Boston Scientific Corp. and Abbott Laboratories continue to parry over clinical trials comparing the latter’s Amplatzer Amulet with Boston Scientific’s Watchman in sealing the heart’s left atrial appendage (LAA) to prevent ischemic stroke in patients with atrial fibrillation (Afib). In one of five presentations at the 34th Transcatheter Cardiovascular Therapeutics annual scientific symposium in Boston in mid-September, Abbott said device-related thrombosis or peri-device leak more frequently preceded strokes in patients with Watchman compared to those with Abbott’s Amplatzer Amulet device.