The impact of atrial fibrillation on oxygen uptake and haemodynamics in patients with heart failure: a systematic review and meta-analysis

Aims

Atrial fibrillation (AF) may exacerbate exercise intolerance and haemodynamic limitations in individuals with heart failure (HF). Therefore, we performed a systematic search and meta-analysis to quantify the impact of AF on exercise tolerance (peak oxygen uptake, VO2peak; primary outcome) and exercise haemodynamics (secondary outcomes) in patients with HF.

Methods and results

PubMed, Scopus, and Web of Science databases were systematically searched for articles from inception to June 2024. Studies were included if they: (i) examined participants with HF; (ii) compared participants with AF to those not in AF (i.e. sinus rhythm); (iii) measured VO2peak from expired gas analysis. A fixed effects meta-analysis was performed, with groups compared using the weighted average effect size, represented as the weighted mean difference (WMD) with 95% confidence intervals (95% CI). Of 573 identified studies, 16 met the full inclusion comparing VO2peak in HF-patients in AF [HF-AF; n = 1,271, 68% male, 67 years, left ventricular ejection fraction (LVEF): 41%], and HF in sinus rhythm (HF-SR; n = 4910; 62% male, 62 years, LVEF: 41%). VO2peak was significantly lower in HF-AF (WMD: -1.55mL/kg/min, 95%-CI: -1.81 to -1.28, n = 6471). This coincided with a slightly lower peak heart rate (WMD: -2.94 b/min, 95%-CI: -4.76 to -1.13 b/min, n = 5115), decreased O2pulse (WMD: -1.58 mL/beat, 95% CI: -1.90 to -1.26, n = 3049), and lower systolic blood pressure (WMD: -11.11 mmHg, 95% CI: -14.01 to -8.21, n = 2409).

Conclusion

In patients with HF, AF is associated with greater VO2peak impairment, potentially due to reduced stroke volume and/or arterio-venous oxygen difference. This highlights the importance of combined strategies to identify and manage AF in individuals with HF.

Prevalence and functional impact of chronotropic incompetence in amyloid cardiomyopathy: a multicentre analysis

BACKGROUND

Little evidence is available about heart rate (HR) response to exercise as well as its relationship with functional capacity in amyloid cardiomyopathy. Then, in a multicentre cohort of patients with amyloid cardiomyopathy, we investigated the prevalence of chronotropic incompetence (CI) and its relationships with cardiopulmonary exercise testing (CPET) variables.

METHODS

Data from 172 outpatients with amyloid cardiomyopathy who performed a maximal CPET and who had no significant rhythm disorders were analysed.

RESULTS

The prevalence of CI differed depending on the age-predicted peak HR (pHR%) cut-off value adopted, ranging from 16% to 59%. pHR% correlated non-linearly with peak oxygen uptake (pVO2), either as expressed as a percentage of the maximum predicted or as mL/kg/min (p<0.001). Although to a lesser extent, pHR% correlated inversely with ventilatory efficiency (p<0.001). A pHR%≤75% resulted in the most accurate cut-off value in identifying a moderate-to-severe exercise impairment (sensitivity 72%; specificity 73%; area under the curve 77.2%).

CONCLUSIONS

CI is prevalent in patients with amyloid cardiomyopathy in sinus rhythm, its percentage varying according to the pHR% cut-off value. A blunted exercise-induced HR response correlated with a poor exercise capacity even in this setting of patients, a pHR%≤75% cut-off value being possibly useful in centres without CPET availability to identify a significant exercise impairment.

Atrial Fibrillation Status and Physical Rehabilitation in Older Patients With Acute Decompensated Heart Failure: An Analysis From the REHAB-HF Trial

BACKGROUND

The REHAB-HF (Rehabilitation Therapy in Older Acute Heart Failure Patients) trial demonstrated that a transitional, tailored, progressive rehabilitation intervention improved physical function, 6-minute walk distance, frailty, quality-of-life, and depression in older patients hospitalized for acute decompensated heart failure. This analysis assessed the impact of atrial fibrillation (AF) on intervention benefits.

METHODS AND RESULTS

Of 349 enrolled patients hospitalized for acute decompensated heart failure (mean age 72.7±8.1 years), 176 (50.4%) had AF. Participants were randomly assigned to 12-week rehabilitation intervention or attention control. The primary outcome was Short Physical Performance Battery score at 3 months. Participants with AF were older (74.4±8.3 versus 70.8±7.5, P<0.0001) and had higher prevalence of heart failure with preserved ejection fraction (58.5% versus 47.4%, P=0.037). Patients with and without AF had similar improvement in Short Physical Performance Battery score (mean difference between rehabilitation intervention and attention control, 1.5 [95% CI, 0.6-2.3] versus 1.5 [95% CI, 0.7-2.3]; P<0.001). Those with AF had significant improvement in 6-minute walk distance (all P<0.05) and each of the Short Physical Performance Battery domains: balance, 4-meter walk, and chair rise. Kansas City Cardiomyopathy Questionnaire score significantly improved in patients with AF (P<0.05) but not those without AF (P>0.05). Interaction P values for 3-month outcomes by AF status were not significant (P>0.1). No significant differences were observed in deaths, all-cause rehospitalizations, or heart failure hospitalizations at 6 months.

CONCLUSIONS

In older, hospitalized patients with acute decompensated heart failure, the presence of AF did not significantly affect the benefit of the rehabilitation intervention on physical function and quality of life. The intervention appears safe and effective regardless of AF status.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique Identifier: NCT02196038.

Quantifying Improvement in V˙ o2peak and Exercise Thresholds in Cardiovascular Disease Using Reliable Change Indices

PURPOSE

Improving aerobic fitness through exercise training is recommended for the treatment of cardiovascular disease (CVD). However, strong justifications for the criteria of assessing improvement in key parameters of aerobic function including estimated lactate threshold (θ LT ), respiratory compensation point (RCP), and peak oxygen uptake (V˙ o2peak ) at the individual level are not established. We applied reliable change index (RCI) statistics to determine minimal meaningful change (MMC RCI ) cutoffs of θ LT , RCP, and V˙ o2peak for individual patients with CVD.

