Resting and exercise characteristics of non-heart failure (HF) subjects with residual exertional dyspnoea (RED) and HF patients
| Variables | RED | HF |
| Subjects | 21 | 20 |
| Demographic/anthropometric | ||
| Age, years | 69.1±8.4 | 68.3±7.2 |
| Men | 12 (57.1) | 11 (55) |
| Body mass index, kg·m−2 | 30.8±6.2* | 26.5±7.3 |
| Obesity, absence/mild/moderate/morbid | 5/10/4/2 | 11/7/1/1 |
| Clinical | ||
| General | ||
| Dyspnoea duration, months, median (range) | 18 (6–32) | 16 (4–20) |
| mMRC dyspnoea score, 0/1/2/3/4 | 0/0/12/8/1 | 0/3/9/6/2 |
| Current/previous smokers | 12 (57.1)* | 16 (80) |
| Anxiety | 9 (42.8) | 7 (35) |
| Depression | 11 (52.3)* | 6 (30) |
| Renal impairment | 2 (9.5)* | 13 (65) |
| Anaemia | 1 (4.7)* | 8 (40) |
| NT-pro-BNP, pg·mL−1 | 168±62 | 1412±231 |
| Sleep disordered breathing | 6/10 (60) | 4/8 (50) |
| Cardiovascular | ||
| LVEF, % | 63.6±8.0* | 30.2±6.9 |
| Previous/current cardiovascular conditions | 18 (85.7) | 20 (100) |
| NYHA functional class 2–3 | 15 (71.4) | 16 (80) |
| Ischaemic dilated cardiomyopathy | 0* | 14 (70) |
| Hypertension | 12 (57)* | 6 (30) |
| Atrial fibrillation/flutter | 11 (52.3) | 9 (45) |
| Supraventricular tachycardia | 7 (33.3) | 6 (30) |
| Ventricular arrythmias | 6 (28.5)* | 14 (70) |
| Other arrhythmias | 6 (28.5)* | 10 (50) |
| LA enlargement, none/mild/moderate/severe | 13/6/2/0* | 2/5/5/8 |
| Diastolic dysfunction, none/mild/moderate/severe | 9/9/2/1 | 4/13/2/1 |
| Implantable cardioverter–defibrillator or pacemaker | 0* | 17 (85%) |
| Previous pulmonary embolism | 3 (14.2)* | 6 (30) |
| Pulmonary hypertension | 4 (19)* | 10 (50) |
| Previous myocardial infarction | 4 (19)* | 14 (70) |
| Previous cardioversion | 2 (9.5)* | 6 (30) |
| Metabolic | ||
| Metabolic syndrome | 12 (57) | 10 (50) |
| Type 2 diabetes mellitus | 13 (61.9) | 9 (60) |
| Hyperthyroidism | 3 (14.2) | 2 (10) |
| Main medications | ||
| Diuretics | 6 (28.5)* | 20 (100) |
| β-blockers | 6 (28.5)* | 18 (83) |
| ACE inhibitors or ARBs | 3 (14.5)* | 13 (65) |
| Sacubitril–valsartan | 0* | 6 (30) |
| Antiarrhythmic | 10 (47.6) | 12 (60) |
| Lung function | ||
| FVC, % predicted | 89.9±14.3* | 71.6±10.9 |
| FEV1, % predicted | 88.1±13.6* | 70.4±11.7 |
| FEV1/FVC | 0.70±0.06* | 0.78±0.10 |
| TLC, % predicted | 95.7±15.8* | 79.3±13.0 |
| DLCO, % predicted | 73.6±14.4* | 58.3±11.4 |
| PaO2, mmHg | 74±6 | 75±5 |
| PaCO2, mmHg | 34±4* | 39±3 |
| VD/VT | 0.35±0.06 * | 0.42±0.05 |
| MIP, % predicted | 89.3±14.5* | 71.9±10.4 |
| CPET | ||
| Metabolic/cardiovascular | ||
| Peak WR, % predicted | 65.1±13.0 | 62.3±10.8 |
| Peak V′O2, % predicted | 64.1±10.6* | 49.6±9.7 |
| V′O2–WR slope, mL·min−1·W−1 | 9.8±2.0* | 6.7±1.4 |
| Chronotropic incompetence# | 7/13 (53.8) | NA |
| Peak MAP, mmHg | 119±24* | 101±20 |
