Wegener's granulomatosis is a necrotizing and granulomatous vasculitis of small vessels with preferential involvement of the respiratory tract. Cardiac involvement is less common with polymorphic clinical presentations. This patient had an episode of relatively severe myopericarditis.
Myopericarditis corresponds to a more or less diffuse inflammation of the myocardium and pericardium with evidence of segmental kinetic disorders and/or an increase in troponin (myocarditis) and clinical, electrocardiographic or ultrasound signs of pericarditis. Although MRI is now the reference diagnostic technique, the electrocardiogram is most often abnormal and allows highlighting the association between signs indicative of pericardial inflammation (transient diffuse atrial and ventricular repolarization abnormalities) and myocardial disease (more localized repolarization abnormalities).
- PQ segment depression: an elevation or a depression of the ST-segment is assessed relative to the isoelectric line (end of the T-wave, start of the P-wave) and in relation to the ST-segment especially in diseases such as myopericarditis where an elevation or a depression of the ST-segment is possible. A PQ segment depression results from abnormalities of atrial repolarization and is a relatively specific sign of pericardial disease. It can be early in the course of the disease, represent the first and only electrocardiographic sign and disappear relatively quickly. As with ventricular repolarization disorders, it can be widespread but is very rarely observed in leads aVR and V1 (as in this patient, frequent observation of an elevation in these leads). Its amplitude is generally maximal in leads II, V5 and V6;
- ST-segment elevation: same observation as for the PQ segment, the elevation or depression of the ST-segment is assessed relative to the isoelectric line. ST-segment elevation may occur as a result of inflammation of the pericardial sac but also in conjunction with a direct myocardial disease. The pattern may therefore be more or less typical of pericarditic elevation (limited amplitude < 5 mm, diffuse with possible depression in aVR and V5, concave in its initial portion), or myocarditic elevation (often more localized with a pattern which can be very similar to that of an acute coronary syndrome). In practice, differentiation is often difficult, the electrocardiogram having little value in diagnosing the extension of the lesions (restricted impairment of the pericardium or extending to the myocardial muscle);
- Q-waves: the presence of Q-waves is an indicator of myocardial involvement although relatively rare and tends to disappear with the evolving condition, except for certain severe forms;
- negative T-waves: the presence of diffuse negative T-waves generally occurs later in the course of the disease;
As in the case of pericarditis, it is standard practice to divide the electrocardiographic evolution into 4 phases (ST-segment elevation, isoelectric ST-segment with T-wave flattening, T-wave inversion, normalization), even if the evidencing of this typical sequence is documented in less than half of patients with myopericarditis.