METHODS

Sixty-six stable patients post-cardiac event performed three exhaustive treadmill-based incremental exercise tests (modified Bruce) ∼1 wk apart (T1-T3). Breath-by-breath gas exchange and ventilatory variables were measured by metabolic cart and used to identify θ LT , RCP, and V˙ o2peak . Using test-retest reliability and mean difference scores to estimate error and test practice/exposure, respectively, MMC RCI values were calculated for V˙ o2 (mL·min -1. kg -1 ) at θ LT , RCP, and V˙ o2peak .

RESULTS

There were no significant between-trial differences in V˙ o2 at θ LT ( P = .78), RCP ( P = .08), or V˙ o2peak ( P = .74) and each variable exhibited excellent test-retest variability (intraclass correlation: 0.97, 0.98, and 0.99; coefficient of variation: 6.5, 5.4, and 4.9% for θ LT , RCP, and V˙ o2peak , respectively). Derived from comparing T1-T2, T1-T3, and T2-T3, the MMC RCI for θ LT were 3.91, 3.56, and 2.64 mL·min -1. kg -1 ; 4.01, 2.80, and 2.79 mL·min -1. kg -1 for RCP; and 3.61, 3.83, and 2.81 mL·min -1. kg -1 for V˙ o2peak . For each variable, MMC RCI scores were lowest for T2-T3 comparisons.

CONCLUSION

These MMC RCI scores may be used to establish cutoff criteria for determining meaningful changes for interventions designed to improve aerobic function in individuals with CVD.

Exercise echocardiography to assess left atrial function in patients with symptomatic AF

Background

Left atrial (LA) function contributes to the augmentation of cardiac output during exercise. However, LA response to exercise in patients with atrial fibrillation (AF) is unknown. We explored the LA mechanical response to exercise and the association between LA dysfunction and exercise intolerance.

Methods

We recruited consecutive patients with symptomatic AF and preserved left ventricular ejection fraction (LVEF). Participants underwent exercise echocardiography and cardiopulmonary exercise testing (CPET). Two-dimensional and speckle-tracking echocardiography were performed to assess LA function at rest and during exercise. Participants were grouped according to presenting rhythm (AF vs sinus rhythm). The relationship between LA function and cardiorespiratory fitness in patients maintaining SR was assessed using linear regression.

Results

Of 177 consecutive symptomatic AF patients awaiting AF ablation, 105 met inclusion criteria; 31 (29.5 %) presented in AF whilst 74 (70.5 %) presented in SR. Patients in SR augmented LA function from rest to exercise, increasing LA emptying fraction (LAEF) and LA reservoir strain. In contrast, patients in AF demonstrated reduced LAEF and reservoir strain at rest, with failure to augment either parameter during exercise. This was associated with reduced VO2Peak compared to those in SR (18.4 ± 5.6 vs 22.5 ± 7.7 ml/kg/min, p = 0.003). In patients maintaining SR, LAEF and reservoir strain at rest and during exercise were associated with VO2Peak, independent of LV function.

Conclusion

The maintenance of SR in patients with AF is associated with greater LA reservoir function at rest and greater augmentation with exercise compared to patients in AF. In patients in SR, reduced LA function is associated with reduced exercise tolerance, independent of LV function.

What about chronotropic incompetence in heart failure with mildly reduced ejection fraction? Clinical and prognostic implications from the Metabolic Exercise combined with Cardiac and Kidney Indexes score dataset

AIMS

Chronotropic incompetence (CI) is a strong predictor of outcome in heart failure with reduced ejection fraction, however no data on its clinical and prognostic impacts in heart failure with mildly reduced ejection fraction (HFmrEF) are available. Therefore, the study aims to investigate, in a large multicentre HFmrEF cohort, the prevalence of CI as well as its relationship with exercise capacity and its prognostic role over the cardiopulmonary exercise testing (CPET) parameters.

METHODS AND RESULTS

Within the Metabolic Exercise combined with Cardiac and Kidney Indexes (MECKI) database, we analysed data of 864 HFmrEF out of 1164 stable outpatients who performed a maximal CPET at the cycle ergometer and who had no significant rhythm disorders or comorbidities. The primary study endpoint was cardiovascular (CV) death. All-cause death was also explored. Chronotropic incompetence prevalence differed depending on the method (peak heart rate, pHR% vs. pHR reserve, pHRR%) and the cut-off adopted (pHR% from ≤75% to ≤60% and pHRR% ≤ 65% to ≤50%), ranging from 11% to 62%. A total of 84 (9.7%) CV deaths were collected, with 39 (4.5%) occurring within 5 years. At multivariate analysis, both pHR% [hazard ratio 0.97 (0.95-0.99), P < 0.05] and pHRR% [hazard ratio 0.977 (0.961-0.993), P < 0.01] were associated with the primary endpoint. A pHR% ≤ 75% and a pHRR% ≤ 50% represented the most accurate cut-off values in predicting the outcome.

CONCLUSION

The study suggests an association between blunted exercise-HR response, functional capacity, and CV death risk among patients with HFmrEF. Whether the CI presence might be adopted in daily HFmrEF management needs to be addressed in larger prospective studies.

Exercise capacity and risk of incident atrial fibrillation in healthy adults

BACKGROUND/AIMS

Atrial fibrillation (AF) is a common arrhythmia and is associated with cardiovascular morbidity and mortality. It is important to identify and control the modifiable risk factors of AF. We aimed to examine the association of exercise capacity with the risk of incident AF within 3 years in healthy subjects.

METHODS

We evaluated asymptomatic adults who had undergone more than two consecutive health checkups. We included subjects who exhibited normal sinus rhythm on the first health examination and who developed AF on the second or subsequent health examinations. Subjects who underwent cardiopulmonary exercise testing within 3 years before the diagnosis of AF were examined.

RESULTS

The study population in the analyses included 428 cases (mean age 58.4 ± 7.6 yr, male 95.6%). There were significant differences in maximal systolic blood pressure (SBP; case 169.4 ± 24.2 vs. control 173.9 ± 22.3 mmHg), peak VO2 (29.5 ± 5.4 vs. 30.4 ± 4.8 mL/kg per minute), and maximal metabolic equivalents (METs; 8.5 ± 1.6 vs. 8.7 ± 1.4) between the two groups. In the multivariable logistic models, adjusted odds ratios were 0.99 for maximal SBP (95% confidence interval [CI] 0.98-0.99), 0.97 for peak VO2 (95% CI 0.95-0.99), and 0.91 for maximal METs (95% CI 0.83-0.98).

