Prognostic Value of Peak Oxygen Uptake in Patients Supported With Left Ventricular Assist Devices (PRO-VAD)

Mechanisms of myocardial reverse remodelling and its clinical significance: A scientific statement of the ESC Working Group on Myocardial Function

Cardiovascular disease (CVD) is the leading cause of morbimortality in Europe and worldwide. CVD imposes a heterogeneous spectrum of cardiac remodelling, depending on the insult nature, that is, pressure or volume overload, ischaemia, arrhythmias, infection, pathogenic gene variant, or cardiotoxicity. Moreover, the progression of CVD-induced remodelling is influenced by sex, age, genetic background and comorbidities, impacting patients' outcomes and prognosis. Cardiac reverse remodelling (RR) is defined as any normative improvement in cardiac geometry and function, driven by therapeutic interventions and rarely occurring spontaneously. While RR is the outcome desired for most CVD treatments, they often only slow/halt its progression or modify risk factors, calling for novel and more timely RR approaches. Interventions triggering RR depend on the myocardial insult and include drugs (renin-angiotensin-aldosterone system inhibitors, beta-blockers, diuretics and sodium-glucose cotransporter 2 inhibitors), devices (cardiac resynchronization therapy, ventricular assist devices), surgeries (valve replacement, coronary artery bypass graft), or physiological responses (deconditioning, postpartum). Subsequently, cardiac RR is inferred from the degree of normalization of left ventricular mass, ejection fraction and end-diastolic/end-systolic volumes, whose extent often correlates with patients' prognosis. However, strategies aimed at achieving sustained cardiac improvement, predictive models assessing the extent of RR, or even clinical endpoints that allow for distinguishing complete from incomplete RR or adverse remodelling objectively, remain limited and controversial. This scientific statement aims to define RR, clarify its underlying (patho)physiologic mechanisms and address (non)pharmacological options and promising strategies to promote RR, focusing on the left heart. We highlight the predictors of the extent of RR and review the prognostic significance/impact of incomplete RR/adverse remodelling. Lastly, we present an overview of RR animal models and potential future strategies under pre-clinical evaluation.

Bioinformatics analysis and identification of potential key genes and pathways in the pathogenesis of nonischemic cardiomyopathy

Nonischemic cardiomyopathy (NICM) is a major cause of advanced heart failure, and the morbidity and mortality associated with NICM are serious medical problems. However, the etiology of NICM is complex and the related mechanisms involved in its pathogenesis remain unclear. The microarray datasets GSE1869 and GSE9128 retrieved from the Gene Expression Omnibus database were used to identify differentially expressed genes (DEGs) between NICM and normal samples. The co-expressed genes were identified using Venn diagrams. Kyoto Encyclopedia of Genes and Genomes pathway analyses and gene ontology enrichment were used to clarify biological functions and signaling pathways. Analysis of protein-protein interaction networks using Search Tool for the Retrieval of Interacting Genes/Proteins online to define the hub genes associated with NICM pathogenesis. A total of 297 DEGs were identified from GSE1869, 261 of which were upregulated genes and 36 were downregulated genes. A total of 360 DEGs were identified from GSE9128, 243 of which were upregulated genes and 117 were downregulated genes. In the 2 datasets, the screening identified 36 co-expressed DEGs. Kyoto Encyclopedia of Genes and Genomes pathway and gene ontology analysis showed that DEGs were mainly enriched in pantothenate and CoA biosynthesis, beta-alanine metabolism, kinetochore, G-protein beta/gamma-subunit complex, and other related pathways. The PPI network analysis revealed that DUSP6, EGR1, ZEB2, and XPO1 are the 4 hub genes of interest in the 2 datasets. Bioinformatics analysis of hub genes and key signaling pathways is an effective way to elucidate the mechanisms involved in the development of NICM. The results will facilitate further studies on the pathogenesis and therapeutic targets of NICM.

Depressive symptoms, right ventricular function, and muscular strength are associated with peak oxygen uptake in patients with implantable left ventricular assist devices

BACKGROUND

Left ventricular assist device (LVAD) implantation is among the most effective treatment options for patients with severe heart failure. Although previous studies have examined the factors related to peak oxygen uptake (peak VO2 ), they were limited by the few patients involved and their focus on medical and physical functions. Therefore, this study comprehensively examined the factors associated with peak VO2 , which is an important prognostic factor in patients with implantable LVADs.

