Arrhythmias in Dilated Cardiomyopathy: Diagnosis and Treatment

Excerpt

In patients with dilated cardiomyopathy (DCM), it is possible to find a broad range of bradyrhythmias and tachyarrhythmias. Bradyrhythmias and supraventricular arrhythmias can frequently occur in some familial forms such as lamin A/C mutations. Nonsustained ventricular arrhythmias (VA) are observed in about 40% of patients with DCM, but their prognostic role is not clear, and conflicting data have been published in the last 30 years. Multiple mechanisms can explain atrial and ventricular tachyarrhythmias in DCM. Reentry is associated with slow conduction across surviving muscle bundles within regions of interstitial fibrosis, but other mechanisms can be involved, as nonuniform anisotropy of impulse propagation, ion channel dysfunction, and reduced gap junction function.

Sudden death (SD) rate has been definitely reduced in the last three decades, but identification of patients at high risk is still a major issue. Despite its limitations, left ventricular (LV) dysfunction is still pivotal for the identification of patients who should be treated with ICD according to current guidelines, while the role of all other invasive and noninvasive parameters is still debated. Cardiac magnetic resonance and possibly genetic analysis, despite not widely available, can be helpful at least in selected cases.

Arrhythmias can be the consequence, but also the cause of DCM, in the presence of a sustained heart rate >100/min, after exclusion of other causes of heart failure and if there is a recovery of LV function after achieving arrhythmia control. Finally, pharmacological and non-pharmacological treatment of arrhythmias (in particular ablation) and the role of ICD are discussed.