Usefulness of Biomarkers for Predicting Response to Cardiac Resynchronization Therapy

The Prognostic Role of Global Longitudinal Strain and NT-proBNP in Heart Failure Patients Receiving Cardiac Resynchronization Therapy

BACKGROUND

We aimed to evaluate whether baseline GLS (global longitudinal strain), NT-proBNP, and changes in these after cardiac resynchronization therapy (CRT) can predict long-term clinical outcomes and the echocardiographic-based response to CRT (defined by 15% relative reduction in left ventricular end-systolic volume).

METHODS

We enrolled 143 patients with stable ischemic heart failure (HF) undergoing CRT-D implantation. NT-proBNP and echocardiography were obtained before and 6 months after. The patients were followed up (median: 58 months) for HF-related deaths and/or HF hospitalizations (primary endpoint) or HF-related deaths (secondary endpoint).

RESULTS

A total of 84 patients achieved the primary and 53 the secondary endpoint, while 104 patients were considered CRT responders and 39 non-responders. At baseline, event-free patients had higher absolute GLS values (p < 0.001) and lower NT-proBNP serum levels (p < 0001) than those achieving the primary endpoint. A similar pattern was observed in favor of CRT responders vs. non-responders. On Cox regression analysis, baseline absolute GLS value (HR = 0.77; 95% CI, 0.51-1.91; p = 0.002) was beneficially associated with lower primary endpoint incidence, while baseline NT-proBNP levels (HR = 1.55; 95% CI, 1.43-2.01; p = 0.002) and diabetes presence (HR = 1.27; 95% CI, 1.12-1.98; p = 0.003) were related to higher primary endpoint incidence.

CONCLUSIONS

In HF patients undergoing CRT-D, baseline GLS and NT-proBNP concentrations may serve as prognostic factors, while they may predict the echocardiographic-based response to CRT.

Effects of Cardiac Resynchronization Therapy on Cardio-Respiratory Coupling

In this study, the effect of cardiac resynchronization therapy (CRT) on the relationship between the cardiovascular and respiratory systems in heart failure subjects was examined for the first time. We hypothesized that alterations in cardio-respiratory interactions, after CRT implantation, quantified by signal complexity, could be a marker of a favorable CRT response. Sample entropy and scaling exponents were calculated from synchronously recorded cardiac and respiratory signals 20 min in duration, collected in 47 heart failure patients at rest, before and 9 months after CRT implantation. Further, cross-sample entropy between these signals was calculated. After CRT, all patients had lower heart rate and CRT responders had reduced breathing frequency. Results revealed that higher cardiac rhythm complexity in CRT non-responders was associated with weak correlations of cardiac rhythm at baseline measurement over long scales and over short scales at follow-up recording. Unlike CRT responders, in non-responders, a significant difference in respiratory rhythm complexity between measurements could be consequence of divergent changes in correlation properties of the respiratory signal over short and long scales. Asynchrony between cardiac and respiratory rhythm increased significantly in CRT non-responders during follow-up. Quantification of complexity and synchrony between cardiac and respiratory signals shows significant associations between CRT success and stability of cardio-respiratory coupling.

Development of a Rapid Diagnostic Kit for Congestive Heart Failure Using Recombinant NT-proBNP Antigen

Background and Objectives: In patients with congestive heart failure, brain natriuretic peptide (BNP) and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) are released due to excessive heart muscle expansion; they can be used for the early detection, progress monitoring, and treatment of congestive heart failure. Recently, considerable efforts have been made to develop an NT-proBNP-based biomarker for detecting heart failure. This study attempts to develop a rapid and accurate congestive heart failure diagnostic kit using NT-proBNP. Materials and Methods: A new gene based on NT-proBNP was selected, recombined, and expressed in Escherichia coli strains, and then monoclonal antibodies were produced using the hybridoma technique. Additionally, antigen-antibody reactivity was confirmed using indirect enzyme-linked immunosorbent assay (ELISA). Furthermore, the first pair and full-strip pair tests were conducted to select candidate clones; these were applied to a rapid diagnosis kit based on gold conjugates and compared with other currently available antigens. Results: NT-proBNP-based antigens with high specificity and monoclonal antibodies were produced, and the optimal antigen-antibody reactivity was confirmed using indirect ELISA. The first pair and full-strip pair tests were performed to select the optimal candidate clones, and a rapid diagnosis kit with excellent reactivity was developed by applying these to a rapid diagnosis kit based on gold conjugates. Conclusions: The development of this rapid diagnosis kit with excellent performance in congestive heart failure is expected to improve disease management by providing an early assessment of the risk of heart failure.