Left Atrium Research Articles (Page 1)

This study compares right heart contrast transthoracic echocardiography (c-TTE) and contrast transesophageal echocardiography (c-TEE) at different states for detecting and grading the right-to-left shunt (RLS) in patients with cryptogenic stroke (CS). A total of 150 CS patients were enrolled. All patients underwent c-TTE and c-TEE at 3 different states: the Rest, the Valsalva Maneuver, and the state of rest shortly after the Valsalva Maneuver (referred to as "Curtain effect"). Right-to-left shunt due to patent foramen ovale (PFO-RLS) or pulmonary right-to-left shunt was identified by the microbubble characteristics in the left atrium. The detection rates and semiquantitative grades of RLS were compared between c-TTE and c-TEE under different states. c-TTE at Valsalva Maneuver detected more RLS than c-TEE (83.3% vs 65.3%, P < .05). c-TTE at "Curtain effect" revealed more PFO-RLS and higher grades of PFO-RLS than c-TTE at Rest (91.8% vs 72.7%, P < .05). c-TTE showed higher grades of PFO-RLS compared to c-TEE at any state (P < .05). c-TTE at Valsalva Maneuver or "Curtain effect" has superiority in detecting RLS and grading PFO-RLS compared to c-TEE; it can be a practical screening approach for suspected RLS in CS patients.

The left atrium (LA) may be labeled as a "forgotten" chamber in echocardiographic evaluation of pediatric myocarditis. We recently demonstrated that LA stiffness can identify both diastolic dysfunction and myocardial injury in children with COVID-19. We sought to investigate whether LA stiffness is abnormal in children with acute myocarditis and preserved ejection fraction. We retrospectively analyzed 51 pediatric patients with acute myocarditis diagnosed by cardiac MRI based on updated Lake-Louise-Criteria, along with 40 age-matched healthy controls. Only patients with preserved LVEF (> 55%) were included, given their increased risk of adverse outcomes due to diastolic impairment. Follow-up imaging was available for 41 of the 51 patients. LV systolic and diastolic function, and LA strain were evaluated by conventional 2D and speckle-tracking echocardiography. LA stiffness was calculated as the ratio of E/e' to peak LA strain as depicted in following equation: [Formula: see text] (%-1). LA stiffness was significantly increased in myocarditis patients (0.27 ± 0.09 vs. 0.15 ± 0.04%-1, p < 0.001) and remained elevated at early follow-up. LA stiffness showed the best correlation with peak BNP (r = 0.66, p < 0.001). Moreover, LA stiffness had the highest diagnostic performance among all echocardiographic indices, with an AUC of 0.94, and remained an independent diagnostic power in multivariable regression model (OR 1.58 [95% CI: 1.32-1.89], p < 0.001). When it was incorporated into a composite score with LV peak longitudinal strain, the AUC yielded the highest with 98% sensitivity. An optimal LA stiffness cutoff of 0.20%-1 may provide incremental value as a new diagnostic marker for the diagnosis of acute myocarditis with preserved LVEF in children, when this value is exceeded.

In patients with ventricular functional mitral regurgitation (VFMR) undergoing transcatheter edge-to-edge repair (M-TEER), the prognostic significance of the ratio between mitral regurgitant volume and left atrial volume (LAV) remains unclear. This ratio may reflect the proportional or disproportionate burden of regurgitation on the left atrium. To address this gap, we aimed to investigate the association between the regurgitant volume (RVol)/LAV ratio and clinical outcomes in patients with VFMR, using data from a multicentre prospective registry. We calculated the RVol/LAV ratio from baseline transthoracic echocardiograms. The median value of the RVol/LAV ratio was 0.40. A total of 1830 patients who underwent M-TEER were allocated into two groups: the low RVol/LAV (RVol/LAV ratio <0.40) and high RVol/LAV (RVol/LAV ratio ≥0.40) groups. The primary endpoint was heart failure hospitalization.Eight hundred eighty-eight and 942 patients were included into the low RVol/LAV ratio and high RVol/LAV ratio groups, respectively. The median follow-up period was 508 days. At three years after repair, 215 (37.6%) and 187 (32.1%) patients in the low RVol/LAV and high RVol/LAV groups, respectively, were hospitalized for heart failure. The patients in the low RVol/LAV group demonstrated a significantly higher risk of heart failure hospitalization than did those in the high RVol/LAV group (hazards ratio, 1.25; 95%confidence interval, 1.03-1.52; p = 0.022). Furthermore, using multivariable Cox regression analysis, the low RVol/LAV was an independent predictor of the primary endpoint. The RVol/LAV ratio might serve as a valuable metric for improving risk stratification in patients with VFMR.