METHODS

Eighty-nine patients who underwent initial LVAD implantation and were eligible for cardiopulmonary exercise testing (CPX) between May 2014 and September 2021 were included. The patients' mean age was 48 ± 12 years, and 70% were males. Based on previous studies, the cut-off was set at 12 and 14 mL/kg/min for patients taking β-blocker and those not taking β-blockers, respectively. Furthermore, factors associated with peak VO2 were examined using multivariate logistic regression analysis.

RESULTS

The mean time from surgery to CPX administration was 73 ± 40 days. The high group had a higher cardiac index, right ventricular stroke work index (RVSWI), and isometric knee extensor muscular strength and lower Patient Health Questionnaire-9 (PHQ-9) and B-type natriuretic peptide values than the low group. Multivariate logistic regression analysis showed that RVSWI and KEMS were positively correlated, whereas PHQ-9 was negatively associated with peak VO2 .

CONCLUSION

Right ventricular function, depressive symptoms, and lower limb muscular strength were associated with exercise capacity in patients with implantable LVADs.

Supervised exercise training in patients with advanced heart failure and left ventricular assist device: A multicentre randomized controlled trial (Ex-VAD trial)

AIMS

Small studies and observations suggested that exercise training may improve peak oxygen consumption (peakVO2 ) in patients with advanced heart failure and left ventricular assist device (LVAD). We investigated whether in this patient group a supervised exercise training can improve exercise capacity.

METHODS AND RESULTS

In this multicentre, prospective, randomized, controlled trial, patients with stable heart failure and LVAD were randomly assigned (2:1) to 12 weeks of supervised exercise training or usual care, with 12 weeks of follow-up. The primary endpoint was the change in peakVO2 after 12 weeks (51 patients provided a power of 90% with an expected group difference in peakVO2 of 3 ml/kg/min). Secondary endpoints included changes in submaximal exercise capacity and quality of life. Among 64 patients enrolled (97% male, mean age 56 years), 54 were included in the analysis. Mean difference in the change of peakVO2 after 12 weeks was 0.826 ml/min/kg (95% confidence interval [CI] -0.37, 2.03; p = 0.183). There was a positive effect of exercise training on 6-min walk distance with a mean increase in the intervention group by 43.4 m (95% CI 16.9, 69.9; p = 0.0024), and on the Kansas City Cardiomyopathy Questionnaire physical domain score (mean 14.3, 95% CI 3.7, 24.9; p = 0.0124), both after 12 weeks. The overall adherence was high (71%), and there were no differences in adverse events between groups.

CONCLUSION

In patients with advanced heart failure and LVAD, 12 weeks of exercise training did not improve peakVO2 but demonstrated positive effects on submaximal exercise capacity and physical quality of life.

The effects of rate pressure product at admission on cardiopulmonary function during hospitalization in patients with acute myocardial infarction

OBJECTIVE

This study aimed to analyze the correlation between the rate pressure product (RPP) and cardiopulmonary function during hospitalization in patients with acute myocardial infarction (AMI).

METHODS

A total of 362 patients with AMI were selected for the study, and the median admission RPP was used as the cutoff point to divide the patients into a low-RPP group (n = 181) and a high-RPP group (n = 181). The relationship between the RPP at admission and the cardiopulmonary function during hospitalization was analyzed.

RESULTS

The patients in the high-RPP group had a higher body mass index (BMI) (p = 0.014), a higher prevalence of combined hypertension and diabetes mellitus (p < 0.001), a lower incidence of smoking (p = 0.044), and a higher incidence of oscillatory ventilation (6.1% vs. 1.7%, p = 0.029). The differences in RPP at rest, during warm-up, and within 1 and 4 minutes of recovery were statistically significant between the two groups (p < 0.01 on each occasion), while the differences in anaerobic threshold (AT) and watt max (Max) were not statistically significant (p > 0.05 for both). The patients in the low-RPP group had higher oxygen uptake (VO2 [AT]: 14.9 ± 3.4 vs. 14.2 ± 3.6, p = 0.048) and (VO2peak [Max]:18.2 ± 3.8 vs. 17.3 ± 3.8, p = 0.020). The RPP at admission was negatively correlated with VO2 (AT) and VO2peak (p < 0.05) using the regression Equation VO2peak = 33.682 + (-0.012 * RPP at admission/100) + (-0.105 * Age) + (-0.350 * BMI), while there was no correlation between the RPP at admission and VO2 (AT) (p = 0.149).

