Coronary microvascular dysfunction, arrythmias, and sudden cardiac death: A literature review

The coronary vascular system has a unique structure and function that is adaptive to myocardial demand. It is composed of a continuous network of vessels receding in size from epicardial arteries to the microvascular circulation. Failure to meet myocardial demand results in ischemia, angina, and adverse myocardial outcomes. It is evident that 50 % of patients with angina have a non-obstructive coronary disease and 66 % of these patients have coronary microvascular dysfunction (CMD). The impact of CMD on the atria and ventricles is exhibited through its association with atrial fibrillation and distortion of ventricular repolarization. Ultimately, this influence increases the risk of mortality, morbidity, and sudden cardiac arrest. CMD serves as an independent risk for atrial fibrillation, increases ventricular electrical inhomogeneity, and contributes to the progression of cardiac disease. The underlying pathogenesis may be attributed to oxidative stress evident through reactive oxygen species, impaired vasoactive function, and structural disorders such as fibrotic changes. Myocardial ischemia, brought about by a demand-supply mismatch in CMD, may create a milieu for ventricular arrythmia and sudden cardiac arrest through distortion of ventricular repolarization parameters such as QT dispersion and corrected QT dispersion.

Tailoring Treatment in Cardiovascular Diseases: The Role of Targeted Therapies

Cardiovascular diseases (CVDs) remain the leading cause of morbidity and mortality around the globe. To address this public health burden, innovative therapeutic agents are being developed to specifically target molecular and genetic markers. Various therapeutic modalities have been implemented, including vaccines, monoclonal or bispecific antibodies, and gene-based therapies. Such drugs precisely target the underlying disease pathophysiology, aiming at notable molecules such as lipid metabolism regulators, proinflammatory cytokines, and growth factors. This review focuses on the latest advancements in different targeted therapies. It provides an insightful overview of the current landscape of targeted cardiovascular therapies, highlighting promising strategies with potential to transform the treatment of CVDs into an era of precision medicine.

Post-TAVR conduction abnormalities leading to permanent pacemaker implantation: Risk factors, prevention, and management

Transcatheter aortic valve replacement (TAVR) often leads to conduction abnormalities, necessitating pacemaker implantation. This review of 38 meta-analyses identified preexisting right bundle branch block (RBBB), LAHB, and new-onset left bundle branch block as key risk factors, with a higher PPM risk in male and older patients. Procedural factors like transfemoral access and self-expandable valves also increase this risk. Prevention focuses on tailoring TAVR to individual electrophysiological and anatomical profiles. However, there's a lack of consensus in managing these conduction disturbances post-TAVR, highlighting the need for further research and standardized treatment strategies.

CAGI, the Critical Assessment of Genome Interpretation, establishes progress and prospects for computational genetic variant interpretation methods

BACKGROUND

The Critical Assessment of Genome Interpretation (CAGI) aims to advance the state-of-the-art for computational prediction of genetic variant impact, particularly where relevant to disease. The five complete editions of the CAGI community experiment comprised 50 challenges, in which participants made blind predictions of phenotypes from genetic data, and these were evaluated by independent assessors.

RESULTS

Performance was particularly strong for clinical pathogenic variants, including some difficult-to-diagnose cases, and extends to interpretation of cancer-related variants. Missense variant interpretation methods were able to estimate biochemical effects with increasing accuracy. Assessment of methods for regulatory variants and complex trait disease risk was less definitive and indicates performance potentially suitable for auxiliary use in the clinic.

CONCLUSIONS

Results show that while current methods are imperfect, they have major utility for research and clinical applications. Emerging methods and increasingly large, robust datasets for training and assessment promise further progress ahead.

Establishing Safe Working Parameters for Radiofrequency Ablation In Vitro Using Acoustic Sensing, Probability Mapping, and Catheter Contact Angle

