Miry Zhu (Berlin / DE), Professor Leonid Goubergrits (Berlin / DE), Professor Jörg Kempfert (Berlin / DE), Juliana Franz (Berlin / DE), Dr. Sarah Nordmeyer (Berlin / DE), Sonja Schmelter (Berlin / DE), Professor Felix Berger (Berlin / DE), Professor Volkmar Falk (Berlin / DE), Professor Titus Kühne (Berlin / DE), Dr. Marcus Kelm (Berlin / DE)
Abstract-Text (inkl. Referenzen und Bildunterschriften)
Objectives Left ventricular myocardial power (LVMP) has been introduced in patients with valvular heart disease and can be used as an estimate of the LV function. We aimed to quantify LVMP and exercise capacity in patients with mitral insufficiency (MI) before and after surgery.
Methods LVMP, and myocardial efficiency were calculated from routine cardiovascular magnetic resonance imaging using phase contrast flow measurements and cine MRI in N=35 patients with MI before and 3-6 months after mitral valve surgery. Exercise capacity was assessed alongside by a standardized Six-Minute-Walk-Test (6MWT).
Results BSA indexed LVMP decreased from preoperative 5.8W/m2 (IQR 4.7-9.0) to 4.2W/m2 (IQR 3.4-4.9, p<0.001) and circulatory efficiency increased from 9.4% (IQR 8.0-11.6) to 13.2% (IQR 9.2-16.3, p<0.001) postoperatively. Patients with higher preoperative LVMP had an increased risk for failing to achieve age-, sex-, and BMI-specific target 6MWT distances (RR 1.38, 95% CI 1.02 – 1.88; p=0.039). A threshold of 8.96W/m2 was found to identify patients who fail to achieve target 6MWT distances postoperatively with a specificity of 94%. Median changes in postoperative 6MWT distances in patients with preoperative LVMP below 8.96W/m2 were +29 (IQR -4 to +66) meters and in those with LVMP above 8.96W/m2 were -21 (-44 to 10) meters (p=0.037).
Conclusion LVMP was a predictor for postoperative exercise capacity in patients with MI. Its non-invasive assessment and applicability was further improved by optimization of the method and adaptation to routine cardiac MRI with the provision of an open-source web-based calculation tool.
Figure 1 Illustration of the concept of left ventricular myocardial power and myocardial efficiency
Figure 2 A Probability of achieving postoperative Six-Minute Walk Test (6MWT) distances dependent on preoperative LV myocardial power B Six-minute-walk test outcome in patients with preoperative LV myocardial power below and above 8.96W/m2