Cardiac resynchronisation therapy: evidence based benefits and patient selection

Enhanced Extraction of Activation Time and Contractility From Myocardial Strain Data Using Parameter Space Features and Computational Simulations

A computational model enables the extraction of two critical myocardial tissue properties: activation time (AT) and contractility (Con) from recorded cardiac strains. However, interference between these parameters reduces the precision and accuracy of the extraction process. This study investigates whether leveraging features in the parameter space can enhance parameter extraction. We utilized a computational model to simulate sarcomere mechanics, creating a parameter space grid of 41 × 41 AT and Con pairs. Each pair generated a simulated strain pattern, and by scanning the grid, we identified cohorts of similar strain patterns for each simulation. These cohorts were represented as binary images-synthetic fingerprints-where the position and shape of each blob indicated extraction uniqueness. We also generated a measurement fingerprint for a strain pattern from a patient with left bundle branch block and compared it to the synthetic fingerprints to calculate a proximity map based on their similarity. This approach allowed us to extract AT and Con using both the measurement fingerprint and the proximity map, corresponding to simple optimization and enhanced parameter extraction methods, respectively. Each synthetic fingerprint consisted of a single connected blob whose size and shape varied characteristically within the parameter space. The AT values extracted from the measurement fingerprint and the proximity map ranged from -59 to 19 ms and from -16 to 14 ms, respectively, while Con values ranged from 48% to 110% and from 85% to 110%, respectively. This study demonstrates that similarity in simulations leads to an asymmetric distribution of parameter values in the parameter space. By using a proximity map, this distortion is considered, significantly improving the accuracy of parameter extraction.

Real-world clinical burden among patients with and without heart failure worsening after cardiac resynchronization therapy

OBJECTIVE

Cardiac resynchronization therapy (CRT) can improve cardiac function in patients with heart failure (HF); however, in some patients, HF worsens despite CRT. This study characterized the long-term clinical burden of patients with and without HF worsening (HFW) within 6 months post CRT implantation.

METHODS

A claims database (2007-2018) was used to identify two cohorts of adults: those with HFW within 180 days post-CRT and those with no HFW (NHFW). The evaluated clinical outcomes were cardiovascular events/complications, HF-related interventions, hospice enrollment, and all-cause mortality. Inverse probability of treatment weighting (IPTW) was used to adjust for confounders; adjusted comparisons were assessed using weighted Cox proportional hazard ratios (HRs).

RESULTS

Among the 12,753 adults analyzed (HFW: N = 4,785; NHFW: N = 7,968), the mean age was 72 years and the mean duration of follow-up was approximately 2 years. The clinical burden was greater for HFW than for NHFW in terms of all-cause mortality (19.7% vs. 12.1%) and occurrence of atrial fibrillation (57.4% vs. 51.2%). In the IPTW-adjusted Cox proportional hazard analyses, patients with HFW had a 54% higher average hazard of experiencing all-cause mortality compared to NHFW (adjusted average HR = 1.54, 95% confidence interval [CI]: 1.41-1.70; p < .001). Of the clinical events experienced by ≥5% of patients, the greatest differences in average hazard were for HF decompensation (adjusted average HR = 1.83, 95% CI: 1.60-2.09) and HF decompensation or death (HR = 1.63, 95%CI: 1.50-1.77).

CONCLUSION

Patients with early HFW post-CRT experienced a significantly higher clinical burden than those without HFW. Vigilance for signs of worsening HF in the first 6 months post-CRT is warranted.

Electrospun Nanofibers Revisited: An Update on the Emerging Applications in Nanomedicine

Electrospinning (ES) has become a straightforward and customizable drug delivery technique for fabricating drug-loaded nanofibers (NFs) using various biodegradable and non-biodegradable polymers. One of NF's pros is to provide a controlled drug release through managing the NF structure by changing the spinneret type and nature of the used polymer. Electrospun NFs are employed as implants in several applications including, cancer therapy, microbial infections, and regenerative medicine. These implants facilitate a unique local delivery of chemotherapy because of their high loading capability, wide surface area, and cost-effectiveness. Multi-drug combination, magnetic, thermal, and gene therapies are promising strategies for improving chemotherapeutic efficiency. In addition, implants are recognized as an effective antimicrobial drug delivery system overriding drawbacks of traditional antibiotic administration routes such as their bioavailability and dosage levels. Recently, a sophisticated strategy has emerged for wound healing by producing biomimetic nanofibrous materials with clinically relevant properties and desirable loading capability with regenerative agents. Electrospun NFs have proposed unique solutions, including pelvic organ prolapse treatment, viable alternatives to surgical operations, and dental tissue regeneration. Conventional ES setups include difficult-assembled mega-sized equipment producing bulky matrices with inadequate stability and storage. Lately, there has become an increasing need for portable ES devices using completely available off-shelf materials to yield highly-efficient NFs for dressing wounds and rapid hemostasis. This review covers recent updates on electrospun NFs in nanomedicine applications. ES of biopolymers and drugs is discussed regarding their current scope and future outlook.

