Defining a Clinically Important Change in 6-Minute Walk Distance in Patients With Heart Failure and Mitral Valve Disease

Changes in 6-min walk test is an independent predictor of death in chronic heart failure with reduced ejection fraction

AIMS

Functional capacity provides important clinical information in patients with heart failure (HF) and reduced ejection fraction (HFrEF). The 6-min walk test (6MWT) is a simple and inexpensive tool for assessing functional capacity and risk. Although change in 6MWT is frequently used as a surrogate outcome in HF trials, the association with mortality is unclear. We aimed to assess the prognostic importance of changes in 6MWT.

METHODS AND RESULTS

Patients with chronic HFrEF referred to HF outpatient clinics in Norway completed a 6MWT at the first visit (baseline) and at a stable follow-up visit after treatment optimization (follow-up). Absolute and relative changes in 6MWT were analysed in association with mortality risk using Cox regression models and flexible cubic splines. The study included 3636 HFrEF patients aged 67.3 ± 11.6 years, 23% women, with left ventricular ejection fraction 30 ± 7%. At baseline, mean 6MWT was 438 ± 125 m, median N-terminal pro-B-type natriuretic peptide (NT-proBNP) 1574 (732-3093) ng/L, and 27% had New York Heart Association (NYHA) class III/IV. After optimization of guideline-directed medical therapy (median 147 [86-240] days), 6MWT increased by mean 40 ± 74 m, NT-proBNP decreased by median 425 (14-1322) ng/L, and NYHA class improved in 38% of patients. Patients with greater improvements in 6MWT were younger, with greater improvements in NYHA class (r = 0.27, p < 0.001) and larger reductions in NT-proBNP concentrations (r = 0.19, p < 0.001). After mean 845 ± 595 days, 419 (11.5%) patients were dead. Both absolute and relative changes in 6MWT were non-linearly associated with survival, attenuating as 6MWT increased. A 50 m increase in 6MWT was associated with a 17% lower mortality risk (hazard ratio 0.84, 95% confidence interval 0.77-0.90, p < 0.001) in the fully adjusted model, including changes in NYHA class, NT-proBNP concentrations, and other established risk factors. The associations were more pronounced in patients with lower baseline 6MWT and higher age.

CONCLUSION

Improvement in 6MWT in patients with HFrEF is associated with increased survival, independent of changes in NT-proBNP and NYHA class. These findings support 6MWT change as a surrogate outcome in HF trials.

Association between self-reported and objectively assessed physical functioning in the general population

Knowledge about a patient's physical fitness can aid in medical decision-making, but objective assessment can be challenging and time-consuming. We aimed to investigate the concordance of self-reported health status and physical functioning with the 6 minute walking distance (6MWD) as objective measure of physical performance. The prospective characteristics and course of heart failure stages A/B and determinants of progression (STAAB) cohort study iteratively follows a representative sample of residents of the city of Würzburg, Germany, aged 30-79 years, without a history of heart failure (HF). The 6MWD was measured in 2752 individuals (aged 58 ± 11 years, 51% women) from a population-based cohort under strictly standardized conditions. Self-reported health status and physical functioning were assessed from items of the short form 36 (SF-36). After the respective classification of self-reported health status and physical functioning into 'good', 'moderate', and 'poor', we determined the association of these categories with 6MWD by applying a generalized linear model adjusted for age and sex. Prevalence of self-reported good/moderate/poor general health and physical functioning was 41/52/7% and 45/48/7%, respectively. Mean 6MWD in the respective categories was 574 ± 70/534 ± 76/510 ± 87 m, and 574 ± 72/534 ± 73/490 ± 82 m, with significant sex-specific differences between all categories (all p < 0.001) as well as significant differences between the respective groups except for the categories 'moderate' and 'poor' health status in men. This cross-sectional analysis revealed a strong association between self-reported health status and physical functioning with the objective assessment of 6MWD, suggesting that physicians can rely on their patients' respective answers. Nevertheless, sex-specific perception and attribution of general health and physical functioning deserve further in-depth investigation. Decision-making based on self-reported health requires prospective evaluation in population-based cohorts as well as adult inpatients.

