Aortic Valve Replacement Versus Conservative Treatment in Asymptomatic Severe Aortic Stenosis: The AVATAR Trial.

BACKGROUND: Surgical aortic valve replacement (SAVR) represents a class I indication in symptomatic patients with severe aortic stenosis (AS). However, indications for early SAVR in asymptomatic patients with severe AS and normal left ventricular function remain debated. METHODS: The AVATAR trial (Aortic Valve Replacement Versus Conservative Treatment in Asymptomatic Severe Aortic Stenosis) is an investigator-initiated international prospective randomized controlled trial that evaluated the safety and efficacy of early SAVR in the treatment of asymptomatic patients with severe AS, according to common criteria (valve area ≤1 cm2 with aortic jet velocity >4 m/s or a mean transaortic gradient ≥40 mm Hg), and with normal left ventricular function. Negative exercise testing was mandatory for inclusion. The primary hypothesis was that early SAVR would reduce the primary composite end point of all-cause death, acute myocardial infarction, stroke, or unplanned hospitalization for heart failure compared with a conservative strategy according to guidelines. The trial was designed as event-driven to reach a minimum of 35 prespecified events. The study was performed in 9 centers in 7 European countries. RESULTS: Between June 2015 and September 2020, 157 patients (mean age, 67 years; 57% men) were randomly allocated to early surgery (n=78) or conservative treatment (n=79). Follow-up was completed in May 2021. Overall median follow-up was 32 months: 28 months in the early surgery group and 35 months in the conservative treatment group. There was a total of 39 events, 13 in early surgery and 26 in the conservative treatment group. In the early surgery group, 72 patients (92.3%) underwent SAVR with operative mortality of 1.4%. In an intention-to-treat analysis, patients randomized to early surgery had a significantly lower incidence of primary composite end point than those in the conservative arm (hazard ratio, 0.46 [95% CI, 0.23-0.90]; P=0.02). There was no statistical difference in secondary end points, including all-cause mortality, first heart failure hospitalizations, major bleeding, or thromboembolic complications, but trends were consistent with the primary outcome. CONCLUSIONS: In asymptomatic patients with severe AS, early surgery reduced a primary composite of all-cause death, acute myocardial infarction, stroke, or unplanned hospitalization for heart failure compared with conservative treatment. This randomized trial provides preliminary support for early SAVR once AS becomes severe, regardless of symptoms. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02436655.

Five-Year Outcomes in Bariatric Surgery Patients.

Background and objectives: Obesity presents as a multifactorial, pandemic disease that arises as a consequence of unequal energy intake and energy consumption. Obesity adversely affects the quality of life, leading not only to disability, but also to various other disorders. Bariatric surgery is the most effective method for achieving significant and sustained weight loss in individuals with extreme obesity. The aim of this study was to examine how well surgically induced weight loss is maintained after five years of follow-up and its effects on cardiovascular risk factors and outcome. Materials and Methods: This is a retrospective cross-sectional study of 66 patients with morbid obesity, with body mass index (BMI) ≥ 40 kg/m2 or BMI ≥ 35 kg/m2 and obesity-related health conditions, aged 20 to 61 years, mostly women (77.3%) who underwent laparoscopic Roux-en-Y gastric bypass surgery. Results: Average follow-up was 6.42 years (95% CI 6.30-6.54 years) after surgery, with survival rate of 97% in operated individuals. There was a statistically significant reduction of weight and body mass index 6 months and 5 years after surgery in comparison to the initial values (p < 0.001). Of 62 patients who presented weight loss at the end of the follow-up period, 38 were able to maintain the amount of weight loss that was attained 6 months after surgery, while 24 patients regained weight compared to their postoperative weight at 6 months. Two patients reported no weight loss after treatment. Significant weight reduction was associated with better control of diabetes and increased self-reported physical activity at 6 months and 5 years after surgery, as well as with a reduction of the use of anti-diabetic and anti-hypertensive medications. Conclusions: Our research demonstrates a positive long-term impact of bariatric surgery on patients' health conditions, significant and sustained weight loss, and decrease in BMI, which were associated with a reduction of co-morbidities and risk factors for cardiovascular diseases.

Stress hormones at rest and following exercise testing predict coronary artery disease severity and outcome.

