Dr. Daniel Levy, Harvard Medical School, reviewed studies of hypertension and cardiovascular disease (CVD). Based on 30 years follow-up, Framingham data show that the risk of CVD increases as BP increases. The Framingham and other studies also found that SBP is as good a predictor of CVD risk as DBP and is a better predictor of risk in older people. The Seven Countries Study reported increased risk of death from CVD per every 10 mmHg SBP in the U.S., Europe, and Japan (total RR=1.28).

The MRFIT trial (N=350,000) found a continuous relationship between SBP or DBP increases and risk of CVD death. The Prospective Studies Collaboration pooled data from 6 studies, including MRFIT and Framingham, dividing subjects into 10-year age groups from age 40 to 89 years. Within each group there was a linear log relationship between increasing DBP or SBP and CVD mortality.

Studies tracking BP in subjects from age 30 to 80 demonstrate a linear relationship between increasing age and increasing SBP. DBP increases from age 30 to 50, leveling off until age 60-64, then declining in most people. The most common type of hypertension in people >50 is isolated systolic hypertension (ISH). The RR of CVD in people with ISH is 2.5 times greater than in those with normal BP.

The SHEP randomized trial (N=4,736) demonstrated unequivocal reductions in stroke (-36%), CHD (-25%), CHF (-54%), and CVD (-32) in elderly patients treated for ISH. The Syst-Eur trial (N=4,696) had similar results.

The ALLHAT trial (N=42,418) randomized hypertensive subjects to a diuretic versus an alpha blocker, ACE inhibitor, or CCB. The alpha blocker arm was terminated early due to increased risk of heart failure (HF). The rates of MI or CHD death were the same for the remaining arms. Stroke risk was higher with lisinopril (RR=1.15) versus amlodipine and chlorthalidone. HF risk was higher with amlodipine (RR=1.38) or lisinopril (RR=1.19) versus chlorthalidone.

The ACCOMPLISH trial (N=11,506) found that hypertensive patients receiving benazepril plus amlodipine had a 20% lower risk of a primary CVD event than those receiving benazepril plus HCTZ (p<0.001).

High BP, especially ISH, is a powerful CVD risk factor. Treating high BP and ISH dramatically reduces CVD risk. These findings support the emphasis on SBP in identifying and treating patients with high BP. Unfortunately, hypertension is only controlled in a small proportion of patients. Poor BP control rates are largely due to inadequate treatment of systolic hypertension, especially in older people.