Bundle branch blocks and/or hemiblocks complicating acute myocardial ischemia or infarction

Fascicular heart blocks and risk of adverse cardiovascular outcomes: Results from a large primary care population

BACKGROUND

Fascicular heart blocks can progress to complete heart blocks, but this risk has not been evaluated in a large general population.

OBJECTIVE

The purpose of this study was to investigate the association between various types of fascicular blocks diagnosed by electrocardiographic (ECG) readings and the risk of incident higher degree atrioventricular block (AVB), syncope, pacemaker implantation, and death.

METHODS

We studied primary care patients referred for ECG recording between 2001 and 2015. Cox regression models were used to estimate hazard ratios (HRs) as well as absolute risks of cardiovascular outcomes.

RESULTS

Of 358,958 primary care patients (median age 54 years; 55% women), 13,636 (3.8%) had any type of fascicular block. Patients were followed up to 15.9 years. We found increasing HRs of incident syncope, pacemaker implantation, and third-degree AVB with increasing complexity of fascicular block. Compared with no block, isolated left anterior fascicular block (LAFB) was associated with 0%-2% increased 10-year risk of developing third-degree AVB (HR 1.6; 95% confidence interval [CI] 1.25-2.05), whereas right bundle branch block combined with LAFB and first-degree AVB was associated with up to 23% increased 10-year risk (HR 11.0; 95% CI 7.7-15.7), depending on age and sex group. Except for left posterior fascicular block (HR 2.09; 95% CI 1.87-2.32), we did not find any relevant associations between fascicular block and death.

CONCLUSION

We found that higher degrees of fascicular blocks were associated with increasing risk of syncope, pacemaker implantation, and complete heart block, but the association with death was negligible.

Fascicular Blocks: Update 2019

Many advances in the knowledge of medical science are due to the observation of an unknown phenomenon that remains an open question. A plausible hypothesis must be demonstrated and proved through a scientific method in order to be accepted by the scientific community and the same results must be reached by following either the same or different techniques. The original case described by Rosenbaum MB et al., in this review triggered a series of anatomic and physiologic investigations with clinical and experimental observations that supported the trifascicular nature of the intraventricular conduction system of the heart and the concept of hemiblocks. The recognition and description of the left fascicular blocks made by the Argentinian School of Electrocardiology bridged an important gap in electrocardiography and many electrocardiograms that could not be explained until that moment could finally be understood. This review intends to redefine reliable criteria for the electrocardiographic and vectorcardiographic diagnosis of left fascicular blocks [hemiblocks]. The anatomy of the left bundle branch is also discussed to better understand the incidence, prevalence, clinical significance and main causes of left anterior and left posterior hemiblock either isolated or associated with right bundle branch block. This review offers the reader a reappraisal of the trifascicular nature of the intraventricular conduction system regarding the anatomy of the left bundle branch system and its pathophysiological and clinical significance.

[High-risk ECGs in acute chest pain : Signs of acute ischemia beyond STEMI]

BACKGROUND

Obtaining an electrocardiogram (ECG) is the gold standard for initial diagnostics of atraumatic chest pain. To provide optimal patient care, the treating physician has to be proficient in recognizing early signs of myocardial ischemia. Information from the clinical assessment and typical ECG signs have to be recognized promptly in order to diagnose myocardial ischemia early.

METHODS

A selective literature search in international databases (PubMed, Cochrane Library, Google Scholar) was conducted; current, topic-specific websites and literature were also included and evaluated.

RESULTS

Several subtle ECG abnormalities exist besides the typical ST-elevation myocardial infarction (STEMI) and well-known STEMI equivalents and may point to possible myocardial ischemia.

DISCUSSION

To fully evaluate the ECG in patients with atraumatic chest pain, typical signs of ischemia like STEMI as well as subtle ECG signs should be recognized to allow early cardiac intervention.

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.

Impact of Primary Percutaneous Coronary Intervention on Complete Atrioventricular Block With Acute Inferior ST-Elevation Myocardial Infarction

Background and aims

Complete atrioventricular block (CAVB) is associated with poor clinical outcomes in ST-elevation myocardial infarction (STEMI). This study determined the frequency and outcomes of primary percutaneous coronary intervention (PPCI) in patients with CAVB with acute inferior STEMI.

Methods

We conducted an observational, prospective study and enrolled 151 patients who were diagnosed with inferior STEMI. All patients received PPCI. The clinical outcomes were compared in patients with and without CAVB. The data was recorded on a collection form and analyzed on Statistical Package for Social Sciences (SPSS) software. Descriptive statistics were applied. For quantitative variables, standard deviation and mean were obtained, and statistical tests were also applied.

Results

Baseline characteristics were homogeneous in all patients. Half of the study population was either diabetic or hypertensive. Out of 151 participants, 21 (13.9%) developed CAVB. Two-thirds of the patients, who had developed heart block, reverted after PPCI. After a follow-up of two weeks, in-hospital mortality did not differ between the groups.

Conclusion

We conclude that PPCI can improve outcomes of CAVB-complicated acute inferior STEMI and suggest that primary PCI should be the preferred reperfusion therapy in patients with CAVB with STEMI.

Circular RNA circDENND2A protects H9c2 cells from oxygen glucose deprivation-induced apoptosis through sponging microRNA-34a

Background/Aims: Myocardial ischemia (MI) is a serious threat to human health. Circular RNAs (circRNAs) play an important role in many diseases including MI. The effect and mechanism of circDENND2A in MI have not been studied.Methods: We used oxygen glucose deprivation (OGD) treatment to simulate MI in vitro. We detected circDENND2A and microRNA (miR)-34a levels by RT-qPCR. The transfection process used INTERFER and jetPRIME. Cell growth indexes including viability, apoptosis, and migration were detected by CCK8, flow cytometry, and transwell assays, respectively. In addition, the Bax, Cleaved-Caspase-3, matrix metalloproteinase (MMP)-2, MMP-9 and pathway-related protein levels were tested by Western blot.Results: OGD upregulated circDENND2A expression in H9c2 cells. Overexpression of circDENND2A enhanced cell viability and migration but declined apoptosis under OGD. Silenced circDENND 2A played the opposite effects. circDENND2A negatively regulated miR-34a. miR-34a overexpression weakened the protective effects of circDENND2A in OGD-injury. Moreover, we considered circDENND2A and miR-34a may work via β-catenin and Ras/Raf/MEK/ERK pathways.Conclusion: circDENND2A overexpression enhanced OGD-inhibited cell viability and migration but declined OGD-promoted apoptosis by downregulating miR-34a and via β-catenin and Ras/Raf/MEK/ERK pathways.