Introduction

Chronic heart failure (HF) is a serious problem, and its prevalence is steadily increasing. The main goals of HF management are to evaluate the clinical characteristics of patients and provide proper ambulatory care to prevent unnecessary hospitalizations and decompensation.1-3 Bendopnea manifests with shortness of breath within 30 seconds of leaning forward, and this condition was suggested as a symptom of chronic HF in 2014.4 Bendopnea is associated with increased ventricular filling pressure during a lean, especially in patients with a low cardiac index. According to Thibodeau et al,4 body mass index (BMI) is higher in patients who experience bendopnea. BMI can affect dyspnea in this population, as obesity probably causes certain restrictions when bending forward and increases intra-abdominal pressure.5,6 To assess the effect of BMI on dyspnea when leaning forward, patients with BMI of less than 30 kg/m2 were recruited in our study.

Patients and methods

The study included 84 outpatients (47 men, 37 women) with chronic HF with functional class II–IV according to the New York Heart Association (NYHA) classification and median (interquartile range [IQR], Q1–Q3) age of 75 (71–79) years. The primary cause of HF was coronary heart disease in 65 patients (77%) and arterial hypertension in 19 (23%). There were 45 patients (54%) with NYHA class II, 38 (45%) with class III, and 1 (1.2%) with class IV. The median (IQR) duration of HF was 24 (12–48) months.

Patients underwent general clinical assessment, electrocardiography, and echocardiography. Pulmonary artery systolic pressure was calculated based on echocardiography. The inclusion criteria were congestive HF with NYHA class II–IV, diagnosis at least 3 months prior to enrollment, age 60 years or older, no hospitalizations for decompensated HF during the previous 3 months, and continuous drug treatment for HF for 1 month before inclusion in the study. The exclusion criteria were acute inflammatory diseases, pulmonary diseases, clinically significant valvular heart diseases, hypertrophic cardiomyopathy, chronic kidney disease stage 4 or 5, liver failure, myocardial infarction (MI), stroke in the 3 months prior to enrolment, inability to lean forward, and obesity.

Each patient was seated in a chair and asked to bend forward to touch their ankles. Bendopnea was diagnosed when shortness of breath occurred within 30 seconds of leaning forward.

The local ethics committee approved the study. All patients signed written informed consent forms. The mean (SD) follow-up period was 24.1 (11.6) months.

Statistical analysis

Categorical variables were presented as the number and percentage of patients, and continuous variables as mean (SD) or median (IQR, Q1–Q3) as appropriate. Differences in clinical characteristics at baseline with regard to bendopnea were compared using the χ2 test for categorical variables and the t test or the nonparametric Mann–Whitney test for continuous variables. Normality was assessed using the Kolmogorov–Smirnov test.

Multivariate logistic regression was used to evaluate the odds ratio (OR) and its 95% CI. Bendopnea was a dependent variable. Left ventricular end-systolic dimension, BMI, waist circumference were continuous variables; low left ventricular ejection fraction (<40%), HF decompensation were dichotomized variables. A 2-tailed P value of less than 0.05 was deemed significant. The statistical analyses were performed using the SPSS software, version 22.0 (IBM Corporation, Armonk, New York, United States).

Results and discussion

Bendopnea was present in 35 patients (41.6%). All patients with bendopnea had dyspnea on exertion and advanced HF with NYHA class III–IV. The characteristics of the study groups are presented in Table 1.

Table 1. Characteristics of the study groups
ParameterBendopnea (n = 35)No bendopnea (n = 49)P value

Male sex, n (%)

26 (74)

11 (22)

<0.001

Age, y, median (IQR, Q1–Q3)

76 (72–80)

75 (66–79)

0.11

BMI, kg/m2, median (IQR, Q1–Q3)

28 (25–30)

30 (24–33)

0.81

Waist circumference, cm, median (IQR, Q1–Q3)

88 (86–89)

85 (82–89)

0.18

CHD, n (%)

34 (97)

26 (53)

<0.001

Hypertension, n (%)

31 (88)

48 (98)

0.16

Anemia, n (%)

9 (26)

16 (33)

0.67

AF, n (%)

19 (54)

15 (31)

0.03

Diabetes, n (%)

10 (28)

16 (33)

0.76

Stroke, n (%)

3 (8)

5 (10)

0.94

Chronic kidney disease, n (%)

25 (71)

27 (55)

0.13

LVEF, %, median (IQR, Q1–Q3)

45 (36–52)

60 (58–63)

<0.001

ILA, cm/m2, median (IQR, Q1–Q3)

2.5 (2.1–2.7)

2 (2–2.7)

0.23

LVEDD, cm, median (IQR, Q1–Q3)

6 (5–6)

4.7 (4.5–4.8)

<0.001

LVESD, cm, median (IQR, Q1–Q3)

4.5 (3.6–4.8)

3.5 (3–3.7)

<0.001

LVEDVI, ml/m2, median (IQR, Q1–Q3)

140 (110–195)

70 (86–110)

<0.001

LVESVI, ml/m2, median (IQR, Q1–Q3)

100 (86–110)

40 (35–47)

<0.001

LVMI, g, median (IQR, Q1–Q3)

125 (110–125)

110 (110–125)

0.29

PASP, mm Hg, median (IQR, Q1–Q3)

35 (34–38)

30 (29–34)

<0.001

SBP, mm Hg, median (IQR, Q1–Q3)

120 (120–147)

138 (120–160)

0.05

DBP, mm Hg, median (IQR, Q1–Q3)

80 (70–80)

80 (77–90)

0.60

HR, bpm, median (IQR, Q1–Q3)

73 (61–86)

65 (60–80)

0.10

NT-proBNP, pg/ml, median (IQR, Q1–Q3)

1584 (459–1808)

