Overview
Heart failure with mid-range ejection fraction (HFmEF), encompassing ejection fractions (EF) typically between 41% and 49%, represents a significant clinical challenge due to its complex pathophysiology and variable clinical presentation. Unlike heart failure with reduced ejection fraction (HFrEF) and preserved ejection fraction (HFpEF), HFmEF lacks a universally accepted classification, complicating diagnosis and management. Epidemiological studies highlight underutilization of palliative care (PC) services among HFmEF patients, suggesting a critical gap in comprehensive care strategies [PMID:35763838]. Understanding the unique characteristics of HFmEF, including its clinical presentation, diagnostic approaches, and management strategies, is essential for optimizing patient outcomes.
Epidemiology
The epidemiology of HFmEF underscores several critical points regarding patient care and resource allocation. A study involving 113,555 patients with various HF subtypes revealed that only 20% received palliative care (PC) during follow-up, indicating a significant underutilization of these services in HFmEF patients [PMID:35763838]. This underutilization may reflect challenges in identifying patients who would benefit from PC early in their disease course or a lack of integration between HF management and palliative care teams. Additionally, demographic factors such as age and gender play roles in clinical outcomes. For instance, elderly patients often exhibit reduced aerobic capacity, as evidenced by lower 6-minute walk distances (6MWD), which correlate inversely with cardiovascular risk factors like percent body fat, systolic blood pressure, and rate-pressure product [PMID:20409599]. These findings suggest that assessing functional capacity through non-invasive methods like the 6MWT can provide valuable insights into cardiovascular health and risk stratification in HFmEF patients.
Clinical Presentation
The clinical presentation of HFmEF is multifaceted, often characterized by symptoms that overlap with both HFrEF and HFpEF, making diagnosis challenging. Functional capacity, as measured by the 6-minute walk test (6MWT), emerges as a pivotal tool in assessing the severity and progression of the disease. Studies consistently demonstrate that the 6MWT offers a straightforward and applicable method to evaluate aerobic capacity in middle-aged and older adults [PMID:25714888]. Notably, the reliability of the 6MWT is further supported by findings showing comparable heart rate responses between treadmill and level ground testing conditions, indicating that treadmill testing can be effectively utilized in clinical settings to assess cardiovascular responses [PMID:22189948]. Gender differences also play a role, with Jenkins et al. reporting that males (mean 682 ± 73 m) achieve significantly greater 6MWD compared to females (mean 643 ± 70 m) [PMID:19925174]. These gender-specific differences highlight the importance of individualized assessment and management strategies in HFmEF patients. Furthermore, decreased 6MWD is significantly associated with higher percent body fat, elevated systolic blood pressure, and increased rate-pressure product, underscoring its utility as a clinical indicator for cardiovascular health [PMID:20409599].
Diagnosis
Diagnosing HFmEF requires a comprehensive approach that integrates clinical symptoms, physical examination findings, and objective measures of cardiac function. The 6-minute walk test (6MWT) serves as a valuable diagnostic adjunct due to its ability to predict physiological parameters relevant to heart failure. Research indicates that the 6MWT can predict oxygen uptake (V˙O2) from walk distance, offering a non-invasive method to gauge functional limitations [PMID:25714888]. This predictive capability is particularly useful in distinguishing between different HF subtypes, as it provides objective data on exercise tolerance and cardiovascular efficiency. However, definitive diagnosis often necessitates echocardiography to confirm the mid-range EF range and rule out other potential causes of symptoms. While the 6MWT is a practical tool, it should be complemented by other diagnostic modalities to ensure accurate classification and tailored management plans.
Management
The management of HFmEF focuses on multifaceted strategies aimed at improving symptoms, functional capacity, and quality of life while mitigating cardiovascular risk factors. Given the complexity of HFmEF, integrating palliative care (PC) early in the disease trajectory is increasingly recognized as beneficial, although current utilization remains suboptimal [PMID:35763838]. Adjusted PC incidence rates are higher in HFrEF compared to HFmEF and HFpEF, suggesting potential opportunities for earlier PC integration in HFmEF to address symptom burden and improve end-of-life care planning. Exercise programs, guided by assessments like the 6MWT, are crucial components of management. The 6MWT, due to its simplicity and lower resource requirements compared to cardiopulmonary exercise testing (CPET), offers a viable method for monitoring functional capacity and tailoring exercise prescriptions [PMID:25714888]. Studies comparing treadmill and level ground 6MWT conditions show no significant differences in outcomes, supporting the use of treadmill testing in clinical settings where resources may be limited [PMID:22189948].
Enhancing aerobic fitness emerges as a key therapeutic goal, given the inverse associations observed between 6MWD and cardiovascular risk factors such as systolic blood pressure and rate-pressure product [PMID:20409599]. Lifestyle modifications, including dietary changes and structured exercise regimens, are essential. Pharmacological management should target underlying comorbidities and symptoms, aligning with guidelines for heart failure while considering the unique EF range of HFmEF. Gender-specific considerations, as highlighted by Jenkins et al.'s regression equations explaining significant variance in 6MWD [PMID:19925174], underscore the need for personalized approaches in exercise prescription and rehabilitation programs. Tailoring interventions based on individual functional capacity and risk profiles can optimize outcomes and improve patient quality of life.
Prognosis & Follow-up
The prognosis of HFmEF varies widely among patients, influenced by factors such as baseline functional capacity, comorbidities, and adherence to treatment plans. Palliative care integration appears to differ across HF subtypes, with HFrEF patients receiving PC earlier than those with HFpEF, though there is no significant difference noted between HFmEF and HFpEF [PMID:35763838]. This suggests that while early PC consultation might be beneficial across all subtypes, specific timing and triggers for PC referral in HFmEF warrant further investigation. Regular follow-up assessments, incorporating functional tests like the 6MWT, are crucial for monitoring disease progression and treatment efficacy. These assessments not only track changes in aerobic capacity but also help in adjusting management strategies to maintain or improve quality of life. Clinicians should remain vigilant for signs of declining functional status and cardiovascular risk factors, leveraging tools like the 6MWT to guide timely interventions and optimize patient outcomes.
Key Recommendations
References
1 Feder SL, Murphy TE, Abel EA, Akgün KM, Warraich HJ, Ersek M et al.. Incidence and Trends in the Use of Palliative Care among Patients with Reduced, Middle-Range, and Preserved Ejection Fraction Heart Failure. Journal of palliative medicine 2022. link 2 Sperandio EF, Arantes RL, Matheus AC, Silva RP, Lauria VT, Romiti M et al.. Intensity and physiological responses to the 6-minute walk test in middle-aged and older adults: a comparison with cardiopulmonary exercise testing. Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas 2015. link 3 Elazzazi A, Chapman N, Murphy E, White R. Measurement of distance walked and physiologic responses to a 6-minute walk test on level ground and on a treadmill: a comparative study. Journal of geriatric physical therapy (2001) 2012. link 4 Wanderley FA, Oliveira J, Mota J, Carvalho MJ. Six-minute walk distance (6MWD) is associated with body fat, systolic blood pressure, and rate-pressure product in community dwelling elderly subjects. Archives of gerontology and geriatrics 2011. link 5 Jenkins S, Cecins N, Camarri B, Williams C, Thompson P, Eastwood P. Regression equations to predict 6-minute walk distance in middle-aged and elderly adults. Physiotherapy theory and practice 2009. link
5 papers cited of 6 indexed.