OBJECTIVES: Despite considerable knowledge regarding the importance of stress in coronary artery disease (CAD) pathogenesis, its underestimation persists in routine clinical practice, in part attributable to lack of a standardized, objective assessment. The current study examined the ability of stress hormones to predict CAD severity and prognosis at basal conditions as well as during and following an exertional stimulus. MATERIALS AND METHODS: Forty Caucasian subjects with significant coronary artery lesions (≥50%) were included. Within 2 months of coronary angiography, cardiopulmonary exercise testing (CPET) on a recumbent ergometer was performed in conjunction with stress echocardiography (SE). At rest, peak and after 3 min of recovery following CPET, plasma levels of cortisol, adrenocorticotropic hormone (ACTH) and NT-pro-brain natriuretic peptide (NT-pro-BNP) were measured by immunoassay sandwich technique, radioimmunoassay, and radioimmunometric technique, respectively. Subjects were subsequently followed a mean of 32 ± 10 months. RESULTS AND DISCUSSION: Mean ejection fraction was 56.7 ± 9.6%. Subjects with 1-2 stenotic coronary arteries (SCA) demonstrated a significantly lower plasma cortisol levels during CPET compared to those with 3-SCA (p < .05), whereas ACTH and NT-pro-BNP were not significantly different (p > .05). Among CPET, SE, and hormonal parameters, cortisol at rest and during CPET recovery demonstrated the best predictive value in distinguishing between 1-, 2-, and 3-SCA [area under ROC curve 0.75 and 0.77 (SE = 0.11, 0.10; p = .043, .04) for rest and recovery, respectively]. ΔCortisol peak/rest predicted cumulative cardiac events (area under ROC curve 0.75, SE = 0.10, p = .049). CONCLUSIONS: Cortisol at rest and following an exercise test holds predictive value for CAD severity and prognosis, further demonstrating a link between stress and unwanted cardiac events.

Gauging the response to cardiac resynchronization therapy: The important interplay between predictor variables and definition of a favorable outcome.

AIMS: Selection of patients who are viable candidates for cardiac resynchronization therapy (CRT), prediction of the response to CRT as well as an optimal definition of a favorable response, all require further exploration. The purpose of this study was to evaluate the interplay between the prediction of the response to CRT and the definition of a favorable outcome. METHODS: Seventy patients who received CRT were included. All patients met current guideline criteria for CRT. Forty-three echocardiographic parameters were evaluated before CRT and at 1, 3, 6, and 12 months. M-mode, 2D echocardiography, and Doppler imaging were used to quantify left ventricular (LV) systolic and diastolic function, mitral regurgitation, right ventricular systolic function, pulmonary artery pressure, and myocardial mechanical dyssynchrony. The following definitions of a favorable CRT response were used: left ventricular ejection fraction (LVEF) improvement more >5% acutely following CRT, LVEF improvement >20% at 12-month follow-up, and a LV end-systolic volume (LVESV) decrease >15% at 12-month follow-up. RESULTS: For the LVEF improvement >5%, the best predictor was isovolumetric relaxation time (IVRT; P=.035). For improvement of LVEF >20%, the best predictors were left ventricular stroke index (LVSI; P=.044) and left ventricular fractional shortening (LVFS; P=.031). For the drop in left ventricular systolic volume (LVESV >15%), the best predictor was septal-to-lateral wall delay (ΔT) (P=.043, RR=1.023, 95% CI for RR=1.001-1.045). CONCLUSION: The definition of a favorable CRT response influenced the optimal predictor variable(s). Standardization of defining a favorable response to CRT is needed to guide clinical decision making processes.

Rationale and design of the Aortic Valve replAcemenT versus conservative treatment in Asymptomatic seveRe aortic stenosis (AVATAR trial): A randomized multicenter controlled event-driven trial.

Aortic valve replacement (AVR) therapy is an obvious choice for symptomatic severe aortic stenosis (AS) patients as it improves symptoms, left ventricular function, and survival. The treatment decisions and indication for AVR in asymptomatic patients with severe AS and normal left ventricular ejection fraction are less well established and the subject of ongoing debate. Many efforts have been made to define the best treatment option in asymptomatic AS patients with normal left ventricular ejection fraction. Retrospective and observational data imply that elective AVR for asymptomatic severe AS may lead to improvement in outcomes in comparison to surgery performed after onset of symptoms. The AVATAR trial will aim to assess outcomes among asymptomatic AS patients randomized to either elective early AVR or medical management with vigilant follow-up. In the latter group, AVR would be delayed until either the onset of symptoms or changes in predefined echocardiographic parameters. To the best of the authors' knowledge, it will be the first large prospective, randomized, controlled, multicenter clinical trial that will evaluate the safety and efficacy of elective AVR in this specific group of patients.