Cardiac implantable electrical devices in patients with hypertrophic cardiomyopathy: single center implant data extracted from the Swedish pacemaker and ICD registry

Objectives: To investigate cardiac implantable electrical device (CIED) first implants in patients with hypertrophic cardiomyopathy (HCM) in a Swedish tertiary university hospital. Design: Clinical and technical data on pacemaker, implantable cardioverter defibrillator (ICD), and cardiac resynchronization therapy (CRT) first implants performed in HCM patients at the Karolinska University Hospital from 2005 to 2016 were extracted from the Swedish Pacemaker and ICD Registry. Echocardiographic data were obtained by review of hospital recordings. Results: The number of first pacemaker implants in HCM patients was 70 (1.5% of total pacemaker implants). The mean age of HCM pacemaker patients was 71 ± 10 years. Pacemaker implants were almost uniformly distributed between genders. Dual-chamber pacemakers with or without CRT properties were prevalent (6 and 93%, respectively). The number of first ICD implants in HCM patients was 99 (5.1% of total ICD implants). HCM patients receiving an ICD were 53 ± 15 years and prevalently men (70%). Sixty-five (66%) patients were implanted for primary prevention. Dual-chamber ICDs with or without CRT were 21 and 65%, respectively. Obstructive HCM was present in 47% pacemaker patients and 25% ICD patients with available pre-implant echo. Conclusions: This retrospective registry-based study provides a picture of CIED first implants in HCM patients in a Swedish tertiary university hospital. ICDs were the most commonly implanted devices, covering 59% of CIED implants. HCM patients receiving a pacemaker or an ICD had different epidemiological and clinical profiles.

Adherence to heart failure management medications following cardiac resynchronization therapy

Objective: The purpose of this study is to assess the real-world impact of cardiac resynchronization therapy (CRT) on adherence to heart failure (HF) medications.Methods: MarketScan administrative health care claims data from 2008 to 2014 among patients with HF were used. The date of first CRT implantation served as the index date. Adherence to guideline-directed medical therapy (GDMT) classes were compared during pre- and post-index periods using proportion of days covered (PDC). Comparisons between the two periods were made using the Wilcoxon sign-rank test for continuous PDC and McNemar's test for dichotomized PDC.Results: Increases in medication adherence were observed for major classes of HF GDMT medications. Specifically, adherence to angiotensin-converting enzyme inhibitors (ACE-I), angiotensin receptor blockers (ARB), beta blockers (BB), and furosemide increased by 22, 24, 32, and 28% (all p < .001), respectively, in the 12 months pre to 12 months post-CRT. Large increases between the pre- and post-CRT period were also observed when considering adherence as dichotomized PDC ≥0.80 in the 12 months pre- versus post-CRT.Conclusion: Adherence to HF medications significantly improved among HF patients post-CRT implantation. Further research is needed to better understand the underlying determinants of this effect, including whether the effect is attributable to factors such as enhanced patient monitoring and improved access to high-quality specialized HF care among patients receiving CRT.

Fibers for hearts: A critical review on electrospinning for cardiac tissue engineering

Cardiac cell therapy holds a real promise for improving heart function and especially of the chronically failing myocardium. Embedding cells into 3D biodegradable scaffolds may better preserve cell survival and enhance cell engraftment after transplantation, consequently improving cardiac cell therapy compared with direct intramyocardial injection of isolated cells. The primary objective of a scaffold used in tissue engineering is the recreation of the natural 3D environment most suitable for an adequate tissue growth. An important aspect of this commitment is to mimic the fibrillar structure of the extracellular matrix, which provides essential guidance for cell organization, survival, and function. Recent advances in nanotechnology have significantly improved our capacities to mimic the extracellular matrix. Among them, electrospinning is well known for being easy to process and cost effective. Consequently, it is becoming increasingly popular for biomedical applications and it is most definitely the cutting edge technique to make scaffolds that mimic the extracellular matrix for industrial applications. Here, the desirable physico-chemical properties of the electrospun scaffolds for cardiac therapy are described, and polymers are categorized to natural and synthetic.Moreover, the methods used for improving functionalities by providing cells with the necessary chemical cues and a more in vivo-like environment are reported.

