP measurement for the prognosis of fatal and nonfatal cardiovascular disease (CVD). There is a general consensus that home BP monitoring is more convenient, more readily available and less costly than ambulatory BP monitoring, but ambulatory BP monitoring has been recognized to be superior for certain clinical problems, for example, for the detection of non-dippers or sleep BP in patients with chronic renal disease, autonomic neuropathies or sleep apnea, and for the estimation of short-term BP variability.…”