For the Supplementary Data which include background information and detailed discussion of the data that have provided the basis for the Guidelines see https://academic.oup.com/eurheartj/article-lookup/doi/10.1093/eurheartj/ehz467#supplementary-data

This article presents the epidemiology, aetiology and pathophysiology of sudden cardiac death. The modern management of survivors as well as of family members of victims is discussed, as are the relevant recommendations of guidelines prepared by learned societies.

The term Mahaim conduction is conventionally used to describe decrementally conducting connections between the right atrium or the AV node and the right ventricle in or close to the right bundle branch. Although such pathways are rare, their unique properties make their diagnosis and treatment cumbersome. In this article we review the published evidence, and discuss the electrocardiographic and electrophysiological characteristics as well as the anatomy and origin of these fibres.

Background: Immunohistochemistry studies suggest that the anatomic substrate of the slow pathway in atrioventricular nodal reentrant tachycardia (AVNRT) is the left inferior nodal extension. We hypothesized that slow pathway ablation from the left septum is an effective alternative to right-sided ablation. Methods and Results: We analyzed our databases of AVNRT in search of cases that had used slow pathway ablation from the left septum because of failure of right septal ablation, and then prospectively subjected consenting patients to a left septal–only procedure. Of 1342 patients subjected to right septal slow pathway ablation for AVNRT, 15 patients, 11 with typical and 4 with atypical AVNRT, had a left septal approach after unsuccessful right-sided ablation (R+L group). Eleven patients were subjected to a left septal–only approach for slow pathway ablation without a previous right septal attempt (L group). Fluoroscopy times in the R+L and L groups were 30.5 (21.0–44.0) and 20.0 (17.0–25.0) minutes, respectively ( P =0.061), and radiofrequency current delivery times were 11.3 (5.0–19.1) and 10.0 (7.0–12.0) minutes, respectively ( P =0.897). There was no need for additional ablation lesions at other anatomic sites in either group, and no cases of atrioventricular block were encountered. Recurrence rates of the arrhythmia for the R+L and L groups were 6.7% and 0%, respectively, in the 3 months after ablation ( P =1.000). Conclusions: Left septal ablation at the anatomic site of the left inferior nodal extension is an alternative for ablation of both typical and atypical AVNRT when ablation at the right posterior septum is ineffective.

In this article we review the role of electrophysiological testing in patients presenting with bradycardia due to sinus node or atrioventricular node disease. In sinus bradycardia the role of electrophysiology studies is not established. In AV conduction disturbances, an electrophysiology study may be necessary both for the establishment of atrioventricular block as the main cause of symptoms, and for identification of the anatomic site of block that may dictate the potential need of permanent pacing.