Atrial fibrillation pathophysiology and prognosis: insights from cardiovascular imaging

Unraveling the Complex Relationship-Atrial Fibrillation and Pulmonary Hypertension

PURPOSE OF REVIEW

In this article, we underscore the importance of identifying risk factors and monitoring pulmonary hypertension patients for signs of arrhythmias, as this proactive approach can reduce morbidity and mortality.

RECENT FINDINGS

Atrial fibrillation is the most prevalent among cardiac arrhythmias and is associated with an increased risk of stroke, morbidity, and mortality. Smoking, obesity, hypertension, a sedentary lifestyle, and diabetes mellitus are some of the modifiable risk factors for atrial fibrillation. Recent studies show that the risk of atrial fibrillation is rising in patients with parenchymal and vascular lung disease. Stretching in the atria and pulmonary veins may lead to the onset of atrial fibrillation in cardiac conditions like hypertension, heart failure, and valvular disease. Atrial fibrillation in patients with pulmonary hypertension (PH) denotes a more advanced disease. Patients with PH are more susceptible to hemodynamic stress caused by tachycardia and an uncoordinated atrioventricular contraction. Therefore, atrial arrhythmias need to be treated because inadequate control of cardiac arrhythmias may result in poor clinical outcomes and lead to disease progression in PH patients. Aside from being a sign of severe disease, AF can also speed up and exacerbate the condition.

Fluid management in septic patients with pulmonary hypertension, review of the literature

The management of sepsis in patients with pulmonary hypertension (PH) is challenging due to significant conflicting goals of management and complex hemodynamics. As PH progresses, the ability of right heart to perfuse lungs at a normal central venous pressure (CVP) is impaired. Elevated pulmonary vascular pressure, due to pulmonary vasoconstriction and vascular remodeling, opposes blood flow through lungs thus limiting the ability of right ventricle (RV) to increase cardiac output (CO) and maintain adequate oxygen delivery to tissue. In sepsis without PH, avoidance of volume depletion with intravascular volume replacement, followed by vasopressor therapy if hypoperfusion persists, remains the cornerstone of therapy. Intravenous fluid (IVF) resuscitation based on individualized hemodynamic assessment can help improve the prognosis of critically ill patients. This is accomplished by optimizing CO by maintaining adequate preload, afterload and contractility. Particular challenges in patients with PH include RV failure as a result of pressure and volume overload, gas exchange abnormalities, and managing IVF and diuretic use. Suggested approaches to remedy these difficulties include early recognition of symptoms associated with pressure and volume overload, intravascular volume management strategies and serial lab monitoring to assess electrolytes and renal function.

Role of Endothelin-1 in Right Atrial Arrhythmogenesis in Rabbits with Monocrotaline-Induced Pulmonary Arterial Hypertension

Atrial arrhythmias are considered prominent phenomena in pulmonary arterial hypertension (PAH) resulting from atrial electrical and structural remodeling. Endothelin (ET)-1 levels correlate with PAH severity and are associated with atrial remodeling and arrhythmia. In this study, hemodynamic measurement, western blot analysis, and histopathology were performed in the control and monocrotaline (MCT, 60 mg/kg)-induced PAH rabbits. Conventional microelectrodes were used to simultaneously record the electrical activity in the isolated sinoatrial node (SAN) and right atrium (RA) tissue preparations before and after ET-1 (10 nM) or BQ-485 (an ET-A receptor antagonist, 100 nM) perfusion. MCT-treated rabbits showed an increased relative wall thickness in the pulmonary arterioles, mean cell width, cross-sectional area of RV myocytes, and higher right ventricular systolic pressure, which were deemed to have PAH. Compared to the control, the spontaneous beating rate of SAN–RA preparations was faster in the MCT-induced PAH group, which can be slowed down by ET-1. MCT-induced PAH rabbits had a higher incidence of sinoatrial conduction blocks, and ET-1 can induce atrial premature beats or short runs of intra-atrial reentrant tachycardia. BQ 485 administration can mitigate ET-1-induced RA arrhythmogenesis in MCT-induced PAH. The RA specimens from MCT-induced PAH rabbits had a smaller connexin 43 and larger ROCK1 and phosphorylated Akt than the control, and similar PKG and Akt to the control. In conclusion, ET-1 acts as a trigger factor to interact with the arrhythmogenic substrate to initiate and maintain atrial arrhythmias in PAH. ET-1/ET-A receptor/ROCK signaling may be a target for therapeutic interventions to treat PAH-induced atrial arrhythmias.

