Fixed PR interval with occasional dropped beats in 2:1, 3:1 or 4:1 pattern with wide QRS complex is seen in:
Type 1 Second-degree AV block, (Mobitz Type I) Wenckebach periodicity characterized by progressive prolongation of the PR interval followed by a blocked P wave (i.e., a 'dropped' QRS complex). After the dropped QRS complex, the PR interval resets and the cycle repeats. Mobitz II hea block is characterized intermittently nonconducted P waves not preceded by PR prolongation and not followed by PR shoening. Ref: Harrison, Edition 18, Page -1871
Wenckebach
Mobitz type II
WPW syndrome with reentrant tachycardia
Complete hea block with atrial fibrillation