Objective: Limited data exist to inform blood pressure (BP) thresholds for patients with atrial fibrillation prescribed direct oral anticoagulants (DOAC) therapy in the real world setting.
Methods: SBP was measured in 9051 primary care patients in England on DOACs for atrial fibrillation with postinitiation BP levels available within the Clinical Practice Research Datalink. The incidence rate for the primary outcome of the first recorded event (defined as a diagnosis of first stroke, recurrent stroke, myocardial infarction, symptomatic intracranial bleed, or significant gastrointestinal bleed) and of secondary outcomes all-cause mortality and cardiovascular mortality were calculated by postinitiation BP groups.
Results: The Cox proportional hazard ratio of an event [crude and adjusted hazard ratio 1.04 (95% confidence interval (CI) 1.00-1.08), P = 0.077 and 0.071, respectively] did not differ significantly with a 10 mmHg increase in SBP. The hazard of all-cause mortality [crude hazard ratio 0.83 (95% CI 0.80-0.86), P = 0.000; adjusted hazard ratio 0.84 (95% CI 0.81-0.87), P = 0.000] and cardiovascular mortality [crude hazard ratio 0.92 (95% CI 0.85-0.99), P = 0.021; adjusted hazard ratio 0.93 (95% CI 0.86-1.00), P = 0.041] demonstrated a significant inverse relationship with a 10 mmHg increase in SBP. Patients with a SBP within 161-210 mmHg had the lowest all-cause death rate, while patients with SBP within 121-140 mmHg had the lowest cardiovascular death rate.
Conclusion: SBP values below 161 mmHg are associated higher all-cause mortality, but lower event risk in patients with atrial fibrillation on DOAC therapy. The nadir SBP for lowest event rate was 120 mmHg, for lowest cardiovascular mortality was 130 mmHg and for lowest all-cause mortality was 160 mmHg. This demonstrates a need for a prospective interventional study of BP control after initiation of anticoagulation.