Atrial Fibrillation in Patients Undergoing Allogeneic Hematopoietic Cell Transplantation

To examine the incidence and risk factors for de novo atrial fibrillation (AF) after allogeneic hematopoietic cell transplantation (HCT) and to describe the impact of AF on HCT-related outcomes.

How Will Machine Learning Inform the Clinical Care of Atrial Fibrillation?

Machine learning applications in cardiology have rapidly evolved in the past decade. With the availability of machine learning tools coupled with vast data sources, the management of atrial fibrillation (AF), a common chronic disease with significant associated morbidity and socioeconomic impact, is undergoing a knowledge and practice transformation in the increasingly complex healthcare environment. Among other advances, deep-learning machine learning methods, including convolutional neural networks, have enabled the development of AF screening pathways using the ubiquitous 12-lead ECG to detect asymptomatic paroxysmal AF in at-risk populations (such as those with cryptogenic stroke), the refinement of AF and stroke prediction schemes through comprehensive digital phenotyping using structured and unstructured data abstraction from the electronic health record or wearable monitoring technologies, and the optimization of treatment strategies, ranging from stroke prophylaxis to monitoring of antiarrhythmic drug (AAD) therapy. Although the clinical and population-wide impact of these tools continues to be elucidated, such transformative progress does not come without challenges, such as the concerns about adopting black box technologies, assessing input data quality for training such models, and the risk of perpetuating rather than alleviating health disparities. This review critically appraises the advances of machine learning related to the care of AF thus far, their potential future directions, and its potential limitations and challenges.

[Arrhythmias in patients with pulmonary hypertension and chronic lung disease]

Pulmonary arterial hypertension (PAH) occurs in 1% of the global population and can be divided in different disease groups. Pathophysiological aspects leading to supraventricular arrhythmias in these patients are due to increased pulmonary and right atrial pressure, increased activity of the sympathetic nervous system leading to right atrial electrical remodeling and ischemia in the right atrium. In the clinical setting these patients present with atrial flutter, atrial fibrillation or with ectopic atrial tachycardia. Regarding ventricular tachycardia there is a lack of data. Occurrence of arrhythmia in these patients leads to a deterioration of PAH, so rhythm control should be the aim. This can be achieved by right atrial ablation, especially in patients presenting with atrial flutter; electric cardioversion or antiarrhythmic drug therapy are without definite guideline recommendations since there are too few clinical trials. Ablation with a transseptal approach in the left atrium is considered rather dangerous and should be avoided. Regarding arrhythmias in patients with chronic lung disease, few data are available. For patients with chronic obstructive pulmonary disease (COPD), there are good data available. These patients often suffer from coronary heart disease, atrial fibrillation, and ventricular tachycardia. Beta-blockers play an important role in COPD patients, even during exacerbation. Interventional therapies are safe but the arrhythmogenic foci often located outside of the pulmonary veins (in the right atrium).

Atrial Arrhythmias in Pulmonary Hypertension: Pathogenesis, Prognosis and Management

Atrial arrhythmias, including atrial fibrillation and atrial flutter, are common in patients with pulmonary hypertension and are closely associated with clinical decompensation and poor clinical outcomes. The mechanisms of arrhythmogenesis and subsequent clinical decompensation are reviewed. Practical implications and current evidence for the management of atrial arrhythmias in patients with pulmonary hypertension are summarised.