Abstract
Background
Post-hoc analysis of the AFFIRM trial has shown a J-curve relationship between all-cause mortality (ACM) and BP in patients (pts) with atrial fibrillation (AF). Given advancements in therapy, catheter ablation in particular, it is unknown whether low BP is currently associated with increased ACM. We performed post-hoc analysis of the CABANA trial dataset to test the hypothesis that low BP in pts with AF undergoing contemporary therapy is associated with adverse outcomes.
Methods
The CABANA trial randomized pts to catheter ablation vs. medical therapy. The primary end point was death, stroke, bleeding, or cardiac arrest (composite outcome). ACM was a secondary endpoint. Univariate analysis and Cox proportional hazards regression models with adjustment were used to investigate the effects of BP as measured over the study period on pt outcomes.
Results
There were 2,054 pts (mean age - 66.2+/-8.34; female gender - 37.0%; hypertension - 79.1%) with available BP data. In the intention to treat, 1,035 had catheter ablation and 1,019 were treated medically. Among pts who had ablation, mean systolic (SBP) (125+/-18.4mmHg) and diastolic BP (DBP) (71.4+/-10.2mmHg) were lower in pts who died compared with pts who survived (SBP: 131+/-12.6; DBP: 76.5+/- 7.7; p = 0.03). There was a higher proportion of pts who died with SBP < 110 or DBP < 60 compared with those who survived (SBP < 110, 14.8% vs 3.5%; p=0.003; DBP < 60 11.1% vs. 1.4%; p <0.001). Cox regression showed a hazard ratio for SBP >120mmHg for ACM of 0.334 (p=0.003) and for the composite outcome of 0.449 (p=0.001). In the medically treated group, univariate analysis showed low DBP was associated with ACM, but on Cox regression models there were no significant associations between BP and ACM or the composite outcome.
Conclusion
Among patients randomized to catheter ablation, there was an association between ACM and SBP <110 and DBP < 60. Similarly, SBP <120 was associated with ACM and the composite outcome. Although low BP may be an independent marker of adverse outcomes, these data raise the question whether strict therapy resulting in low or low-normal blood pressure in the peri- and broader post-ablation period increases the risk of poor outcomes.