Role of the learning curve in very high–risk patients treated with MitraClip device for functional mitral regurgitation: a single-centre experience

METHODS The study summarises a single-centre experience on all MitraClip procedures performed from 2012 to 2017. In this research, a retrospective analysis of clinical data was performed. The technical aspects of the MitraClip device implantation performed under transoesophageal echocardiography (TEE) guidance were described previously [1]. There were three interventional cardiologists (A.W., Z.C., and J.P.) including one (J.P.) who attended all the procedures guided by the same echocardiographer (P.S.). Except for the first two procedures, we used the same TEE device (General Electric Healthcare, Chicago, IL, USA) with the three-dimensional option. The clips were finally implanted and released if a significant reduction of MR was achieved without creating significant stenosis defined as a mean mitral gradient (MMG) ≥ 5 mmHg. The total device time was defined as the period between transseptal puncture and removal of a steerable guiding catheter from the femoral vein. Prior to discharge, all patients underwent control transthoracic echocardiography (TTE) with a focus on the stability of the clip position, MR grade, and MMG. An uncomplicated MitraClip implantation and MR reduction to grade ≤ 2+ assessed on the pre-discharge TTE was defined as a procedural success. All patients were scheduled for 30-day clinical follow-up. The procedure-related variables as well as immediate and 30-day results were compared between two groups of patients treated in two consecutive time periods. Continuous data were presented as mean ± standard deviation. We used either the independent-samples t test or the Mann-Whitney test to compare continuous variables. Categorical variables were presented as numbers and percentages and were compared using the c2 test.