Incremental prognostic value of functional impairment assessed by 6-min walking test for the prediction of mortality in heart failure

Natriuretic peptides (NP) are recognized as the most powerful predictors of adverse outcomes in heart failure (HF). We hypothesized that a measure of functional limitation, as assessed by 6-min walking test (6MWT), would improve the accuracy of a prognostic model incorporating a NP. This was a multicenter observational retrospective study. We studied the prognostic value of severe functional impairment (SFI), defined as the inability to perform a 6MWT or a distance walked during a 6MWT < 300 m, in 1696 patients with HF admitted to cardiac rehabilitation. The primary outcome was 1-year all-cause mortality. After adjusting for the baseline multivariable risk model-including age, sex, systolic blood pressure, anemia, renal dysfunction, sodium level, and NT-proBNP-or for the MAGGIC score, SFI had an odds ratio of 2.58 (95% CI 1.72-3.88; p < 0.001) and 3.12 (95% CI 2.16-4.52; p < 0.001), respectively. Adding SFI to the baseline risk model or the MAGGIC score yielded a significant improvement in discrimination and risk classification. Our data suggest that a simple, 6MWT-derived measure of SFI is a strong predictor of death and provide incremental prognostic information over well-established risk markers in HF, including NP, and the MAGGIC score.

Tricuspid Valve Academic Research Consortium Definitions for Tricuspid Regurgitation and Trial Endpoints

Interest in the pathophysiology, etiology, management, and outcomes of patients with tricuspid regurgitation (TR) has grown in the wake of multiple natural history studies showing progressively worse outcomes associated with increasing TR severity, even after adjusting for multiple comorbidities. Historically, isolated tricuspid valve surgery has been associated with high in-hospital mortality rates, leading to the development of transcatheter treatment options. The aim of this first Tricuspid Valve Academic Research Consortium document is to standardize definitions of disease etiology and severity, as well as endpoints for trials that aim to address the gaps in our knowledge related to identification and management of patients with TR. Standardizing endpoints for trials should provide consistency and enable meaningful comparisons between clinical trials. A second Tricuspid Valve Academic Research Consortium document will focus on further defining trial endpoints and will discuss trial design options.

Tricuspid Valve Academic Research Consortium Definitions for Tricuspid Regurgitation and Trial Endpoints

Interest in the pathophysiology, etiology, management, and outcomes of patients with tricuspid regurgitation (TR) has grown in the wake of multiple natural history studies showing progressively worse outcomes associated with increasing TR severity, even after adjusting for multiple comorbidities. Historically, isolated tricuspid valve surgery has been associated with high in-hospital mortality rates, leading to the development of transcatheter treatment options. The aim of this first Tricuspid Valve Academic Research Consortium document is to standardize definitions of disease etiology and severity, as well as endpoints for trials that aim to address the gaps in our knowledge related to identification and management of patients with TR. Standardizing endpoints for trials should provide consistency and enable meaningful comparisons between clinical trials. A second Tricuspid Valve Academic Research Consortium document will focus on further defining trial endpoints and will discuss trial design options.

Tricuspid Valve Academic Research Consortium Definitions for Tricuspid Regurgitation and Trial Endpoints

Interest in the pathophysiology, etiology, management, and outcomes of patients with tricuspid regurgitation (TR) has grown in the wake of multiple natural history studies showing progressively worse outcomes associated with increasing TR severity, even after adjusting for multiple comorbidities. Historically, isolated tricuspid valve surgery has been associated with high in-hospital mortality rates, leading to the development of transcatheter treatment options. The aim of this first Tricuspid Valve Academic Research Consortium document is to standardize definitions of disease etiology and severity, as well as endpoints for trials that aim to address the gaps in our knowledge related to identification and management of patients with TR. Standardizing endpoints for trials should provide consistency and enable meaningful comparisons between clinical trials. A second Tricuspid Valve Academic Research Consortium document will focus on further defining trial endpoints and will discuss trial design options.