178 (120–295)

0.03

Abbreviations: AF, atrial fibrillation; BMI, body mass index; CHD, coronary heart disease; DBP, diastolic blood pressure; HR, heart rate; ILA, index of left atrial size; IQR, interquartile range; LVEDD, left ventricular end-diastolic dimension; LVEDVI, left ventricular end-diastolic volume indexed to body surface area; LVEF, left ventricular ejection fraction; LVESD, left ventricular end-systolic dimension; LVESVI, left ventricular end-systolic volume indexed to body surface area; LVMI, left ventricular mass indexed to body surface area; NT-proBNP, N-terminal fragment of the prohormone brain natriuretic peptide; PASP, pulmonary artery systolic pressure; SBP, systolic blood pressure; Q1, lower quartile; Q3, upper quartile

Bendopnea was associated with a history of MI (OR, 9.5; 95% CI, 1.5–60.5; P <0.001), left ventricular aneurysm (OR, 13.3; 95% CI, 2.6–65.0; P = 0.002), left ventricular end-systolic dimension (OR, 14.3; 95% CI, 3.28–62.5; P <0.00.1), and low left ventricular ejection fraction (LVEF) (OR, 17.6; 95% CI, 6.8–84.3; P <0.001). No association was established between bendopnea and BMI or waist circumference. There were 28 patients (80%) with bendopnea and 27 patients (55%) without bendopnea who were hospitalized due to HF decompensation (OR, 3.3; 95% CI, 1.2–8.9) during the follow-up. The association between bendopnea and hospital admissions persisted after correction for BMI (OR, 7.6; 95% CI, 2.0–28.3; P = 0.003) and LVEF (OR, 1.3; 95% CI, 1.1–1.4; P <0.001).

The main important findings of this study are: 1) the prevalence of bendopnea was 41.6% in a cohort of outpatients with HF and BMI of less than 30 kg/m2; 2) this symptom was associated with the severity of patients’ clinical state and hospitalizations.

Increasing pressure in pulmonary capillaries results in extravasating fluid into the alveolar–capillary barrier, increases diffusion distance there, and finally worsens diffusion (primarily of oxygen). Subsequently, shortness of breath occurs as a result of several mechanisms: stimulation of the juxtacapillary receptors, reduction in lung capacity, closure of the small airways, and stimulation of chemoreceptors in response to hypoxemia. According to Thibodeau et al,4 bendopnea usually develops in patients with initially elevated filling pressure, who have a higher probability of achieving the threshold level of pressure necessary for the development of clinical manifestations. Dyspnea is a frequent symptom of not only HF but also bronchopulmonary pathology and obesity. Furthermore, it is common among elderly people. Therefore, the differential diagnosis of these conditions poses a challenge.

Thibodeau et al4 reported that BMI was higher in patients with bendopnea. Obesity contributes to the development and progression of myocardial remodeling through a variety of mechanisms and is associated with hemodynamic overload, which leads to dilatation and hypertrophy of the left ventricle.7,8

To eliminate the effect of BMI on dyspnea when leaning forward, outpatients older than 60 years and with BMI of less than 30 kg/m2 were included in the present study. Thibodeau et al4 found that BMI was higher in patients with bendopnea, but there were no significant differences in the circumference of the hips and waist or the ratio of the circumference of the waist to that of hips between those with bendopnea and those without. However, the results of our study and those presented by Baeza-Trinidad et al9 did not confirm the link between BMI or the waist circumference and bendopnea.

A Portuguese study assessed the relationship of dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea, and bendopnea with chronic diseases, especially HF and its different phenotypes. The studies examined 633 outpatients aged 45 to 99 years. They showed that paroxysmal nocturnal dyspnea (OR, 2.42; 95% CI, 1.10–5.29) and bendopnea (OR, 2.59; 95% CI, 1.52–4.44) were associated with HF. In multivariate analyses, bendopnea had no association with chronic obstructive pulmonary disease, ischemic heart disease, or MI. Even after correction for depression and MI, the association was maintained for HF and bendopnea, regardless of LVEF, which suggests that bendopnea could be a promising symptom to differentiate HF from other chronic diseases.10

Changes in ventricular filling due to congestion, including shortness of breath when the body leans forward, can be considered a marker of HF decompensation and an unfavorable course of the disease.11

Ventricular remodeling after MI may explain the association between the etiology of coronary heart disease and bendopnea. The sequelae of MI, with loss of active myocytes, results in an increase in pressure that induces a unique pattern of remodeling involving the infarct zone, the infarct border zone, and the remote noninfarcted myocardium. Late remodeling affects the left ventricle globally and is morphologically associated with dilation and myocyte hypertrophy.12 Left ventricular remodeling creates a de novo mechanical burden for the heart and its processes can independently contribute to the progression of HF, including the risk of bendopnea, which is associated with higher levels of pulmonary artery wedge pressure and right atrial pressure.

The present results showed that bendopnea was associated with hospitalization (OR, 3.3; 95% CI, 1.2–8.9). Baeza-Trinidad et al9 reported on similar data, where 62.3% of patients with bendopnea were rehospitalized, and bendopnea was assocated with an increased risk of death in patients with HF with NYHA class III–IV (OR, 2.3; 95% CI, 1.05–5.14). Later, Thibodeau et al4 confirmed the association of bendopnea with unfavorable clinical prognosis.4

Conclusions

Bendopnea was observed in 42 patients (41%) with congestive HR and BMI of less than 30 kg/m2.

The condition did not depend on BMI but was closely associated with the severity of patients’ clinical status and hospitalization, even after adjusting for BMI and LVEF. This finding suggests that bendopnea could be a clinical tool to assess the severity of congestive HF in elderly outpatients only with BMI of less than 30 kg/m2.