Valvulo-arterial impedance is the best mortality predictor in asymptomatic aortic stenosis patients.

BACKGROUND AND AIM OF THE STUDY: Risk stratification is particularly complex in asymptomatic patients with significant aortic stenosis (AS). The study aim was to assess which hemodynamic/Doppler-echocardiographic parameter best predicts mortality in asymptomatic patients with severe AS and a normal left ventricular ejection fraction (LVEF). METHODS: This prospective study included 128 consecutive asymptomatic patients (75 males, 53 females; mean age 66.35 ± 10.51 years) with severe AS (aortic valve area (AVA) ± 1.0 cm2) and a normal LVEF (55%). The patients were followed up for 47 months (median 35.5 months, IQR 7 months). Clinical data at follow up were obtained from all patients by either direct examination or telephone interview. RESULTS: During the follow up, 55 patients (43.0%) underwent aortic valve replacement (AVR) surgery due to AS-related symptoms. Of the 12 patients that died (9.4%), eight deaths occurred before surgery (four patients refused operation), and one patient died after surgery due to postoperative infection. Those patients who died had a significantly higher valvulo-arterial impedance (Z(va)) (7.81 versus 4.86 mmHg x ml/m2, p < 0.001), a higher N-terminal pro-brain natriuretic peptide (NT-proBNP) level (1708.5 versus 376.5 pg/ml, p = 0.003) and a lower AVA (0.65 versus 0.86 cm2, p = 0.002), but there were no differences in LVEF, P(mean) or age between the groups (69.68% versus 72.24%, p = 0.206; 44.95 versus 41.75 mmHg; and 69 versus 66 years, p = 0.332, respectively). When parameters that were predictors of mortality according to univariate analysis were further analyzed with Cox multivariate analysis, Z(va) was found to be the best independent predictor (B = 0.460, HR = 1.584, 95% CI = 1.064-2.359, p = 0.024). A Z(va) value of 6.1 mmHg x ml/m2 was identified as the best (cut-off) predictive value for the occurrence of death, with a sensitivity 61.1% and a specificity 86.0%. CONCLUSION: Z(va) is the best mortality predictor in asymptomatic patients with severe AS and a normal LVEF. Future studies are required to focus further on predictors of outcome, the aim being to achieve an optimal selection of asymptomatic patients considered to be at risk and who would benefit from early AVR.

Acute insulin resistance in ST-segment elevation myocardial infarction in non-diabetic patients is associated with incomplete myocardial reperfusion and impaired coronary microcirculatory function.

BACKGROUND: Insulin resistance (IR) assessed by the Homeostatic Model Assessment (HOMA) index in the acute phase of myocardial infarction in non-diabetic patients was recently established as an independent predictor of intrahospital mortality. In this study we postulated that acute IR is a dynamic phenomenon associated with the development of myocardial and microvascular injury and larger final infarct size in patients with ST-segment elevation myocardial infarction (STEMI) treated by primary percutaneous coronary intervention (pPCI). METHODS: In 104 consecutive patients with the first anterior STEMI without diabetes, the HOMA index was determined on the 2nd and 7th day after pPCI. Worst-lead residual ST-segment elevation (ST-E) on postprocedural ECG, coronary flow reserve (CFR) determined by transthoracic Doppler echocardiography on the 2nd day after pPCI and fixed perfusion defect on single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) determined six weeks after pPCI were analyzed according to HOMA indices. RESULTS: IR was present in 55 % and 58 % of patients on day 2 and day 7, respectively. Incomplete post-procedural ST-E resolution was more frequent in patients with IR compared to patients without IR, both on day 2 (p = 0.001) and day 7 (p < 0.001). The HOMA index on day 7 correlated with SPECT-MPI perfusion defect (r = 0.331), whereas both HOMA indices correlated well with CFR (r = -0.331 to -0.386) (p < 0.01 for all). In multivariable backward logistic regression analysis adjusted for significant univariate predictors and potential confounding variables, IR on day 2 was an independent predictor of residual ST-E ≥ 2 mm (OR 11.70, 95% CI 2.46-55.51, p = 0.002) and CFR < 2 (OR = 5.98, 95% CI 1.88-19.03, p = 0.002), whereas IR on day 7 was an independent predictor of SPECT-MPI perfusion defect > 20% (OR 11.37, 95% CI 1.34-96.21, p = 0.026). CONCLUSION: IR assessed by the HOMA index during the acute phase of the first anterior STEMI in patients without diabetes treated by pPCI is independently associated with poorer myocardial reperfusion, impaired coronary microcirculatory function and potentially with larger final infarct size.

