Systolic hypertension

Overview
Systolic hypertension is defined as an elevated systolic blood pressure with a normal diastolic blood pressure. Systolic hypertension may be due to reduced compliance of the aorta with increasing age.

Treatment
Two randomized controlled trials have established the value of treating systolic hypertension.

SHEP study
This randomized controlled trial showed a reduction of three strokes per 100 patients treated for five years
 * Patients: inclusion criteria were SBP greater than 160 to 219 mm Hg and DBP less than 90 mm Hg. Mean initial BP was 170/77.
 * Treatment goal: 20 mmHg reduction in systolic pressure or a systolic pressure of less than 160 mmHg, whichever was lower
 * Mean final blood pressure in the treatment group: 143/68

Syst-Eur Trial
This randomized controlled trial showed a reduction of 0.3 strokes per 100 patients treated for a median follow-up of two years.
 * Patients: inclusion criteria were systolic of 160-219 mm Hg and diastolic blood pressure lower than 95 mm Hg. Average was 174/86.
 * Treatment goal: "We aimed to reduce the sitting systolic blood pressure by at least 20 mm Hg to less than 150 mm Hg"
 * Mean final blood pressure in the treatment group: 151/79. 44% of patients reached the target blood pressure goals.

The treatment goal
Based on these studies, treating to a systolic blood pressure of 140, as long as the diastolic blood pressure is 68 or more seems safe. Corroborating this, a re-analysis of the SHEP data suggest that allowing the diastolic to go below 70 may increase adverse effects. .

A meta-analysis of individual-patient data from randomized controlled trials found that the nadir diastolic blood pressure below which cardiovascular outcomes increase is 85 mm Hg for untreated hypertensives and 85 mm Hg for treated hypertensives. The authors concluded "poor health conditions leading to low blood pressure and an increased risk for death probably explain the J-shaped curve". Interpreting the meta-analysis is difficult, but avoiding a diastolic blood pressure below 68-70 mm Hg seems reasonable because:
 * The nadir value of 85 mm Hg for treated hypertensives in the meta-analysis is higher than the value of 68-70 mm Hg that is the nadir suggested by the two major randomized controlled trials of isolated systolic hypertension
 * The two largest trials in the meta-analysis, Hypertension Detection and Follow-up Program (HDFP) and Medical Research Council trial in mild hypertension (MRC1) were predominantly middle aged subjects, all of whom had diastolic hypertension before treatment.
 * The independent contributions of incidental comorbid diseases versus effects of treatment are not clear in the meta-analysis