Arrhythmic Burden and Outcomes in Pulmonary Arterial Hypertension

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.

Arrhythmias in Patients with Pulmonary Hypertension and Right Ventricular Failure: Importance of Rhythm Control Strategies

Arrhythmias frequently complicate the course of advanced pulmonary hypertension, often leading to hemodynamic compromise, functional impairment, and mortality. Given the importance of right atrial function in this physiology, the restoration and maintenance of sinus rhythm are of critical importance. In this review, we outline the pathophysiology of arrhythmias and their impact on right heart performance; describe considerations for antiarrhythmic drug selection, anesthetic and periprocedural management; and discuss the results of catheter ablation techniques in this complex and challenging patient population.

TRPV2 inhibitor tranilast prevents atrial fibrillation in rat models of pulmonary hypertension

Atrial fibrillation (AF) is common in pulmonary hypertension (PH), whereas the mechanisms and treatments remain to be explored. TRPV2 regulates the structure and function of the cardiovascular system; however, little attention has been given to its role in AF. This study was to determine whether TRPV2 was involved in PH-induced AF and the effects of TRPV2 inhibitor tranilast on AF in rat models of PH. Monocrotaline (MCT) and SU5416/hypoxia (SuHx)-induced PH models were performed to detect atrial electrophysiological parameters. Daily tranilast (a TRPV2 inhibitor) or saline was given starting 1 day before PH establishment. PH increased the susceptibility to AF, with TRPV2 up-regulated in the right atria. Compared to PH rats, tranilast reduced AF inducibility and the prolongations of ERP and APD; mitigated cardiopulmonary remodeling and the increases in P-wave duration and P-R interval; partially reversed the down-regulation of ion channels such as Cav1.2, Nav1.5, Kv4.3, Kv4.2, Kv1.5, Kir2.1, Kir3.1, Kir3.4 as well as connexin (Cx) 40 and Cx43; improved right atrial (RA) fibrosis, enlargement, and myocardial hypertrophy; decreased the accumulation of inflammatory cells; down-regulated inflammatory indicators such as TNF-α, IL-1β, CXCL1, and CXCL2; and inhibited the activation of the PI3K-AKT-NF-κB signaling pathway. Our results reveal that TRPV2 participates in PH-induced AF, and TRPV2 inhibitor tranilast prevents PH-induced RA remodeling. TRPV2 might be a promising target for PH-induced AF.

Electrical Remodeling in Right Ventricular Failure Due to Pulmonary Hypertension: Unraveling Novel Therapeutic Targets

Arrhythmias in the setting of right-ventricular (RV) remodeling contribute to majority of deaths in patients with pulmonary hypertension. However, the underlying mechanism of electrical remodeling remains elusive, especially ventricular arrhythmias. Here, we analyzed the RV transcriptome of pulmonary arterial hypertension (PAH) patients with compensated RV or decompensated RV and identified 8 and 45 differentially expressed genes known to be involved in regulating the electrophysiological properties of excitation and contraction of cardiac myocytes, respectively. Transcripts encoding voltage-gated Ca2+ and Na+ channels were notably decreased in PAH patients with decompensated RV, along with significant dysregulation of KV and Kir channels. We further showed similarity of the RV channelome signature with two well-known animal models of PAH, monocrotaline (MCT)- and Sugen-hypoxia (SuHx)-treated rats. We identified 15 common transcripts among MCT, SuHx, and PAH patients with decompensated RV failure. In addition, data-driven drug repurposing using the channelome signature of PAH patients with decompensated RV failure predicted drug candidates that may reverse the altered gene expression. Comparative analysis provided further insight into clinical relevance and potential preclinical therapeutic studies targeting mechanisms involved in arrhythmogenesis.

