So-called primary electrical disease: Is there any correlation between clinical arrhythmia history and endomyocardial biopsy findings?

Primary electrical disease (PED) is an inconsistent diagnostic term indicating complex, usually ventricular, arrhythmias presenting in patients with apparently normal hearts, or better without patient cardiac disease. In 14 patients with an initial diagnosis of PED, a diagnostic protocol was performed, including electrophysiologic study, echocardiogram, coronary angiography, isotopic imaging, NMR and endomyocardial biopsy (EMB). A clinical history of abrupt onset, highly symptomatic severe ventricular arrhythmias was present in 7/14 patients, including ventricular fibrillation and torsade des pointes in 2 and sustained ventricular tachycardia in 5 (Group A); in the other 7 symptoms were long-lasting, less severe or even absent and only nonsustained ventricular tachycardia was detected (Group B). Thorough investigation by cardiac imaging and electrophysiologic tests uncovered underlying abnormalities in 12/14 cases (not including a patient in whom only mitral valve prolapse was found). EMB disclosed inflammatory cells and/or lipomatous infiltration in 6/7 Group A patients and were consistent with the diagnosis of subclinical myocarditis in 3 or early stage ARVD in 3 (an aspecific patten was found in the patient resuscitated from VF). Fibrosis and myocytic degeneration observed in 6/7 Group B patients (only one presenting with lymphocytic infiltrates and widespread fibrosis) supported the clinical suggestion of aspecific cardiomyopathy. Two patients remained for whom no satisfactory diagnosis was possible. The foregoing findings indicate that PED configurates a merely presumptive diagnostic suggestion, always requiring an 'in depth' clinico-pathological control to rule out underlying heart disease. From the present data it is assumed that myocarditis or early-stage ARVD seem to be more frequent in patients with abrupt-onset sustained ventricular arrhythmias, whereas features consistent with chronic cardiomyopathy prevail in those with a longer history of less severe and complex arrhythmias.