CONCLUSION

We demonstrated that poorer exercise capacity was associated with the development of AF in a healthy population. A prospective, systematic trial is necessary to confirm that appropriate exercise training will be beneficial in preventing the development of AF in such patients.

Real-Time Estimation of Anaerobic Threshold during Exercise Using Electrocardiogram in Heart Failure Patients

Exercise therapy at the aerobic level is highly recommended to improve clinical outcomes in patients with heart failure, in which cardiopulmonary exercise testing (CPX) is required to determine anaerobic thresholds (ATs) but is not available everywhere. This study aimed to validate a method to estimate the AT using heart rate variability (HRV) analysis from electrocardiography data in patients with heart failure. Between 2014 and 2019, 67 patients with symptomatic heart failure underwent CPXs in a single university hospital. During the CPX, RR intervals was measured continuously and the HRV threshold (HRVT), defined as the inflection point of <5 ms2 of a high-frequency component (HFC) using the power spectrum analysis, was determined. Patients were divided into two groups according to the mean HFC at rest (high-HFC group, n = 34 and low-HFC group, n = 33). The high-HFC group showed good correlation between the VO2 at AT and HRVT (r = 0.63, p < 0.001) and strong agreement (mean difference, -0.38 mL/kg, p = 0.571). The low-HFC group also showed modest correlation (r = 0.41, p = 0.017) but poor agreement (mean differences, 3.75 mL/kg, p < 0.001). In conclusion, the HRVT obtained from electrocardiography may be a useful indicator for estimating AT in patients with heart failure.

The role of cardiopulmonary exercise testing in risk stratification and prognosis of atrial fibrillation: a scoping review of the literature

BACKGROUND

Cardiopulmonary exercise testing (CPET) is a significant tool for evaluating exercise capacity in healthy individuals and in various pulmonary and cardiovascular conditions, quantifying symptoms and predicting outcomes. Atrial fibrillation (AF) poses a significant burden on patients and health systems; a research marathon is ongoing for discovering the pathophysiologic substrate, natural history, prognostic tools and optimal treatment strategies for AF. Among the plethora of variables measured during CPET, there is a series of parameters of interest concerning AF.

METHODS

We conducted a scoping review aiming to identify significant CPET-related parameters linked to AF, as well as indicate the impact of other cardiac disease-related variables. We searched PubMed from its inception to 12 January 2022 for reports underlining the contribution of CPET in the assessment of patients with AF. Only clinical trials, observational studies and systematic reviews were included, while narrative reviews, expert opinions and other forms of manuscripts were excluded.

RESULTS

In our scoping review, we report a group of heterogeneous, thus noteworthy parameters relevant to the potential contribution of CPET in AF. CPET helps phenotype AF populations, evaluates exercise capacity after cardioversion or catheter ablation, and assesses heart rate response to exercise; peak VO2 and VE/VCO2, commonly measured indices during CPET, also serve as prognostic tools in patients with AF and heart failure.

CONCLUSIONS

CPET seems to hold a clinically important predictive value for future cardiovascular events both in patients with pre-existing cardiac conditions and in healthy individuals. CPET variables may play a fundamental role in the prediction of future AF-related events.

Old and new equations for maximal heart rate prediction in patients with heart failure and reduced ejection fraction on beta-blockers treatment: results from the MECKI score data set

AIMS

Predicting maximal heart rate (MHR) in heart failure with reduced ejection fraction (HFrEF) still remains a major concern. In such a context, the Keteyian equation is the only one derived in a HFrEF cohort on optimized β-blockers treatment. Therefore, using the Metabolic Exercise combined with Cardiac and Kidney Indexes (MECKI) data set, we looked for a possible MHR equation, for an external validation of Keteyien formula and, contextually, for accuracy of the historical MHR formulas and their relationship with the HR measured at the anaerobic threshold (AT).

METHODS AND RESULTS

Data from 3487 HFrEF outpatients on optimized β-blockers treatment from the MECKI data set were analyzed. Besides excluding all possible confounders, the new equation was derived by using HR data coming from maximal cardiopulmonary exercise test. The simplified derived equation was [109-(0.5*age) + (0.5*HR rest) + (0.2*LVEF)-(5 if haemoglobin <11 g/dL)]. The R2 and the standard error of the estimate were 0.24 and 17.5 beats min-1 with a mean absolute percentage error (MAPE) = 11.9%. The Keteyian equation had a slightly higher MAPE = 12.3%. Conversely, the Fox and Tanaka equations showed extremely higher MAPE values. The range 75-80% of MHR according to the new and the Keteyian equations was the most accurate in identifying the HR at the AT (MAPEs = 11.3-11.6%).

CONCLUSION

The derived equation to estimate the MHR in HFrEF patients, by accounting also for the systolic dysfunction degree and anaemia, improved slightly the Keteyian formula. Both formulas might be helpful in identifying the true maximal effort during an exercise test and the intensity domain during a rehabilitation programme.

Chronotropic index and long-term outcomes in heart failure with preserved ejection fraction

INTRODUCTION AND OBJECTIVES

Little is known about the usefulness of heart rate (HR) response to exercise for risk stratification in heart failure with preserved ejection fraction (HFpEF). Therefore, this study aimed to assess the association between HR response to exercise and the risk of total episodes of worsening heart failure (WHF) in symptomatic stable patients with HFpEF.

METHODS

This single-center study included 133 patients with HFpEF (NYHA II-III) who performed maximal cardiopulmonary exercise testing. HR response to exercise was evaluated using the chronotropic index (CI_x) formula. A negative binomial regression method was used.

RESULTS

The mean age of the sample was 73.2± 10.5 years; 56.4% were female, and 51.1% were in atrial fibrillation. The median for CI_x was 0.4 [0.3-0.55]. At a median follow-up of 2.4 [1.6-5.3] years, a total of 146 WHF events in 58 patients and 41 (30.8%) deaths were registered. In the whole sample, CI_x was not associated with adverse outcomes (death, P=.319, and WHF events, P=.573). However, we found a differential effect across electrocardiographic rhythms for WHF events (P for interaction=.002). CI_x was inversely and linearly associated with the risk of WHF events in patients with sinus rhythm and was positively and linearly associated with those with atrial fibrillation.