Cardiac Resynchronization Therapy prevents progression of renal failure in heart failure patients

BACKGROUND

The goal of this study is to assess the effect of cardiac resynchronization therapy (CRT) over time on renal function and its impact on mortality. The effect of CRT on renal function in patients with heart failure is not well understood.

METHODS

All patients who underwent CRT implantation at University of Kansas between year 2000 and 2009 were reviewed and patients who had pre and post CRT renal function studied were included in our study. Stages of chronic kidney disease (CKD) were defined based on Kidney Disease Outcome Quality Initiative (KDOQI) guidelines. The effect of CRT on renal and cardiac function were studied at short term (≤6 months post implantation) and long term (>6 months).

RESULTS

A total of 588 patients with mean age of 67 ± 12 yrs were included in the study. CRT responders (defined by increase in LVEF ≥ 5%) were 54% during short term follow-up and 65% on long term follow-up. When compared to baseline, there was no significant deterioration in mean Glomerular Filtration Rate (GFR) during follow up. When analyzed based on the stages of CKD, there was significant improvement of renal function in patients with advanced kidney disease. Multivariate logistic regression analysis showed that stable GFR or an improvement in GFR independently predicted mortality after adjusting for co-morbidities.

CONCLUSIONS

CRT was associated with stabilization of renal function in patients with severe LV dysfunction and improvement in stage 4 and 5 CKD. Improved renal function was associated with a lower mortality.

General anesthesia versus sedation for implantation of a biventricular pacing device for cardiac resynchronization therapy

OBJECTIVE

Heart failure carries significant risk for major noncardiac surgery. Whether this risk is transferable to minor surgery is less well-documented. Thus, the aim of this study was to assess the outcome of a contemporary cohort of heart failure patients undergoing cardiac resynchronization therapy (CRT) device insertion under general anesthesia or sedation.

DESIGN

Retrospective observational study.

SETTING

Tertiary cardiac specialist hospital.

PARTICIPANTS

Heart failure patients.

INTERVENTIONS

CRT insertion under general anesthesia or sedation.

MEASUREMENTS AND MAIN RESULTS

Anesthesia, heart failure, and outcome data were collected on a consecutive series of patients having CRT device insertion between 2002 and 2010. A total of 242 patients were managed by the anesthesia department during the study period. After exclusion criteria were applied, data for 183 patients were analyzed. Immediate perioperative (<24 hours) mortality was zero; 30-day mortality of 138 patients was 2.2%. One patient (0.5%) required unplanned intensive care admission. A comparison was made between the sedation (n = 76) group and the general anesthesia (GA) group (n = 107). When compared with the sedation group, the GA group had more intraoperative hypotension (26.2% versus 4.0%, p<0.00001). There was no difference between the GA and sedation groups with regard to 30-day mortality (1.4% versus 3.1%, p = 0.57), unplanned intensive care admission (0% versus 1.3%, p = 0.42), and length of stay in days (3 versus 3, p = 0.82).

CONCLUSION

The authors found that patients with heart failure undergoing CRT insertion with concurrent general anesthesia or sedation had minimal immediate perioperative risk and that there was no difference in postoperative outcome between general anesthesia and sedation.

[Embryonic stem cells in the treatment of severe cardiac insufficiency]

The experience accumulated in cardiac cell therapy suggests that regeneration of extensively necrotic myocardial areas is unlikely to be achieved by the sole paracrine effects of the grafted cells but rather requires the conversion of these cells into cardiomyocytes featuring the capacity to substitute for those which have been irreversibly lost. In this setting, the use of human pluripotent embryonic stem cells has a strong rationale. The experimental results obtained in animal models of myocardial infarction are encouraging. However, the switch to clinical applications still requires to address some critical issues, among which optimizing cardiac specification of the embryonic stem cells, purifying the resulting progenitor cells so as to graft a purified population devoid from any contamination by residual pluripotent cells which carry the risk of tumorigenesis and controlling the expected allogeneic rejection by clinically acceptable methods. If the solution to these problems is a pre-requisite, the therapeutic success of this approach will also depend on the capacity to efficiently transfer the cells to the target tissue, to keep them alive once engrafted and to allow them to spatially organize in such a way that they can contribute to the contractile function of the heart.