CONCLUSION

The RPP at admission was negatively correlated with cardiopulmonary function during hospitalization in patients with AMI. Patients with a high RPP were more likely to have a combination of obesity, hypertension, diabetes mellitus, and reduced oxygen uptake during exercise, while a high RPP at admission appeared to affect their cardiovascular response indicators during exercise.

Determinants of exercise performance in heart failure patients with extremely reduced cardiac output and left ventricular assist device

The evaluation of exercise capacity and cardiac output (QC) is fundamental in the management of patients with advanced heart failure (AdHF). QC and peak oxygen uptake (VO2) have a pivotal role in the prognostic stratification and in the definition of therapeutic interventions, including medical therapies and devices, but also specific treatments such as heart transplantation and left ventricular assist device (LVAD) implantation. Due to the intertwined relationship between exercise capacity and daily activities, exercise intolerance dramatically has impact on the quality of life of patients. It is a multifactorial process that includes alterations in central and peripheral haemodynamic regulation, anaemia and iron deficiency, pulmonary congestion, pulmonary hypertension, and peripheral O2 extraction. This paper aims to review the pathophysiological background of exercise limitations in HF patients and to examine the complex physiology of exercise in LVAD recipients, analysing the interactions between the cardiopulmonary system, the musculoskeletal system, the autonomic nervous system, and the pump. We performed a literature review to highlight the current knowledge on this topic and possible interventions that can be implemented to increase exercise capacity in AdHF patients-including administration of levosimendan, rehabilitation, and the intriguing field of LVAD speed changes. The present paper confirms the role of CPET in the follow-up of this peculiar population and the impact of exercise capacity on the quality of life of AdHF patients.

Exercise Performance and Quality of Life of Left Ventricular Assist Device Patients After Long-Term Outpatient Cardiac Rehabilitation

PURPOSE

Exercise performance and quality of life (QoL) of left ventricular assist device (LVAD) patients improve after early cardiac rehabilitation (CR). The purpose of this study was to examine the efficacy of multiprofessional long term phase 3 outpatient CR, and whether cardiopulmonary exercise testing (CPX) and 6-min walk testing (6MWT) post-LVAD implantation predict hospital readmission.

METHODS

This retrospective observational cohort study included 29 LVAD patients (58.6 ± 7.7 yr, female: 13.8%, body mass index: 29.4 ± 3.3 kg/m 2 ). Functional performance tests (CPX, 6MWT, sit-to-stand test), QoL, and psychological surveys (Kansas City Cardiomyopathy Questionnaire, hospital anxiety and depression scale, and Control Convictions about Disease and Health [KKG]) were performed at baseline and at the end of CR.

RESULTS

The CR was initiated at a median (IQR) of 159 (130-260) d after LVAD implantation for a duration of 340 (180-363) d with 46.8 ± 23.2 trainings. The 6MWT (408.4 ± 113.3 vs 455.4 ± 115.5 m, P = .003) and sit-to-stand test (16.7 ± 6.9 vs 19.0 ± 5.3 repetitions, P = .033) improved, but relative peak oxygen uptake (V˙ o2peak : 9.4 [8.2-14.4] vs 9.3 [7.8-13.4] mL/min/kg, P = .57) did not change. Using receiver operating characteristic curve analysis, baseline V˙ o2peak values were associated with readmission 1-yr after CR onset (C-statistic = 0.88) with a cutoff value of V˙ o2peak < 9.15 mL/min/kg (100% sensitivity, 78% specificity, P < .001). The Kansas City Cardiomyopathy Questionnaire self-efficacy and knowledge (+6.3 points), QoL (+5.0 points), and social limitation (+7.1 points) demonstrated clinically important changes. In addition, the hospital anxiety and depression scale showed a significant reduction in anxiety (4.6 ± 3.2 vs 2.6 ± 2.4, P = .03).

