Table 1.
Characteristics of the study patients stratified according to percent predicted VO2 below/above 85%.
| Variable | Entire cohort (n = 200) | Percentage predicted VO2 below 85% (n = 99) | Percentage predicted VO2 above 85% (n = 101) | p value |
|---|---|---|---|---|
| Baseline and clinical characteristics | ||||
| Age (years) | 58.8 (51.6–66.0) | 57.0 (51.0–65.4) | 59.8 (52.8–67.1) | 0.124 |
| Sex (female) | 86 (43.0) | 41 (41.4) | 45 (44.6) | 0.760 |
| Height (centimeters) | 168.0 (163.0–176.0) | 170.0 (163.0–175.5) | 168.0 (163.0–176.0) | 0.942 |
| Body weight (kg) | 81.0 (69.0–92.0) | 80.0 (67.2–90.0) | 82.0 (70.0–95.0) | 0.218 |
| Body mass index (kg/m2) | 26.6 (24.1–30.2) | 26.0 (23.4–29.4) | 27.7 (25.0–31.2) | 0.027 |
| Hypertension | 83 (41.5) | 45 (45.5) | 38 (37.6) | 0.327 |
| Diabetes | 12 (6.0) | 10 (10.1) | 2 (2.0) | 0.034 |
| Active smoke | 85 (42.5) | 49 (49.5) | 36 (35.6) | 0.136 |
| Dyslipidemia | 76 (38.0) | 33 (33.3) | 43 (42.6) | 0.230 |
| CKD | 6 (3.0) | 5 (5.1) | 1 (1.0) | 0.205 |
| Heart failure | 10 (5.0) | 6 (6.1) | 4 (4.0) | 0.567 |
| Previous MI | 12(6.0) | 7(7.1) | 5 (5.0) | 0.127 |
| COPD | 15 (7.5) | 8 (8.1) | 7 (6.9) | 0.968 |
| Oxygen support during hospitalization | ||||
| No | 22 (11.0) | 14 (14.1) | 8 (7.9) | 0.002 |
| Venturi mask | 74 (37.0) | 25 (25.3) | 49 (48.5) | |
| NIV | 75 (37.5) | 39 (39.4) | 36 (35.6) | |
| MV | 29 (14.5) | 21 (21.2) | 8 (7.9) | |
| Steroid therapy | 200 (100.0) | 99 (100.0) | 101 (100.0) | 1.000 |
| Baseline ejection fraction | 60.0 (60.0–60.0) | 60.0 (55.0–60.0) | 60.0 (60.0–60.0) | 0.030 |
| Time from hospital discharge to CPET (days) |
107.0 (83.0–189.0) | 102.4 (74.2–166.0) | 111.0 (84.0–202.0) | 0.407 |
| Length of hospital stay (days) | 17.0 (5.0–32.0) | 23.5 (10.0–38.0) | 14.0 (3.0–24.0) | 0.001 |
| Three-month clinical evaluation | ||||
| 6MWT (meters) | 540.0 (476.2–597.5) | 525.0 (450.0–577.5) | 540.0 (480.0–600.0) | 0.061 |
| Ejection fraction | 60.0 (60.0–60.0) | 60.0 (55.0–60.0) | 60.0 (60.0–60.0) | 0.092 |
| Body weight (kg) | 77.0 (66.0–88.0) | 73.0 (65.0–84.0) | 78.0 (67.0–90.0) | 0.032 |
| Absolute weight loss (kg) | 7.0 (4.0–11.0) | 7.0 (5.0–12.0) | 6.0 (4.0–10.0) | 0.133 |
| Percent weight loss (%) | 8.8 (5.4–13.0) | 10.0 (6.7–15.3) | 7.9 (5.1–12.1) | 0.031 |
| Body mass index (kg/m2) | 26.6 (24.1–30.2) | 26.0 (23.4–29.4) | 27.7 (25.0–31.2) | 0.027 |
| Dyspnea | 118 (59.0) | 64 (64.6) | 54 (53.5) | 0.143 |
| NYHA class III/IV | 54 (27.0) | 34 (34.3) | 20 (19.8) | 0.058 |
| Chest pain | 63 (31.5) | 34 (34.3) | 29 (28.7) | 0.481 |
| Angina pectoris | 14 (7.0) | 9 (9.1) | 5 (5.0) | 0.342 |
| Fatigue | 115 (57.5) | 60(60.6) | 55 (54.5) | 0.069 |
| Palpitations | 51 (25.5) | 25 (25.3) | 26 (25.7) | 1.000 |
| Lipothymia/syncope | 1 (0.5) | 0 (0.0) | 1 (1.0) | 1.000 |
| Three-month cardiopulmonary exercise testing | ||||
| Reason for CPET interruption | ||||
| Exhaustion/leg fatigue | 186 (93.0) | 90 (90.9) | 75 (74.3) | 0.782 |
| Dyspnea | 10 (5.0) | 6 (6.1) | 4 (4.0) | |
