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

P373 Left atrial mechanics and aortic stiffness following high intensity interval training: a randomised controlled study

Background

Physical inactivity is associated with an increased risk of cardiovascular disease. High intensity interval training (HIIT) has been shown to improve important health parameters, including aerobic capacity, arterial blood pressure, cardiac autonomic modulation and left ventricular mechanics. However, adaptations in left atrial (LA) mechanics and aortic stiffness remain unclear. Therefore, the aim of the present study was to assess any left atrial and aortic adaptations to HIIT.

Methods

Forty-one physically inactive males and females (aged 23 ± 2.7 years) volunteered for the study. Participants were randomised to either a 4-week HIIT intervention (n = 21) or 4-week control period (n = 20). The HIIT protocol consisted of 3 x 30-second maximal cycle ergometer sprints with a resistance of 7.5% body weight, interspersed with 2-minutes of active unloaded recovery. Speckle tracking imaging of the left atrium and M-Mode tracing of the aorta was performed pre and post HIIT and control period using commercially available software (EchoPac; GE Medical Systems). Analysis of covariance, with baseline measures as the covariate, was used to explore any differences in left atrial mechanics and aortic stiffness between the intervention and control groups. Stepwise linear regression analysis using LA stiffness as the dependent variable was conducted.

Results

Following 4-weeks of HIIT, there was significant improvement in LA mechanics, including LA reservoir (13.9 ± 13.4%, p = 0.033) and LA stiffness (-0.05 ± 0.04%-1, p = 0.032) compared to the control condition. In addition, improvements were observed in aortic distensibility (2.1 ± 2.7 cm2 × dyn×-1 × 103, p = 0.031) and aortic stiffness index (-2.6 ± 4.6, p = 0.041) compared to the control condition. In stepwise linear regression analysis, aortic distensibility change was significantly associated with LA stiffness change (p = 0.002), with an R2 of 0.613.

Conclusion

A short-term programme of HIIT was associated with a significant improvement in LA mechanics and aortic stiffness. These adaptations may have important health implications and contribute to the improved left ventricular diastolic and systolic mechanics, aerobic capacity and reduced arterial blood pressure previously documented following HIIT.