Inflammation of the myocardium as a trigger for arrhythmias

In patients with acute or chronic myocarditis, arrhythmias are a common and often the only clinical symptom in the natural course of the disease. The potentially malignant tachy- and bradyanhythmias are of particular signific ance in the differential diagnosis of sudden cardiac death in myocarditis. Factors responsible for the increased incidence of cardiac arrhythmias are structural changes, parameters of ventricular dynamics and vascular changes . On the one hand, inflammatory processes in the cardiac myocytes and inter stitium can lead directly to fluctuations in membrane potential. Fibrosis a nd scarring of the myocardial tissue and secondary hypertrophy and atrophy of the myocytes favor the development of ectopic pacemakers, late potential s and reentry as a result of inhomogeneous stimulus conduction. Furthermore , parameters of ventricular dynamics such as increased wall tension, increa sed myocardial oxygen consumption and diminished coronary reserve in the ca se of disturbed systolic or diastolic left ventricular function also contri bute to the increased incidence of arrhythmias. Lastly, vascular factors ca n further increase the arrhythmogenicity of the inflamed myocardium through the disturbance of micro- and macrovascular perfusion and the resulting my ocardial ischemia. Non-invasive rhythmological evaluation by 24 h Holter EG G, measurement of ventricular late potentials and heart rate variability ca n be used for orienting risk stratification of the at-risk patient with myo carditis. Programmed atrial and ventricular electrophysiological stimulatio n also has a relatively high predictive value for spontaneous ventricular t achyarrhythmias. It should be emphasized that, at the present time, optimal electrophysiological parameters with a high predictive value do not exist. In a selected patient population, immunosuppressive therapy in addition to conventional antiarrhythmic therapy can lead to the reduction or complete suppression of spontaneous and inducible arrhythmias. Nevertheless, in the interim, further precautionary antiarrhythmic measures such as serial antia rrhythmic treatment, VT ablation and AICD implantation are necessary in pat ients with malignant cardiac arrhythmias. Right ventricular myocardial biop sy for demonstration or exclusion of myocarditis is an important additional examination which can improve the differential diagnosis and treatment of patients with cardiac arrhythmias of unclear etiology.