CPEX outcomes by cardiomyopathy phase
| Whole cohort (n=42) | Cardiomyopathy phase | P value | ||||
| Phase I (n=8) | Phase II (n=11) | Phase III (n=9) | Phase IV (n=14) | |||
| Primary outcomes | ||||||
| V̇O2peak (mL/kg/min) | ||||||
| Observed | 24.8±9.0 | 28.7±7.7 | 30.6±10.9 | 19.9±6.7 | 21.2±6.1 | 0.010 |
| Expected* | 36.1±3.7 | 37.3±3.2 | 37.7±4.3 | 34.9±3.9 | 34.8±2.9 | 0.060 |
| Age-normalised/Sex-normalised† | −32%±22 | −23%±17 | −19%±27 | −43%±17 | −39%±15 | 0.018 |
| FEV1 (L) | ||||||
| Observed | 2.61±1.00 | 2.85±0.99 | 2.63±1.31 | 2.42±1.08 | 2.56±0.69 | 0.834 |
| Expected‡ | 3.18±0.71 | 3.15±0.69 | 3.40±0.82 | 3.02±0.84 | 3.13±0.52 | 0.552 |
| Age-normalised/Sex-normalised/Height-normalised† | −18%±25 | −10%±18 | −23%±30 | −20%±30 | −17%±20 | 0.683 |
| Secondary CPEX outcomes | ||||||
| V̇O2 at VT1 (mL/kg/min) | 15.0±4.9 | 16.7±4.2 | 17.1±6.5 | 13.0±3.7 | 13.7±3.8 | 0.063 |
| Peak PET CO2 (mm Hg) | 36.1±5.0 | 37.7±4.1 | 36.9±3.1 | 35.5±4.7 | 34.8±6.9 | 0.047 |
| Peak O2 pulse (mL/beat) | 13.1±3.6 | 13.5±2.2 | 12.9±3.6 | 13.8±5.1 | 12.6±3.5 | 0.718 |
| VE/VCO2 slope | 31.2±5.1 | 28.8±2.5 | 31.4±3.3 | 30.7±5.5 | 32.8±6.9 | 0.215 |
| Markers of effort | ||||||
| Peak heart rate (bpm) | ||||||
| Observed | 144±31 | 166±23 | 153±26 | 126±19 | 135±36 | 0.006 |
| Age-normalised§ | −15%±17 | −10%±7 | −13%±14 | −22%±12 | −15%±23 | 0.294 |
| Peak systolic blood pressure (mm Hg) | 161±29 | 158±33 | 161±27 | 158±20 | 165±34 | 0.590 |
| Peak diastolic blood pressure (mm Hg) | 81±15 | 78±20 | 76±11 | 82±15 | 85±15 | 0.077 |
| Respiratory exchange ratio | 1.15±0.08 | 1.15±0.06 | 1.17±0.07 | 1.12±0.10 | 1.15±0.09 | 0.701 |
| RPE score (% >16)¶ | 61% (19/31) | 43% (3/7) | 63% (5/8) | 75% (3/4) | 67% (8/12) | 0.367¶ |
Data are reported as ‘mean±SD’, with p values from Jonckheere-Terpstra tests, unless stated otherwise; bold p values are significant at p<0.05.
*The expected V̇O2peak, based on the normative 50th percentile for a patient’s age and sex, using the reported equations.11
†The average percentage difference between the observed versus expected measurements.
‡The expected FEV1, based on the normative 50th percentile for a patient’s age, sex and height, using the reported equations.13
§The average percentage difference from the expected peak heart rate, defined as 220 minus age (in years).
¶RPE scores were only recorded for n=31; due to the preponderance of patients scoring 17, data are summarised as the percentage of patients above the threshold of ‘hard’ exercise (ie, >16)—the p value is based on the ungrouped data.
CPEX, cardiopulmonary exercise testing; FEV1, forced expiratory volume in 1 s; PET CO2, end-tidal CO2 pressure; RPE, rating of perceived exertion; VE/VCO2, ventilation/CO2 production; V̇O2peak, peak oxygen uptake; VT1, ventilatory threshold.