The impact of atrial fibrillation and atrial tachycardias on the hemodynamic status of patients with pulmonary hypertension

The impact of atrial fibrillation and atrial tachycardias (AF/AT), and their optimal treatment strategy in PH patients is still being discussed. The goal of this study was to evaluate the effect of AF/AT termination on the hemodynamic parameters in PH patients. We compared patients with pre-capillary pulmonary hypertension (PH group), left ventricular heart failure (LV-HF group), and a Control group. A repeated right heart catheterization was performed during the catheter ablation (CA) procedure. The first measurement was done in arrhythmia, the second after the sinus rhythm (SR) was restored. High frequency atrial stimulation was used to simulate AT in patients without arrhythmia presence at the time of the CA. The variation of pressure parameters in PH patients did not differ significantly from the Controls. There was a significant increase in the right ventricle pressure after the SR restoration in the LV-HF group compared to the Controls and PH group (+4 vs. -2 vs. -3 mmHg, p < 0.05). The cardiac index (CI) variation was not significant when compared between the study groups. An increase of the CI after the SR restoration was found in those patients with AF (+0.31 l/min/m² [IQR 0.18; 0.58]) in contrast to those patients with organized AT/high frequency atrial stimulation (-0.09 l/min/m², [IQR - 0.45; 0.19]). This difference was statistically significant (p < 0.05). The acute hemodynamic response to arrhythmia termination was not significantly different in the PH patients when compared to the Controls. In contrast to AT/high frequency stimulation, the restoration of SR in AF patients leads to an increased CI, irrespective of the presence or absence of PH.

The impact of atrial fibrillation and atrial tachycardias on the hemodynamic status of patients with pulmonary hypertension

The impact of atrial fibrillation and atrial tachycardias (AF/AT), and their optimal treatment strategy in PH patients is still being discussed. The goal of this study was to evaluate the effect of AF/AT termination on the hemodynamic parameters in PH patients. We compared patients with pre-capillary pulmonary hypertension (PH group), left ventricular heart failure (LV-HF group), and a Control group. A repeated right heart catheterization was performed during the catheter ablation (CA) procedure. The first measurement was done in arrhythmia, the second after the sinus rhythm (SR) was restored. High frequency atrial stimulation was used to simulate AT in patients without arrhythmia presence at the time of the CA. The variation of pressure parameters in PH patients did not differ significantly from the Controls. There was a significant increase in the right ventricle pressure after the SR restoration in the LV-HF group compared to the Controls and PH group (+4 vs. -2 vs. -3 mmHg, p<0.05). The cardiac index (CI) variation was not significant when compared between the study groups. An increase of the CI after the SR restoration was found in those patients with AF (+0.31 l/min/m2 [IQR 0.18; 0.58]) in contrast to those patients with organized AT/high frequency atrial stimulation ( 0.09 l/min/m2, [IQR - 0.45; 0.19]). This difference was statistically significant (p<0.05). The acute hemodynamic response to arrhythmia termination was not significantly different in the PH patients when compared to the Controls. In contrast to AT/high frequency stimulation, the restoration of SR in AF patients leads to an increased CI, irrespective of the presence or absence of PH.

Dapagliflozin reduces the vulnerability of rats with pulmonary arterial hypertension-induced right heart failure to ventricular arrhythmia by restoring calcium handling

Background

Malignant ventricular arrhythmia (VA) is a major contributor to sudden cardiac death (SCD) in patients with pulmonary arterial hypertension (PAH)-induced right heart failure (RHF). Recently, dapagliflozin (DAPA), a sodium/glucose cotransporter-2 inhibitor (SGLT2i), has been found to exhibit cardioprotective effects in patients with left ventricular systolic dysfunction. In this study, we examined the effects of DAPA on VA vulnerability in a rat model of PAH-induced RHF.

Methods

Rats randomly received monocrotaline (MCT, 60 mg/kg) or vehicle via a single intraperitoneal injection. A day later, MCT-injected rats were randomly treated with placebo, low-dose DAPA (1 mg/kg/day), or high-dose (3 mg/kg/day) DAPA orally for 35 days. Echocardiographic analysis, haemodynamic experiments, and histological assessments were subsequently performed to confirm the presence of PAH-induced RHF. Right ventricle (RV) expression of calcium (Ca²⁺) handling proteins were detected via Western blotting. RV expression of connexin 43 (Cx43) was determined via immunohistochemical staining. An optical mapping study was performed to assess the electrophysiological characteristics in isolated hearts. Cellular Ca²⁺ imaging from RV cardiomyocytes (RVCMs) was recorded using Fura-2 AM or Fluo-4 AM.