CONCLUSIONS

Long-term CR is safe and LVAD outpatients showed improvement of QoL, anxiety, and submaximal exercise performance. In addition, V˙ o2peak and 6MWT have prognostic value for readmission.

Prognostic Role of Metabolic Exercise Testing in Heart Failure

Heart failure is a clinical syndrome with significant heterogeneity in presentation and severity. Serial risk-stratification and prognostication can guide management decisions, particularly in advanced heart failure, when progression toward advanced therapies or end-of-life care is warranted. Each currently utilized prognostic marker carries its own set of challenges in acquisition, reproducibility, accuracy, and significance. Left ventricular ejection fraction is foundational for heart failure syndrome classification after clinical diagnosis and remains the primary parameter for inclusion in most clinical trials; however, it does not consistently correlate with symptoms and functional capacity, which are also independently prognostic in this patient population. Utilizing the left ventricular ejection fraction as the sole basis of prognostication provides an incomplete characterization of this condition and is prone to misguide medical decision-making when used in isolation. In this review article, we survey and exposit the important role of metabolic exercise testing across the heart failure spectrum, as a complementary diagnostic and prognostic modality. Metabolic exercise testing, also known as cardiopulmonary exercise testing, provides a comprehensive evaluation of the multisystem (i.e., neurological, respiratory, circulatory, and musculoskeletal) response to exercise performance. These differential responses can help identify the predominant contributors to exercise intolerance and exercise symptoms. Additionally, the aerobic exercise capacity (i.e., oxygen consumption during exercise) is directly correlated with overall life expectancy and prognosis in many disease states. Specifically in heart failure patients, metabolic exercise testing provides an accurate, objective, and reproducible assessment of the overall circulatory sufficiency and circulatory reserve during physical stress, being able to isolate the concurrent chronotropic and stroke volume responses for a reliable depiction of the circulatory flow rate in real time.

Increased Dead Space Ventilation as a Contributing Factor to Persistent Exercise Limitation in Patients with a Left Ventricular Assist Device

(1) Background: The exercise capacity of patients with a left ventricular assist device (LVAD) remains limited despite mechanical support. Higher dead space ventilation (VD/VT) may be a surrogate for right ventricular to pulmonary artery uncoupling (RV-PA) during cardiopulmonary exercise testing (CPET) to explain persistent exercise limitations. (2) Methods: We investigated 197 patients with heart failure and reduced ejection fraction with (n = 89) and without (HFrEF, n = 108) LVAD. As a primary outcome NTproBNP, CPET, and echocardiographic variables were analyzed for their potential to discriminate between HFrEF and LVAD. As a secondary outcome CPET variables were evaluated for a composite of hospitalization due to worsening heart failure and overall mortality over 22 months. (3) Results: NTproBNP (OR 0.6315, 0.5037-0.7647) and RV function (OR 0.45, 0.34-0.56) discriminated between LVAD and HFrEF. The rise of endtidal CO2 (OR 4.25, 1.31-15.81) and VD/VT (OR 1.23, 1.10-1.40) were higher in LVAD patients. Group (OR 2.01, 1.07-3.85), VE/VCO2 (OR 1.04, 1.00-1.08), and ventilatory power (OR 0.74, 0.55-0.98) were best associated with rehospitalization and mortality. (4) Conclusions: LVAD patients displayed higher VD/VT compared to HFrEF. Higher VD/VT as a surrogate for RV-PA uncoupling could be another marker of persistent exercise limitations in LVAD patients.

