Longitudinal Study of Left Ventricular Mass Growth

Hypertension occurs in at least 70% of people with chronic kidney disease (CKD), which is estimated to affect 11% (19.2 million) of the US adult population; CKD is associated with a large and disproportionate burden of cardiovascular morbidity and mortality. CKD rivals diabetes mellitus as a coronary risk equivalent in veterans. Established risk factors for cardiovascular disease include left ventricular (LV) mass and blood pressure (BP). Although both LV mass and BP are powerful cardiovascular risk factors, little information is available on how LV mass evolves among people with CKD. The cross-sectional relationship between LV mass and BP is well recognized but among those with CKD how LV mass changes over time and how BP predicts this change remains poorly understood. Accumulating evidence suggests that BP measurements made outside the clinic may provide prognostically superior information. However, the comparative value of BP obtained in the clinic and that obtained using 24-hour ambulatory BP in assessing LV mass index is unclear. People receiving antihypertensive therapy who have hypertension out-of-office but have normal BP in the clinic are said to have masked uncontrolled hypertension (MUCH). An earlier report from my group has reported that the prevalence of MUCH is strongly dependent on the level of clinic BP. Thus, those who repeatedly have a low clinic systolic BP (<110 mm Hg) are unlikely to have MUCH. However, among those with usual clinic BP of 130 to 139 mm Hg, MUCH is prevalent in 2 of 3 and those with usual clinic BP of 120 to 129 mm Hg, MUCH is prevalent in 1 of 3. Whether MUCH diagnosed by ambulatory BP monitoring is associated with an increased LV mass is unknown. In this study, I explored the trajectory and pattern of growth of LV mass, clinic systolic BP, 24-hour ambulatory BP, including sleep and awake BP. Whether ambulatory BP measurement is superior to clinic BP was explored by asking the following questions: (1) compared with clinic BP, is there a stronger association between target organ damage and ambulatory BP; (2) does ambulatory BP-diagnosed MUCH associate with LV mass index and if so by which definition (24-hour, awake or sleep ambulatory BP); and (3) compared with clinic BP, is there an incremental value of ambulatory BP (24-hour, awake, or sleep) in detecting and predicting target organ damage. Abstract—Left ventricular (LV) hypertrophy is an established cardiovascular risk factor, yet little is known about its trajectory in people with chronic kidney disease. The goal of this prospective research study was to describe the trajectory of LV mass index, its relationship with blood pressure (BP), and specifically to compare the relationship of BP measured in the clinic and 24-hour ambulatory BP monitoring with LV mass index. Among 274 veterans with chronic kidney disease followed for over ≤4 years, the rate of growth of log LV mass index was inversely related to baseline LV mass index; it was rapid in the first 2 years, and plateaued subsequently. Systolic BP also significantly increased, but linearly, 1.7 mm Hg/y by clinic measurements and 1.8 mm Hg/y by 24-hour ambulatory BP. Cross-sectional and longitudinal associations of both clinic BP and 24-hour ambulatory BP with LV mass index were similar; both BP recording methods were associated with LV mass index and its growth over time. Controlled hypertension, masked uncontrolled hypertension, and uncontrolled hypertension categories had increasing LV mass index when diagnosed by 24-hour ambulatory and awake BP (P<0.05 for linear trend) but not sleep BP. After accounting for clinic BP both at baseline and longitudinally, LV mass index among individuals was additionally predicted by the difference in sleep systolic BP and clinic systolic BP (P=0.032). In conclusion, among people with chronic kidney disease, the growth of LV mass index is rapid. Researchgrade clinic BP is useful to assess LV mass index and its growth over time. (Hypertension. 2016;67:710-716. DOI: 10.1161/HYPERTENSIONAHA.115.07052.) • Online Data Supplement