- Variable QRS complex rate, average 31/min
- Normal P waves in the first three beats; in the fourth beat the P wave immediately follows the QRS complex
- Normal QRS complexes and T waves
This is the ‘sick sinus syndrome’ or ‘sinoatrial disease’. The record shows sinus rhythm with a junctional escape beat (fourth beat), in which the atrium is activated retrogradely.
The palpitations described by the patient are probably due to a paroxysmal supraventricular tachycardia, so he probably has the ‘bradycardia–tachycardia’ variant of sinoatrial disease.
What to do ?
Ambulatory ECG recording will confirm the cause of the patient’s palpitations. Even though his bradycardia is asymptomatic, he will need a permanent pacemaker because antiarrhythmic agents given for the tachycardia may make his bradycardia worse.
READ MORE: ECG Interpretation – All you need to know