Inconsistencies in relationships between symptoms and objective measures of severity of illness contribute to uncertainty regarding the value of patient report of heart failure (HF) symptoms. The paucity of evidence is partially explained by differences in measurement of HF symptom burden. Symptom burden of HF has been quantified using the presence or absence of HF symptoms, extrapolated symptoms from quality-of-life measures or functional status, as well as limited assessment of dyspnea and fatigue or simply on the basis of clinician perspective. All of these measurement issues potentially diminish the value of patient report. Importantly, few investigators quantified a full range of potential physical HF symptoms or included psychological symptoms (eg, depression) commonly experienced by patients with HF. As Denfeld and colleagues1 recognize, symptoms of HF are the main drivers of healthcare use as well as important indicators of health status and quality of life. The study by Denfeld and colleagues1 provides compelling evidence about the relationship of HF symptoms and biomechanical indices contributing to understanding of the pathogenesis underlying HF symptoms.

Symptoms of HF vary between patients and within patients depending on factors such as severity of illness, comorbidity, age, environment, mood, and activity.2-6 Disregarding the heterogeneity of symptoms among patients with HF may confound the relationship between objective HF indices and symptom burden. Accurate assessment of HF symptoms poses challenges. It is important to note that patients may report absence of dyspnea if asymptomatic at rest, that some patients do not consider fatigue as a symptom, and that patients are known to deny edema later found on physical examination.7,8 Assessment of both nonspecific and specific HF symptoms, anxiety, and depression in relation to cardiac biomechanics is a strength of the current study. The interplay of physical and psychological symptoms is particularly interesting. Specifically, 17.1% of the variance in physical symptom burden and 24.1% of the variance in anxiety scores were explained in cardiac biomechanics and related clinical characteristics. These results provide further evidence supporting symptom burden as a therapeutic target. Importantly, because symptoms predict survival,9 careful assessment and tracking of symptoms beyond those typically documented in the medical record (eg, dyspnea, fatigue, and weight gain) are warranted.

The pathogenesis of HF symptoms is decidedly complex considering the interplay of physiological, psychological, environmental, and social factors. The heterogeneity of symptoms and subpopulations among patients with HF add additional challenges to understanding relationships between patient perception of symptoms and objective measures of HF. To further understand how symptoms of HF are manifested and experienced by patients, future research exploring the many subgroups among patients with HF is needed (eg, by age, HF type, comorbid illness). As indicated by Denfeld and colleagues,1 to answer these questions, advanced statistical methods, longitudinal data, and incorporation of a full range of HF symptoms are important.

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