Abstract Body (Do not enter title and authors here): Introduction: M-TEER is a minimally invasive procedure for selected patients with symptomatic mitral regurgitation. It remains unknown whether the concomitant C-CTO would affect the outcomes of M-TEER procedure.

Methodology: We used the Nationwide Inpatient Sample Data between January 2016 and December 2020 to identify M-TEER hospitalizations with concomitant C-CTO. Baseline characteristics including demographic data and comorbidities were identified. Primary outcomes were in-hospital all-cause mortality and net all cardiac periprocedural complications defined as a composite of acute myocardial infarction, pacemaker placement, cardiac tamponade, pericardiocentesis, pericardiotomy, pericarditis, and hemopericardium.

Results: 48,835 cases of M-TEER were identified during the study period, of whom 700 patients (1.5%) had the diagnosis of C-CTO. The mean age of M-TEER patients was not significantly different between the two groups (76 vs. 75 years, p=0.11), however the CTO cohort had more males (66.72% vs. 53.41%, p=0.002), and more comorbisities as; previous myocardial infarction (32.14% vs.15.66%, p= 0.0003), peripheral artery disease (32.1% vs. 22.67%, p=0.03), complicated hypertension (80% vs. 68.6%, p= 0.001) and renal failure (52.8% vs. 37.3%, p= 0.0007). A higher percentage of M-TEER procedures in patients with CTO were performed in elective setting (62.8% vs. 46.5%, p=0.0008). M-TEER among patients with CTO was associated with a higher incidence of net all periprocedural cardiac complications (21.4% vs. 13.4%, p=0.04) with however similar in-hospital mortality between both groups (3.57% vs. 2.35%, p=0.46). The results remained consistent on adjusted analysis; M-TEER-CTO cohort had higher odds of net all cardiac periprocedural complications (aOR 1.83 ,95% CI (1.17-2.84), p=0.007) with no difference in in-hospital mortality (aOR 1.54, 95 %CI (0.52-4.56), p =0.43). M-TEER utilization in CTO patients was associated with higher costs ($270,385 vs. $237,190 p=0.05), however, no significant difference in mean length of stay (5.8 vs. 4.8 days, p 0.17)

Conclusions: In patient undergoing M-TEER, concomitant C-CTO increases the risk of net all cardiac periprocedural complications with no significant increase in mortality