Long-term assist device patients admitted to ICU: Tips and pitfalls

Left ventricular assist device (LVAD) therapy is well-established in the treatment of end-stage cardiac failure. Indications are bridge to transplant (BTT), bridge to candidacy (BTC), bridge to recovery (BTR), and destination therapy (DT). The durability and adverse event (AE) rate of LVADs have improved over the years. However, due to donor shortage, the duration of support in the BTT population has increased tremendously; similarly, DT patients are on the device for a long time. Consequently, the number of readmissions of long-term LVAD patients has increased. In cases of severe AEs, intensive care unit (ICU) treatment can be necessary. Infectious complications are the most common AE. Furthermore, embolic or hemorrhagic strokes can occur due to foreign surfaces, acquired von Willebrand syndrome, and anticoagulation treatment. Another consequence of the coagulative status, in combination with the continuous flow, are gastrointestinal bleeding events. Moreover, in most patients, an isolated LVAD is implanted, and this involves the risk of late right heart failure. Adjustment of pump speed and optimization of the volume status can help solve this issue. Malignant arrhythmias, pre-existing or de novo after LVAD implantation, can be a life-threatening AE. Antiarrhythmic medical therapy or ablation are potential treatment options. As for specific LVADs, the Medtronic HeartWare™ ventricular assist device (HVAD) is not manufactured and distributed currently; however, 4000 patients are still on the device. Pump thrombosis can occur, wherein thrombolytic therapy is the first-line treatment option. Additionally, the HVAD can fail to restart after controller exchange due to technical issues, and precautions must be taken. The Momentum 3 trial showed superior survival without pump exchange or disabling stroke in patients treated with the HeartMate 3^Ⓡ (HM3; Abbott, Abbott Park, IL, USA) device in comparison to the HeartMate II (HMII). However, in a few cases, a twisted graft or bio debris formation between the outflow graft and bend relief could be observed, causing outflow graft obstruction. Patients on LVADs are still heart failure patients, in many cases with comorbidities. Therefore, many situations can occur requiring ICU treatment. Ethical aspects should always be the focus when taking care of these patients.

Effectiveness of high intensity interval training on cardiorespiratory fitness and endothelial function in type 2 diabetes: A systematic review

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a chronic metabolic syndrome characterized by insulin resistance and hyperglycemia that may lead to endothelial dysfunction, reduced functional capacity and exercise intolerance. Regular aerobic exercise has been promoted as the most beneficial non-pharmacological treatment of cardiovascular diseases. High intensity interval training (HIIT) seems to be superior than moderate-intensity continuous training (MICT) in cardiovascular diseases by improving brachial artery flow-mediated dilation (FMD) and cardiorespiratory fitness to a greater extent. However, the beneficial effects of HIIT in patients with T2DM still remain under investigation and number of studies is limited.

AIM

To evaluate the effectiveness of high intensity interval training on cardiorespiratory fitness and endothelial function in patients with T2DM.

METHODS

We performed a search on PubMed, PEDro and CINAHL databases, selecting papers published between December 2012 and December 2022 and identified published randomized controlled trials (RCTs) in the English language that included community or outpatient exercise training programs in patients with T2DM. RCTs were assessed for methodological rigor and risk of bias via the Physiotherapy Evidence Database (PEDro). The primary outcome was peak VO₂ and the secondary outcome was endothelial function assessed either by FMD or other indices of microcirculation.

RESULTS

Twelve studies were included in our systematic review. The 12 RCTs resulted in 661 participants in total. HIIT was performed in 310 patients (46.8%), MICT to 271 and the rest 80 belonged to the control group. Peak VO₂ increased in 10 out of 12 studies after HIIT. Ten studies compared HIIT with other exercise regimens (MICT or strength endurance) and 4 of them demonstrated additional beneficial effects of HIIT over MICT or other exercise regimens. Moreover, 4 studies explored the effects of HIIT on endothelial function and FMD in T2DM patients. In 2 of them, HIIT further improved endothelial function compared to MICT and/or the control group while in the rest 2 studies no differences between HIIT and MICT were observed.

CONCLUSION

Regular aerobic exercise training has beneficial effects on cardiorespiratory fitness and endothelial function in T2DM patients. HIIT may be superior by improving these parameters to a greater extent than MICT.

Heart failure classification based on resting ejection fraction does not display a unique exercise response pattern

BACKGROUND

Heart failure with preserved (HFpEF), mildly reduced (HFmrEF) and reduced (HFrEF) ejection fraction (EF) remains a controversial categorization. Whether these three categories reflect a distinct pattern of exercise limitation in cardiopulmonary exercise testing (CPET) needs to be investigated. We aimed to analyze whether CPET variables differ between all heart failure categories (HF).

