Novel Index for Non-Invasive Myocardial Recovery Assessment in LVAD-Supported Heart Failure Patients

Accurate assessment of residual cardiac function in left ventricular assist device (LVAD) supported heart failure (HF) patients is necessary for their effective clinical management, assessing the presence and degree of myocardial recovery (MR), and facilitating strategies for its active encouragement. The aim of this study was to develop a novel, non-invasive myocardial recovery index that uses data from the LVAD to provide this assessment, while addressing the limitations of current clinical methods and existing indices, including their sensitivity to cardiac loading and heart rate (HR).

We proposed the index ${\text{J}}_{\text{nV}}$, a ratio between maximum pump flow jerk during systole and the LVAD's hydraulic power. We evaluated this potential recovery index against 69 others also derived from LVAD pump parameters, as well as the current best-performing non-invasive index ${\text{RI}}_{\text{Q}}$, a ratio of the maximum derivative and peak-to-peak of flow. Using a computational simulation model of an LVAD-supported cardiovascular system, each index was subjected to simulations across a wide array of cardiac function conditions to evaluate accuracy, and preload (mean left ventricular end diastolic pressure), afterload (mean aortic pressure), and HR conditions to measure sensitivity to each.

The proposed index ${\text{J}}_{\text{nV}}$ performed best overall. ${\text{J}}_{\text{nV}}$ demonstrated a significant reduction in cardiac loading sensitivity compared to the standard set by ${\text{RI}}_{\text{Q}}$; $\pm {\kern1.5pt} \text{0.0568}$ vs. $\text{0.1041}{\kern1.5pt} {\text{mL}}^{-1}$ for preload sensitivity, and $\pm {\kern1.5pt} \text{0.0085}$ vs. $\text{0.0283}{\kern1.5pt} {\text{mL}}^{-1}$ for afterload. ${\text{J}}_{\text{nV}}$ also demonstrated the lowest HR sensitivity among all indices, with $ \pm {\kern1.5pt} \text{0.0111}$ vs. $ \text{0.0336}{\kern1.5pt} \frac {\text{mmHg}\cdot \text{mL}^{-1}}{{\kern1.5pt}\text{BPM}}$ for ${\text{RI}}_{\text{Q}}$. This was achieved while maintaining a slightly higher assessment accuracy compared to the same standard ($\overline{{\text{R}}^{2}} = \text{0.9875}$ vs. $\text{0.9790}$).

${\text{J}}_{\text{nV}}$ is a viable, novel index for non-invasively assessing native cardiac function and MR in patients supported by LVADs. The index demonstrated improved performance over existing non-invasive indices, and addresses limitations of current clinical assessment methods.

Assessment of MR in LVAD patients is necessary to improve clinical management, treatment, and long-term outcomes. A first-of-its-kind, systematic, multi-patient simulation analysis to evaluate and present a novel diagnostic index for MR that improves upon current options, was performed. To do so, a previously non-existent standardized protocol for evaluating and comparing MR indices was also established.