Electrophysiological studies in patients with paroxysmal supraventricular tachycardias but no electrocardiogram documentation: findings from a prospective registry.

Aims: A significant proportion of patients presenting with paroxysmal supraventricular tachycardia (PSVT) has no electrocardiogram (ECG) documentation. In these patients an electrophysiological study (EPS) may be performed to facilitate the diagnosis.

Methods And Results: In a prospective registry we compared the prevalence of inducible arrhythmias and the clinical outcome in 525 patients with and without ECG documentation. Compared with patients with a documented PSVT a smaller but substantial proportion of patients (63.7%) without ECG documentation had inducible supraventricular tachycardias (SVT). Atrio-ventricular nodal reentrant tachycardia was the most common type in both groups. Patients with an inducible SVT and no documentation were significantly younger, had a shorter episode duration and a lower hospitalization rate, which may be the cause for the lacking documentation. Similar to patients with documented PSVTs most of these patients (90.0%) were asymptomatic or clinically improved after the EPS. Even 43% of patients without an inducible tachycardia improved clinically, probably due to a placebo effect of the EPS. In particular, patients between 31 and 60 years of age seemed to benefit from an EPS because they were more likely to have inducible SVTs that could be cured by radiofrequency ablation.

Conclusion: Our data show that a substantial proportion of patients with suspected paroxysmal tachycardia, but without ECG documentation, have inducible SVTs and obtain a clear clinical benefit from an EPS. Thus, our data provide justification for using EPS for patients in this category. To the best of our knowledge, ours is the first prospective registry that supports this approach.