An electrocardiographic criterion for diagnosis of patent foramen ovale associated with ischemic stroke

An M-shaped bifid notch on the ascending branch, or on the zenith, of the R wave in inferior ECG leads (II, III, aVF), so called "crochetage," is an indicator of ostium secundum atrial septal defects. The pathophysiology underlying this finding remains unknown. A crochetage pattern has not been previously reported in patients with patent foramen ovale (PFO); however, the location of this defect and the secundum atrial septum are similar. The purpose of this study was to determine the prevalence of crochetage in cryptogenic stroke patients with or without PFO. A conservative selection scheme was used to identify patients likely to have had PFO-associated strokes (ie, cryptogenic) and to exclude any structural, functional, or vascular heart disease responsible for ECG changes. All patients had a standard 12-lead ECG. The prevalence of crochetage in each group was determined. Sixty consecutive patients were studied (28 with echo-documented PFO and 32 echo-negative control subjects). The crochetage pattern was present in at least 1 inferior limb lead in 10 of 28 PFO patients (36%) and 3 of 32 control subjects (9%) (P