CONCLUSIONS

In patients with HFpEF, CI_x was differentially associated with the risk of total WHF events across rhythm status. Lower CI_x emerged as a risk factor for predicting higher risk in patients with sinus rhythm. In contrast, higher CI_x identified a higher risk in those with atrial fibrillation.

Exercise Training in Heart Failure With Reduced Ejection Fraction and Permanent Atrial Fibrillation: A Randomized Clinical Trial

BACKGROUND

Heart failure (HF) associated with atrial fibrillation (AF) increases patients' physical inactivity, worsening their clinical condition and mortality. Exercise training is safe and has clear benefits in HF. However, little is known about the effects of exercise training on heart failure patients with reduced ejection fraction and permanent atrial fibrillation (HFAF).

OBJECTIVE

To test the hypothesis that exercise training improves functional capacity, cardiac function, and quality of life in patients with HFAF.

METHODS

This randomized clinical trial was conducted at the Heart Institute. Patients with HFAF, LVEF ≤40% and resting HR ≤80 bpm were included in the study. Cardiopulmonary testing, echocardiography, autonomic, and quality of life assessment were performed before and after the 12-week protocol period.

RESULTS

Twenty-six patients, 58±1 years, were randomized to exercise training (HFAF-trained, n=13) or no training (HFAF-untrained, n=13). At baseline, no differences between groups were found. Exercise improved VO₂ peak, slope VE/VCO₂, and quality of life. HFAF-trained significantly decreased resting HR (from 73±2 to 69±2 bpm, P=.02) and recovery HR (from 148±11 to 128±9 bpm, P=.001). Concomitantly, LVEF increased (from 31±1 to 36±0.9 %, P=.01), LA decreased (from 52±1.2 to 47±1mm, P=.03), and LV-ESV and LV-EDV deceased (from 69±2 to 64±1.8 mL/m², and 99±2.1 to 91±2, P<.05, respectively). No changes were observed in the untrained group.

CONCLUSION

Exercise training can improve exercise capacity, quality of life, and cardiac function in patients with heart failure with reduced ejection fraction and permanent atrial fibrillation.

Effect of atrial fibrillation on response to exercise-based cardiac rehabilitation in older individuals with heart failure

BACKGROUND

Although the coexistence of heart failure (HF) with atrial fibrillation (AF) exhibits poor outcomes, the correlation between AF status and outcomes after exercise-based cardiac rehabilitation (CR) remains unclear in older individuals with HF.

OBJECTIVE

This retrospective study aimed to investigate the impact of AF on changes in physical function and prognosis after CR in older individuals with HF.

METHODS

We enrolled consecutive individuals with HF who were ≥ 60 years old who received 5-month CR. Exercise-based CR involved moderate-intensity aerobic exercises tailored to each participant. Isometric quadriceps strength (QS) and 6-min walk distance (6MWD) were measured as physical function, at baseline and 5 months thereafter. We compared QS and 6MWD changes from baseline to the 5-month observation period (QS and 6MWD) between sinus rhythm and AF. We examined composite incidence of all-cause death or unplanned readmission after 5-month CR and analysed the association of QS and 6MWD with clinical events, estimating adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs).

RESULTS

Of the 764 participants, 476 (62%) had sinus rhythm, and 288 (38%) had AF. AF was associated with lower QS and 6MWD at baseline. The 2 groups did not differ in QS and 6MWD after adjusting for clinical confounders. With sinus rhythm, greater change in QS and 6MWD was significantly associated with reduced incidence of clinical events (QS tertile: aHR 0.75 [95% CI 0.60-0.92]; 6MWD tertile: aHR 0.59 [95% CI 0.46-0.76]); however, with AF, this association was observed for only 6MWD and not QS (QS: aHR 0.92 [95% CI 0.72-1.17]; 6MWD: aHR 0.73 [95% CI 0.54-0.98]).

CONCLUSION

AF in older individuals with HF is associated with reduced physical function at baseline but not response to exercise-based CR. Furthermore, positive response of physical function after CR is associated with better prognosis regardless of AF, which suggests that exercise-based CR is potentially effective in older individuals with HF and AF.

Listing Criteria for Heart Transplant: Role of Cardiopulmonary Exercise Test and of Prognostic Scores

Patients with advanced heart failure (AdHF) have a reduced quality of life and poor prognosis. A heart transplant (HT) is an effective treatment for such patients. Still, because of a shortage of donor organs, the final decision to place a patient without contraindications on the HT waiting list is based on detailed risk-benefit analysis. Cardiopulmonary exercise tests (CPETs) play a pivotal role in guiding selection in patients with AdHF considered for an HT. Furthermore, several validated multivariable predicting scores obtained through various techniques, including the CPETs, are available and part of the decision-making process for HT listing.

Exercise Dynamic of Patients with Chronic Heart Failure and Reduced Ejection Fraction

PURPOSE OF REVIEW

Exercise causes various dynamic changes in all body parts either in healthy subject or in heart failure (HF) patients. The present review of current knowledge about HF patients with reduced ejection fraction focuses on dynamic changes along a "metabo-hemodynamic" perspective.

RECENT FINDINGS

Studies on the dynamic changes occurring during exercise span many years. Thanks to the availability of advanced methods, it is nowadays possible to properly characterize respiratory, hemodynamic, and muscular function adjustments and their mismatch with the pulmonary and systemic circulations. Exercise is a dynamic event that involves several body functions. In HF patients, it is important to know at what level the limitation takes place in order to better manage these patients and to optimize therapeutic strategies.

