Acute arrhythmias in adults with congenital heart disease

### Learning objectives Before the advent of central shunts and cardiopulmonary bypass, the natural history studies characterising mortality in those with complex congenital heart disease (CHD) described dismal long-term outcome statistics with few reaching adulthood.1 Subsequent to these innovations—and coupled with outstanding advances in surgical techniques and cardiological care—the practising community has witnessed the emergence of a new population of survivors. Mortality has dropped profoundly; yet with the improved longevity, most of the patients with CHD with moderate/severely complex lesions (table 1) remain at high risk for recurrent haemodynamic issues.2 Yet, the most frequent cause for hospitalisation is arrhythmia, and sudden cardiac death and heart failure remain the primary causes for mortality.3–8 It is more the rule than the exception that the first presentation of these rhythm disturbances is acute as opposed to chronic. It is therefore crucial that the clinician recognise the important differences in managing this group of patients compared with those with acquired heart disease or a normal heart. View this table: Table 1 Common congenital heart disease lesions, their complexity and associated arrhythmias Even the more ‘benign’ atrial arrhythmias, which frequently are well tolerated in the normal heart, can result in marked haemodynamic compromise for the patient with CHD and limited cardiac reserve. Atrial arrhythmias alone are associated with an almost 50% increase in mortality compared with those patients without atrial arrhythmias4 and are by far the most common type of arrhythmia and cause of morbidity.9 Ventricular arrhythmias are up to 100-fold more common in patients with CHD than in age-matched controls, but are lesion specific.10 Those repairs which entail ventricular incisions/patches or significant …