Baseline systolic blood pressure (SBP) between 145 and 180 mmHg before starting oral anticoagulation therapy can more than double the risk of hemorrhagic stroke in patients with atrial fibrillation, as published in the Journal of Hypertension.
Researchers conducted an observational cohort study to assess the risk of hemorrhagic stroke at different baseline SBP levels prior to initiating oral anticoagulation therapy in patients with hypertension and atrial fibrillation.
Participants were part of Skaraborg’s Swedish Cardiovascular Primary Care Database (SPCCD-SKA) between 2006 and 2016, which included primary care patients from a rural area in southwestern Sweden. Patients with atrial fibrillation and hypertension treated with an oral anticoagulant during the study period were eligible for inclusion; The primary study result was hemorrhagic stroke.
A total of 3972 patients (mean age 77 ± 8.5 years; 47.8% women) with atrial fibrillation, high blood pressure and newly started oral anticoagulant treatment were included in the study, which had a total follow-up time of 17,264 person-years (mean 4.3 per patient). Patients were stratified by SBP levels: <130 mmHg (n = 1031), 130 to 139 mmHg (n = 829), 140 to 159 mmHg (n = 1440), 160 to 179 mmHg (n = 479), and at least 180 mmHg (n = 175).
The most common basic comorbidities were coronary artery disease, cerebrovascular disease, heart failure and diabetes, which were found in 34%, 26.4%, 29.1% and 24.7% of the patients, respectively. Regarding oral anticoagulation therapy, 87.7% of patients were taking warfarin; 11.6% took rivaroxaban, apixaban or edoxaban; and 1% took dabigatran; 34.2% of patients were using antiplatelet drugs at baseline.
Forty patients had a hemorrhagic stroke with the highest incidence rate (5.8 per 1000 person-years) in the blood pressure category of 160 to 179 mmHg. The lowest incidence rates (1.2 per 1000 person-years) were found in the blood pressure group <130 mmHg.
The constrained cubic spline curve indicates that the hazard ratio (HR) for hemorrhagic stroke in the blood pressure group 120 to 130 mmHg (nadir, approximately 125 mmHg) was less than 1. The HR in this blood pressure range was not significantly lower than the reference (130 mmHg). In the 145 to 180 mmHg range, however, the risk of hemorrhagic stroke more than doubled – a statistically significant difference.
The diagnosis of stroke, either ischemic or hemorrhagic, was made in 208 patients. The 160-179 mmHg blood pressure group had the highest incidence rate (18.7 per 1000 person-years), while the lowest incidence rate was 10.6 per 1000 person-years in the <130 mmHg group. Those in the 155 to 170 mmHg group were at increased risk for either type of stroke.
There were 312 bleeding events of all types. The highest bleeding incidence rates were in the blood pressure group of 160 to 179 mmHg (24.7 per 1000 person-years), while the lowest incidence rates were in the group of at least 180 mmHg (8.5 per 1000 person-years).
Investigators identified 590 deaths during the follow-up period. The highest mortality rates were in the <130 mmHg group (37.4 per 1000 person-years), while the 160-179 mmHg group had the lowest mortality rate (29.5 per 1000 person-years). A systolic blood pressure below 105 mmHg was associated with an increased risk of death in the continuous analysis compared to the reference (130 mmHg).
Limitations of the study include those inherent in observational cohort research, the equation of dispensing with drugs that forego treatment, which can lead to misclassification errors in patients who received their drugs but did not take, and limitations on external validity due to the high number of warfarin users within the cohort.
“[P]Patients with high blood pressure, atrial fibrillation and an SBP above 145 mmHg before starting anticoagulant treatment have an increased risk of hemorrhagic stroke, ”the researchers concluded.
“This indicates that the SBP will be lowered from below 145 mmHg before the start [oral anticoagulation therapy]may reduce the risk of hemorrhagic stroke in patients with high blood pressure and atrial fibrillation. “
Bager JE, Hjerpe P., Schiöler L. et al. Blood pressure and risk of hemorrhagic stroke in patients with atrial fibrillation and oral anticoagulants: results from the Swedish database of primary cardiovascular care in Skaraborg. Published online March 11, 2021. J Hypertens. doi: 10.1097 / HJH 0000000000002838
This article originally appeared on The Cardiology Advisor