Stage 1 and stage 2 hypertension are both associated with a heightened risk of heart failure, atrial fibrillation (AFib), myocardial infarction (MI) and stroke, according to new data published in Circulation.

The researchers used guidelines from the American College of Cardiology and American Heart Association to define stage 1 and stage 2 hypertension. Stage 1 hypertension was defined as a systolic blood pressure (SBP) of 130 to 139 mm Hg or diastolic blood pressure (DBP) of 80 to 89 mm Hg. Stage 2 hypertension, on the other hand, was defined as an SBP ≥ 140 mm Hg or DBP ≥ 90 mm Hg.

For this analysis, the authors tracked more than 2.1 million patients from Japan with a mean age of 44 years old. No patients were taking antihypertensive medication or had a known history of cardiovascular disease at baseline, though many did present with elevated blood pressure (337,390), stage 1 (459,820) or stage 2 (243,342) hypertension.

After a mean follow-up period of more than three years, 28,056 heart failure events and more than 7,774 AFib events were recorded. Event rates among patients with normal blood pressure were 2.99 per 1,000 person-years for heart failure and 0.78 per 1,000 person-years for AFib. For patients with elevated blood pressure, those rates increased to 3.56 and 1.04, respectively. The rates continued to increase for patients with stage 1 hypertension (5.00 and 1.54) and stage 2 hypertension (9.53 and 2.41).

The team noted that their findings suggest important ways clinicians could improve patient care in the future.

“Given the relationship between stage 1 hypertension and a higher incidence of HF and AFib in our study population, which mainly included subjects with relatively low cardiovascular disease (CVD) risk, an optimal management strategy is needed even among subjects with stage 1 hypertension and low CVD risk,” wrote first author Hidehiro Kaneko, MD, a cardiologist at the University of Tokyo, and colleagues. “For this reason, we need to consider the amount of time required to accumulate a sufficient number of HF and AFib events among a sample population of adults with stage 1 hypertension with low CVD risk. Therefore, studies to evaluate left ventricular hypertrophy, which often precedes the development of HF and AFib, as a primary outcome would be an initial step toward providing evidence that pharmacological treatment is essential for subjects with elevated blood pressure or stage 1 hypertension.”

Kaneko et al. also explored the MI and stroke risk of this patient population. After the same follow-up period, 3,540 MI events and 13,401 stroke events had occurred. The team found that those events were the most common among patients with stage 2 hypertension, followed by patients with stage 1 hypertension.