Baseline Left Ventricle Longitudinal Strain as a Predictor for Clinical Improvement Following Coronary Sinus Reducer Implantation

Coronary sinus narrowing device (reducer) implantation has emerged as an effective treatment to improve the quality of life and functional capacity in patients suffering from disabling refractory angina. Left ventricle global longitudinal strain (LV-GLS) is a useful tool for early diagnosis of subclinical cardiac injury and an independent predictor for coronary artery disease. We aimed to investigate whether LV-GLS could help predict clinical improvement after coronary sinus reducer implantation. LV-GLS assessments were performed at baseline and 6 months after reducer implantation in consecutive patients treated for refractory angina. Patients were divided into 2 groups based on reduced (<17% absolute value) or preserved baseline LV-GLS. Clinical improvement was defined as an increase of ≥25 m in the 6-minute walk test (6MWT) at follow-up. Overall, 41 patients were included, 31 in the reduced LV-GLS group and 10 in the preserved LV-GLS group. The mean age was 68 ± 8 years, with only 2 female patients (5%). Baseline characteristics did not differ significantly between the 2 groups. Univariable analysis revealed that LV-GLS was the only significant predictor for 6MWT improvement. Baseline preserved LV-GLS reduced the likelihood of 6MWT improvement by 82% (odds ratio 0.18 [0.04 to 0.83], p = 0.029). A significant increase in 6MWT (307 ± 97 m to 343 ± 92 m, p = 0.017) was observed in the reduced LV-GLS group, compared with a decrease in the preserved LV-GLS group (378 ± 86 m to 361 ± 123 m, p = 0.651). In conclusion, reduced LV-GLS may serve as a marker for potential clinical improvement in patients with refractory angina treated with reducer. Larger clinical trials are needed to establish its role.

Physical Activity During Breast Cancer Therapy Associates With Preserved Exercise Capacity and Cardiac Function (WF97415)

Background

Cancer treatment increases cardiovascular disease risk, but physical activity (PA) may prevent cardiovascular disease.

Objectives

This study examined whether greater PA was associated with better submaximal exercise capacity and cardiac function during cancer therapy.

Methods

Participants included 223 women with stage I to III breast cancer (BC) before and 3 months after undergoing treatment and 126 control participants. Leisure-time PA (LTPA) was reported using the Godin-Shephard LTPA questionnaire. Cardiac function was assessed by cardiac magnetic resonance. Submaximal exercise capacity was determined by 6-minute walk distance.

Results

BC participants reported similar baseline LTPA scores (24.7; 95% CI: 21.7-28.0) as control participants (29.4; 95% CI: 25.0-34.2). The BC group declined to 16.9 (95% CI: 14.4-19.6) at 3 months relative to 30.8 (95% CI: 26.2-35.8) in control participants. Among BC participants, more LTPA was related to better exercise capacity (β ± SE: 7.1 ± 1.6; 95% CI: 4.0-10.1) and left ventricular (LV) circumferential strain (-0.16 ± 0.07; 95% CI: -0.29 to -0.02). Increased LTPA over the 3 months was associated with decreased likelihood of treatment-induced cardiac dysfunction according to LV circumferential strain classifications (OR: 0.98; 95% CI: 0.97-0.998). BC participants reporting insufficient LTPA according to PA guidelines exhibited deteriorations in exercise capacity (adjusted mean difference ± SE: -29 ± 10 m; P = 0.029), LV end-systolic volume (5.8 ± 1.3 mL; P < 0.001), LV ejection fraction (-3.2% ± 0.8%; P = 0.002), and LV circumferential strain (2.5% ± 0.5%; P < 0.001), but BC participants meeting LTPA guidelines did not exhibit these adverse changes.