Surgical quality and safety in radiofrequency catheter ablation (RFA) are critical in arrhythmia procedures. Steam pops, in particular, are potentially catastrophic events that must be avoided; otherwise, they may cause significant damage to the myocardium. This study aimed to evaluate the effect of applied RFA inclination angle and tissue contact parameters on the ablated volume and “steam pop” formation. An ex vivo model consisting of a viable ovine myocardium, an ablation catheter, and a circulating warmed 0.9% NaCl saline solution was used. RFA was conducted while controlling for contact force, electrical power, ablation time, flow rate, irrigation, and catheter tip angle. Irrigation was delivered to the catheter tip manually when indicated. Acoustic transducers were included in the setup to detect preliminary acoustic signals. A total dataset of 567 measurements was taken. Benign precursory signals (hissing and lower-intensity “pops”) were detected by acoustic sensors preceding the occurrence of “steam pops.” Furthermore, a Pearson coefficient of r = 0.809 with P < .01 was shown to exist between the acoustic intensity of a “steam pop” and the ablated lesion volume. RFA powers of 25 and 30 W with a duration of 20 s induced more “steam pops” than ablation powers of ≤20 W with a duration of ≥30 s. There was also an increased probability of “steam pop” formation with the use of a non-irrigated catheter tip, as compared to an irrigated catheter tip. A more acute catheter angle increased the lesion size at powers of 20 and 25 W (r = −0.568 and r = −0.653, both P < .05, respectively). There is a potential benefit of using acoustic sensing as a warning before the occurrence of “steam pops.” Varying power, duration, and catheter tip angle will generate different ablation sizes and need to be tailored to individual needs and procedures.

Is there a need for a novel algorithm for accessory pathways localization?

Wolff Parkinson White Syndrome (WPW) affects between 0.1% and 0.2% of the population, causes morbidity due to supraventricular tachycardia (SVT) and can lead to sudden cardiac arrest [1-3]. This article is protected by copyright. All rights reserved.

Teaching critical appraisal to large classes of undergraduate medical students using team-based learning versus group discussions: a randomized controlled trial

BACKGROUND

Evidence on the effectiveness of team-based learning in teaching critical appraisal to large classes of preclinical medical students is scarce. This study investigated whether team-based learning is effective in teaching critical appraisal to large classes of preclinical medical students.

METHODS

Between April 2018 and May 2019, 107 first-year medical students were randomly allocated to receive instruction in critical appraisal using team-based learning or traditional group discussions as teaching methods. The primary outcome was students' performance on the Berlin Questionnaire administered at the end of second year.

RESULTS

Students' mean (SD) age was 22.0 (0.7) years. Baseline characteristics of the two groups were similar (all p values > 0.05). The mean (SD) Berlin scores of both groups were 80.4 (11.6) and 80.1 (12.1) for team-based learning and group discussions, respectively. Multivariate stepwise linear regression analysis revealed that the student's academic achievement in medical school was the sole predictor of performance on the Berlin Questionnaire (ß = 1.079, p < 0.001), adjusting for gender, Medical College Admission Test score, student's self-reported preferred teaching method, rank upon admission to medical school, score on the Epidemiology and Biostatistics course, and teaching method (team-based learning versus group discussions).

CONCLUSIONS

Team-based learning and group discussions were equally effective instructional strategies to teach critical appraisal to large classes of undergraduate medical students. Replication of our findings is needed in other educational settings.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN15430424 , retrospectively registered on December 30, 2021.

Patients' and Family Members' Views on Pacemaker Reuse: an International Survey

INTRODUCTION

The reuse of cardiac implantable electronic devices may help increase access to these therapies in low- and middle-income countries (LMICs). No published data exist regarding the views of patients and family members in LMICs regarding this practice.

METHODS AND RESULTS

A paper questionnaire eliciting attitudes regarding pacemaker reuse was administered to ambulatory adult patients and patients' family members at outpatient clinics at Centro Nacional Cardiologia in Managua, Nicaragua, Indus Hospital in Karachi, Pakistan, Hospital Carlos Andrade Marín and Hospital Eugenio Espejo in Quito, Ecuador, and American University of Beirut Medical Center in Beirut, Lebanon. There were 945 responses (Nicaragua - 100; Pakistan - 493; Ecuador - 252; Lebanon - 100). A majority of respondents agreed or strongly agreed that they would be willing to accept a reused pacemaker if risks were similar to a new device (707, 75%), if there were a higher risk of device failure compared to a new device (584, 70%), or if there were a higher risk of infection compared to a new device (458, 56%). A large majority would be willing to donate their own pacemaker at the time of their death (884, 96%) or the device of a family member (805, 93%). Respondents who were unable to afford a new device were more likely to be willing to accept a reused device (79% vs. 63%, P<0.001).

CONCLUSIONS

Patients and their family members support the concept of pacemaker reuse for patients who cannot afford new devices. This article is protected by copyright. All rights reserved.

