AIMS: Pulsed field ablation (PFA) is a non-thermal energy modality for ablation of atrial fibrillation (AF). Although PFA has demonstrated an excellent overall safety profile, increasing evidence suggests an association with intravascular haemolysis, and acute kidney injury (AKI). However, the extent of haemolysis across different PFA catheters remains poorly characterized and warrants further investigation. METHODS AND RESULTS: We prospectively enrolled 239 patients undergoing AF ablation using the pentaspline (n = 107), balloon-in-basket (n = 71), or lattice-tip (n = 61) catheter. Laboratory markers of haemolysis, myocardial injury, renal function and haemoglobin were collected pre- and 24h post-procedure. Significant haptoglobin depletion was observed exclusively with pentaspline, [pre 99.8 mg/dL (70.2-122) vs. post 55.7 mg/dL (23.2-91.8); P < 0.001] Reductions with the lattice-tip (P = 0.074) and the balloon-in-basket (P = 0.201) catheter did not reach statistical significance. AKI was only observed with the pentaspline catheter (pentaspline: 4.9%; balloon-in-basket: 0.0%; lattice tip: 0.0%; P = 0.020). Myocardial markers increased across all groups, but significantly higher in pentaspline and balloon-in-basket (P = n.s.) vs. lattice-tip (P < 0.001 vs. pentaspline, P < 0.001 vs. balloon in basket). CONCLUSION: In this large cohort, contemporary PFA systems appear safe but catheter design influences the extent of haemolysis, AKI, and myocardial injury. The pentaspline catheter was associated with the greatest haemolytic effect and higher transient AKI, without clinically relevant reductions in haemoglobin or persistent renal impairment. Higher levels of myocardial injury in the pentaspline and balloon-in-basket groups correspond to the larger lesion footprints of these devices.