Conclusions

PA declined during BC therapy; however, PA participation was associated with attenuated declines in exercise capacity and cardiac function that are often observed in this population. (Understanding and Predicting Breast Cancer Events After Treatment [WF97415 UPBEAT]; NCT02791581).

Prognostic Value of 6-Minute Walk Test in Advanced Heart Failure With Reduced Ejection Fraction

There is limited evidence regarding the prognostic value of the 6-minute walk test for patients with advanced heart failure (HF). Accordingly, we studied 260 patients presenting to inpatient cardiac rehabilitation (CR) with advanced HF. The primary outcome was 3-year all-cause mortality after discharge from CR. The association between 6-minute walk distance (6MWD) and the primary outcome was determined using the multivariable Cox regression analysis. To avoid collinearity, 6MWD at admission (6MWDadm) to CR and 6MWD at discharge (6MWDdisch) from CR were analyzed separately. At multivariable analysis, 4 baseline characteristics (age, ejection fraction, systolic blood pressure, and blood urea nitrogen) were identified as prognostic of the primary outcome (baseline risk model). After adjusting for the baseline risk model, the hazard ratios of 6MWDadm and 6MWDdisch modeled as per 50-m increase for the primary outcome were 0.92 (95% confidence interval [CI] 0.85 to 0.99, p = 0.035) and 0.93 (95% CI 0.88 to 0.99, p = -017), respectively. After adjusting for the Meta-analysis Global Group in Chronic Heart Failure (MAGGIC) score, the corresponding hazard ratios were 0.91 (95% CI 0.84 to 0.98, p = 0.017) and 0.93 (95% CI 0.88 to 0.99, p = 0.016). The addition of either 6MWDadm or 6MWDdisch to the baseline risk model or the MAGGIC score yielded a statistically significant increase in global chi-square and in the net proportion of survivors reclassified downward. In conclusion, our data suggest that the distance covered during a 6-minute walk test predicts survival and provides incremental prognostic information on the top of well-established prognostic factors and the MAGGIC risk score in advanced HF.

Functional outcome after cardiac rehabilitation and its association with survival in heart failure across the spectrum of ejection fraction

BACKGROUND

There is limited evidence regarding the effects of cardiac rehabilitation (CR) in patients with heart failure and preserved ejection fraction (HFpEF).

METHODS

We studied 1784 patients admitted to inpatient CR. The patients were grouped into HFpEF (EF≥0.50), HF with mildly reduced EF (HFmrEF; EF 41-49), and HF with reduced EF (HFrEF; EF≤0.40). A standardized 6-min walking test was performed at admission and discharge. Measures of functional outcome were: (1) absolute increase in 6-min walking distance (6MWD) from admission to discharge >50 m and (2) increase in 6MWD to ≥300 among the patients who walked <300 m at admission.

RESULTS

After adjustment, the patients with HFpEF or HFmrEF were as likely as those with HFrEF to achieve an increase in 6MWD >50 m (odds ratio 0.95 [95%CI 0.71-1.24; p=0.648] and 1.04 [95%CI 0.77-1.41; p=0.769], respectively) or an increase in 6MWD to ≥300 m (odds ratio 0.79 [95%CI 0.51-1.23; p=0.299] and 0.65 [95%CI 0.38-1.12; p=0.118], respectively). The adjusted hazard ratio of 5-year mortality for patients who achieved an increase in 6MWD >50 m was 0.60 (95%CI 0.51-0.71; p<0.001) and that for patients who achieved an increase in 6MWD at discharge to ≥300 m 0.61 (95%CI 0.48-0.79; p<0.001). In each EF group, both outcomes remained independently associated with improved survival.

CONCLUSIONS

Our data suggest that patients with HFpEF or HFmrEF are as likely as those with HFrEF to benefit from CR in terms of functional improvement. Functional improvement was independently associated with improved long-term survival, regardless of EF.