Embryonic stem cells for severe heart failure: why and how?

The experience accumulated in cardiac cell therapy suggests that regeneration of extensively necrotic myocardial areas is unlikely to be achieved by the sole paracrine effects of the grafted cells but rather requires the conversion of these cells into cardiomyocytes featuring the capacity to substitute for those which have been irreversibly lost. In this setting, the use of human pluripotent embryonic stem cells has a strong rationale. The experimental results obtained in animal models of myocardial infarction are encouraging. However, the switch to clinical applications still requires to address some critical issues, among which the optimization of the cardiac specification of the embryonic stem cells, the purification of the resulting progenitor cells so as to graft a purified population devoid from any contamination by residual pluripotent cells which carry the risk of tumorigenesis, and the control of the expected allogeneic rejection by clinically acceptable methods. If the solution to these problems is a prerequisite, the therapeutic success of this approach will also depend on the capacity to efficiently transfer the cells to the target tissue, to keep them alive once engrafted, and to allow them to spatially organize in such a way that they can contribute to the contractile function of the heart.

Phase space analysis of myocardial coordination related to left ventricular ejection fraction by echocardiographic speckle-tracking radial strain

Phase space reconstruction, which is performed by converting echocardiogram-derived strain data from different ventricular regions into phase space trajectories, is applied in this study to describe nonlinear behaviour of myocardial coordination. A new method was developed to quantify patterns of phase space trajectories. Echocardiograms of 31 healthy individuals and 63 patients with left bundle branch block (LBBB) and different left ventricular ejection fractions (LVEFs) were used to evaluate this method. The LBBB patients were separated into two groups: LBBB with a LVEF≥50% and LBBB with a LVEF<50%. LVEF is used to represent levels of systolic function and disease severity. A classifying map was constructed to separate the reconstructed phase space into three zones and to acquire the parameters Pz1, Pz2 and Pz3 as percentiles of phase points related to the zones. The criteria used to define the zones were cross-tested. Based on these parameters, significant group-related differences in myocardial coordination were observed. Significantly smaller Pz1 and significantly larger Pz2 values were observed in the healthy group, as compared to the patient group, and similar, significant results were obtained for the patients with LVEF≥50%, as compared to the patients with LVEF<50% (p<.05). A significantly larger Pz3 was observed in patients with LVEF<50%, as compared to the other patients (p<.05). In addition, different inter-regional relationships among strain pairs (all, near-side, middle-side and opposite-wall) were examined to create phase space trajectories. Consistent group-related differences were observed when different inter-regional relationships were applied. Expanding the use of the proposed method to assess various pathological factors and therapeutic impacts is promising.

Response to cardiac resynchronization therapy: is it time to expand the criteria?

BACKGROUND

Cardiac resynchronization therapy (CRT) is a promising treatment for a subgroup of patients with advanced congestive heart failure and a prolonged QRS interval. Despite the majority of patients benefiting from CRT, 10-40% of patients do not respond to this treatment and are labeled as nonresponders. Given that there is a lack of consensus on how to define response to CRT, the purpose of this viewpoint is to discuss currently used definitions and their shortcomings, and to provide recommendations as to how an expansion of the criteria for CRT response may be useful to clinicians.

METHODS AND RESULTS

Analysis of the literature and case reports indicates that the majority of established measures of CRT response, including New York Heart Association functional class and echocardiographic, hemodynamic, and neurohormonal parameters, are poor associates of patient-reported symptoms and quality of life. Moreover, the potential moderating role of psychological factors in determining health outcomes after CRT has largely been neglected.

CONCLUSIONS

It is recommended to routinely assess health status after CRT with a disease-specific questionnaire in standard clinical practice and to examine its determinants, including psychological factors such as personality traits and depression. This may lead to improved (secondary) treatment and prognosis in CHF patients treated with CRT.