192 - Acute Hemodynamic Changes with Resynchronization in Patients with Continuous Flow Mechanical Circulatory Support: A Pilot Study

Abstract

Introduction: Both cardiac resynchronization therapy (CRT) and durable mechanical circulatory support (MCS) improve survival and symptoms in chronic systolic heart failure. However, the benefit of these therapies together has not been demonstrated in clinical studies. Acute hemodynamic studies of CRT in MCS have not been reported. Methods: We identified 7 patients with previously implanted CRT devices who underwent implantation of continuous flow MCS devices. CRT had been turned off at the time of MCS implant. Patients were studied 7 to 24 months after MCS. Pacing parameters were measured. When LV pacing was possible and tolerated, patients underwent routine right heart catheterization without resynchronization and after 15 minutes of resynchronization. Pump speed was unchanged pre- and post-resynchronization. Results: Last LV threshold prior to implantation ranged from 0.5 V at 0.5 ms to 2.63 V at 1 ms. One patient was unable to tolerate LV pacing after MCS due to diaphragmatic stimulation. In another patient, LV pacing threshold increased beyond the capability of device. Five patients with FDA approved MCS devices (two HeartMate II, three HVAD) were studied.Tabled 1MCSMCS + CRTAbsolute Difference% ChangeP-valueRA pressure (mmHg)12.0011.4-0.6-2.560.43PA pressure (mmHg)23.822.8-1-3.980.14PCWP (mmHg)1715.66-1.4-6.250.11Estimated pump flow (L/min)4.884.45-0.375-5.220.41Thermal Dilution CO (L/min)5.2746.5041.2320.650.05 Open table in a new tab Tabled 1MCSMCS + CRTAbsolute DifferenceP-valueRVPacing (V)0.780.960.180.35Sensing (mV)13.269.88-1.940.24RAPacing (V)0.9171.460.5420.42Sensing (mV)3.232.82-0.410.73 Open table in a new tab Cardiac index by thermodilution increased in five of five patients. No adverse effects to resynchronization were noted. Improvement in right atrial and pulmonary capillary wedge pressures was observed but was not statistically significant. There was a trend toward worsening right-sided pacing parameters. Conclusions: Acute hemodynamic studies suggest a potential benefit to CRT in patients with MCS. The increase in overall cardiac output in the setting of unchanged pump flow is likely due to improved LV systolic function and increased flow across the aortic valve. Changes in CRT device function after MCS may require system revision after MCS.