Atrial Dilated Cardiomyopathy: From Molecular Pathogenesis to Clinical Implications.

Atrial dilated cardiomyopathy with progression to atrial standstill is an ultrarare arrhythmogenic disorder characterized by complete loss of atrial electrical and mechanical activity. This condition, which may occur sporadically or in familial clusters, is associated with a markedly increased thromboembolic risk. The electrocardiographic hallmark is the absence of P waves combined with a bradycardic junctional escape rhythm. Biatrial enlargement gradually evolves into giant atria with preserved biventricular systolic function, while supraventricular arrhythmias and progressive atrial inexcitability dominate the clinical course. Valvular regurgitation frequently worsens in parallel with atrial remodelling, and patients often require permanent pacemaker implantation as well as lifelong anticoagulation. Among the few genetic determinants identified, the homozygous c.449G>A (p.Arg150Gln) mutation in the Natriuretic Peptide A gene represents one of the best characterized mechanisms. Disertori et al. first reported this pathogenic variant in 13 affected individuals from Italian families, establishing a recessive inheritance pattern. More recently, Silva et al. and Forleo et al. described additional cases, expanding the phenotypic spectrum of NPPA-related atrial cardiomyopathy. These findings confirm that homozygous carriers develop a severe atrial phenotype, whereas heterozygous relatives typically remain asymptomatic, underlining the importance of genetic testing in young patients with unexplained atrial fibrillation or standstill. Recognition of atrial cardiomyopathy as a distinct clinical entity is crucial, since early diagnosis may guide timely anticoagulation, arrhythmia management, and tailored follow-up. Broader adoption of genetic screening in patients with isolated atrial dysfunction could support precision medicine approaches, improve risk stratification, and ultimately prevent adverse outcomes in this ultrarare but highly morbid condition.