Results

High-dose DAPA treatment attenuated RV structural remodelling, improved RV function, alleviated Cx43 remodelling, increased the conduction velocity, restored the expression of key Ca²⁺ handling proteins, increased the threshold for Ca²⁺ and action potential duration (APD) alternans, decreased susceptibility to spatially discordant APD alternans and spontaneous Ca²⁺ events, promoted cellular Ca²⁺ handling, and reduced VA vulnerability in PAH-induced RHF rats. Low-dose DAPA treatment also showed antiarrhythmic effects in hearts with PAH-induced RHF, although with a lower level of efficacy.

Conclusion

DAPA administration reduced VA vulnerability in rats with PAH-induced RHF by improving RVCM Ca²⁺ handling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01614-5.

Critical Care Management of Decompensated Right Heart Failure in Pulmonary Arterial Hypertension Patients - An Ongoing Approach

Despite substantial advancements in diagnosis and specific medical therapy in pulmonary arterial hypertension patients’ management, this condition continues to represent a major cause of mortality worldwide. In pulmonary arterial hypertension, the continuous increase of pulmonary vascular resistance and rapid development of right heart failure determine a poor prognosis. Against targeted therapy, patients inexorable deteriorate over time. Pulmonary arterial hypertension patients with acute right heart failure who need intensive care unit admission present a complexity of the disease pathophysiology. Intensive care management challenges are multifaceted. Awareness of algorithms of right-sided heart failure monitoring in intensive care units, targeted pulmonary hypertension therapies, and recognition of precipitating factors, hemodynamic instability and progressive multisystem organ failure requires a multidisciplinary pulmonary hypertension team. This paper summarizes the management strategies of acute right-sided heart failure in pulmonary arterial hypertension adult cases based on recently available data.

Avalanches in cardiology

Sudden cardiac death (SCD) accounts for 15%–60% of mortality in patients with heart disease. Generally, this has been attributed to ventricular tachyarrhythmia. However, ventricular tachyarrhythmia has been documented or strongly suspected on clinical grounds in a relatively small proportion of SCD patients (8%–50%). Attempted prophylaxis of SCD by implantation of cardioverter-defibrillator is associated with variable success in different subsets of high-risk cardiac patients (30%–70%). A significant number of SCD, therefore, appear to be due to catastrophic circulatory failure. Multiple interdependent compensatory mechanisms help to maintain circulation in advanced cardiac disease. Rapid, unexpected, and massive breakdown of the compensated state can be precipitated by small and often imperceptible triggers. The initial critical but stable state followed by rapid circulatory failure and death has been considered to be analogous to snow avalanches. It is typically described in patients with left ventricular (LV) dysfunction (ischemic or nonischemic). It is now recognized that SCD can also happen in conditions where the right ventricle (RV) takes the brunt of the hemodynamic load. Advanced pulmonary arterial hypertension and operated patients of tetralogy of Fallot with pulmonary regurgitation are of particular interest to pediatric cardiologists. A large amount of data is available on LV changes and mechanics, while relatively little information is available on the mechanisms of RV adaptation to increased load and RV failure. Whether the triggers and the decompensatory processes are similar for the two ventricles is a moot point. This article highlights the currently available knowledge on the pathophysiology of SCD in RV overload states, with special reference to RV adaptive and decompensatory mechanisms, and therapeutic measures that can potentially interrupt the vicious downward course (cardiac avalanches).

Radiofrequency Catheter Ablation of Supraventricular Tachycardia in Patients With Pulmonary Hypertension: Feasibility and Long-Term Outcome

Background

Supraventricular tachycardia (SVT) occurs commonly and is strongly correlated with clinical deterioration in patients with pulmonary hypertension (PH). This study aimed to investigate the feasibility and long-term outcome of radiofrequency catheter ablation (RFCA) in PH patients with SVT.