The Relationship of Dehydration and Body Mass Index With the Occurrence of Atrial Fibrillation in Heart Failure Patients

Purpose: The aim of the study was to assess the relationship of dehydration, body mass index (BMI) and other indices with the occurrence of atrial fibrillation (AF) in heart failure (HF) patients. Methods: The study included 113 patients [median age 64 years; 57.52% male] hospitalized due to HF. Baseline demographics, body mass analysis, echocardiographic results, key cardiopulmonary exercise test (CPET) parameters, 6 min walk distance (6MWD) and Kansas City Cardiomyopathy Questionnaire (KCCQ) score were assessed. Results: Of all patients, 23 (20.35%) had AF, and 90 (79.65%) had sinus rhythm (SR). Patients with AF were older (med. 66 vs. 64 years; p = 0.039), with higher BMI (32.02 vs. 28.51 kg/m2; p = 0.017) and percentage of fat content (37.0 vs. 27.9%, p = 0.014). They were more dehydrated, with a lower percentage of total body water (TBW%) (45.7 vs. 50.0%; p = 0.022). Clinically, patients with AF had more often higher New York Heart Association (NYHA) class (III vs. II; p < 0.001), shorter 6MWD (median 292.35 vs. 378.4 m; p = 0.001) and a lower KCCQ overall summary score (52.60 vs. 73.96 points; p = 0.002). Patients with AF had significantly lower exercise capacity as measured by peak oxygen consumption (peak VO2) (0.92 vs. 1.26 mL/min, p = 0.016), peak VO2/kg (11 vs. 15 mL/kg/min; p < 0.001), and percentage of predicted VO2max (pp-peak VO2) (62.5 vs 70.0; p=0.010). We also found VE/VCO2 (med. 33.85 vs. 32.20; p = 0.049) to be higher and peak oxygen pulse (8.5 vs. 11 mL/beat; p = 0.038) to be lower in patients with AF than in patients without AF. In a multiple logistic regression model higher BMI (OR 1.23 per unit increase, p < 0.001) and higher left atrial volume index (LAVI) (OR 1.07 per unit increase, p = 0.03), lower tricuspid annular plane systolic excursion (TAPSE) (OR 0.74 per unit increase, p =0.03) and lower TBW% in body mass analysis (OR 0.90 per unit increase, p =0.03) were independently related to AF in patients with HF. Conclusion: Increased volume of left atrium and right ventricular systolic dysfunction are well-known predictors of AF occurrence in patients with HF, but hydration status and increased body mass also seem to be important factors of AF in HF patients.

Role of comorbidities in heart failure prognosis Part I: Anaemia, iron deficiency, diabetes, atrial fibrillation

Cardiovascular and non-cardiovascular comorbidities are frequently observed in heart failure patients, complicating the therapeutic management and leading to poor prognosis. The prompt recognition of associated comorbid conditions is of great importance to optimize the clinical management, the follow-up, and the treatment of patients affected by chronic heart failure. Anaemia and iron deficiency are commonly reported in all heart failure forms, have a multifactorial aetiology and are responsible for reduced exercise tolerance, impaired quality of life, and poor long-term prognosis. Diabetes mellitus is highly prevalent in heart failure and a poor glycaemic control is associated with worst outcome. Two specific heart failure forms are usually observed in diabetic patients: an ischaemic cardiomyopathy or a typical diabetic cardiomyopathy. The implementation of use of sodium-glucose cotransporter-2 inhibitors will much improve in the near future the long-term prognosis of patients affected by heart failure and diabetes. Among cardiovascular comorbidities, atrial fibrillation is the most common arrhythmic disease of heart failure patients and it is still not clear whether its presence should be considered as a prognostic indicator or as a marker of advanced disease. The aim of the present review was to explore the clinical and prognostic impact of anaemia and iron deficiency, diabetes mellitus, and atrial fibrillation in patients affected by chronic heart failure.

Choosing among β-blockers in heart failure patients according to β-receptors' location and functions in the cardiopulmonary system

Several large clinical trials showed a favorable effect of β-blocker treatment in patients with chronic heart failure (HF) as regards overall mortality, cardiovascular mortality, and hospitalizations. Indeed, the use of β-blockers is strongly recommended by current international guidelines, and it remains a cornerstone in the pharmacological treatment of HF. Although different types of β-blockers are currently approved for HF therapy, possible criteria to choose the best β-blocking agent according to HF patients' characteristics and to β-receptors' location and functions in the cardiopulmonary system are still lacking. In such a context, a growing body of literature shows remarkable differences between β-blocker types (β1-selective blockers versus β1-β2 blockers) with respect to alveolar-capillary gas diffusion and chemoreceptor response in HF patients, both factors able to impact on quality of life and, most likely, on prognosis. This review suggests an original algorithm for choosing among the currently available β-blocking agents based on the knowledge of cardiopulmonary pathophysiology. Particularly, starting from lung physiology and from some experimental models, it focuses on the mechanisms underlying lung mechanics, chemoreceptors, and alveolar-capillary unit impairment in HF. This paper also remarks the significant benefit deriving from the correct use of the different β-blockers in HF patients through a brief overview of the most important clinical trials.

Postablation Atrial Fibrillation Burden and Patient Activity Level: Insights From the DISCERN AF Study

Background Recent evidence shows an association between the level of physical activity and cardiovascular mortality and morbidity in patients with atrial fibrillation ( AF ). We sought to assess the impact of AF daily burden on the activity level of the patient who underwent pulmonary vein isolation. Methods and Results Patients enrolled in the DISCERN AF (Discerning Symptomatic and Asymptomatic Episodes Pre and Post Radiofrequency Ablation of Atrial Fibrillation) study all had insertable cardiac monitors, which provided the daily burden of atrial tachycardia and atrial fibrillation ( AT / AF ) and a corresponding activity level. A total of 44 341 daily AT / AF burden points were collected from 50 patients with an average of 887 observations for every patient, with <5 minutes of AT / AF reported on 82.6% of days. The daily burden of AT / AF after ablation ranged between 0 and 1440 minutes. The minimum and maximum daily activity was 0 and 600 minutes per day, respectively. A significant inverse association was detected between activity levels and AF burden ( P<0.001; 95% confidence interval, 0.01-0.04). The daily activity starts progressively decreasing after 500 minutes of AF and considerably drops after 1000 minutes. The association between activity level and burden of AT / AF was still statistically significant after adjustment for clinical variables ( P =0.02; 95% confidence interval, -003 to 0.04). Conclusions Daily activity level correlates with daily AT / AF burden in patients who underwent AF ablation. The daily activity started decreasing after a daily burden of 500 minutes of AF and greatly drops after 1000 minutes. Therefore, the amount of AT / AF burden that may impact the activity level seems to be related to hours and not minutes of arrhythmias. Clinical Trial Registration URL : https://www.clinicaltrials.gov . Unique identifier: NCT 00745706.

