Reduction of diastolic blood pressure: Should hypertension guidelines include a lower threshold target?

Reduction of diastolic blood pressure to less than 60-80 mm Hg does not improve mortality and may lead to adversecardiovascular events in high risk patient populations. Despite a growing body of evidence supporting the J-curve phenomenon, no major society guidelines on hypertension include a lower threshold target for diastolic blood pressure. Many major society guidelines for hypertension have been updated in the last 5 years. Some guidelines include goals specific to age and co-morbid conditions. The Sixth Joint Task Force of the European Society of Cardiology and the Canadian Hypertension Education Program are the only guidelines to date that have recommended a lower threshold target, with the Canadian guidelines recommending a caution against diastolic blood pressure less than or equal to 60 mm Hg in patients with coronary artery disease. While systolic blood pressure has been proven to be the overriding risk factor in hypertensive patients over the age of 50 years, diastolic blood pressure is an important predictor of mortality in younger adults. Post hoc data analysis of previous clinical trials regarding safe lower diastolic blood pressure threshold remains inconsistent. Randomized clinical trials designed to determine the appropriate diastolic blood pressure targets among different age groups and populations with different comorbidities are warranted. Hypertension guideline goals should be based on an individual's age, level of risk, and certain co-morbid conditions, especially coronary artery disease, stroke, chronic kidney disease, and diabetes.

Achieving control of resistant hypertension:Not just the number of blood pressure medications

Resistant hypertension(RH) has a prevalence of around 12% and is associated with an increased risk of cardiovascular disease, progression to end-stage renal disease, and even mortality. In 2017, the American College of Cardiology and American Heart Association released updated guidelines that detail steps to ensure proper diagnosis of RH, including the exclusion of pseudoresistance.Lifestyle modifications, such as low salt diet and physical exercise, remain at the forefront of optimizing blood pressure control. Secondary causes of RH also need to be investigated, including screening for obstructive sleep apnea. Notably, the guidelines demonstrate a major change in medication management recommendations to include mineralocorticoid receptor antagonists. In addition to advances in medication optimization, there are several device-based therapies that have been showing efficacy in the treatment of RH. Renal denervation therapy has struggled to show efficacy for blood pressure control, but with a redesigned catheter device, it is once again being tested in clinical trials. Carotid baroreceptor activation therapy(BAT) via an implantable pulse generator has been shown to be effective in lowering blood pressure both acutely and in longterm follow up data, but there is some concern about the safety profile. Both a second-generation pulse generator and an endovascular implant are being tested in new clinical trials with hopes for improved safety profiles while maintaining therapeutic efficacy. Both renal denervation and carotid BAT need continued study before widespread clinical implementation. Central arteriovenous anastomosis has emerged as another possible therapy and is being actively explored. The ongoing pursuit of blood pressure control is a vital part of minimizing adverse patient outcomes. The future landscape appears hopeful for helping patients achieve blood pressure goals not only through the optimization of antihypertensive medications but also through device-based therapies in select individuals.

Blood pressure goals: A moving target

Clinical guidelines on hypertension have evolved over the past several decades. Each recommends varying blood pressure(BP) cut-offs which define hypertension, determine the thresholds to initiate pharmacotherapy, and guide treatment targets. In addition, different techniques of measuring BP in clinical trials may further contribute to the discrepancies in the achieved BP targets. Physicians find it difficult to navigate through different recommendations for hypertension management based on studies among different age groups and patients with a variety of co-morbidities and target organ involvement. In 2003, JNC 7 recommended a BP goal of <140/90 mmHg in the general population and <130/80 mmHg in those with diabetes mellitus or renal disease. JNC 8 re-set the BP target at <140/90 mm Hg for all adults under the age of 60 regardless of co-morbidities, and an even higher target of <150/90 mm Hg for those 60 years or older without diabetes or chronic kidney disease. The more recent results of the Systolic BP Intervention Trial(SPRINT) have a significant influence on the 2017 American College of Cardiology(ACC) and American Heart Association(AHA) guideline which redefines hypertension as BP ≥130/80 mmHg. It emphasizes individualized cardiovascular risk assessment and recommends a more aggressive BP target of <130/80 mmHg and a treatment threshold based on the age, co-morbidities, and cardiovascular risk. The 2017 ACC/AHA guideline also advocates proper BP measurement and provides the estimates of corresponding BP values for clinic, home, and ambulatory BP monitoring measurements. A higher prevalence of hypertension is expected based on the ACC/AHA 2017 guideline. Its implementation may potentially lead to better BP control through enhanced awareness, improved adherence, and more timely initiation and intensification of pharmacologic therapy. Although there is no one-size-fits-all BP target, the ACC/AHA 2017 guideline is simple, inclusive and practical. Nonetheless, more studies are warranted to help further individualize BP goals for elderly patients and those with certain co-morbidities or multiple cardiovascular risk factors.