Baseline characteristics of the subjects
| Nonconversion group | Conversion group | p-value | |
| Subjects | 80 | 18 | |
| Age yrs | 64.3±1.0 | 59.3±2.8 | 0.05 |
| Sex M:F | 76:4 | 18:0 | 1.00 |
| BMI kg·m−2 | 28.5±0.6 | 32.9±1.5 | 0.002 |
| AHI n·h−1 | 38.5±1.8 | 39.1±4.2 | 0.87 |
| Cause of HF | 0.55 | ||
| IDCM | 21 (26) | 6 (33) | |
| Ischaemic | 56 (70) | 11 (61) | |
| Hypertensive | 3 (4) | 1 (6) | |
| LVEF | 24.3±0.9 | 24.3±1.7 | 0.99 |
| NYHA class | 0.49 | ||
| II | 59 (74) | 13 (72) | |
| III | 20 (25) | 4 (22) | |
| IV | 1 (1) | 1 (6) | |
| Atrial fibrillation | |||
| Present | 13 (16) | 3 (17) | 1.00 |
| Medications | |||
| Digoxin | 43 (54) | 9 (50) | 0.80 |
| Loop diuretics | 72 (90) | 16 (89) | 1.00 |
| Spironolactone | 27 (34) | 12 (67) | 0.02 |
| ACE inhibitors | 63 (79) | 17 (94) | 0.18 |
| β-blockers | 61 (76) | 15 (83) | 0.76 |
| CHFQ score | |||
| Dyspnoea | 4.4±0.1 | 3.5±0.2 | 0.004 |
| Blood pressure mmHg | |||
| Systolic | 116±2 | 103±3 | 0.005 |
| Diastolic | 71±1 | 69±3 | 0.51 |
Data are presented as n, mean±sem (for continuous values), or n (%), unless otherwise indicated. M: male; F: female; BMI: body mass index; AHI: apnoea/hypopnoea index; HF: heart failure; IDCM: idiopathic dilated cardiomyopathy; LVEF: left ventricular ejection fraction; NYHA: New York Heart Association; ACE: angiotensin-converting enzyme; CHFQ score: Chronic Heart Failure Questionnaire score (lower scores indicate more dyspnoea). The nonconversion and the conversion groups were defined as having ≥50% central events and >50% obstructive events, respectively.