Intracytoplasmic inclusions in atrial cardiomyocytes of guinea pigs were incidentally identified on routine postmortem evaluation. This study was conducted to assess their location, incidence, morphology, staining properties, ultrastructural appearance, epidemiological characteristics, and pathologic significance. Retrospective cases from 2014 to 2022 with right and/or left atria sampled for histologic examination were selected, and hearts of guinea pigs necropsied in 2023 were systematically formalin-fixed and included. Inclusions were identified in 27 of 28 animals (96%). They were significantly more numerous in the right atrium compared with the left atrium (P < .001, Wilcoxon signed-rank test) and preferentially located as clusters in the subendocardial region. None of these inclusions were detected in the ventricular myocardium. These inclusions were intracytoplasmic, ovoid to linear, frequently fragmented, slightly basophilic to amphophilic in hemalum, eosin, and saffron-stained sections and measured from 1 to 130 µm in length. They stained positively with periodic acid-Schiff, Gomori-Grocott's methenamine silver, and Alcian blue pH 2.5; negatively or unstained with Alcian blue pH 1, toluidine blue, von Kossa, Congo red, and Masson's trichrome; and were amylase resistant. Transmission electronic microscopy revealed slightly electron-dense, non-membrane-bound aggregates of filaments interspersed with granular material compatible with polyglucosan bodies. Animals under 1-year-old had significantly fewer inclusions than older animals (P = .002, Mann-Whitney U test). Inclusion density in the right atrium was not associated with sex, body weight, local heart lesions, or cardiac or systemic disease. Those features are similar to a human condition named basophilic degeneration, reported here for the first time in guinea pigs.

In atrial fibrillation (AF), atrial biomechanics are altered, reducing atrial movement. It remains unclear whether these changes are due to altered anatomy, myocardial stiffness, or constraints from surrounding structures. Understanding the causes of changed atrial deformation in AF could enhance tissue characterization and inform AF diagnosis, stratification, and treatment. We created patient-specific anatomical models of the left atrium (LA) from CT images. Passive LA biomechanics were simulated using finite deformation continuum mechanics equations. LA stiffness was represented by the Guccione material law, where α scaled the anisotropic stiffness parameters. Regional passive stiffness parameters were calibrated to peak regional deformation during the reservoir phase and validated against deformation transients derived from retrospective gated CT images during the reservoir and conduit phase. Physiological LA deformation varies regionally, with the roof deforming significantly less than other regions during the reservoir phase. The fitted model matched peak patient deformations globally and regionally with an average error of [Formula: see text] mm over our cohort. We compared deformation transients through the reservoir and conduit phases and found that the simulated deformation transients were within an average of [Formula: see text] mm per unit time of the CT-derived deformation transients. Regional stiffness varied across the atria with average α values of 1.8, 1.6, 2.2, 1.6 and 2.1 across the cohort in the anterior, posterior, septum, lateral and roof regions respectively. Using mixed effect models, we found no correlation between regional patient LA deformation and regional estimates of wall thickness or regional volumes of epicardial adipose tissue. We found a significant correlation between regionally calibrated stiffness and CT-derived LA biomechanics (p = 0.023). We have shown that regional heterogeneity in stiffness contributes to regional LA biomechanics, while anatomical features appeared less important. These findings provide insight into the underlying causes of altered LA biomechanics in AF.

Introduction: Atrial fibrillation (AF) is the most common arrhythmia in patients with hypertrophic cardiomyopathy (HCM) and associated with significant morbidity and mortality. Early identification of patients high risk of AF is vital for closer monitoring and allowing early treatment to improve outcomes. While a novel risk prediction model (HCM-AF score) identifies HCM patients at risk for new-onset AF, there remains ability to improve sensitivity and specificity for select patients. Left atrium (LA) strain is an emerging noninvasive marker, which reflects LA function and remodeling and may identify individuals at higher risk for AF. Therefore, we aim to investigate if LA reservoir strain by cardiovascular magnetic resonance (CMR) is associated with development of new onset AF in patients with HCM. Methods: In this retrospective, multi-center study, we measured LA strain in HCM patients referred for CMR without prior AF history. LA strain was derived from 2-chamber and 4-chamber view using Medis (Medis Medical Imaging, Leiden, the Netherlands, Version 4.0.62.4). Patients were followed for primary endpoint of new onset AF. Univariable and multivariable cox proportional hazard model were performed. Results: A total of 1020 HCM patients were included (62.7% male, 53.4 ± 16.0 years). During a follow up of 3.3±2.0 years, 124 patients (12.2%) developed new onset AF. Reservoir strain was significantly lower in patients with new onset AF (19.3±8.8 vs 24±9.1, p&lt;0.05). Univariable cox regression showed every 5 unit decrease in reservoir strain is significantly associated with increased risk of AF (HR 1.41 [1.23, 1.59], p&lt;0.001). LA reservoir strain remained significant in multivariable analysis when adjusting for HCM AF score (HR 1.16 [1.01, 1.32], p&lt;0.05), and remained independent after further adjusting for hypertension, left ventricular end-diastolic diameter and late gadolinium enhancement (HR 1.15 [1.01, 1.32], p&lt;0.05) (Table 1). Conclusions: CMR-derived LA reservoir strain is an independent predictor of new onset AF in HCM patients and provides incremental prognostic value beyond tradition risk factors. Incorporating LA strain into risk assessment may guide intensity of arrhythmia surveillance, and aid in early identification and treatment of high-risk patients.