Heart rate during exercise: mechanisms, behavior, and therapeutic and prognostic implications in heart failure patients with reduced ejection fraction

Exercise intolerance is a typical manifestation of patients affected by heart failure with reduced ejection fraction (HFrEF); however, the relationship among functional capacity, mortality, and exercise-induced heart rate response during exercise remains unclear in either sinus rhythm or atrial fibrillation subjects. Heart rate increase during incremental load exercise has a typical pattern in normal subjects, whereas it is commonly compromised in HFrEF patients, mainly due to the imbalance of the autonomic nervous system. In the present review, we aim to describe the behavior of heart rate during exercise in normal subjects and in HFrEF patients in sinus rhythm and atrial fibrillation, understanding and explaining the mechanism leading to a different exercise performance and functional limitation. Moreover, the role of chronotropic incompetence and the need of standardizing the cutoff criteria are also discussed in order to clarify the clinical importance, the prognostic relevance, and the potential therapeutic implications of this condition. Looking into the relative contribution and interaction of heart rate response during exercise might represent an important issue to guide individualized therapeutic interventions and prognostic assessment in HFrEF patients.

Influence of atrial fibrillation on oxygen uptake and exercise tolerance in cardiovascular patients; close association with heart rate response

To investigate the effect of atrial fibrillation (AF) on the oxygen uptake and exercise tolerance, we evaluated cardiopulmonary exercise test (CPET) data in AF patients and heart rate-matched controls with sinus rhythm (cSR) who received ambulatory cardiac rehabilitation. We compared CPET data between AF (N = 27) and cSR patients (N = 106) who had similar HRs at rest and the peak points. Oxygen uptake (VO₂)/kg and relative O₂ pulse (ml/bpm/kg) at rest and the anaerobic threshold (AT) level was not different between AF and cSR patients, but these parameters above the AT level were significantly lower in AF than in cSR patients. Concisely the parallel increase of relative O₂ pulse during exercise was blunted above the respiratory compensation level (Rc) in the AF group. In addition, the HR change during exercise was inversely correlated with the increase of the O₂ pulse above the AT level and this inverse correlation was more prominent in AF patients than in cSR patients. In conclusion, the value of VO₂ was significantly lower above the AT level in AF patients. The trend of O₂ pulse above the AT level was strongly associated with the detrimental response of HR increase and the response was markedly exaggerated in the AF patients.

Exercise Training in Heart Failure Patients With Persistent Atrial Fibrillation: a Practical Approach

Persistent AF is present in at least 20 % of patients with chronic heart failure (CHF) and is related to a poor prognosis and more severe cardiac arrhythmias. CHF and AF share a common pathophysiology and can exacerbate one another. Exercise programmes for people with CHF have been shown to improve aerobic capacity, prognosis and quality of life. Given that patients with both CHF and AF show greater impairment in exercise performance, exercise training programmes have the potential to be highly beneficial. Optimal clinical evaluation using a cardiopulmonary exercise test should be performed before starting a training programme. Heart rate should be calculated over a longer period of time In patients with CHF and AF than those in sinus rhythm. The use of telemetry is advised to measure HR accurately during training. If telemetry is not available, patients can be safely trained based on the concomitant workload. An aerobic exercise training programme of moderate to high intensity, whether or not combined with strength training, is advised in patients with CHF and AF. Optimal training modalities and their intensity require further investigation.

Treatment Strategies for Atrial Fibrillation With Left Ventricular Systolic Dysfunction - Meta-Analysis

BACKGROUND

Atrial fibrillation (AF) frequently coexists with heart failure (HF) with reduced ejection fraction (EF). This meta-analysis compared AF control strategies, that is, rhythm vs. rate, and catheter ablation (CA) vs. anti-arrhythmic drugs (AAD) in patients with AF combined with HF.

METHODS AND RESULTS

The MEDLINE, EMBASE, and CENTRAL databases were searched, and 13 articles from 11 randomized controlled trials with 5,256 patients were included in this meta-analysis. The outcomes were echocardiographic parameters (left ventricular EF, LVEF), left atrial (LA) size, and left ventricular end-systolic volume, LVESV), clinical outcomes (mortality, hospitalization, and thromboembolism), exercise capacity, and quality of life (QOL). In a random effects model, rhythm control was associated with higher LVEF, better exercise capacity, and better QOL than the rate control. When the 2 different rhythm control strategies were compared (CA vs. AAD), the CA group had significantly decreased LA size and LVESV, and improved LVEF and 6-min walk distance, but mortality, hospitalization, and thromboembolism rates were not different between the rhythm and rate control groups.

CONCLUSIONS

In AF combined with HF, even though mortality, hospitalization and thromboembolism rates were similar, a rhythm control strategy was superior to rate control in terms of improvement in LVEF, exercise capacity, and QOL. In particular, the CA group was superior to the AAD group for reversal of cardiac remodeling.

Impact of Atrial Fibrillation on Exercise Capacity and Mortality in Heart Failure With Preserved Ejection Fraction: Insights From Cardiopulmonary Stress Testing

Background

Atrial fibrillation (AF) has been objectively associated with exercise intolerance in patients with heart failure with reduced ejection fraction; however, its impact in patients with heart failure with preserved ejection fraction has not been fully scrutinized.

Methods and Results

We identified 1744 patients with heart failure and ejection fraction ≥50% referred for cardiopulmonary stress testing at the Cleveland Clinic (Cleveland, OH), 239 of whom had AF. We used inverse probability of treatment weighting to balance clinical characteristics between patients with and without AF. A weighted linear regression model, adjusted for unbalanced variables (age, sex, diagnosis, hypertension, and β‐blocker use), was used to compare metabolic stress parameters and 8‐year total mortality (social security index) between both groups. Weighted mean ejection fraction was 58±5.9% in the entire population. After adjusting for unbalanced weighted variables, patients with AF versus those without AF had lower mean peak oxygen consumption (18.5±6.2 versus 20.3±7.1 mL/kg per minute), oxygen pulse (12.4±4.3 versus 12.9±4.7 mL/beat), and circulatory power (2877±1402 versus 3351±1788 mm Hg·mL/kg per minute) (P<0.001 for all comparisons) but similar submaximal exercise capacity (oxygen consumption at anaerobic threshold, 12.0±5.1 versus 12.4±6.0mL/kg per minute; P =0.3). Both groups had similar peak heart rate, whereas mean peak systolic blood pressure was lower in the AF group (150±35 versus 160±51 mm Hg; P<0.001). Moreover, AF was associated with higher total mortality.