Exercise-Induced Ventricular Ectopy and Cardiovascular Mortality in Asymptomatic Individuals

BACKGROUND

The prognosis of exercise-induced premature ventricular contractions (PVCs) in asymptomatic individuals is unclear.

OBJECTIVES

This study sought to investigate whether high-grade PVCs during stress testing predict mortality in asymptomatic individuals.

METHODS

A cohort of 5,486 asymptomatic individuals who took part in the Lipid Research Clinics prospective cohort had baseline interview, physical examination, blood tests, and underwent Bruce protocol treadmill testing. Adjusted Cox survival models evaluated the association of exercise-induced high-grade PVCs (defined as either frequent (>10 per minute), multifocal, R-on-T type, or ≥2 PVCs in a row) with all-cause and cardiovascular mortality.

RESULTS

Mean baseline age was 45.4 ± 10.8 years; 42% were women. During a mean follow-up of 20.2 ± 3.9 years, 840 deaths occurred, including 311 cardiovascular deaths. High-grade PVCs occurred during exercise in 1.8% of individuals, during recovery in 2.4%, and during both in 0.8%. After adjusting for age, sex, diabetes, hypertension, lipids, smoking, body mass index, and family history of premature coronary disease, high-grade PVCs during recovery were associated with cardiovascular mortality (hazard ratio [HR]: 1.82; 95% CI: 1.19-2.79; P = 0.006), which remained significant after further adjusting for exercise duration, heart rate recovery, achieving target heart rate, and ST-segment depression (HR: 1.68; 95% CI: 1.09-2.60; P = 0.020). Results were similar by clinical subgroups. High-grade PVCs occurring during the exercise phase were not associated with increased risk. Recovery PVCs did not improve 20-year cardiovascular mortality risk discrimination beyond clinical variables.

CONCLUSIONS

High-grade PVCs occurring during recovery were associated with long-term risk of cardiovascular mortality in asymptomatic individuals, whereas PVCs occurring only during exercise were not associated with increased risk.

The association of cardiovascular mortality with a first-degree family member history of different cardiovascular diseases

OBJECTIVE

To investigate which history of cardiovascular disease [coronary heart disease (CHD), stroke, or peripheral arterial disease] in a first-degree family member predicts cardiovascular mortality.

METHODS

We studied a prospective cohort (the Lipid Research Clinics Prevalence Study) from ten primary care centers across North America. The primary outcome was cardiovascular mortality, assessed using Cox survival models.

RESULTS

There were 8,646 participants (mean age: 47.4 ± 12.1 years, 46% women, 52% of participants with hyperlipidemia) who were followed up for a mean duration of 19.4 ± 4.9 years. There were 1,851 deaths (21%), including 852 cardiovascular deaths. A paternal, maternal or sibling history of premature CHD (before 60 years) was present in 26% of participants, of stroke in 27% of participants, and of peripheral arterial disease in 24% of participants. After adjusting for risk factors (age, sex, systolic blood pressure, diastolic blood pressure, body mass index, smoking, fasting glucose, low-density lipoprotein cholesterol and triglycerides), only a paternal history of premature or any CHD, a maternal history of diabetes mellitus or premature or any CHD, and a sibling history of premature CHD, hypertension, or hyperlipidemia were individually predictive of cardiovascular mortality. After adjusting for risk factors and the mentioned familial factors, only paternal and maternal histories of CHD, especially before 60 years, remained predictive of cardiovascular mortality, with a somewhat higher association for a maternal history [adjusted hazard ratio (aHR) = 1.99, 95% CI: 1.36-2.92,P < 0.001 for maternal history of premature CHD; aHR = 1.52, 95% CI: 1.10-2.10, P = 0.011 for paternal history of premature CHD]. Family history of stroke or peripheral arterial disease did not predict cardiovascular mortality. Parental history of premature CHD predicted cardiovascular mortality independently of baseline age (< 60 years and ≥ 60 years), hypertension, or hyperlipidemia and carried more important prognostic value in men rather than women.

CONCLUSIONS

In this study, a parental history of CHD, especially before 60 years, best predicted cardiovascular mortality. This finding could help more accurately identify high-risk patients who would benefit from preventive strategies.

Abstract P264: Protective Effects Of Angiotensin II Inhibitors In Lebanese SARS-COV2 Hospitalized Patients

Introduction: SARS-CoV2 leads to increased Angiotensin II resulting in worsened cardiovascular disease (CVD) outcome and prognosis. ACEIs and ARBs prescribed drugs could be a crucial player in SARS-COV2 prognosis, owing that ACE2 is one SARS-CoV2 binding site and that ACE2 expression in the cardiovascular system is markedly elevated following the treatment with ACEIs and ARBs.

