Cardiac catheterization remains a standard tool when diagnosis, prognosis, or management re- quire a) more precise definition of anatomy than is achievable via advanced noninvasive imaging (eg, structures with low flow or those shielded from other techniques), b) calculation of pressures and resistances, or c) physiological or anatomic simu- lation to allow additional calculation or anatomic visualization. Cardiac catheterization can provide unique information not reliably available from other diagnostic modalities (eg, direct pressure measure- ment in a vessel or chamber, determination of pul- monary artery (PA) pressures and resistance, and optimal imaging of vessels in which flow is com- promised). Procedures should be planned with ap- preciation of the anatomy and physiology likely to be encountered, including sequelae and residua of prior surgery and interventions. The expansion of interventional catheter tech- niques has dramatically expanded possibilities for interventional treatment for an increasing number of conditions. Operators require specialized train- ing and expertise in ACHD. In addition, catheteri- zation laboratories specially equipped with devices and tools used in ACHD intervention are needed and personnel trained in their use. Such equipment and expertise differ from those found in catheteri- zation laboratories devoted primarily to diagnostic catheterization and coronary interventions. 2. For patients at low or intermediate risk of obstruc- tive coronary disease, CT coronary angiography can be an alternative to cardiac catheterization for assessing coronary artery course and patency. 3.4.7. Exercise Testing Recommendations for Exercise Testing Referenced studies that support recommendations are summarized in Online Data Supplement 11. COR LOE Recommendations IIa B-NR In patients with ACHD, cardiopulmonary exercise testing (CPET) can be useful for baseline functional assessment and serial IIa C-LD In symptomatic patients with ACHD, a 6-minute walk test can be useful to objectively assess symptom severity, functional capacity, and response to therapy.S3.4.7-3,S3.4.7-4 Recommendation-Specific Supportive Text 1. 