View point: 2018 guidelines of the Indian society of chronomedicine in the light of 2017 ACC/AHA guidelines

The exact cause and physiological limits of hypertension are not known; hence controversies in its diagnosis and drug therapy have continued for over three decades. The new ACC/AHA 2017 Guidelines for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults have several limitations: they do not give much consideration to ambulatory blood pressure (BP) monitoring (ABPM) and to its circadian variation, including asleep blood pressure. The majority of the recommendations support a more aggressive treatment approach and are consistent with growing evidence from clinical trials and epidemiological studies that did not rely on ABPM. The challenge is how clinicians will translate these guidelines into clinical practice without over-diagnosing hypertension in the absence of ABPM, for optimal drug therapy. Because the thresholds at the new goals will be even lower, and the aim is to more effectively treat BP at individual and population levels, many more are likely to be treated. Identification of high-risk individuals, disregarding circadian BP patterning and BP values during sleep, leads to potential misclassification of 50% of all evaluated persons. Experts concerned with the 2017 ACC/AHA Guidelines may not be aware of this important fact. The guidelines continue to advise home BP measurement for the diagnosis of hypertension. ABPM for longer than 24 hours should be mandatory as the recommended reference standard for the diagnosis of hypertension and an accurate assessment of cardiovascular risk in all adults, regardless of whether office BP is elevated or within acceptable limits. The International Society of Chronobiology has proposed that mean systolic BP during sleep should be considered as an independent predictor of cardiovascular events. The sleep-time relative systolic BP decline adds prognostic value to the statistical model that already includes the asleep systolic BP mean, corrected for relevant confounding variables. However, 24-hour ABPM ignores BP variations that are observed throughout the week, indicating greater target organ damage and greater accuracy in the assessment of overall risk, indicating that 7-day/24-hour ABPM may be the future of BP assessment. The Indian Society of Chronomedicine provides a balanced view between that of the ACC/AHA and that of the International Society of Chronobiology.