Background: Increased aortic stiffness is associated with decreased exercise capacity and adverse cardiovascular outcome. It improves prediction when added to conventional cardiovascular risk factors. Assessment of aortic stiffness by 320-slice cardiac computed tomography angiography (CTA) is feasible, but associations with exercise have not been previously explored.
Methods: All patients were identified who underwent Bruce protocol exercise stress testing and CTA with functional imaging within 90 days, between September 2008 and December 2010 (47 patients). Images were reconstructed at 10% phase intervals throughout the cardiac cycle. Aortic strain ((systolic area − diastolic area)/diastolic area) was calculated 5 cm distal to the plane of the aortic valve. Exercise testing was terminated according to usual clinical indications, predominantly exhaustion.
Results: Exercise duration was associated with aortic strain (P < 0.001, r2 = 0.25), age (P < 0.001, r2 = 0.25) and gender (P < 0.01) (lower in females). Strain and gender, but not age, were independently associated with exercise duration, with strain entering the model first (P < 0.001, r2 = 0.32). Neither strain nor exercise duration was associated with rest or peak blood pressure, or rate pressure product. Aortic strain was not associated with the presence or severity of coronary artery disease in this moderate to high risk cohort. The relationship between aortic strain and exercise duration was similar in those with and without evidence of exercise induced myocardial ischaemia (ST depression ≥1 mm).
Conclusion: Aortic strain is associated with exercise duration in patients with and without myocardial ischaemia. Further research is merited to assess its potential to improve risk stratification or as a therapeutic target.
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© 2011 Published by Elsevier Inc.