METHODS

We analyzed CPET variables of stable HFpEF (n = 123), HFmrEF (n = 31), and HFrEF (n = 153; 74 patients with and 79 patients without left ventricular assist device, LVAD) patients. The association between HF and peak oxygen consumption (VO_2peak) was used as a primary outcome, while the association between HF, oxygen uptake efficiency slope (OUES), and increase of O₂ pulse (ΔO₂ pulse) were analyzed as secondary outcomes.

RESULTS

VO_2peak displayed a consistent decline across all HF categories (19.8 ml ± 6.2/kg/min vs. 17.5 ± 7.9 ml/kg/min vs. 13.7 ± 4.0 ml/kg/min, p < 0.001). OUES only showed differences between HFpEF and HFrEF (1.8 ± 0.6 vs. 1.4 ± 0.5, p < 0.001) as well as HFmrEF and HFrEF (1.9 ± 0.9 vs. 1.4 ± 0.5, p = 0.004). ΔO₂ pulse differed between HFpEF and HFrEF (7.7 ± 3.5 ml/beat/kg*100 vs. 5.5 ± 3.0 ml/beat/kg*100, p < 0.001) as well as HFpEF and HFmrEF (7.7 ± 3.5 ml/beat/kg*100 vs. 6.3 ± 4.1 ml/beat/kg*100, p = 0.049). Outcome variables did not differ between HFrEF with and without LVAD support (VO_2peak: p = 0.364, OUES: p = 0.129, ΔO₂ pulse: p = 0.564).

CONCLUSIONS

HF did not display a distinct CPET profile. Thus, EF-based categorization does not entirely reflect exercise limitations. CPET variables could contribute to better characterize HF phenotypes.

[Cardiac rehabilitation in LVAD patients : Aspects regarding exercise and rhythm]

After implantation of a left ventricular assist device (LVAD), it is strongly recommended that patients participate in an inpatient cardiac rehabilitation program (CR). Relevant topics during CR include sports and exercise therapy as well as aspects of cardiac rhythm control. Over time, LVAD patients usually regain a good quality of life and an adequate functional capacity can be observed. However, maximum performance values remain markedly reduced, in part due to the fixed LVAD pump speed and the limited total cardiac output. Therefore, structured long-term exercise training programs (even beyond CR phase II) are of particular importance in order to optimize neuromuscular control and muscle metabolism. Limitations to physical performance values may also be caused by the occurrence of supraventricular and/or ventricular arrhythmias. In both cases, the cause is an increasing hemodynamic impairment of the right heart, which may also lead to a reduced LVAD pump flow. In addition, inadequate setting of other cardiac implantable electronic devices (e.g., implantable cardioverter-defibrillator [ICD] or cardiac resynchronization therapy with defibrillator [CRT-D]) may also have a crucial impact on hemodynamics after LVAD implantation. In this article, we will discuss specific aspects of LVAD therapy related to exercise and rhythm control, particularly in the context of CR programs.

Cardiopulmonary exercise testing for heart failure: pathophysiology and predictive markers

Despite the numerous recent advancements in therapy, heart failure (HF) remains a principle cause of both morbidity and mortality. HF with preserved ejection fraction (HFpEF), a condition that shares the prevalence and adverse outcomes of HF with reduced ejection fraction, remains poorly recognised in its initial manifestations. Cardiopulmonary exercise testing (CPET), defined as a progressive work exercise test that includes non-invasive continuous measurement of cardiovascular and respiratory parameters, provides a reliable mode to evaluate for early features and for the assessment of prognostic features of both forms of HF. While CPET measurements are standard of care for advanced HF and transplant programmes, they merit a broader clinical application in the early diagnosis and assessment of patients with HFpEF. In this review, we provide an overview of the pathophysiology of exercise intolerance in HF and discuss key findings in CPETs used to evaluate both severity of impairment and the prognostic implications.