Background: While non-contrast CT scans are routinely used to assess the risk of major adverse cardiac events by quantifying coronary artery calcium (CAC), there is growing interest in leveraging cardiac chamber volumetry derived from these scans to improve the prediction of heart failure (HF). However, it is unknown whether cardiac chamber volumes from varying phases of the cardiac cycle differ in ability to predict HF risk. Research Question: Does the phase of cardiac cycle during CT acquisition affect the predictive value of chamber volumes for heart failure risk? Methods: This is a retrospective cohort of 5,325 asymptomatic patients aged 45-75 years, without known cardiac disease, who underwent CT imaging for CAC scoring between 2010-2023. CT images were analyzed using a previously validated convolutional neural network-based autoencoder model to derive chamber volumes. Patients were divided into groups based on cardiac phase during CT acquisition (diastolic or systolic). Cox proportional hazard regression was used to assess the association between chamber volumes and heart failure. Hazard ratios (HR) were adjusted for clinical risk factors. Results: Patients were imaged during diastole (n=3,172, 58±9 years old, 44% women, 81% White) and during systole (n=2,153, 58±10 years old, 46% women, 84% White). Over a mean follow-up period of 4.7±2.6 years, 7.2% (n=384) developed HF within 10 years. There were 215 HF diagnoses in the diastolic group (6.8%) and 169 in the systolic group (7.8%). The strongest predictors of HF were left atrium (LA) and myocardial volumes. Optimal cutoffs for risk stratification were higher for diastolic chamber volumes (LA: &gt;90.4 mL vs &gt;82.1 mL; myocardium: &gt;136.4 mL vs &gt;102.2 mL). Greater LA and myocardial diastolic chamber volumes were independently associated with higher risk of HF than systolic volumes (LA: HR 1.379 [95% CI, 1.233-1.542] vs HR 1.223 [95% CI, 1.084-1.380], P&lt;0.0001; myocardium: HR 1.513 [95% CI, 1.329-1.764] vs HR 1.426 [95% CI, 1.169-1.740], P&lt;0.0001). Diastolic volumes had significant predictive improvement over systolic volumes (LA: AUC 0.712 [0.669-0.753) vs 0.703 [0.659-0.745]; myocardium: AUC 0.717 [0.674-0.757] vs 0.705 [0.662-0.745]). Conclusion: AI-derived diastolic chamber volumes from CAC CT scans outperformed systolic volumes in prediction of HF risk. These findings highlight the need for consideration of cardiac cycle phase during CT acquisition in the use of chamber volumetry for HF risk stratification.