Demystifying the Value of Minimal Clinically Important Difference in the Cardiothoracic Surgery Context

The aim of this review is to describe the different statistical methods used in estimating the minimal clinically important difference (MCID) for the assessment of quality of life (QOL)-related and clinical improvement interventions, along with their implementation in cardiothoracic surgery. A thorough literature search was performed in three databases (PubMed/Medline, Scopus, Google Scholar) for relevant articles from 1980 to 2022. We included articles that implemented and assessed statistical methods used to estimate the concept of MCID in cardiothoracic surgery. MCID has been successfully implemented in several medical specialties. Anchor-based and distribution-based methods are the most common approaches when evaluating the MCID. Nonetheless, we found only five studies investigating the MCID in the context of cardiothoracic surgery. Four of them used anchor-based approaches, and one used both anchor-based and distribution-based methods. MCID values were very variable depending on the methods applied, as was the clinical context of the study. The variables of interest were certain QOL measuring questionnaires, used as anchors. Multiple anchors and methods were applied, leading to different estimations of MCID. Since cardiothoracic surgery is related to important perioperative morbidity, MCID might represent an important and efficient adjunct tool to interpret clinical outcomes. The need for MCID methodology implementation is even higher in patients with heart failure undergoing cardiac surgery. More studies are needed to validate different MCID methods in this context.

Cardiac Rehabilitation for Older Women with Heart Failure

Background: the role that sex plays in impacting cardiac rehabilitation (CR) outcomes remains an important gap in knowledge. Methods: we assessed sex differences in clinical and functional outcomes in 2345 older patients with heart failure (HF) admitted to inpatient CR. Three outcomes were considered: (1) the composite outcome of death during the index admission to CR or transfer to acute care; (2) three-year mortality; (3) change in six-minute walking distance (6MWD) from admission to discharge. Sex differences in outcomes were assessed using multivariable Cox or logistic regression models. Results: the hazard ratios of the composite outcome and of three-year mortality for females vs. males were 0.71 (95%CI:0.50−1.00; p = 0.049) and 0.68 (95%CI:0.59−0.79; p < 0.001), respectively. The standardized mean difference in 6MWD increase from admission to discharge between males and females was 0.10. The odds ratio of achieving an increase in 6MWD at discharge to values higher than the optimal sex-specific thresholds for predicting mortality for females vs. males was 2.21 (95%CI:1.53−3.20; p < 0.001). Conclusion: our findings suggest that older females with HF undergoing CR have better prognosis and garner similar improvement in 6MWD compared with their male counterparts. Nonetheless, females were more likely to achieve levels of functional capacity predictive of improved survival.

Feasibility of inpatient cardiac rehabilitation after percutaneous mitral valve reconstruction using clipping procedures: a retrospective analysis

Background

To date, no studies on the feasibility or outcomes of cardiac rehabilitation (CR) after percutaneous mitral valve reconstruction using clipping procedures have been published. The aim of this study was to report on our first experiences with this special target group.

Methods

Monocentric retrospective analysis of 27 patients (72 ± 12 years old, 52% female) who underwent multimodal inpatient CR in the first 2 month after MitraClip™ implantation. A six-minute-walking-test, a handgrip-strength-test and the Berg-Balance-Scale was conducted at the beginning and end of CR. Echocardiography was performed to rule out device-related complications.

Results

Adapted inpatient CR started 16 ± 13 days after clipping intervention and lasted 22 ± 4 days. In 4 patients (15%) CR had to be interrupted or aborted prematurely due to cardiac decompensations. All other patients (85%) completed CR period without complications. Six-minute-walking-distance improved from 272 ± 97 to 304 ± 111 m (p < .05) and dependence on rollator walker or walking aids was significantly reduced (p < .05). Results of handgrip-strength-test and Berg-Balance-Scale increased (p < .05). Overall, social-medical and psychological consultations were well received by the patients and no device-related complications occurred during rehabilitation treatments.