Exercise oscillatory ventilation in patients with advanced heart failure with and without left ventricular assist device

BACKGROUND

Exercise oscillatory ventilation (EOV), indicating pathological fluctuations on pulmonary arterial pressure, is associated with mortality in patients with heart failure (HF). Whether left ventricular assist device (LVAD)-induced ventricular unloading can reverse EOV and may prevent short-term rehospitalization has not been investigated.

METHODS

We performed a retrospective single-center in- and outpatient analysis of patients with (n = 20, LVAD) and without (n = 27, HF) circulatory support and reduced ejection fraction (EF, 22.8 ± 7.9%). The association of cardiopulmonary exercise testing (CPET) variables and 3 months-rehospitalization (3MR) as a primary outcome was analyzed. Furthermore, CPET variables were compared regarding the presence of EOV (+/-).

RESULTS

Lower VO_2peak (11.6 ± 4.9 ml/kg/min vs. 14.4 ± 4.3 ml/kg/min, p = 0.039), lower increase of PETCO₂ (CI = 0.049-1.127; p = 0.068), and higher VE/VCO₂ (43.8 ± 9.5 vs. 38.3 ± 10.6; p = 0.069) were associated with 3MR. Flattening of O₂ pulse (CI = 0.139-2.379; p = 0.487) had no impact on 3MR. EOV was present in 59.5% (n = 28/47) of patients, without a significant difference between LVAD and HF patients (p = 0.959). Patients with HF/EOV+ demonstrated significantly lower VO_2peak compared with HF/EOV- (p = 0.039). LVAD/EOV+ displayed significantly lower EF (p = 0.004) and fewer aortic valve opening than LVAD/EOV- (p = 0.027).

CONCLUSIONS

Lower VO_2peak , but not EOV, was associated with 3MR. EOV occurred at a similar rate in LVAD and HF patients, which may illustrate insufficient unloading during exercise in chronic LVAD therapy and may contribute to the limited exercise capacity following LVAD implantation. Simultaneous CPET and right heart catheterization studies are needed to elucidate whether EOV may serve as a non-invasive predictor of insufficient LV unloading necessitating LVAD reprograming.

Impact of Mechanical Circulatory Support on Exercise Capacity in Patients With Advanced Heart Failure

Approximately 6 million individuals have heart failure in the United States alone and 15 million in Europe. Left ventricular assist devices (LVAD) improve survival in these patients, but functional capacity may not fully improve. This article examines the hypothesis that patients supported by LVAD experience persistent reductions in functional capacity and explores mechanisms accounting for abnormalities in exercise tolerance.

LVAD as a Bridge to Remission from Advanced Heart Failure: Current Data and Opportunities for Improvement

Left ventricular assist devices (LVADs) are an established treatment modality for advanced heart failure (HF). It has been shown that through volume and pressure unloading they can lead to significant functional and structural cardiac improvement, allowing LVAD support withdrawal in a subset of patients. In the first part of this review, we discuss the historical background, current evidence on the incidence and assessment of LVAD-mediated cardiac recovery, and out-comes including quality of life after LVAD support withdrawal. In the second part, we discuss current and future opportunities to promote LVAD-mediated reverse remodeling and improve our pathophysiological understanding of HF and recovery for the benefit of the greater HF population.

Exercise in patients with left ventricular devices: The interaction between the device and the patient

Advances in the engineering of surgically implanted, durable left ventricular assist devices (LVAD) has led to improvements in the two-year survival of patients on LVAD support, which is now comparable to that of heart transplant (HT) recipients. And with the advent of magnetic levitation technology, both the survival rate and average time on LVAD support are expected to improve even further. However, despite these advances, the functional capacity of patients on LVAD support remains reduced compared to those who received a HT. A few small clinical trials have shown improvement in functional capacity with exercise training. Peak oxygen uptake improves modestly (10%-20%) with exercise training, suggesting a possible celling-effect linked to the ability of the LVAD to increase flow during exercise. This paper reviews both (a) the effect of the LVAD on the cardiorespiratory responses during a single, acute bout of exercise up to maximum and (b) the central and peripheral adaptations that occur among patients with an LVAD who undergo an exercise training regimen. We also address the tenets of the exercise prescription that are unique to patients with a durable LVAD.