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

Purpose: High intensity interval training (HIIT) has been shown to improve important health parameters, including aerobic capacity, blood pressure, cardiac autonomic modulation and left ventricular (LV) mechanics. However, adaptations in left atrial (LA) mechanics and aortic stiffness remain unclear. Methods: Forty-one physically inactive males and females were recruited. Participants were randomised to either a 4-week HIIT intervention (n=21) or 4-week control period (n=20). The HIIT protocol consisted of 3x30-second maximal cycle ergometer sprints with a resistance of 7.5% body weight, interspersed with 2-minutes of active unloaded recovery, 3 times per week. Speckle tracking imaging of the LA and M-Mode tracing of the aorta was performed pre and post HIIT and control period. Results: Following HIIT, there was significant improvement in LA mechanics, including LA reservoir (13.9±13.4%, p=0.033), LA conduit (8.9±11.2%, p=0.023) and LA contractile (5±4.5%, p=0.044) mechanics compared to the control condition. In addition, aortic distensibility (2.1±2.7cm2dyn-1103, p=0.031) and aortic stiffness index (-2.6±4.6, p=0.041) were improved compared to the control condition. In stepwise linear regression analysis, aortic distensibility change was significantly associated with LA stiffness change R2 of 0.613 (p=0.002). 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 LV diastolic and systolic mechanics, aerobic capacity and blood pressure previously documented following HIIT

Cardiovascular magnetic resonance measures of aortic stiffness in asymptomatic patients with type 2 diabetes: association with glycaemic control and clinical outcomes

Background: We aimed to investigate in patients with type 2 diabetes whether aortic stiffness is: (i) associated with glycaemic control, (ii) associated with adverse outcomes and (iii) can be reversed on treatment with RAAS inhibition. Methods: Patients with type 2 diabetes (N = 94) and low vascular risk underwent assessment of cardiovascular risk and CMR assessment of ascending aortic distensibility (AAD), descending aortic distensibility (DAD) and aortic pulse wave velocity (PWV). Of these patients a subgroup with recent onset microalbuminuria (N = 25) were treated with renin–angiotensin–aldosterone system (RAAS) inhibition and imaging repeated after 1 year. All 94 patients were followed up for 2.4 years for major adverse cardiovascular disease (CVD) events including myocardial infarction detected on late gadolinium enhancement CMR. Results: Ascending aortic distensibility, DAD and PWV all had a significant association with age and 24 h systolic blood pressure but only AAD had a significant association with glycaemic control, measured as HbA1c (Beta − 0.016, P = 0.04). The association between HbA1c and AAD persisted even after correction for age and hypertension. CVD events occurred in 19/94 patients. AAD, but not DAD or PWV, was associated with CVD events (hazard ratio 0.49, 95% confidence interval 0.25–0.95, P = 0.01). On treatment with RAAS inhibition, AAD, but not DAD or PWV, showed significant improvement from 1.51 ± 1.15 to 1.97 ± 1.07 10−3 mmHg−1, P = 0.007. Conclusions: Ascending aortic distensibility measured by CMR is independently associated with poor glycaemic control and adverse cardiovascular events. Furthermore it may be reversible on treatment with RAAS inhibition. AAD is a promising marker of cardiovascular risk in asymptomatic patients with type 2 diabetes and has potential use as a surrogate cardiovascular endpoint in studies of novel hypoglycaemic agents