Hypothesis: We hypothesized that hospitalized SARS-COV2 Lebanese patients with varying stages of heart failure (A through C) taking ACEIs or ARBs will exhibit an overall better cardiovascular prognosis than control patients with comparable demographics but on other cardiovascular medications.

Method: Lebanese patients (N=66) classified as heart failure A-C and admitted to AUBMC for SARS-CoV2 infection were recruited as a part of an ongoing clinical study. Patients were assigned to the control group (No ACEIs or ARBs) or the study sample group (on ACEIs or ARBs). Baseline characteristics including cardiovascular, inflammatory, respiratory and overall outcomes were collected from the patients’ medical charts and analyzed. Unadjusted associations on recruited patients are presented here. Adjusted analyses will be performed when a total of 200 patients is reached.

Results: The average age of patients was 69±12.42. The total average weight was 84.24±15.59 Kg and significantly higher in ACEIs/ARBs group (p=0.032). Most patients were males (48 of 66) and patients on ACEIs/ARBs medication were 38 of 66. Heart failure stage, systolic and diastolic blood pressures and heart rate were comparable on presentation between patients on ACEIs/ARBs and controls. Unadjusted analysis showed a significantly higher percentage of death (p=0.024), mechanical ventilation (p=0.05), and elevated troponin (p=0.03) in the control group. A trend towards higher percentage of elevated NT-ProBNP and high levels of peak IL-6 were observed in the control group (p = 0.088 and p=0.076 respectively). All patients had elevated CRP on admission. SARS-CoV2 treatments were comparable between the two groups.

Conclusion: Higher mortality and worsened prognosis were observed in the control groups when compared to the ACEIs/ARBs group. Ongoing recruitment is currently underway to perform adjusted analyses.

'Real-world' observational studies in arrhythmia research: data sources, methodology, and interpretation. A position document from European Heart Rhythm Association (EHRA), endorsed by Heart Rhythm Society (HRS), Asia-Pacific HRS (APHRS), and Latin America HRS (LAHRS)

The field of observational studies or "real world studies" is in rapid development with many new techniques introduced and increased understanding of traditional methods. For this reason the current paper provides an overview of current methods with focus on new techniques. Some highlights can be emphasized: We provide an overview of sources of data for observational studies. There is an overview of sources of bias and confounding. Next There is an overview of causal inference techniques that are increasingly used. The most commonly used techniques for statistical modelling are reviewed with focus on the important distinction of risk versus prediction. The final section provides examples of common problems with reporting observational data.

Prognostic role of albumin level in heart failure: A systematic review and meta-analysis

BACKGROUND

Hypoalbuminemia (HA) is common in HF, however, its pathophysiology and clinical implications are poorly understood. While multiple studies have been published in the past decade investigating the role of serum albumin in HF, there is still no consensus on the prognostic value of this widely available measure. The objective of this study is to assess the prognostic role of albumin in heart failure (HF) patient.

METHODS

Unrestricted searches of MEDLINE, EMBASE, Cochrane databases were performed. The results were screened for relevance and eligibility criteria. Relevant data were extracted and analyzed using Comprehensive Meta-Analysis software. The Begg and Mazumdar rank correlation test was utilized to evaluate for publication bias.

RESULTS

A total of 48 studies examining 44,048 patients with HF were analyzed. HA was found in 32% (95% confidence interval [CI] 28.4%-37.4%) HF patients with marked heterogeneity (I2 = 98%). In 10 studies evaluating acute HF, in-hospital mortality was almost 4 times more likely in HA with an odds ratios (OR) of 3.77 (95% CI 1.96-7.23). HA was also associated with a significant increase in long-term mortality (OR: 1.5; 95% CI: 1.36-1.64) especially at 1-year post-discharge (OR: 2.44; 95% CI: 2.05-2.91; I2 = 11%). Pooled area under the curve (AUC 0.73; 95% CI 0.67-0.78) was comparable to serum brain natriuretic peptide (BNP) in predicting mortality in HF patients.

CONCLUSION

Our results suggest that HA is associated with significantly higher in-hospital mortality as well as long-term mortality with a predictive accuracy comparable to that reported for serum BNP. These findings suggest that serum albumin may be useful in determining high-risk patients.

