Electrophysiological Testing for the Investigation of Bradycardias

Infra-Hisian Conduction Disturbance and Alternating Left Anterior/Posterior Fascicular Block

We present an unusual case of alternating left anterior and left posterior fascicular block. Given the known risk for progression to complete atrioventricular block with alternating right bundle and left bundle branch block, we performed an electrophysiological study. Findings were consistent with infra-Hisian disease, and the patient underwent pacemaker implantation.

A long-standing conundrum: an unusual case of 2:1 atrioventricular block with conflicting findings

A 2:1 atrioventricular (AV) block can occur anywhere within the conduction system, and noninvasive measurements may not always predict the exact site of the block. Although localization of the block is critical for deciding any treatment, patients should also be carefully questioned about symptoms both at rest and during exertion. A case of 2:1 AV block that was symptomatic only during exertion, appeared infranodal by noninvasive diagnostic methods, but was found to be intranodal on electrophysiological study is reported.

The Tip of the Iceberg-Concealing of Advanced Conduction Abnormality

This case report describes a patient in their 80s who presented with dyspnea and syncope during exercise and a history of essential hypertension and Parkinson disease.

Utility of rapid atrial pacing before and after TAVR with balloon-expandable valve in predicting permanent pacemaker implantation

BACKGROUND

High-grade or complete atrioventricular block (AVB) requiring permanent pacemaker (PPM) implantation is a known complication of transcatheter aortic valve replacement (TAVR). Wenckebach AVB induced by rapid atrial pacing (RAP) after TAVR was previously demonstrated in an observational analysis to be an independent predictor for PPM. We sought to investigate the utility of both pre- and post-TAVR RAP in predicting PPM implantation.

METHODS

In a single-center, prospective study, 421 patients underwent TAVR with balloon-expandable valves (BEV) between April 2020 and August 2021. Intraprocedural RAP was performed in patients without a pre-existing pacemaker, atrial fibrillation/flutter, or intraprocedural complete AVB to assess for RAP-induced Wenckebach AVB. The primary outcome was PPM within 30 days after TAVR.

RESULTS

RAP was performed in 253 patients, of whom 91.3% underwent post-TAVR RAP and 61.2% underwent pre-TAVR RAP. The overall PPM implantation rate at 30 days was 9.9%. Although there was a numerically higher rate of PPM at 30 days in patients with RAP-induced Wenckebach AVB, it did not reach statistical significance (13.3% vs. 8.4%, p = 0.23). In a multivariable analysis, RAP-induced Wenckebach was not an independent predictor for PPM implantation at 30 days after TAVR. PPM rates at 30 days were comparable in patients with or without pre-TAVR pacing-induced Wenckebach AVB (11.8% vs. 8.2%, p = 0.51) and post-TAVR pacing-induced Wenckebach AVB (10.2% vs. 5.8%, p = 0.25).

CONCLUSION

In patients who underwent TAVR with BEV, there were no statistically significant differences in PPM implantation rates at 30 days regardless of the presence or absence of RAP-induced Wenckebach AVB. Due to conflicting results between the present study and the prior observational analysis, future studies with larger sample sizes are warranted to determine the role of RAP during TAVR as a risk-stratification tool for significant AVB requiring PPM after TAVR.

EHRA clinical consensus statement on conduction system pacing implantation: executive summary. Endorsed by the Asia-Pacific Heart Rhythm Society (APHRS), Canadian Heart Rhythm Society (CHRS) and Latin-American Heart Rhythm Society (LAHRS)

Conduction system pacing (CSP) has emerged as a more physiological alternative to right ventricular pacing and is also being used in selected cases for cardiac resynchronization therapy. His bundle pacing was first introduced over two decades ago and its use has risen over the last years with the advent of tools which have facilitated implantation. Left bundle branch area pacing is more recent but its adoption is growing fast due to a wider target area and excellent electrical parameters. Nevertheless, as with any intervention, proper technique is a prerequisite for safe and effective delivery of therapy. This document aims to standardize the procedure and to provide a framework for physicians who wish to start CSP implantation, or who wish to improve their technique. A synopsis is provided in this print edition of EP-Europace. The full document may be consulted online, and a 'Key Messages' App can be downloaded from the EHRA website.

