Cardiomyopathy induced by artificial cardiac pacing: myth or reality sustained by evidence?

Magnetic Resonance Detects Structural Heart Disease in Patients with Frequent Ventricular Ectopy and Normal Echocardiographic Findings

The prognosis of patients with ventricular ectopy and a normal heart, as evaluated by echocardiography, is virtually unknown. Cardiac magnetic resonance (CMR) can detect focal ventricular anomalies that could act as a possible site of origin for premature ventricular contractions (PVCs). The aim of this study was to investigate the presence of cardiac anomalies in patients with normal findings at echocardiogram.

METHODS

Fifty-one consecutive patients (23 women, 28 men, mean age 59 years) with very high PVC burden (>10,000 PVC/day) and normal findings at standard echocardiography and exercise test were examined with CMR. The outcome was pathologic findings, defined as impaired ejection fraction, regional wall motion abnormalities, abnormal ventricular volume, myocardial edema and fibrosis.

RESULTS

Sixteen out of 51 patients (32%) had structural ventricular abnormalities at CMR. In five patients CMR showed impairment of the left ventricular and/or right ventricular systolic function, and six patients had a dilated left and/or right ventricle. Regional wall motion abnormalities were seen in six patients and fibrosis in four. No patient had CMR signs of edema or met CMR criteria for arrhythmogenic right ventricular cardiomyopathy. Five patients had extra-ventricular findings (enlarged atria in three cases, enlarged thoracic aorta in one case and pericardial effusion in one case).

CONCLUSIONS

In this study 16 out of 51 patients with a high PVC burden and normal findings at echocardiography showed signs of pathology in the ventricles with CMR. These findings indicate that CMR should be considered in evaluating patients with a high PVC burden and a normal standard investigation.

Recent approaches to His-Purkinje system pacing

OBJECTIVE

Physiologic cardiac pacing is a novel technique which has been largely popularized in recent decades. His bundle pacing (HBP) has been long considered the most physiologic pacing method; however, with the widespread implementation of this method, its disadvantages have become apparent. In this context, left bundle branch pacing (LBBP)-directly engaged in the His-Purkinje system-has been foreseen as the best pacing method to mimic physiologic activation patterns. This review aimed to summarize recent approaches to physiologic cardiac pacing.

DATA SOURCES

This review included fully peer reviewed publications up to July 2018, found in the PubMed database using the keywords "His bundle branch pacing," "right ventricular pacing," and "physiologic pacing."

STUDY SELECTION

All selected articles were in English, with no restriction on study design.

RESULTS

The HBP has been studied worldwide, and is currently considered the most physiologic pacing method. However, it has disadvantages, such as high pacing threshold, unsatisfactory sensing and long procedure times, among others. Although LBBP is theoretically superior to HBP, the clinical relevance of this difference remains under debate, as few large randomized clinical trials with LBBP have been published.

CONCLUSIONS

Although HBP indeed appears to be the most physiologic pacing method, it has certain shortcomings, such as high pacing threshold, difficult implantation due to specific anatomic features, and others. Further studies are required to clarify the clinical significance of LBBP.

Analysis of Dyssynchrony and Ventricular Function in Right Univentricular Stimulation at Different Positions

INTRODUCTION

Chronic stimulation of the right ventricle with pacemaker is associated with ventricular dyssynchrony and loss of contractility, even in subjects without previous dysfunction. In these patients, there is a debate of which pacing site is less associated with loss of ventricular function.

OBJECTIVE

To compare pacemaker-induced dyssynchrony among different pacing sites in right ventricular stimulation.

METHODS

Cross-sectional study of outpatients with right ventricle stimulation higher than 80% and preserved left ventricular ejection fraction. Pacing lead position (apical, medial septum or free wall) was assessed through chest X-rays. Every patient underwent echocardiogram to evaluate for dyssynchrony according to CARE-HF criteria: aortic pre-ejection time, interventricular delay and septum/posterior wall delay on M mode.

RESULTS

Forty patients were included. Fifty-two percent had apical electrode position, 42% mid septum and 6% free wall. Mean QRS time 148.97±15.52 milliseconds. A weak correlation between the mean QRS width and pre-aortic ejection time (r=0.32; P=0.04) was found. No difference in QRS width among the positions could be noted. Intraventricular delay was lower in apical patients against mid septal (34.4±17.2 vs. 54.3±19.1 P<0.05) - no difference with those electrode on the free wall. No difference was noted in the pre-aortic ejection time (P=0.9).

CONCLUSION

Apical pacing showed a lower interventricular conduction delay when compared to medial septum site. Our findings suggest that apical pacing dyssynchrony is not ubiquitous, as previously thought, and that it should remain an option for lead placement.

Permanent Pacing After Transcatheter Aortic Valve Implantation: Incidence, Predictors and Evolution of Left Ventricular Function

Background

Transcatheter aortic valve implantation (TAVI) is a well-established procedure; however, atrioventricular block requiring permanent pacemaker implantation (PPI) is a common complication.

Objectives

To determine the incidence, predictors and clinical outcomes of PPI after TAVI, focusing on how PPI affects left ventricular ejection fraction (LVEF) after TAVI.

Methods

The Brazilian Multicenter TAVI Registry included 819 patients submitted to TAVI due to severe aortic stenosis from 22 centers from January/2008 to January/2015. After exclusions, the predictors of PPI were assessed in 670 patients by use of multivariate regression. Analysis of the ROC curve was used to measure the ability of the predictors; p < 0.05 was the significance level adopted.

Results

Within 30 days from TAVI, 135 patients (20.1%) required PPI. Those patients were older (82.5 vs. 81.1 years; p = 0.047) and mainly of the male sex (59.3% vs 45%; p = 0.003). Hospital length of stay was longer in patients submitted to PPI (mean = 15.7 ± 25.7 vs. 11.8 ± 22.9 days; p < 0.001), but PPI affected neither all-cause death (26.7% vs. 25.6%; p = 0.80) nor cardiovascular death (14.1% vs. 14.8%; p = 0.84). By use of multivariate analysis, the previous presence of right bundle-branch block (RBBB) (OR, 6.19; 3.56-10.75; p ≤ 0.001), the use of CoreValve^® prosthesis (OR, 3.16; 1.74-5.72; p ≤ 0.001) and baseline transaortic gradient > 50 mm Hg (OR, 1.86; 1.08-3.2; p = 0.025) were predictors of PPI. The estimated risk of PPI ranged from 4%, when none of those predictors was present, to 63%, in the presence of all of them. The model showed good ability to predict the need for PPI: 0.69 (95%CI: 0.64 - 0.74) in the ROC curve. The substudy of 287 echocardiograms during the 1-year follow-up showed worse LVEF course in patients submitted to PPI (p = 0.01).

Conclusion

BRD prévio, gradiente aórtico médio > 50 mmHg e CoreValve® são preditores independentes de implante de MPD pós-TAVI. Ocorreu implante de MPD em aproximadamente 20% dos casos de TAVI, o que prolongou a internação hospitalar, mas não afetou a mortalidade. O implante de MPD afetou negativamente a FEVE pós-TAVI.