Circumstances Where CMR, CCT, TEE, and/or Cardiac Catheterization May be Superior to TTE Assessment of RV size and function in repaired TOF, systemic right ventricles, and other conditions associated with RV volume and pressure Identification of anomalous pulmonary venous connectionsS3.4.4-16 Serial assessment of thoracic aortic aneurysms, especially when the dilation might extend beyond the echocardiographic windowsS3.4.4-7 Accurate assessment of PA pressure and pulmonary vascular resistance Assessment for recoarctation of the aorta Sinus venosus defects Vascular rings Evaluation of coronary anomalies Quantification of valvular regurgitation CCT indicates cardiac computed tomography; CMR, cardiovascular magnetic resonance; PA, pulmonary artery; RV, right ventricular; TEE, transesophageal echocardiography; and TOF, tetralogy of Fallot. CLINICAL STATEMENTS AND GUIDELINES Recommendations for Electrocardiogram COR LOE Recommendations I C-EO A standard 12-lead electrocardiogram (ECG) is recommended in adults with CHD with serial assessment depending on the specific ACHD AP classification or when symptoms develop or worsen. I C-EO Ambulatory electrocardiographic monitoring should be performed in patients with CHD who are at risk of tachyarrhythmia, bradyarrhythmia or heart block, or when symptoms possibly of arrhythmic origin develop. Recommendation-Specific Supportive Text 1. The ECG is an essential part of a complete car- diovascular evaluation of a patient with ACHD, similar to elements of the physical examination. Regardless of anatomic diagnosis, it is important to obtain an ECG at baseline for comparison to any subsequently obtained ECG, because an ab- normal baseline ECG is expected in many forms of CHD, particularly those who have undergone surgical repair. A follow-up ECG is recommended in specific lesions and in the setting of new or worsening congestion or low cardiac output syn- drome (Table 7). 2. Asymptomatic arrhythmias seen in patients with ACHD may be associated with development of symptoms and increased risk of death, and are more common in particular lesions or repairs. 