Materials and Methods

Consecutive PH patients with SVT who were scheduled to undergo electrophysiological study and RFCA between September 2010 and July 2019 were included. The acute results and long-term success of RFCA were assessed after the procedure.

Results

In total, 71 PH patients with 76 episodes of SVT were analyzed. Cavotricuspid isthmus-dependent atrial flutter (n = 33, 43.5%) was the most common SVT type, followed by atrioventricular nodal reentrant tachycardia (n = 16, 21.1%). Of the 71 patients, 60 (84.5%) underwent successful electrophysiological study and were subsequently treated by RFCA. Among them, acute sinus rhythm was restored in 54 (90.0%) patients, and procedure-related complications were observed in 4 (6.7%) patients. Univariate logistic regression analysis showed that cavotricuspid isthmus-independent atrial flutter [odds ratio (OR) 25.00, 95% confidence interval (CI) 3.45–180.98, p = 0.001] and wider pulmonary artery diameter (OR 1.19, 95% CI 1.03–1.38; p = 0.016) were associated with RFCA failure. During a median follow-up of 36 (range, 3–108) months, 7 patients with atrial flutter experienced recurrence, yielding a 78.3% 3-year success rate for RFCA treatment.

Conclusion

The findings suggest that RFCA of SVT in PH patients is feasible and has a good long-term success rate. Cavotricuspid isthmus-independent atrial flutter and a wider PAD could increase the risk for ablation failure.

In-Hospital Outcomes of Patients With Pulmonary Hypertension and Cirrhosis: A 6-Year Population Cohort Study of Over One Million Patients

INTRODUCTION

There is a paucity of data on the influence of sex, race, insurance, pulmonary hypertension-related complications, and cirrhosis-related complications on mortality, hospital length of stay (LOS), and total hospital charges. The aim of this study was to identify risk factors in a national population cohort (in the USA) admitted to hospital between 2012 and 2017.

METHODS

All patients aged > 18 years with pulmonary hypertension and cirrhosis, who had been admitted to hospital between 2012 and 2017, were identified from the US Nationwide Inpatient Sample (NIS), a large publicly available all-payer inpatient care database in the USA. Multivariate regression analysis was used to estimate the odds ratios of in-hospital mortality, average length of hospital stay, and hospital charges, after adjusting for age, gender, race, primary insurance payer status, hospital type and size (number of beds), hospital region, hospital teaching status, and other demographic characteristics.

RESULTS

Our study identified 1,111,594 patients who had been discharged from hospital from 2012 to 2017. Of these patients, 355,455 were admitted with pulmonary hypertension, with 9.8% having cirrhosis as a complication (n = 34,986). The analysis revealed that patients with both pulmonary hypertension and cirrhosis compared to patients with only pulmonary hypertension experience increased mortality, hospital LOS, total hospital charges, and pulmonary hypertension-related and cirrhosis-related complications. Independent positive predictors of mortality were Asian/Pacific Islander race and "other" insurance status (worker's compensation; other US health benefits plans [CHAMPUS/TRICARE, CHAMPVA, Title V]). Independent positive predictors of increased hospital LOS were black race and "other" patients (more than one race/mixed). Independent positive predictors of increased total hospital charges were male gender, Hispanic ethnicity, Asian/Pacific Islander race, and other insurance status. Pulmonary hypertension-related complications (cor pulmonale, pulmonary embolism, hemoptysis, cardiac arrest, atrial fibrillation, ventricular tachycardia) and cirrhosis-related complications (ascites, hepatorenal syndrome, hepatic encephalopathy, variceal bleeding, portal hypertension) were independent positive predictors of mortality, hospital LOS, and total hospital charges.

CONCLUSIONS

Patients with pulmonary hypertension and cirrhosis have increased mortality and hospital utilization compared to patients with only pulmonary hypertension. We identified key drivers for these outcomes. Targeted interventions, such as novel medications, right-to-left shunts, more evaluations for lung transplantation, and reversal of pulmonary vacular remodeling, are needed for the subgroups identified in this study in order to improve outcomes.