Left atrial (LA) four-dimensional (4D) flow quantification and strain may help predict stroke and thrombus formation in patients with atrial fibrillation (AF). We aimed to characterize flow changes in AF patients undergoing pulmonary vein isolation (PVI) and their associations with LA remodelling and contractility markers. Fifty-seven consecutive patients referred for magnetic resonance imaging before first-time PVI and twelve healthy volunteers (HV). LA velocity and stasis maps were obtained from 4D flow. Cine images were used for LA volume, ejection fraction, and strain. Patients’ age was 60 ± 9 years (25% female), versus 44 ± 15 years in HV (8% female). LA 4D flow markers showed LA stasis was reduced in AF patients (median [Q1, Q3] 45.0% (36.0, 54.0) vs. 34.5% (22.8, 45.3); p = 0.040). LA stasis and mean LA velocity were associated in AF patients (r = −0.52; p < 0.001) and HV (r = −0.9; p < 0.001). Associations were poorer for peak LA velocity in AF patients (r = −0.39; p = 0.003). LA stasis was not associated with any marker of LA contractile function in either the AF or HV cohorts. In conclusion, compared with HV patients, patients with AF showed greater LA stasis on 4D flow. LA stasis was not associated with markers of LA contractile function.