Incidence, clinical correlates, timing, and consequences of acute thrombus formation in patients undergoing the MitraClip procedure.

Background: Despite adequate heparinization, formation of fresh intracardiac thrombi during the MitraClip procedure was reported.

Aims: We aimed to evaluate the incidence and clinical consequences of intracardiac thrombus formation during the MitraClip device implantation.

Methods: Clinical data and transesophageal echocardiography findings obtained during MitraClip procedures in 100 consecutive patients (81 men; mean [SD] age, 67.8 [8.3] years) were reviewed. In all patients, a heparin bolus was given immediately after a successful transseptal puncture, and the activated clotting time above 250 seconds was maintained throughout the procedure.

Results: Thrombus formation was documented in 9 patients (9%). In 6 patients, thrombi formed on a transseptal needle/sheath (2 attached to the sheath in the right atrium and 4 on the sheath immediately after the puncture in the left atrium), and in 3 patients, on the MitraClip device in the left atrium (2 on a steerable guiding catheter and 1 on the clip delivery system). Overall, 6 thrombi (67%) formed prior to and 3 (33%) after heparin administration. All thrombi were transient and disappeared within minutes. No periprocedural ischemic stroke, transient ischemic attack, or other embolic complications were reported. Clinical characteristics were similar in patients with and without thrombi, except for lower left ventricular ejection fraction (LVEF; mean [SD], 23% [10%] and 30% [10%], respectively; P = 0.03). In-hospital death was reported in 6 patients: 2 with a visible thrombus and 4 without (P = 0.09).

Conclusions: Transient thrombus formation is relatively common during the MitraClip procedure, especially in patients with low LVEF; however, acute clinical consequences are benign.