Prognostic value of coronary flow reserve in asymptomatic moderate or severe aortic stenosis with preserved ejection fraction and nonobstructed coronary arteries.

AIM: Patients with moderate and severe aortic stenosis (AS) and without obstructive epicardial coronary disease have been shown to have an impairment of coronary flow reserve (CFR). We investigated the prognostic significance of CFR in predicting death during mid-to-long-term follow-up in asymptomatic patients with moderate/severe AS, preserved ejection fraction (EF), and with nonobstructed coronary arteries. METHOD AND RESULT: A total of 127 patients with moderate or severe AS (effective orifice area of 1.5 cm(2) or less), mean age 66 ± 11 were enrolled in this prospective study. The median follow-up was 32 ± 7 months. All patients had standard Doppler echo study, coronary angiography, and adenosine-stress transthoracic Doppler echo for CFR measurement. Univariate analysis showed that diabetes mellitus, CFR, aortic valve area (AVA), maximal velocity (Vmax ), mean pressure gradient (Pmean ), energy loss index (ELI), aortic valve resistance (AVR), NT-proBNP, E/E', valvulo-arterial impedance (Zva ), and stroke work loss (SWL) were associated (P < 0.05) with death. Multivariable logistic regression analysis revealed that only Zva and CFR were independent predictors of death, with the CFR being the single strongest predictor (Table 2). Using receiver operating characteristics (ROC) analysis, the CFR value of 1.85 had the highest accuracy in predicting the death during mid-to-long-term follow-up (area under the curve; AUC 0.890, P = 0.009, sensitivity 96.3%, specificity 75%; 95% CI 0.287-0.946; Fig. 1). The Zva value of 5.52 Hg/mL per m had a sensitivity 70.0% and specificity 72.0% (AUC 0.766, 95% CI 0.587-0.946; P = 0.005). CONCLUSION: This study demonstrates that CFR has a prognostic value in patients with asymptomatic moderate or severe AS with preserved EF and nonobstructed coronary arteries.

Acute Coronary Syndrome Following Transcatheter Aortic Valve Replacement.

Extending the indication of transcatheter aortic valve replacement (TAVR) to younger and lower-risk patients naturally results in longer life expectancy and survival rates after the intervention. The longer life expectancy of these patients leads to an increased possibility of future acute coronary events, necessitating the development of effective and appropriate treatment strategies. Acute coronary syndromes (ACS) in patients with previous TAVR procedures present with modified clinical characteristics when compared to the non-TAVR population. In populations with prior TAVR procedures, plaque rupture remains the main cause of ACS. However, unlike the non-TAVR population, there is an increased frequency of nonatherotrombotic mechanisms, like emboli and mechanical obstruction of coronary ostia by valve components. The main observation related to the treatment of ACS TAVR patients is the significantly lower percentage of patients undergoing invasive management. Furthermore, ACS in TAVR patients is associated with poor prognosis, higher long-term mortality rates, and higher incidence of MACE. It is surprising that considering this significant and increasingly recognized issue, there are only a few studies that have investigated ACS after TAVR. The scope of the present review is to address available data about ACS following TAVR, focusing on incidence, timing, mechanism, and causes. We also examined current knowledge regarding optimal invasive treatment and analyzed short and long-term clinical outcomes.

Asymptomatic Aortic Stenosis: From Risk Stratification to Treatment.

Our understanding of the natural history of aortic stenosis has significantly increased over the last decade. There have been considerable advances in the diagnosis and risk stratification of patients with aortic stenosis and in surgical and anesthetic techniques. In addition, transcatheter aortic valve replacement has established itself as a viable alternative to surgical management. Inevitably, these developments have raised questions regarding the merits of waiting for symptom onset in asymptomatic patients with severe aortic stenosis before offering treatment. Recent observational and randomized trial data suggest that early intervention in asymptomatic patients with severe aortic stenosis and normal left ventricular function may confer a prognostic advantage to a watchful waiting strategy. In this review, we highlight advances in the management and risk stratification of patients with asymptomatic severe aortic stenosis with particular consideration of recent findings supporting early valvular intervention.

