Comparing the design of the primary-care based Hygia Chronotherapy Trial and the Internet-Based TIME Study

Prognostic significance of reverse dipping status on lower limb event in type 2 diabetic patients without peripheral arterial disease

AIMS

We assessed reverse dipping influence on the risk of lower limb events in type 2 diabetic patients without peripheral arterial disease.

METHODS

Patients with type 2 diabetes addressed for cardiovascular risk stratification in our university hospital from 2008 to 2012 underwent 24 h blood pressure monitoring. Patients with a prior history of limb revascularization or with a stenosis > 50% of the legs were excluded. Reverse dipping was defined as a greater night-versus day-time systolic blood pressure. The endpoint was the first occurrence of lower limb revascularization or limb amputation. Hazard ratios (HRs) and 95% confidence intervals were calculated using the Cox model.

RESULTS

Two hundred and eighty-one patients were included. During a median follow-up of 9.4 [7.7-10.6] years, 20 lower limb events and 45 all-cause deaths were observed. Thirty-five patients were reverse dippers. The reverse dipping status was associated with lower limb events when considering all-cause death as a competitive risk, (HR 3.61 [1.16-11.2], P = 0.026). Reverse dipping, HbA1C and proteinuria were independently associated with lower limb outcome in a multivariable analysis (respectively HR 4.09 [1.29-12.9], P = 0.017, HR 1.30 [1.04-1.63], P = 0.022 and HR 1.06 [1.02-1.11], P = 0.001).

CONCLUSIONS

Reverse dipping status is independently associated with worse limb outcome in type 2 diabetic patients.

Circadian Rhythm, Clock Genes, and Hypertension: Recent Advances in Hypertension

Accumulating evidence suggests that the molecular circadian clock is crucial in blood pressure (BP) control. Circadian rhythms are controlled by the central clock, which resides in the suprachiasmatic nucleus of the hypothalamus and peripheral clocks throughout the body. Both light and food cues entrain these clocks but whether these cues are important for the circadian rhythm of BP is a growing area of interest. The peripheral clocks in the smooth muscle, perivascular adipose tissue, liver, adrenal gland, and kidney have been recently implicated in the regulation of BP rhythm. Dysregulation of the circadian rhythm of BP is associated with adverse cardiorenal outcomes and increased risk of cardiovascular mortality. In this review, we summarize the most recent advances in peripheral clocks as BP regulators, highlight the adverse outcomes of disrupted circadian BP rhythm in hypertension, and provide insight into potential future work in areas exploring the circadian clock in BP control and chronotherapy. A better understanding of peripheral clock function in regulating the circadian rhythm of BP will help pave the way for targeted therapeutics in the treatment of circadian BP dysregulation and hypertension.

Circadian control of human cardiovascular function

Endogenous circadian rhythms prepare the cardiovascular (CV) system for optimal function to match the daily anticipated behavioral and environmental cycles, including variable activities when awake during the day and recuperation when sleeping at night. The overall day-night patterns in most CV variables result from the summation of predictable circadian effects with variable behavioral and environmental effects on the CV system. The circadian system has also been implicated in the morning peak in the incidence of adverse CV events, including myocardial infarction, stroke, and sudden cardiac death. We discuss the resting and stress-reactive circadian control of CV physiology in humans and suggest future research opportunities, including improving CV therapy by optimally timing therapy relative to a person's internal body clock time.

Chronotherapy of cardiac and vascular disease: timing medications to circadian rhythms to optimize treatment effects and outcomes

Circadian rhythms impact cardiac and vascular pathophysiology, resulting in 24-hour patterning of symptoms and life-threatening/ending events (chronopathology), plus kinetics and dynamics of medications (chronopharmacology), resulting in administration-time differences in efficacy and safety. Scheduling medications according to circadian rhythm determinants (chronotherapy) can improve treatment effects, for example, before dinner/bedtime ingestion of cholesterol-lowering medications and acetylsalicylic acid, respectively, exerts enhanced control of hypercholesterolemia and after-awakening peak of platelet aggregation; bedtime ingestion of conventional hypertension medications optimizes normalization of sleep-time blood pressure (BP)-strongest independent BP marker of cardiovascular disease (CVD) risk-and most effectively prevents (chronoprevention) CVD morbidity and mortality. Exploration of chronotherapeutic strategies to improve management of cardiac arrhythmias and vascular pathophysiology is still awaited.