Familial atrial tachyarrhythmia with short PR interval.

A family had an unusual and perhaps unique familial dysrhythmia. The proband had a short PR interval with normal QRS and chronic recurrent paroxysmal atrial tachycardia (Lown-Ganong-Levine syndrome). The arrhythmia produced left ventricular dysfunction. Both paroxysmal atrial tachycardia (PAT) and left ventricular dysfunction were reversed with administration of digoxin and propranolol hydrochloride. Three family members had paroxysmal or chronic atrial fibrillation, first diagnosed at a relatively young age (23 years, 38 years, and early 40s, respectively). Five additional family members had short PR intervals with normal QRS, and eight other family members had borderline short PR intervals. The mode of inheritance appeared to be autosomal dominant with varying expressivity. We have described a familial syndrome characterized by PAT or atrial fibrillation in its advanced form with short PR interval as a possible identifying trait. The future course of members with isolated short PR is unknown.