Background

Transcatheter mitral edge-to-edge repair (TEER) has prevailed worldwide as the routinely-used alternative to open-heart surgery for patients with relevant mitral regurgitation. Although serum levels of troponin T are commonly used to establish the diagnosis of acute coronary syndromes, elevated serum levels of troponin T are also associated with increased rates of mortality and rehospitalization following non-cardiac surgery.

Despite its generous use in clinical reality, risk prediction for patients scheduled for TEER remains controversial and is inadequately mapped by traditional surgical risk scores.

Objectives

The aim of this study was to assess the prognostic relevance of baseline troponin levels as well as the 6-month follow-up delta in patients undergoing TEER.

Methods

All patients with available data on high-sensitive troponin T serum levels (hs-TnT) treated by TEER between 04/2011 and 11/2019 were included and adjudicated to interventional therapy by heart team consensus and provided written informed consent to prior to both TEER and study inclusion. The group of patients with baseline hs-TnT <50pg/ml was retrospectively compared to patients with baseline hs-TnT ≥50pg/ml. Available data at 6-month follow-up has been used to measure Δhs-TnT (6-month-Follow-up/baseline) for 184 patients (76.5±8.3 years, female gender 44%) with an optimal cut-off identified at 91%. The primary endpoint was all-cause mortality.

Results

In total 582 patients (76.7 ± 8.5 years; female gender: 42.6%; STS score 5.0% ± 6.9, 59.8% secondary MR) were included. After stratification for baseline values, 442 patients with low (hs-TnT <50pg/ml) were compared to 140 patients with elevated (hs-TnT ≥50pg/ml) troponin. Baseline characteristics revealed a high burden of cardiac (atrial fibrillation: 70.8%, coronary artery disease: 66%, cardiomyopathy: 72.4%) and non-cardiac (chronic renal insufficiency: 54.9%, COPD: 18.5%, peripheral artery disease: 11.2%) co-morbidities without significant differences between the groups. During follow-up, a total of 135 patients died (23.2%).

Kaplan-Meier survival curves indicated significant differences with higher survival rates in patients with baseline hsTnT <50pg/ml (p<0.001; Figure 1). Aptly, Kaplan-Meier analysis for the combined endpoint of death or rehospitalization demonstrated higher event rates in patients with baseline hsTnT ≥50pg/ml (p<0.001). After univariable (HR=1.96; 95%-CI: 1.44; 2.67; p<0.001) and multivariable (HR=1.92; 95%-CI: 1.34; 2.77; p<0.001; Co-variates: age, male gender, atrial fibrillation, LVEF <30%, GFR <60ml/min, procedural success) Cox regression analysis, troponin T ≥50pg/ml proved to be an independent predictor for long-term mortality.

After stratification according to Δhs-TnT, 97 patients with low (Δhs-TnT ≤91%) were compared to 87 patients with high (Δhs-TnT >91%) delta values after 6-month follow-up. Kaplan-Meier survival curves indicated higher survival rates in patients with Δhs-TnT ≤91% (p=0.024).

Conclusion

Both low baseline hsTnT levels <50pg/ml as well as a further decrease in serum levels out to 6-months follow-up (Δhs-TnT ≤91%) are associated with improved long-term outcomes in patients undergoing TEER. Troponin T and its evolution out to 6-month follow-up offer an easy-to-use risk prediction tool to identify patients at higher risk and with increased need for a granular follow-up strategy.

Figure 1: Impact of elevated Troponin T levels on long-term outcomes following TEER