Abstract 3379: The Extent of Myocardial Recovery as Assessed by the Response of Echocardiographic Parameters to Exercise in Patients With Heartmate I and Heartmate II Left Ventricular Assist Devices (LVADs)
The difference in the extent of myocardial recovery between pulsatile and continuous flow LVADs has not been adequately studied. Contractile reserve (CR) assessment to physiologic stress in the absence of LVAD support provides an objective means of assessing myocardial recovery. In this study we assessed the level of CR after exercise in patients with pulsatile HeartMate I (HM I) and continuous flow HeartMate II (HMII) LVADs.
Methods: 16 recovered HM I (13 males) and 11 recovered HM II (9 males) patients were studied using transthoracic echocardiography. Measurements included ventricular dimensions and EF and were performed after 15 minutes of switching off HM I device “off-pump”; 6000 RPM in HM II group “low-speed”. If either “off-pump” or “low speed” was tolerated patients were asked to perform a six-minute walk (6MW) test followed by repeating the echocardiographic assessment. CR was determined as the percentage change in EF after 6MW compared to 15 minutes “off-pump/low speed”.
Results: Pre-implantation data were similar between the two groups (PCWP, 26.4±7.7 mmHg vs 28.8±3.5 mmHg, p=0.5; CI, 1.9±0.6 l/min/m2 vs 1.7±0.6 l/min/m2, p=0.6). Off-pump testing was tolerated by all HM I patients (118 occasions). Low-speed testing was tolerated by all HM II patients (77 occasions). In each group the 6MW test was discontinued on 4 occasions. None of the patients reported short or long term untoward effects. After 6MW, EF was significantly higher in HMI group compared to 15 minutes “off-pump” (61.8±11.8% vs 60.3±11.6%, p=0.02), a 2.7% change. HM II patients showed an improvement in EF after 6MW compared to 15 minutes “low speed” (69.5±8.5%vs 63.1±9.5%, p<0.0001), a 10.2% change. The percentage change in EF following 6MW was significantly higher in HM II compared to HM I (10.2% vs 2.7%, p=0.001). In both groups ESD was significantly lower after 6MW compared to 15 minutes measurements (HMI, 40±8.5 mm vs 41.1±9.8 mm, p=0.01; HM II, 33.9±7.2 mm vs 35.4±7.2 mm, p=0.003). The distance walked by HM II patients was significantly higher compared to HM I patients (615±151 m vs 522±141 m, p<0.01).
Conclusion: The 6MW is a safe test that needs to be performed under supervision. CR improves significantly in patients with HM II in comparison to patients with HM I LVAD.