Conclusions

In the largest study of its kind, we demonstrate that AF is associated with peak exercise intolerance, impaired contractile reserve, and increased mortality in patients with heart failure with preserved ejection fraction. Whether AF is the primary offender in these patients or merely a bystander to worse diastolic function requires further investigation.

Role of cardiopulmonary exercise testing in clinical stratification in heart failure. A position paper from the Committee on Exercise Physiology and Training of the Heart Failure Association of the European Society of Cardiology

Traditionally, the main indication for cardiopulmonary exercise testing (CPET) in heart failure (HF) was for the selection of candidates to heart transplantation: CPET was mainly performed in middle-aged male patients with HF and reduced left ventricular ejection fraction. Today, CPET is used in broader patients' populations, including women, elderly, patients with co-morbidities, those with preserved ejection fraction, or left ventricular assistance device recipients, i.e. individuals with different responses to incremental exercise and markedly different prognosis. Moreover, the diagnostic and prognostic utility of symptom-limited CPET parameters derived from submaximal tests is more and more considered, since many patients are unable to achieve maximal aerobic power. Repeated tests are also being used for risk stratification and evaluation of intervention, so that these data are now available. Finally, patients, physicians and healthcare decision makers are increasingly considering how treatments might impact morbidity and quality of life rather than focusing more exclusively on hard endpoints (such as mortality) as was often the case in the past. Innovative prognostic flowcharts, with CPET at their core, that help optimize risk stratification and the selection of management options in HF patients, have been developed.

Delayed Anaerobic Threshold in Heart Failure Patients With Atrial Fibrillation

PURPOSE

To assess whether atrial fibrillation (AF) in heart failure (HF) affects oxygen uptake at anaerobic threshold ((Equation is included in full-text article.)O2 AT) and heart rate (HR) kinetics.

METHODS

A total of 15 patients with HF and AF and 18 with HF and sinus rhythm (SR) performed a maximal incremental and 2 constant workload cycle ergometer cardiopulmonary exercise tests (below and above AT, at 25% and 75% of maximal workload, respectively). At constant workload tests, kinetics of (Equation is included in full-text article.)O2 and HR were assessed by calculating time constant (τ).

RESULTS

HF patients with AF showed a similar peak (Equation is included in full-text article.)O2 to those with SR (16.7 ± 4.5 mL/kg/min vs 16.6 ± 3.9 mL/kg/min). However, (Equation is included in full-text article.)O2 AT (11.3 ± 2.9 mL/kg/min vs 9.3 ± 2.8 mL/kg/min; P < .05), peak HR (149 ± 18.8 bpm vs 116.4 ± 20.4 bpm; P < .001), HR AT (125.3 ± 19.1 bpm vs 90.3 ± 15.5 bpm; P < .001), and HR increase during exercise were greater in HF patients with AF. Finally, τHR and τ(Equation is included in full-text article.)O2 below and above AT were not significantly different.

CONCLUSIONS

In HF patients with AF, despite a similar peak (Equation is included in full-text article.)O2 compared with patients with HF and SR, (Equation is included in full-text article.)O2 AT is higher because of a higher HR and a greater HR increase during exercise. One postulated mechanism would be a greater cardiac output increase at the beginning of exercise in HF patients with AF. The delayed AT generates uncertainty about the meaning of a (Equation is included in full-text article.)O2 value at AT in HF patients with AF, because a higher AT is usually associated with better performance and a better prognosis.

Prognostic role of atrial fibrillation in patients affected by chronic heart failure. Data from the MECKI score research group

BACKGROUND

Atrial fibrillation (AF) is common in heart failure (HF). It is unclear whether AF has an independent prognostic role in HF. The aim of the present study was to assess the prognostic role of AF in HF patients with reduced ejection fraction (EF).

METHODS

HF patients were followed in 17 centers for 3.15years (1.51-5.24). Study endpoints were the composite of cardiovascular (CV) death and heart transplant (HTX) and all-cause death. Data analysis was performed considering the entire population and a 1 to 1 match between sinus rhythm (SR) and AF patients. Match process was done for age±5, gender, left ventricle EF±5, peakVO2±3 (ml/min/kg) and recruiting center.

RESULTS

A total of 3447 patients (SR=2882, AF=565) were included in the study. Considering the entire population, CV death and HTX occurred in 114 (20%) AF vs. 471 (16%) SR (p=0.026) and all-cause death in 130 (23%) AF vs. 554 (19.2%) SR patients (p=0.039). At univariable Cox analysis, AF was significantly related to prognosis. Applying a multivariable model based on all variables significant at univariable analysis (EF, peakVO2, ventilation/carbon dioxide relationship slope, sodium, kidney function, hemoglobin, beta-blockers and digoxin) AF was no longer associated with adverse outcomes. Matching procedure resulted in 338 couples. CV death and HTX occurred in 63 (18.6%) AF vs. 74 (21.9%) SR (p=0.293) and all-cause death in 71 (21%) AF vs. 80 (23.6%) SR (p=0.406), with no survival differences between groups.

CONCLUSION

In systolic HF AF is a marker of disease severity but not an independent prognostic indicator.