Asymptomatic Severe and Moderate Aortic Stenosis: Time for Appraisal of Treatment Indications.

Over the last decades, we have witnessed considerable improvements in diagnostics and risk stratification of patients with significant aortic stenosis (AS), paralleled by advances in operative and anesthetic techniques. In addition, accumulating evidence points to the potential benefit of early valve replacement in such patients prior to the onset of symptoms. In parallel, interventional randomized trials have proven the benefit of transcatheter aortic valve replacement in comparison to a surgical approach to valve replacement over a broad risk spectrum in symptomatic patients with AS. This article reviews contemporary management approaches and scrutinizes open questions regarding timing and mode of intervention in asymptomatic patients with severe AS. We also discuss the challenges surrounding the management of symptomatic patients with moderate AS as well as emerging dilemmas related to the concept of a life-long treatment strategy for patients with AS.

Impact of diabetes on remodelling, microvascular function and exercise capacity in aortic stenosis.

OBJECTIVE: To characterise cardiac remodelling, exercise capacity and fibroinflammatory biomarkers in patients with aortic stenosis (AS) with and without diabetes, and assess the impact of diabetes on outcomes. METHODS: Patients with moderate or severe AS with and without diabetes underwent echocardiography, stress cardiovascular magnetic resonance (CMR), cardiopulmonary exercise testing and plasma biomarker analysis. Primary endpoint for survival analysis was a composite of cardiovascular mortality, myocardial infarction, hospitalisation with heart failure, syncope or arrhythmia. Secondary endpoint was all-cause death. RESULTS: Diabetes (n=56) and non-diabetes groups (n=198) were well matched for age, sex, ethnicity, blood pressure and severity of AS. The diabetes group had higher body mass index, lower estimated glomerular filtration rate and higher rates of hypertension, hyperlipidaemia and symptoms of AS. Biventricular volumes and systolic function were similar, but the diabetes group had higher extracellular volume fraction (25.9%±3.1% vs 24.8%±2.4%, p=0.020), lower myocardial perfusion reserve (2.02±0.75 vs 2.34±0.68, p=0.046) and lower percentage predicted peak oxygen consumption (68%±21% vs 77%±17%, p=0.002) compared with the non-diabetes group. Higher levels of renin (log10renin: 3.27±0.59 vs 2.82±0.69 pg/mL, p<0.001) were found in diabetes. Multivariable Cox regression analysis showed diabetes was not associated with cardiovascular outcomes, but was independently associated with all-cause mortality (HR 2.04, 95% CI 1.05 to 4.00; p=0.037). CONCLUSIONS: In patients with moderate-to-severe AS, diabetes is associated with reduced exercise capacity, increased diffuse myocardial fibrosis and microvascular dysfunction, but not cardiovascular events despite a small increase in mortality.

Prediction of a good response to cardiac resynchronization therapy in patients with severe dilated cardyomyopathy: could conventional echocardiography be the answer after all?

OBJECTIVES: The aim of this study was to assess the performance of echocardiographic parameters to predict response to cardiac resynchronization therapy (CRT). BACKGROUND: CRT reduces morbidity and mortality due to the proper selection of candidates for CRT. METHODS: The 12-month trial was performed on 70 optimally medicated patients with standard inclusion criteria: NYHA class III or IV heart failure, left ventricular ejection fraction (LVEF) ≤ 35%, and QRS ≥ 120 ms. All parameters were evaluated by conventional and tissue Doppler-based methods. Indicator of positive CRT response was more than 20% in improvement of LVEF. RESULTS: LVEF increased >20% in 42 patients. Out of 43 tested baseline echocardiographic parameters, 12 showed statistical difference between responders and nonresponders. Out of these 12 parameters, six (LVSV, LVSI, LVFS, RVd, VPMR, and PISA) had modest to moderately good ability to predict LVEF response with sensitivity ranging from 62.2% to 82.4%, and specificity ranging from 56.5% to 81.2%. For those parameters, the area under the receiver-operating characteristic curve for positive response to CRT was ≤0.76. Multivariate regression analysis resulted in selection of LVSI and LVFS as possible predictive independent parameters for a good response. The cutoff value for LVSI was 38.7 mL/m(2) (P = 0.045) and for LVFS was 13% (P = 0.032). CONCLUSIONS: Contribution of LVSI and LVFS is to be confirmed in larger trials. Simplicity of their assessment by conventional echocardiography could be an argument for adding them to the inclusion criteria for CRT in severe heart failure patients.