| New arrhythmia | 4 (2.0) | 3 (3.0) | 1 (1.0) | |
| Peak VO2 (ml O2/min) | 1507.0 (1191.8–1976.8) | 1258.0 (1054.5–1588.5) | 1730.0 (1410.0–2258.0) | <0.001 |
| Percent predicted peak VO2 (%) | 85.0 (74.0–98.2) | 74.0 (63.5–79.2) | 98.1 (89.7–111.0) | <0.001 |
| Peak VO2/kg (mL O2/min /kg) | 20.1 (16.5–24.4) | 17.7 (14.6–20.2) | 23.0 (19.2–28.0) | <0.001 |
| Peak W (Watt) | 121.5 (91.8–165.2) | 103.0 (82.5–144.5) | 137.0 (112.0–187.0) | <0.001 |
| Percent predicted peak W (%) | 90.2 (67.8–110.1) | 63.0 (50.3–71.7) | 105.2 (92.8–119.7) | <0.001 |
| Peak HR (beat/min) | 149.0 (133.8–161.0) | 143.0 (121.5–157.5) | 152.0 (142.0–164.0) | 0.001 |
| Percent predicted HR (%) | 91.9 (82.2–98.2) | 85.0 (76.0–95.0) | 95.0 (89.0–99.4) | <0.001 |
| OUES | 1695.0 (1363.2–2169.5) | 1487.0 (1175.0–1853.0) | 1959.0 (1578.0–2379.0) | <0.001 |
| RER | 1.1 (1.1–1.2) | 1.1 (1.0–1.2) | 1.1 (1.1–1.2) | 0.597 |
| VE (L/min) | 66.8 (52.3–87.9) | 61.0 (45.6–73.8) | 74.2 (61.3–96.6) | <0.001 |
| VT (mL) | 1729.0 (1385.2–2188.2) | 1593.0 (1208.0–1974.0) | 1900.0 (1526.0–2435.0) | <0.001 |
| BR (breath/min) | 39.2 (34.3–43.9) | 38.0 (32.9–42.9) | 39.8 (35.4–45.7) | 0.032 |
| BrR | 50.9 (40.9–60.0) | 55.6 (47.9–59.7) | 48.6 (35.7–60.5) | 0.019 |
| AT W (watt) | 68.0 (48.0–93.0) | 60.0 (38.5–81.0) | 77.0 (57.0–103.0) | <0.001 |
| AT VO2 (mL O2/min) | 1019.5 (822.0–1283.8) | 899.0 (747.0–1076.0) | 1168.0 (963.0–1435.0) | <0.001 |
| AT HR (beat/min) | 113.0 (101.0–125.2) | 109.0 (98.5–125.5) | 114.0 (103.0–125.0) | 0.331 |
| Pulmonary function testing | ||||
| FEV1 (L) | 2.9 (2.5–3.7) | 2.9 (2.4–3.5) | 3.0 (2.5–3.8) | 0.418 |
| Percent predicted FEV1 (%) | 102.0 (89.0–113.0) | 95.5 (82.2–108.0) | 108.0 (92.8–116.0) | <0.001 |
| FVC (L) | 3.6 (3.0–4.4) | 3.5 (3.0–4.3) | 3.7 (3.0–4.5) | 0.443 |
| Percent predicted FVC (%) | 99.0 (85.5–109.0) | 95.0 (79.5–104.0) | 102.0 (91.0–111.0) | 0.001 |
| Percent FEV1/FVC (%) | 104.0 (99.0–110.0) | 104.0 (98.0–109.8) | 105.0 (100.0–113.0) | 0.089 |
| Percent predicted DLCO (%) | 77.0 (62.0–90.0) | 70.0 (56.0–83.5) | 85.5 (72.5–98.0) | <0.001 |
| Strength evaluation | ||||
| DLE maximal strength (kg) | 22.0 (14.2–30.0) | 20.0 (14.0–30.0) | 22.0 (15.0–30.0) | 0.654 |
| DLE maximal strength per BW | 0.3 (0.2–0.4) | 0.3 0.2–0.4) | 0.3 (0.2–0.4) | 0.845 |
| Sit-to-stand test | 10.5 (9.3–13.2) | 10.7 (9.3–13.2) | 10.5 (9.4–12.7) | 0.849 |
6MWT: 6 min walking test; AT: anaerobic threshold; BR: breathing rate; BrR: breathing reserve; CKD: chronic kidney disease; COPD: chronic obstructive pulmonary disease; CPET: cardiopulmonary exercise testing; DLCO: diffusing capacity of lungs for carbon monoxide; DLE: dominant leg extension; FEV1: forced expiratory volume in one second; FVC: forced vital capacity. HR: heart rate; MI: myocardial infarction; MV: mechanical ventilation; MVV: maximal voluntary ventilation; NIV: non-invasive ventilation; OUES: oxygen uptake efficiency slope; Peak VO2: peak oxygen uptake; RER: respiratory exchange ratio; VE= minute ventilation; VT= tidal volume; W: work level.