Six-month outcomes of a high intensity exercise programme in young patients with hypertrophic cardiomyopathy: The SAFE-HCM trial

Funding Acknowledgements

Type of funding sources: Other. Main funding source(s): Cardiac Risk in the Young

Background

Moderate intensity exercise training in older patients with hypertrophic cardiomyopathy (HCM) can improve functional capacity, without significant harm. However, younger patients are attracted to high intensity training (HIT) regimes. The SAFE-HCM study demonstrated that an individually tailored, HIT programme in young patients with HCM was feasible, and provided both health and psychological benefits, without an increase in the burden of arrhythmia.

Purpose

To assess whether observed benefits of a HIT programme in young patients with HCM are sustained at 6 months.

Methods

Eighty patients with HCM (45.7y+/-8.6) underwent baseline clinical and psychological assessment. Individuals were randomised to a 12-week HIT programme (n = 40) or usual care (n = 40). Baseline evaluation was repeated at 12 weeks (T12). Feasibility, safety, health and psychological benefits were assessed. At 12-weeks individuals were encouraged to continue with the frequency and intensity of physical activity (PA) achieved at the end of the cardiac rehabilitation programme. Participants in the exercise arm were invited to follow-up at 6 months (T6m).

Results

The majority (83%) of participants completed the 12-week study. At T12 there was no significant difference between groups in the composite arrhythmia safety outcome (p = 0.99). The indices of exercise capacity were significantly improved in the exercise compared to the control group; peak VO2 (+3.7ml/kg/min [CI 1.1,6.3], p = 0.006), VO2/kg at anaerobic threshold (VO2/kgAT) (+2.44ml/kg/min [CI 0.6,4.2], p = 0.009), time to AT (+115s [CI 54.3,175.9], p < 0.001) and exercise time (max ET) (+108s [CI 33.7,182.2], p = 0.005). The exercise group also demonstrated greater reduction in systolic BP (-7.3mmHg [CI -11.7,-2.8], p = 0.002), BMI (-0.8kg/m2 [CI-1.1,-0.4], p < 0.001), anxiety (-2.6 [CI-3.6,-1.6], p= <0.001) and depression (-1.1 [CI -2.0,-0.2], p = 0.015) scores. At T6m patient reported exercise adherence was comparable to baseline PA in 33/34 of the exercise group attending for follow up. Most exercise gains dissipated with the exception of time to AT (p = 0.002), max ET (p = 0.003), VO2/kgAT (p = 0.04) and anxiety score (p < 0.001) (Figure 1). There were no sustained episodes of atrial or ventricular arrhythmias. The incidence of NSVT did not differ between time points (p = 0.09).

Conclusion

A 12-week HIT programme in young patients with HCM offers considerable gains in fitness and psychological outcomes, with no increase in arrhythmic burden. At T6m exercise levels as well as most physiological adaptations and health benefits returned to baseline, as seen in other studies when formal participation in an exercise programme comes to an end. This highlights the importance of the implementation of strategies to encourage ongoing engagement in PA. Potential solutions include identification of barriers to exercise, as well as adoption of novel tele-rehabilation approaches.

Abstract Figure 1 Sustained benefits at T6m

The Chelsea critical care physical assessment tool (CPAx): validation of an innovative new tool to measure physical morbidity in the general adult critical care population; an observational proof-of-concept pilot study

OBJECTIVE

To develop a scoring system to measure physical morbidity in critical care - the Chelsea Critical Care Physical Assessment Tool (CPAx).

METHOD

The development process was iterative involving content validity indices (CVI), a focus group and an observational study of 33 patients to test construct validity against the Medical Research Council score for muscle strength, peak cough flow, Australian Therapy Outcome Measures score, Glasgow Coma Scale score, Bloomsbury sedation score, Sequential Organ Failure Assessment score, Short Form 36 (SF-36) score, days of mechanical ventilation and inter-rater reliability.

PARTICIPANTS

Trauma and general critical care patients from two London teaching hospitals.

