The role for cardiopulmonary exercise testing in patients with atrial septal defects: a review

Secundum atrial septal defects (ASD) are the commonest congenital cardiac abnormality. They are often identified incidentally, or in conjunction with an acquired cardiac abnormality. Untreated they may lead to significant morbidity and mortality, with consequences including right ventricular overload and right heart failure, pulmonary arterial hypertension, shunt reversal and cyanosis, and arrhythmias. Deciding whether to close an ASD can consume as much clinical time as finding them or indeed closing them. In the past when surgical closure was the only option, the morbidity of the procedure, including the need for sternotomy or thoracotomy, limited its use to large defects considered likely to result in shunt reversal or heart failure. Smaller defects were often managed conservatively. However within the past 2 decades percutaneous closure has come to the fore and is now considered first line when morphology allows. With lower morbidity, this has "lowered the bar" in terms of who is considered for closure, although the absolute mortality risk of either procedure is low. However, even though mortality is low, morbidity is still significant after percutaneous closure. Despite this, the utilisation of ASD closure has dramatically increased in the last decade with a sudden rise from 2001, owing largely to growth in percutaneous closures. Instead of looking for symptoms, which are subjective, or evidence of large shunt/RV failure, an objective measure of exercise capacity might help identify other patients who would benefit from closure. This review will look at the current evidence of cardiopulmonary exercise testing (CPET) in ASD closure.