Conclusions

The results indicate that an adapted inpatient CR in selected patients after MitraClip™ implantation is feasible. Patients benefited from treatments both at functional and social-medical level and no device-related complications occurred. Larger controlled studies are needed.

Prognostic value of functional capacity after transitional rehabilitation in older patients hospitalized for heart failure

BACKGROUND

Poor functional status is highly prevalent among older patients hospitalized for HF and marks a downward inflection point in functional and prognostic trajectories. We assessed the prognostic value of 6-min walk test after transitional cardiac rehabilitation in older patients hospitalized for heart failure (HF).

METHODS

We studied 759 patients aged ≥60 years who had been transferred to six inpatient rehabilitation facilities (IRF) from acute care hospitals after a hospitalization for acute HF. The primary outcome was 3-year all-cause mortality. We used multivariable Cox analysis to determine the association between 6-min walk distance (6MWD) at discharge from the IRFs and the primary outcome, adjusting for established predictors of death. The optimal cutoff for 6MWD was considered as the one that maximized the chi-square statistic.

RESULTS

Mean age was 75 ± 8 years. 6MWD significantly increased from admission to discharge (145 to 210 m; p < 0.001). The optimal cutoff for 6MWD was 198 m. After full adjustment, the hazard ratio for each 50 m-increase in discharge 6MWD was 0.90 (0.87-0.94; p < 0.001) and that for discharge 6MWD dichotomized at the optimal cutoff 0.48 (0.38-0.60; p < 0.001). The incidence rate of death/100 person-years for the patients who walked >198 m was 13.0 (10.0-15.5) compared with 30.8 (26.9-35.4) for those who walked <198 m. A statistically significant interaction of discharge 6MWD with left ventricular ejection fraction (EF) on the risk of death was observed (p value for interaction 0.047).

CONCLUSIONS

A rehabilitation intervention provided in the critical hospital-to-home transition period to older patients hospitalized for HF resulted in improved functional capacity. Increasing levels of functional capacity following rehabilitation were closely associated with decreasing risk of death; this association was significantly stronger for the subgroup with preserved EF.

Prognostic Importance of Health Status Versus Functional Status in Heart Failure and Secondary Mitral Regurgitation

OBJECTIVES

This study sought to understand the extent to which health status and exercise capacity are independently associated with long-term outcomes in patients with heart failure (HF) and secondary mitral regurgitation (MR).

BACKGROUND

Secondary MR in patients with HF leads to impaired health status (Kansas City Cardiomyopathy Questionnaire Overall Summary Score [KCCQ-OS]) and exercise capacity (6-minute walk distance [6MWD]), both of which improve after transcatheter mitral valve repair (TMVr).

METHODS

The study used data from the COAPT trial (N = 604) to examine the association of baseline KCCQ-OS and 6MWD with 2-year mortality and HF hospitalization, adjusting for treatment arm and patient factors. We also examined the association of change in KCCQ-OS and 6MWD from baseline to 1 month with risk of outcomes from 1 month to 2 years. Interactions of KCCQ-OS and 6MWD with treatment assignment were explored.

RESULTS

Mean baseline KCCQ-OS was 53 ± 23 points, and 6MWD was 240 ± 125 meters. In models including both measures, greater baseline 6MWD (but not KCCQ-OS) was associated with reduced 2-year mortality (HR per 125 meters: 0.75, 95% CI: 0.61-0.92). When stratified by treatment group, both baseline KCCQ-OS and 6MWD were independently associated with HF hospitalization in patients treated with medical therapy, whereas only KCCQ-OS was associated with HF hospitalization in patients treated with TMVr. In separate analyses, 1-month improvements in KCCQ-OS and 6MWD were each associated with lower subsequent risk of mortality and HF hospitalization, independent of treatment group.

CONCLUSIONS

Among patients with HF and severe secondary MR, assessment of both health status and exercise capacity provide complementary prognostic information for patients with HF and severe secondary MR-both before and after TMVr. (Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients With Functional Mitral Regurgitation [The COAPT Trial]; NCT01626079).