RESULTS

Users of the CPAx felt that it possessed content validity, giving a final CVI of 1.00 (P<0.05). Construct validation data showed moderate to strong significant correlations between the CPAx score and all secondary measures, apart from the mental component of the SF-36 which demonstrated weak correlation with the CPAx score (r=0.024, P=0.720). Reliability testing showed internal consistency of α=0.798 and inter-rater reliability of κ=0.988 (95% confidence interval 0.791 to 1.000) between five raters.

CONCLUSION

This pilot work supports proof of concept of the CPAx as a measure of physical morbidity in the critical care population, and is a cogent argument for further investigation of the scoring system.

Abdominal muscle and quadriceps strength in chronic obstructive pulmonary disease

BACKGROUND

Quadriceps muscle weakness is common in chronic obstructive pulmonary disease (COPD) but is not observed in a small hand muscle (adductor pollicis). Although this could be explained by reduced activity in the quadriceps, the observation could also be explained by anatomical location of the muscle or fibre type composition. However, the abdominal muscles are of a similar anatomical and fibre type distribution to the quadriceps, although they remain active in COPD. Cough gastric pressure is a recently described technique that assesses abdominal muscle (and hence expiratory muscle) strength more accurately than traditional techniques. A study was undertaken to test the hypothesis that more severe weakness exists in the quadriceps than in the abdominal muscles of patients with COPD compared with healthy elderly controls.

METHODS

Maximum cough gastric pressure and quadriceps isometric strength were measured in 43 patients with stable COPD and 25 healthy elderly volunteers matched for anthropometric variables.

RESULTS

Despite a significant reduction in mean quadriceps strength (29.9 kg v 41.2 kg; 95% CI -17.9 to -4.6; p = 0.001), cough gastric pressure was preserved in patients with COPD (227.3 cm H(2)O v 204.8 cm H(2)O; 95% CI -5.4 to 50.6; p = 0.11).

CONCLUSIONS

Abdominal muscle strength is preserved in stable COPD outpatients in the presence of quadriceps weakness. This suggests that anatomical location and fibre type cannot explain quadriceps weakness in COPD. By inference, we conclude that disuse and consequent deconditioning are important factors in the development of quadriceps muscle weakness in COPD patients, or that activity protects the abdominal muscles from possible systemic myopathic processes.

Effect of salmeterol on respiratory muscle activity during exercise in poorly reversible COPD

BACKGROUND

Some patients with irreversible chronic obstructive pulmonary disease (COPD) experience subjective benefit from long acting bronchodilators without change in forced expiratory volume in 1 second (FEV(1)). Dynamic hyperinflation is an important determinant of exercise induced dyspnoea in COPD. We hypothesised that long acting bronchodilators improve symptoms by reducing dynamic hyperinflation and work of breathing, as measured by respiratory muscle pressure-time products.

METHODS

Sixteen patients with "irreversible" COPD (<10% improvement in FEV(1) following a bronchodilator challenge; mean FEV(1) 31.1% predicted) were recruited into a randomised, double blind, placebo controlled, crossover study of salmeterol (50 micro g twice a day). Treatment periods were of 2 weeks duration with a 2 week washout period. Primary outcome measures were end exercise isotime transdiaphragmatic pressure-time product and dynamic hyperinflation as measured by inspiratory capacity.

RESULTS

Salmeterol significantly reduced the transdiaphragmatic pressure-time product (294.5 v 348.6 cm H(2)O/s/min; p = 0.03), dynamic hyperinflation (0.22 v 0.33 litres; p = 0.002), and Borg scores during endurance treadmill walk (3.78 v 4.62; p = 0.02). There was no significant change in exercise endurance time. Improvements in isotime Borg score were significantly correlated to changes in tidal volume/oesophageal pressure swings, end expiratory lung volume, and inspiratory capacity, but not pressure-time products.

CONCLUSIONS

Despite apparent "non-reversibility" in spirometric parameters, long acting bronchodilators can cause both symptomatic and physiological improvement during exercise in severe COPD.