| Ventilatory | ||
| V′E–V′CO2 slope | 38.6±9.1 | 39.2±8.3 |
| EOV duration, % test | 79.3±10.1 | 80.1±9.4 |
| Amplitude of V′E cycles, L·min−1 | ||
| 1st test quartile | 16.3±10.2* | 13.4±8.0 |
| 2nd test quartile | 14.7±6.4* | 12.6±7.0 |
| 3rd test quartile | 11.4±7.8 | 10.8±6.4 |
| Duration of V′E cycles, s | ||
| 1st test quartile | 55.4±12.3 | 52.1±11.5 |
| 2nd test quartile | 53.41±9.0 | 56.31±10.1 |
| 3rd test quartile | 44.6±10.4 | 47.4±9.7 |
| Lung-mechanical/breathing pattern | ||
| VT/IC | ||
| 1st test quartile | 0.64±0.06* | 0.60±0.05 |
| 2nd test quartile | 0.68±0.07* | 0.64±0.05 |
| 3rd test quartile | 0.74±0.09 | 0.69±0.07 |
| IRV, % TLC | ||
| 1st test quartile | 35.4±9.2* | 41.7±10.1 |
| 2nd test quartile | 29.1±7.5* | 35.4±8.3 |
| 3rd test quartile | 18.2±8.3* | 22.1±8.7.0 |
| Pulmonary gas exchange | ||
| Peak SpO2, % | 94±3 | 93±4 |
| Peak PETCO2, mmHg | 33±4* | 28±4 |
| Peak PcCO2, mmHg¶ | 32±3* | 35±3 |
| Peak Pc−ETCO2, mmHg¶ | −1±3* | 7±4 |
| Peak VD/VT¶ | 0.30±0.07* | 0.41±0.04 |
| Sensory | ||
| Dyspnoea scores | ||
| 1st test quartile | 3 (0.5–4)* | 1 (0–3) |
| 2nd test quartile | 4 (2–6)* | 2 (0–4) |
| 3rd test quartile | 4.5 (3–8) | 3.5 (1–5) |
| Peak | 7 (4–10)* | 4 (2–8) |
| Peak leg effort scores | 4 (2–7)* | 6.5 (4–9) |
| Peak dyspnoea−leg effort score differences | 2.5 (−2–6)* | −3 (−4–3) |
| Peak dyspnoea ≥leg effort scores | 15 (71.4)* | 7 (35) |
Data are presented as mean±sd, n (%) or n/N (%), unless otherwise stated. All subjects presented with exertional oscillatory ventilation (EOV) during an incremental cardiopulmonary exercise test (CPET). Data relative to the last quartile of CPET are not shown due to the low frequency of EOV close to exercise termination. mMRC: modified Medical Research Council scale; NT-pro-BNP: N-terminal pro-hormone of B-type natriuretic peptide; LVEF: left ventricular ejection fraction; NYHA: New York Heart Association; LA: left atrium; ACE: angiotensin-converting enzyme; ARB: angiotensin receptor blocker; FVC: forced vital capacity; FEV1: forced expiratory volume in 1 s; TLC: total lung capacity; DLCO: capacity of the lung for carbon monoxide; PaO2: arterial oxygen tension; PaCO2: arterial carbon dioxide tension; VD: dead space volume; VT: tidal volume ratio; MIP: maximal inspiratory pressure; WR: work rate; V′O2: oxygen uptake; MAP: mean arterial pressure; V′E: ventilation; V′CO2: carbon dioxide output; IC: inspiratory capacity; IRV: inspiratory reserve volume; SpO2: oxygen saturation by pulse oximetry; PETCO2: end-tidal carbon dioxide tension; PcCO2: capillary carbon dioxide tension; Pc−ETCO2: capillary–end-tidal carbon dioxide gradient; NA: not available. #: Wilkoff index [7); ¶: n=10 and n=11 for RED and HF, respectively. *: p<0.05.