A Normal Electrocardiogram Does Not Exclude Infra-Hisian Conduction Disease in Patients With Myotonic Dystrophy Type 1

OBJECTIVES

This study aimed to identify electrocardiographic (ECG) predictors of a prolonged His-ventricular (HV) interval in patients with type 1 myotonic dystrophy (DM1).

BACKGROUND

Patients with DM1 have an increased risk of sudden cardiac death. The presence of His-Purkinje system disease/prolonged HV interval (≥70 ms) is associated with a higher risk of potentially life-threatening bradyarrhythmic events.

METHODS

Electrophysiology studies (EPSs) were performed in all DM1 patients referred to 2 tertiary centers for routine cardiac assessment. In a subgroup of patients, the EPS was repeated at varying intervals.

RESULTS

A total of 154 patients (mean age: 43.7 ± 13.3; 58.1% male) underwent 202 diagnostic EPSs. HV ≥70 ms was found on 58 EPSs (28.7%); 9 of 59 patients (15.2%) with PR <200 ms and QRS interval <110 ms on baseline ECG had an HV ≥70 ms on EPS. Among those with PR ≥200 ms and/or QRS interval ≥100 ms, only 33.9% had an HV ≥70 ms on EPS. There were 38 patients who underwent repeated EPS, in which 28.8% demonstrated a prolongation of the HV interval overall compared with baseline. QRS duration demonstrated the most powerful discriminative capacity for HV ≥70 ms (area under the receiver operating characteristic curve: 0.76; 95% confidence interval [CI]: 0.68 to 0.84; p < 0.001). On multivariate analysis, QRS interval ≥112 ms had the highest predictive value for HV ≥70 ms (odds ratio: 7.94; 95% CI: 3.85 to 16.37.

CONCLUSIONS

ECG parameters have a poor predictive value for infra-Hisian conduction block in DM1 patients. QRS and PR intervals are normal in up to 15.2% of DM1 patients with prolonged HV, and 66.1% of those with PR ≥200 ms and/or QRS ≥100 ms do not have advanced His-Purkinje conduction system disease on EPS. Electrophysiology testing should be a mandatory part of screening for all patients to guide prophylactic pacemaker implantation.

Conduction Disorders: The Value of Surface ECG

PURPOSE OF REVIEW

The purpose of the current mini-review is to describe the importance of surface ECG for the diagnosis of conduction disorder.

METHODS

The MEDLINE/PubMed database was used, with the keywords "ECG" and "conduction disorders"; over the past 10 years. Other documents were included because of their relevance.

MAIN FINDINGS

Data on the anatomy and function of the cardiac electrical system have been described. Conduction disorders including sinus node dysfunction, atrioventricular blocks, intraventricular conduction disorders are exposed as to their epidemiology, etiology, presentation, anatomical site of impaired conduction of the electrical stimulus. The importance of ECG in patients with a cardiac implantable electronic device was also discussed, in addition to future perspectives.

CONCLUSION

Surface ECG allows the diagnosis of atrioventricular and intraventricular conduction disorder and its anatomical block site most of the time, without the need for invasive tests such as electrophysiological study. Dysfunctions of cardiac implantable electronic devices can be diagnosed by ECG, as well as the prediction of response to cardiac resynchronization therapy.

Use of Electrophysiological Studies in Transcatheter Aortic Valve Implantation

New conduction disturbances requiring permanent pacemaker implantation remain common complications following transcatheter aortic valve implantation (TAVI). It has been suggested that electrophysiological studies could help identify patients who will require permanent pacemaker implantation after TAVI. This article summarises contemporary data on the use of electrophysiological studies in patients undergoing TAVI.