Cough augmentation in amyotrophic lateral sclerosis

Cough flows and pressures were measured during cough augmentation in healthy subjects and patients with bulbar and nonbulbar amyotrophic lateral sclerosis. Manual assistance increased flow 11% in bulbar (p < 0.01) and 13% in nonbulbar (p < 0.001) patients. Mechanical insufflation-exsufflation increased flow 17% in healthy subjects (p < 0.05), 26% (p < 0.001) in bulbar, and 28% (p < 0.001) in nonbulbar patients. The greatest improvements were in patients with the weakest coughs. Patient group and level of weakness influenced the effect of augmentation.

Non-volitional assessment of skeletal muscle strength in patients with chronic obstructive pulmonary disease

BACKGROUND

Although quadriceps weakness is well recognised in chronic obstructive pulmonary disease (COPD), the aetiology remains unknown. In disabled patients the quadriceps is a particularly underused muscle and may not reflect skeletal muscle function as a whole. Loss of muscle function is likely to be equally distributed if the underlying pathology is a systemic abnormality. Conversely, if deconditioning and disuse are the principal aetiological factors, weakness would be most marked in the lower limb muscles.

METHODS

The non-volitional technique of supramaximal magnetic stimulation was used to assess twitch tensions of the adductor pollicis, quadriceps, and diaphragm muscles (TwAP, TwQ, and TwPdi) in 22 stable non-weight losing COPD patients and 18 elderly controls.

RESULTS

Mean (SD) TwQ tension was reduced in the COPD patients (7.1 (2.2) kg v 10.0 (2.7) kg; 95% confidence intervals (CI) -4.4 to -1.4; p<0.001). Neither TwAP nor TwPdi (when corrected for lung volume) differed significantly between patients and controls (mean (SD) TwAP 6.52 (1.90) N for COPD patients and 6.80 (1.99) N for controls (95% CI -1.5 to 0.97, p=0.65; TwPdi 23.0 (5.6) cm H(2)O for COPD patients and 23.5 (5.2) cm H(2)O for controls (95% CI -4.5 to 3.5, p=0.81).

CONCLUSIONS

The strength of the adductor pollicis muscle (and the diaphragm) is normal in patients with stable COPD whereas quadriceps strength is substantially reduced. Disuse may be the principal factor in the development of skeletal muscle weakness in COPD, but a systemic process preferentially affecting the proximal muscles cannot be excluded.

Proportional assist ventilation as an aid to exercise training in severe chronic obstructive pulmonary disease

BACKGROUND

The effects of providing ventilatory assistance to patients with severe chronic obstructive pulmonary disease (COPD) during a high intensity outpatient cycle exercise programme were examined.

METHODS

Nineteen patients (17 men) with severe COPD (mean (SD) forced expiratory volume in 1 second (FEV(1)) 27 (7)% predicted) underwent a 6 week supervised outpatient cycle exercise programme. Ten patients were randomised to exercise with ventilatory assistance using proportional assist ventilation (PAV) and nine (two women) to exercise unaided. Before and after training patients performed a maximal symptom limited incremental cycle test to determine peak work rate (Wpeak) followed by a constant work rate (CWR) test at 70% of Wpeak achieved in the baseline incremental test. Minute ventilation (VE), heart rate, and arterialised venous plasma lactate concentration [La(+)] were measured before and after each test.

RESULTS

Mean training intensity (Wt/Wpeak) at 6 weeks was 15.2% (95% CI 3.2 to 27.1) higher in the group that used ventilatory assistance (p=0.016). Peak work rate after training was 18.4% (95% CI 6.4 to 30.5) higher (p=0.005) in the assisted group (p=0.09). [La(+)] at an identical workload after training was reduced by 30% (95% CI 16 to 44) in the assisted group (p=0.002 compared with baseline) and by 11% (95% CI -7 to 31) (p=0.08 compared with baseline) in the unassisted group (mean difference 18.4% (95% CI 3.3 to 40), p=0.09). A significant inverse relationship was found between reduction in plasma lactate concentration (DeltaL) at an equivalent workload after training during the CWR test and Wt/Wpeak achieved during the last week of training (r=-0.7, p=0.0006).

CONCLUSIONS

PAV enables a higher intensity of training in patients with severe COPD, leading to greater improvements in maximum exercise capacity with evidence of true physiological adaptation.