You receive the following transmission:

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What is the correct diagnosis?

The transmission diagnosed as “ventricular run” is indeed an episode of nonsustained ventricular tachycardia (NSVT). As the pacemaker makes the diagnosis based on fast consecutive ventricular events, it is imperative to confirm the diagnosis using the atrial EGM in order to exclude paroxysmal supraventricular tachycardia. In this case, the diagnosis is easily confirmed as there are more ventricular events than atrial events. Another possible diagnosis is the occurrence of lead noise. This is a rare reason for the existence of “ventricular run” (<5% of episodes) but it is the most important as it may be the first sign of ventricular lead failure, with catastrophic consequences. Finally, the manual overreading of these episodes may reveal other more rare etiologies such as algorithm behaviour or undersensing/oversensing.

The clinical significance of NSVT recorded by pacemakers is not well known. Most of the episodes are asymptomatic and many patients implanted with pacemakers record NSVTs during follow-up. On the other hand, we do know that in patients implanted with an ICD, the occurrence of NSVTs have up to five times more risk of developing sustained VT or VF than patients without such episodes. There is probably an association between NSVT heart rate (short cycles), duration and morphology (monomorphic or polymorphic), but there are no well defined cut-offs. In clinical practice, remote monitoring staff may contact the patient in case of fast (for example >200bpm), long (for example >10 seconds) and/or polymorphic NSVT. The existence of conciding symptoms or underlying heart disease (e.g. ischemic heart disease) may help in assessing a risk profile of the patient. Treatment may consist of betablockers with the goal to prevent sustained ventricular arrythmia. Further investigations are sometimes performed for example to search for ischemia or valvular disease. In very rare cases, the registration of a NSVT on a pacemaker may result in an “upgrade” towards an ICD.