© 2014 The Authors European Journal of Heart Failure. Aims To investigate the association between baseline systolic blood pressure levels and mortality in patients with AF with or without LV dysfunction. Hypertension leads to cardiovascular disease but, in specific groups, low blood pressure has been associated with a paradoxical increase in mortality. In patients with AF and heart failure, the relationship between blood pressure and death remains largely unknown.Methods and results We conducted a post-hoc combined analysis on pooled data from AFFIRM and AF-CHF trials and assessed the relationship between baseline systolic blood pressure (SBP) and mortality and hospitalizations. Patients were classified according to LVEF (>40%, ≤40%) and baseline SBP (<120 mmHg, 120-140 mmHg, >140 mmHg). A total of 5436 patients with non-permanent AF were followed for 41 ± 16 months. In patients with LVEF >40%, baseline SBP was not related to mortality using multivariate Cox regression analyses to adjust for baseline differences (P = 0.563). In contrast, in patients with LVEF ≤40% (n = 1980), SBP <120 mmHg and SBP >140 mmHg were both associated with a significant increase in total mortality compared with SBP 120-140 mmHg [hazard ratio (HR) 1.75, 95% confidence interval (CI) 1.41-2.17; and HR 1.40, 95% CI 1.04-1.90, respectively]. Hospitalizations were unrelated to SBP regardless of LVEF.Conclusions Mortality is modulated by baseline SBP levels in patients with AF and depressed EF but not in patients with normal EF. Targeted therapy of AF patients based on SBP merits further prospective investigation.