Case Presentation: A 67-year-old woman with history of remote surgical atrial septal defect (ASD) repair in childhood and severe mitral regurgitation presented for surgical mitral valve (MV) repair. Pre-operative transesophageal echocardiography (TEE) revealed flail P2 scallop of the MV and no evidence of intracardiac shunt. She underwent redo sternotomy with chordal-sparing bioprosthetic MV replacement on cardiopulmonary bypass (CPB) via femoral cannulation. After coming off CPB, she experienced hypoxemia despite supplemental oxygen. Chest X-ray revealed no acute pulmonary pathology. Initial transthoracic echocardiogram (TTE) showed normal biventricular function, well-seated and normal position and function of the mitral bioprosthesis. TEE showed no evidence of transseptal shunting but revealed a communication between the inferior vena cava (IVC) and left atrium (LA) with continuous right to left shunting (Fig 1). CT angiography of the chest demonstrated an inferoposterior interatrial communication associated with an overriding IVC, consistent with an inferior sinus venosus defect (ISVD) (Fig 2a). Review of historical records from her childhood surgery revealed that she was born with an interatrial communication and anomalous right pulmonary venous drainage into the right atrium – likely ISVD – that was repaired with primary suture closure of the defect that also re-routed the pulmonary venous drainage into the LA. Based on this history and CT findings, trauma from the IVC cannula likely caused reopening of the ISVD at the suture site, creating a right-to-left shunt at the precise location of the IVC override into the LA (Fig 2b). Given patient preference to avoid redo sternotomy, she underwent percutaneous transcatheter closure of the defect using a 12 mm Amplatzer vascular plug (AVP II) with immediate resolution of the hypoxemia following implantation (Fig 3). She returned to her functional baseline with preserved exercise tolerance on follow up with no recurrence of hypoxemia. Discussion: This case highlights the importance of extensive record review and the role of cross-sectional imaging in evaluating cardiac anatomy prior to surgical intervention in a patient with a history of congenital heart disease. Moreover, a high index of suspicion is needed to diagnose ISVD, which may not be seen on TTE or routine TEE views.

Background: Left atrial appendage (LAA) membranes and congenital absence of LAA are extremely rare anatomical variants seen on transesophageal echocardiography (TEE). There are very few cases reported of LAA membrane and congenital absence of LAA in the literature. We present two cases with a LAA membrane, with the second case mimicking congenital LAA absence. Description of Case: Case 1: A 57-year-old male with persistent AF and dilated cardiomyopathy underwent TEE prior to pulmonary vein isolation. TEE revealed a fenestrated membrane at the ostium of the LAA, causing partial obstruction evidenced by a well-defined jet into the left atrium. The fenestrated membrane was well demonstrated by advancing intra-cardiac echocardiogram (ICE) probe into the left atrium (Figure 1). Case 2: A 60-year-old female with paroxysmal AF and hypertension, presented with non-ST-elevation myocardial infarction and was found to have triple vessel disease. She was planned for coronary artery bypass grafting (CABG), MAZE procedure, and LAA excision. Intraoperative TEE did not visualize any LAA, suggesting congenital absence of LAA. However, a LAA was seen intra-op, which was empty and collapsed due to the presence of complete membrane at the ostium without any fenestrations (Figure 2). Discussion: These cases illustrate that LAA membranes can rarely be present, which can be partial, fenestrated or complete. Presence of a complete membrane leads to a collapsed LAA, which can not be visualized on TEE mimicking congenital absence of LAA.

Hepatopulmonary syndrome (HPS), a serious yet underrecognized cause of hypoxia in patients with liver disease, can mimic cardiopulmonary pathology. Multimodal cardiac imaging plays a critical role in distinguishing HPS from intracardiac shunts. Median survival is 10.6 months if untreated, making timely diagnosis essential. Case: A 55-year-old Peruvian female with cirrhosis from metabolic dysfunction-associated steatotic liver disease, type 2 diabetes mellitus and hypertension presented with worsening shortness of breath and increasing oxygen requirements from her baseline (3 L/min via nasal cannula). She was hypotensive and hypoxic, requiring high-flow nasal cannula. Physical examination revealed bilateral decreased breath sounds and digital clubbing. Laboratory findings were notable for normocytic anemia, mild thrombocytopenia, elevated transaminases, procalcitonin, and lactate. Chest computed tomography (CT) suggested pulmonary edema and signs of portal hypertension with varices. An outpatient transthoracic echocardiogram (TTE) with bubble study had shown early microbubbles in the left atrium, raising concern for an intracardiac shunt. Transesophageal echocardiography (TEE) was deferred due to esophageal varices. Repeat inpatient contrast TTE revealed a moderately dilated left ventricle but no evidence of ASD or PFO. Cardiac Magnetic resonance imaging (MRI) demonstrated a normal Qp:Qs and no anomalous venous return or intracardiac shunt. Due to persistent hypoxemia, the patient was transferred to a tertiary center. There, repeat contrast TTE showed innumerable microbubbles in the left heart after four cardiac cycles suggestive of an intrapulmonary shunt. Chest CT with contrast showed no structural evidence of an intrapulmonary shunt. Right heart catheterization confirmed a right-to-left shunt with Qp:Qs = 0.6, and microbubbles were visualized crossing from the pulmonary artery into the left atrium on intracardiac echocardiography (ICE), Discussion: This case demonstrates the crucial role of multimodality cardiac imaging—including contrast echo, MRI, RHC, and ICE—in identifying HPS in a cirrhotic patient with unexplained hypoxemia. In cardiology clinics, such patients may be misdiagnosed with intracardiac shunts or heart failure, delaying a life-limiting diagnosis. Early recognition of HPS can significantly impact outcomes by prompting timely transplant referral.