Nicotinamide adenine dinucleotide: Biosynthesis, consumption and therapeutic role in cardiac diseases

Nicotinamide adenine dinucleotide (NAD) is an abundant cofactor that plays crucial roles in several cellular processes. NAD can be synthesized de novo starting with tryptophan, or from salvage pathways starting with NAD precursors like nicotinic acid (NA), nicotinamide (NAM) or nicotinamide riboside (NR), referred to as niacin/B₃ vitamins, arising from dietary supply or from cellular NAD catabolism. Given the interconversion between its oxidized (NAD⁺ ) and reduced form (NADH), NAD participates in a wide range of reactions: regulation of cellular redox status, energy metabolism and mitochondrial biogenesis. Plus, NAD acts as a signalling molecule, being a cosubstrate for several enzymes such as sirtuins, poly-ADP-ribose-polymerases (PARPs) and some ectoenzymes like CD38, regulating critical biological processes like gene expression, DNA repair, calcium signalling and circadian rhythms. Given the large number of mitochondria present in cardiac tissue, the heart has the highest NAD levels and is one of the most metabolically demanding organs. In several models of heart failure, myocardial NAD levels are depressed and this depression is caused by mitochondrial dysfunction, metabolic remodelling and inflammation. Emerging evidence suggests that regulating NAD homeostasis by NAD precursor supplementation has therapeutic efficiency in improving myocardial bioenergetics and function. This review provides an overview of the latest understanding of the different NAD biosynthesis pathways, as well as its role as a signalling molecule particularly in cardiac tissue. We highlight the significance of preserving NAD equilibrium in various models of heart diseases and shed light on the potential pharmacological interventions aiming to use NAD boosters as therapeutic agents.

Genomic and Proteomic Study of the Inflammatory Pathway in Patients With Atrial Fibrillation and Cardiometabolic Syndrome

Atrial fibrillation (AF) and cardiometabolic syndrome (CMS) have been linked to inflammation and fibrosis. However, it is still unknown which inflammatory cytokines contribute to the pathogenesis of AF. Furthermore, cardiometabolic syndrome (CMS) risk factors such as obesity, hypertension, insulin resistance/glucose intolerance are also associated with inflammation and increased level of cytokines and adipokines. We hypothesized that the inflammatory immune response is exacerbated in patients with both AF and CMS compared to either AF or CMS alone. We investigated inflammatory cytokines and fibrotic markers as well as cytokine genetic profiles in patients with lone AF and CMS. CMS, lone AF patients, patients with both lone AF and CMS, and control patients were recruited. Genetic polymorphisms in inflammatory and fibrotic markers were assessed. Serum levels of connective tissue growth factor (CTGF) were tested along with other inflammatory markers including platelet-to-lymphocyte ratio (PLR), monocyte-to-HDL ratio (MHR) in three groups of AF+CMS, AF, and CMS patients. There was a trend in the CTGF levels for statistical significance between the AF and AF+CMS group (P = 0.084). Genotyping showed high percentages of patients in all groups with high secretor genotypes of Interleukin-6 (IL-6) (P = 0.037). Genotyping of IFN-γ and IL-10 at high level showed an increase in expression in the AF + CMS group compared to AF and CMS alone suggesting an imbalance between the inflammatory and anti-inflammatory cytokines which is exacerbated by AF. Serum cytokine inflammatory cytokine levels showed that IL-4, IL-5, IL-10, IL-17F, and IL-22 were significant between the AF, AF+CMS, and CMS patients. Combination of both CMS and AF may be associated with a higher degree of inflammation than what is seen in either CMS or AF alone. Thus, the identification of a biomarker capable of identifying metabolic syndrome associated with disease will help in identification of a therapeutic target in treating this devastating disease.

Radiofrequency Catheter Ablation: How to Manage and Prevent Collateral Damage?

Radiofrequency catheter ablation has become the standard of care for the management of various arrhythmias and, in fact, the first-line therapy for many tachyarrhythmias. It entails creating scar tissue in the heart in regions where abnormal impulses form or propagate to restore normal cardiac conduction. As the heart is a complex organ and is surrounded by and related to many other anatomical structures, it is important to avoid the collateral damage that can happen from radiofrequency (RF) ablation on the endocardium as well as on the epicardium. This review explores methods for mitigating or limiting collateral damage during catheter ablation.