The RSR' complex not related to right bundle branch block: diagnostic value as a sign of myocardial infarction scar.

An abnormal electrocardiographic (ECG) wave pattern--the RSR' complex--associated with a wide QRS (greater than or equal to 110 msec), unrelated to right bundle branch block (RBBB) or left bundle branch block (LBBB) was identified in 26 patients with old myocardial infarction. Patients were assigned to three groups: in group I (n = 13) the RSR' was present in the precordial leads; in group II (n = 9) the RSR' was present in the inferior limb leads; and in group III (n = 4) the RSR' was present in both. For each patient a severe segmental wall motion abnormality (akinetic in 16 and dyskinetic in 10 patients) consistent with myocardial infarction scar tissue was detected using the equilibrium radionuclide angiocardiogram (n = 24) and the two-dimensional echocardiogram (n = 2). The abnormal RSR' complex arises from a terminal conduction delay (dissimilar to either RBBB or LBBB using the vectorcardiogram) of left ventricular (LV) depolarization within impaired tissue surrounding the infarct scar. This study suggests that the RSR' complex, a unique mural conduction defect, although poorly sensitive has specific diagnostic value and reliability as a sign of myocardial infarction scar.