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A 70-year-old male was admitted to the hospital due to palpitations, dyspnea and decreased exercise tolerance during the last 2 months. The past ECGs were interpreted by the GP as sinus tachycardia resistant to medical treatment.

The patient was treated with maximal tolerated doses of bisoprolol 10mg, although tachycardia 110/min persisted, and the patient was referred to a cardiologist.

ECG at admission revealed wide QRS tachycardia with a heart rate of 110 (fig. 1). Typical RBBB QRS morphology and visible non-sinus P waves with long RP’ interval suggested atrial tachycardia (AT). The patient was qualified for EPS and ablation.

In intracardiac electrograms (IEGMs) concentric atrial conduction was shown (fig. 2). Pacing maneuvers – ventricular overdrive pacing (VOP), cycle length (CL) 500ms confirmed AT – VAAV response (fig. 3). The local activation time (LAT) map of the right atrium (RA) suggest a depolarization wave coming from the broad area of interatrial septum (IAS). The area of the earliest activation was in the LA, close (10mm) to the His bundle potential recorded on the distal HBE electrode. A few applications in the IAS were performed. The arrhythmia terminated during application (fig. 4). The EPS study did not induce AT.

Michał Marchel, MD, PhD
Michał Peller, MD, PhD
1st Department of Cardiology
Medical University of Warsaw