Do all patients with asymptomatic severe aortic stenosis need treatment?

INTRODUCTION: Although guidelines recommend a watchful waiting strategy for patients with asymptomatic severe aortic stenosis, there have been considerable advancements in surgical and anesthetic techniques along with the success of transcatheter aortic valve replacement (AVR) as a viable alternative to surgical AVR. Inevitably, these developments have raised questions as to whether or not there is still merit in waiting for symptoms to ensue before treatment may be offered to these patients. AREA COVERED: The principal purpose of this paper is to review the data supporting earlier intervention in patients with asymptomatic severe aortic stenosis, and to project the implications these and other ongoing trials will have on indications for AVR in asymptomatic patients in the future. EXPERT OPINION: The threshold for intervention in certain subgroups of asymptomatic patients with severe AS has already been lowered. The next frontier will inevitably be determining whether all patients with severe AS should undergo AVR irrespective of their symptomatic status.

Challenges in Diagnosis and Functional Assessment of Coronary Artery Disease in Patients With Severe Aortic Stenosis.

More than half of patients with severe aortic stenosis (AS) over 70 years old have coronary artery disease (CAD). Exertional angina is often present in AS-patients, even in the absence of significant CAD, as a result of oxygen supply/demand mismatch and exercise-induced myocardial ischemia. Moreover, persistent myocardial ischemia leads to extensive myocardial fibrosis and subsequent coronary microvascular dysfunction (CMD) which is defined as reduced coronary vasodilatory capacity below ischemic threshold. Therefore, angina, as well as noninvasive stress tests, have a low specificity and positive predictive value (PPV) for the assessment of epicardial coronary stenosis severity in AS-patients. Moreover, in symptomatic patients with severe AS exercise testing is even contraindicated. Given the limitations of noninvasive stress tests, coronary angiography remains the standard examination for determining the presence and severity of CAD in AS-patients, although angiography alone has poor accuracy in the evaluation of its functional severity. To overcome this limitation, the well-established invasive indices for the assessment of coronary stenosis severity, such as fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR), are now in focus, especially in the contemporary era with the rapid increment of transcatheter aortic valve replacement (TAVR) for the treatment of AS-patients. TAVR induces an immediate decrease in hyperemic microcirculatory resistance and a concomitant increase in hyperemic flow velocity, whereas resting coronary hemodynamics remain unaltered. These findings suggest that FFR may underestimate coronary stenosis severity in AS-patients, whereas iFR as the non-hyperemic index is independent of the AS severity. However, because resting coronary hemodynamics do not improve immediately after TAVR, the coronary vasodilatory capacity in AS-patients treated by TAVR remain impaired, and thus the iFR may overestimate coronary stenosis severity in these patients. The optimal method for evaluating myocardial ischemia in patients with AS and co-existing CAD has not yet been fully established, and this important issue is under further investigation. This review is focused on challenges, limitations, and future perspectives in the functional assessment of coronary stenosis severity in these patients, bearing in mind the complexity of coronary physiology in the presence of this valvular heart disease.

Contemporary Challenges of Regenerative Therapy in Patients with Ischemic and Non-Ischemic Heart Failure.

It has now been almost 20 years since first clinical trials of stem cell therapy for heart repair were initiated. While initial preclinical data were promising and suggested that stem cells may be able to directly restore a diseased myocardium, this was never unequivocally confirmed in the clinical setting. Clinical trials of cell therapy did show the process to be feasible and safe. However, the clinical benefits of this treatment modality in patients with ischemic and non-ischemic heart failure have not been consistently confirmed. What is more, in the rapidly developing field of stem cell therapy in patients with heart failure, relevant questions regarding clinical trials' protocol streamlining, optimal patient selection, stem cell type and dose, and the mode of cell delivery remain largely unanswered. Recently, novel approaches to myocardial regeneration, including the use of pluripotent and allogeneic stem cells and cell-free therapeutic approaches, have been proposed. Thus, in this review, we aim to outline current knowledge and highlight contemporary challenges and dilemmas in clinical aspects of stem cell and regenerative therapy in patients with chronic ischemic and non-ischemic heart failure.