In the study, Kringeland et al analyzed associations of stage 1 hypertension with ACS in 12,329 participants (average baseline age 41 years, 52% women). Participants were grouped via baseline blood pressure (BP) category: normotension (BP <130/80 mmHg), and stage 1 and stage 2 hypertension (BP >140/90 mmHg). ACS was defined as hospitalization or death due to myocardial infarction or unstable angina pectoris during 16 years of follow-up. At baseline, a lower percentage of women than men had stage 1 and 2 hypertension, respectively (25 vs. 35% and 14 vs. 31%, P <.001). During follow-up, 1.4% of women and 5.7% of men experienced incident ACS (P <.001).
Adapted for diabetes, smoking, body mass index, cholesterol, and physical activity, stage 1 hypertension was linked with a higher risk of ACS in women (hazard ratio [HR] 2.18, 95% confidence interval [CI], 1.32-3.60), while the association was nonsignificant in men (HR 1.30, 95% CI 0.98-1.71). After additional adjustment for systolic and diastolic BP, respectively, stage 1 diastolic hypertension was associated with ACS in women (HR 2.79 [95% CI, 1.62-4.82]), but not in men (HR 1.24 [95% CI, 0.95-1.62]), while stage 1 systolic hypertension was not correlated with ACS in either gender.
Based on their findings, the study authors hypothesized that gender-based variations in how small arteries respond to elevated blood pressure may explain the greater vulnerability of women at lower pressures. The authors concluded that in the Hordaland Health Study, BP 130–139/80–89 mmHg (stage 1 hypertension by American guidelines) in the age early 40s doubled the risk of ACS during midlife in women, while the correlation was nonsignificant in men when modified for confounding CVD factors.
Stage 1 diastolic BP was a stronger indicator of ACS risk than stage 1 systolic BP, and their results may contribute to an explanation as to why incidence rates of ACS have declined at slower rates among young and middle-aged women than in their male counterparts. In an interview on the Medical News Today website, lead author and researcher Dr. Kringeland noted, "Several studies have documented that women with hypertension are more prone to develop blood pressure-associated organ damage and that hypertension is a stronger risk factor for cardiovascular disease [CVD] in women than men. Whether gender-specific thresholds for the definition of hypertension would improve CVD risk detection should be considered in future guidelines for hypertension management and CVD prevention."