The end of an electrocardiographic dogma: a prominent R wave in V1 is caused by a lateral not posterior myocardial infarction—new evidence based on contrast-enhanced cardiac magnetic resonance—electrocardiogram correlations

Since 1964, a tall and broad R wave in V1–V2, in the absence of right ventricular hypertrophy, complete right bundle-branch block, or Wolff–Parkinson–White syndrome, has been considered the sign of a posterior myocardial infarction (MI).1 According to this theory, the basal segment of the left ventricular (LV) inferior wall (formerly called posterior) bends upwards in the living subject, as a true posterior wall, so that an MI of this wall generates a necrosis vector directed forward. Thus, a prominent R wave in V1–V2 has been considered a mirror image of a Q wave in posterior leads ( Figure 1 ). However, the study by Perloff1 that defines the most frequently used electrocardiogram (ECG) criteria for posterior MI assessed 20 patients, with autopsy verification in only 4 of them. At autopsy, the heart is evaluated outside of the chest, in a position (antero-posterior) completely different from the usual orientation of the heart inside the thorax, an approach usually referred to as St. Valentine's.2 The anatomical relationships between heart and thorax are better evaluated in vivo using cardiac magnetic resonance (CMR). Using this method, the basal segment of the LV inferior wall follows a straight alignment with respect to the other segments of this wall in more than two-thirds of subjects. In a small number of cases, the basal segment of the inferior wall bends upward, and only in rare cases of very lean subjects, the heart is in a more vertical position, with the entire inferior wall being more posterior.3,4 Figure 1 Original drawing of true posterior infarction with the QRS morphology according to Perloff.1 Already …