Left atrial phasic function interacts to support left ventricular filling during exercise in healthy athletes

We studied the contribution of phasic left atrial (LA) function to left ventricular (LV) filling during exercise. We hypothesized that reduced LV filling time at moderate-intensity exercise limits LA passive emptying and increases LA active emptying. Twenty endurance-trained males (55 ± 6 yr) were studied at rest and during light- (∼100 beats/min) and moderate-intensity (∼130 beats/min) exercise. Two-dimensional and Doppler echocardiography were used to assess phasic volumes and diastolic function. LV end-diastolic volume increased from rest to light exercise (54 ± 6 to 58 ± 5 ml/m2, P < 0.01) and from light to moderate exercise (58 ± 5 to 62 ± 6 ml/m2, P < 0.01). LA maximal volume increased from rest to light exercise (26 ± 4 to 30 ± 5 ml/m2, P < 0.01) related to atrioventricular plane displacement ( r = 0.55, P < 0.005), without further change at moderate exercise. LA passive emptying increased at light exercise (9 ± 2 to 13 ± 3 ml/m2, P < 0.01) and then returned to baseline at moderate exercise, whereas LA active emptying increased appreciably only at moderate exercise (6 ± 2 to 14 ± 3 ml/m2, P < 0.01). Thus, the total atrial emptying volume did not increase beyond light exercise, and the increase in LV filling at moderate exercise could be attributed primarily to an increase in the conduit flow volume (19 ± 3 to 25 ± 5 ml/m2, P < 0.01). LA filling increases during exercise in relation to augmented LV longitudinal contraction. Conduit flow increases progressively with exercise in athletes, although this is driven by LV properties rather than intrinsic LA function. The pump function of the LA augments only at moderate exercise due to a reduced diastolic filling time and the Frank-Starling mechanism.

Kinetics of left ventricular rotation during exercise and its relation to exercise tolerance in atrial fibrillation: assessment by two-dimensional speckle tracking echocardiography

BACKGROUND

Left ventricular (LV) rotation plays an important role in cardiac function both at rest and during exercise in sinus rhythm. The kinetics of rotation during exercise and the relation between exercise tolerance and rotation-related parameters in patients with atrial fibrillation (AF) are unknown.

METHODS

Twenty-nine patients (age 62 ± 13 years, 6 females) with AF and preserved LV ejection fraction (LVEF) were studied using two-dimensional speckle tracking echocardiography at rest and during exercise with a supine bicycle ergometer (20 W, 10 min). We measured the systolic rotation (Rot) and the peak rotation rate in systole and early diastole (eRotR) at the apical and basal levels of the LV. All patients underwent cardiopulmonary exercise testing to obtain their percent achieved of the predicted peak oxygen consumption (% peak VO2) value.

RESULTS

During exercise, apical Rot-related indices were significantly increased only in the preserved % peak VO2 group. In contrast, E/e' was significantly elevated only in the reduced % peak VO2 group. Multivariable stepwise regression analysis showed that apical ΔRot was independently associated with % peak VO2 (β = 0.72; p < 0.01). Apical ΔeRotR, which could not be selected as an independent predictor of % peak VO2, had a good linear correlation with apical ΔRot (r = 0.81, p < 0.01).

CONCLUSIONS

The augmentation of apical rotation in response to exercise may coincide with an increase of the apical derotation rate, and apical rotation reserve may reflect exercise tolerance in patients with AF and preserved LVEF.

Impact of atrial fibrillation on exercise capacity in heart failure with preserved ejection fraction: a RELAX trial ancillary study

BACKGROUND

Atrial fibrillation (AF) is common among patients with heart failure and preserved ejection fraction (HFpEF), but its clinical profile and impact on exercise capacity remain unclear. RELAX (Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in HFpEF) was a multicenter randomized trial testing the impact of sildenafil on peak VO2 in stable outpatients with chronic HFpEF. We sought to compare clinical features and exercise capacity among patients with HFpEF who were in sinus rhythm (SR) or AF.

METHODS AND RESULTS

RELAX enrolled 216 patients with HFpEF, of whom 79 (37%) were in AF, 124 (57%) in SR, and 13 in other rhythms. Participants underwent baseline cardiopulmonary exercise testing, echocardiogram, biomarker assessment, and rhythm status assessment before randomization. Patients with AF were older than those in SR but had similar symptom severity, comorbidities, and renal function. β-blocker use and chronotropic indices were also similar. Despite comparable left ventricular size and mass, AF was associated with worse systolic (lower EF, stroke volume, and cardiac index) and diastolic (shorter deceleration time and larger left atria) function compared with SR. Pulmonary artery systolic pressure was higher in AF. Patients with AF had higher N-terminal pro-B-type natriuretic peptide, aldosterone, endothelin-1, troponin I, and C-telopeptide for type I collagen levels, suggesting more severe neurohumoral activation, myocyte necrosis, and fibrosis. Peak VO2 was lower in AF, even after adjustment for age, sex, and chronotropic response, and VE/VCO2 was higher.

CONCLUSIONS

AF identifies an HFpEF cohort with more advanced disease and significantly reduced exercise capacity. These data suggest that evaluation of the impact of different rate or rhythm control strategies on exercise tolerance in patients with HFpEF and AF is warranted.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00763867.

Association of aldosterone synthase polymorphism (CYP11B2 -344T>C) and genetic ancestry with atrial fibrillation and serum aldosterone in African Americans with heart failure

The objective of this study was to examine the extent to which aldosterone synthase genotype (CYP11B2) and genetic ancestry correlate with atrial fibrillation (AF) and serum aldosterone in African Americans with heart failure. Clinical data, echocardiographic measurements, and a genetic sample for determination of CYP11B2 -344T>C (rs1799998) genotype and genetic ancestry were collected from 194 self-reported African Americans with chronic, ambulatory heart failure. Genetic ancestry was determined using 105 autosomal ancestry informative markers. In a sub-set of patients (n = 126), serum was also collected for determination of circulating aldosterone. The CYP11B2 -344C allele frequency was 18% among the study population, and 19% of patients had AF. Multiple logistic regression revealed that the CYP11B2 -344CC genotype was a significant independent predictor of AF (OR 12.7, 95% CI 1.60-98.4, p = 0.0150, empirical p = 0.011) while holding multiple clinical factors, left atrial size, and percent European ancestry constant. Serum aldosterone was significantly higher among patients with AF (p = 0.036), whereas increased West African ancestry was inversely correlated with serum aldosterone (r = -0.19, p = 0.037). The CYP11B2 -344CC genotype was also overrepresented among patients with extreme aldosterone elevation (≥90th percentile, p = 0.0145). In this cohort of African Americans with chronic ambulatory heart failure, the CYP11B2 -344T>C genotype was a significant independent predictor of AF while holding clinical, echocardiographic predictors, and genetic ancestry constant. In addition, increased West African ancestry was associated with decreased serum aldosterone levels, potentially providing an explanation for the lower risk for AF observed among African Americans.