Target organ damage is more closely associated with ambulatory (ABPM) than with clinic blood pressure (BP). In particular, the reduction of the normal 10 to 20% sleep-time BP decline (non-dipper pattern) is associated with elevated risk of end-organ injury, particularly to the heart, brain and kidney. These results suggest that cardiovascular risk could be influenced not by BP elevation alone, but also by the magnitude of the circadian BP variability. Moreover, at least two independent prospective studies have suggested that nighttime BP is a better predictor of risk than daytime BP. Common to all previous trials is that prognostic significance of ABPM has relied on a single baseline profile from each participant, without accounting for possible changes in the BP pattern, mainly associated to antihypertensive therapy and aging during follow-up. The MAPEC study investigates, first, the comparative prognostic value of several BP parameters (including, among many others, BP variability, the diurnal/nocturnal ratio, diurnal and nocturnal means, slope of morning rise, etc) in the prediction of cardiovascular morbidity and mortality; and, second, whether potential changes in the circadian BP pattern after Chronotherapy with antihypertensive drugs are associated to changes in cardiovascular risk.
