Abstract 2988: Contractile Reserve Assessment in DCM Patients Supported With Continuous Flow Left Ventricular Assist Device (LVAD)
Contractile reserve (CR) in LVAD patients is the response of ejection fraction (EF) to physiological stress during the absence of pump support. CR was assessed using the 6-minute walk (6MW) test on patients receiving HeartMate II continuous flow LVAD after reducing the speed to 6000 RPM “off-pump”. The aim of the study is to evaluate the relevance of CR as a predictive factor of myocardial recovery.
Methods: After ensuring an INR of 2.0 and above, the speed of HeartMate II was reduced from baseline to 6000 RPM in 26 patients. Echocahrdio-graphic and peripheral haemodynamic parameters were measured at baseline speed (range 8800–9800 RPM), and at 5 and 15 min after reducing the speed to 6000 RPM. Measurements included ventricular dimensions, ejection fraction (EF), MAP and HR. If speed 6000 RPM was tolerated, measurements were repeated after the 6MW to assess CR.
Results: The speed was reduced in a total of 194 occasions; 77 were performed on 11 recovered patients (Group A; support duration 252.5 ±112.2 days) and 117 on 15 non-recovered patients (Group B; support duration 467.6 ±280.5 days). All Group A patients tolerated the speed reduction to 6000 RPM, however, the 6MW was stopped on 4 occasions due to SOB in 2, dizziness in 1 and abdominal pain in 1. In Group B, speed reduction was not tolerated by 1 patient on 3 occasions due to non-specific chest pain and the 6MW was discontinued on 12 occasions due to SOB in 10, dizziness in 1, and nausea in 1. Group A patients showed an increase in EF by 10.2% after
6MW compared to the 15 min of 6000 PRM (69.5±8.5% vs 63.1±9.5%, p<0.001). Both MAP and HR increased significantly after 6MW compared to 15 min (71±10.9 mmHg vs 64.3±10.1 mmHg, p<0.001; 106.1±23.6 bpm vs 83.7±17.7 bpm, p<0.001, respectively). In Group B, EF worsened by 2% after 6MW compared to 15 min (43.5±16.6% vs 44.4±16.1%, p=0.35). There was a non significant increase in MAP (66.0±10.4 mmHg vs 64.1±9.4, p=0.09). ROC analysis revealed that an EF of 59.5% and above after 6MW is a strong predictor of myocardial recovery (AUC=0.93, sensitivity 86%, specificity 84%, p<0.001).
Conclusion: Speed reduction is a relatively safe procedure and needs to be performed under supervision. CR as assessed following speed reduction could predict myocardial recovery and hence guide device explantation.