Prominent anterior QRS forces: clinical, electrocardiographic and prospective study.

Recent data suggest that the prominent anterior QRS forces (R greater than or equal to S in V1 and/or V2 leads), in the absence of posterior myocardial infarction, right ventricular hypertrophy, or WPW syndrome, are related to an intraventricular conduction disturbance, at times rate-dependent. We followed 240 subjects with prominent anterior QRS forces and without the above mentioned diseases (study group), (mean age: 44.6 +/- 16 years, mean follow-up: 8 +/- 2 years) and 240 subjects without the anterior displacement (control group), (mean age: 44.4 +/- 14 years, mean follow-up: 7.9 +/- 1.9 years). The age distribution, sex, prevalence of organic heart disease, and follow-up period did not show significant differences between the two groups. QRS duration, prevalence of left ventricular hypertrophy pattern, S1 S2 S3 morphology, terminal r wave in AVR and s wave in V6 were similar in the two groups. During the follow-up period the incidence of right and left bundle branch block and fascicular block was very similar in the two groups of patients. These data suggest that prominent anterior QRS forces do not appear to be related to an initial involvement of the main bundle branches and fascicles and do not increase the likelihood of appearance of an intraventricular block of more advanced degree. The clinical, ECG and prospective data are not helpful in localizing either the ventricle or the area of the ventricle affected by conduction disturbance responsible for the anterior displacement. Our data suggest that the prominent anterior QRS forces express a normal variant of ventricular depolarization and that this finding does not have, per se, any unfavourable clinical implication.