Background: Circumferential calcification of the left atrium, commonly referred to as "porcelain atrium" or "coconut atrium," was first documented in 1898 in patients with rheumatic heart disease. This condition has also been observed in individuals with end-stage renal disease and those who have undergone thoracic radiotherapy. It predominantly affects women, accounting for approximately 74% of reported cases. Methodology: Informed, written consent was obtained from the patient prior to the preparation of this case report. All clinical data and patient history were collected through a one-on-one interview with the patient and a review of the patient’s electronic health records. Clinical Case: A 50-year-old female with a history of rheumatic heart disease, previously treated with closed mitral valvuloplasty and percutaneous transvenous mitral commissurotomy, presented with severe dyspnea and heartburn. She was admitted for a coronary angiogram in preparation for a double valve replacement. The angiogram revealed normal coronary arteries but significant calcification of the left atrium. Transthoracic echocardiography confirmed severe mitral stenosis, mild mitral regurgitation, moderate aortic regurgitation, and a grossly dilated left atrium, with preserved left ventricular systolic function. Following an uneventful recovery, the patient was discharged and scheduled for the planned valve surgeries. Conclusion: This case underscores the rare occurrence of massive left atrial calcification, often termed "porcelain atrium," in patients with long-standing rheumatic heart disease. Despite its rarity, such calcification can complicate surgical interventions, highlighting the need for thorough preoperative imaging and careful surgical planning. Specialized surgical techniques such as total endoatriectomy of the left atrium or calcium core debridement with valve replacement may be considered.

Introduction: Standard echocardiographic measures of mitral regurgitation (MR) severity, such as vena contracta width (VCW) and effective regurgitant orifice area (EROA), are often unreliable after transcatheter mitral interventions due to altered valve anatomy. This case series highlights indirect echocardiographic parameters that collectively aid in assessing successful MR reduction after mitral interventions such as transcatheter edge-to-edge repair (TEER). Case Descriptions: Case 1: An 80-year-old woman with severe degenerative MR had a large, central MR jet occupying most of the left atrium (LA) and an LVOT stroke volume of 31 mL. Post-TEER, the MR jet resolved and LVOT stroke volume rose to 53 mL. Case 2: A 53-year-old man with severe functional MR had a dense, early-peaking with low-Vmax, triangular MR jet on spectral Doppler and a peak/mean iatrogenic atrial septal defect (ASD) gradient of 72/28 mm Hg. Post-TEER, the MR jet became parabolic with low Vmax and less dense, and the ASD gradient dropped to 16/9 mm Hg. Case 3: An 82-year-old woman with degenerative MR showed an E-wave dominant mitral inflow pattern with slow deceleration and pulmonary S wave reversal in the right upper pulmonary vein (RUPV). After TEER, the inflow pattern became A-wave dominant, and S wave reversal resolved. Case 4: A 54-year-old woman with chronic atrial fibrillation and severe MR after surgical valve replacement showed no spontaneous echo contrast (SEC) in the left atrial appendage (LAA). After valve-in-valve (ViV), there is now persistence of SEC. Discussion: Key echocardiographic indicators of resolved severe MR post-intervention include: (1) marked reduction in jet area on color Doppler, (2) increased LVOT stroke volume indicating improved forward flow, (3) transition from a dense, low-Vmax, triangular MR jet contour to a less dense, high Vmax, parabolic MR jet contour on spectral Doppler reflecting improved LA hemodynamics, (4) decreased transseptal pressure gradient across the iatrogenic ASD reflecting improved LA pressure, (5) shift from E-wave to A-wave dominant mitral inflow in the absence of significant mitral stenosis, (6) return of antegrade pulmonary S wave flow reflecting decreased LA pressure, and (7) reappearance of LAA SEC, as the MR jet no longer washes away the SEC seen in chronic atrial fibrillation. While no single measure is definitive, these findings support a multimodal approach to residual MR assessment and highlight the need for further validation.

The left ventricle (LV) is the primary pumping chamber of the heart, generating high systolic pressure to sustain systemic circulation. LV contractile dysfunction is a hallmark of various cardiovascular diseases and is associated with mitochondrial dysfunction, characterised by decreased oxidative phosphorylation (OXPHOS) capacity and increased oxidative stress. While our understanding of cardiac mitochondrial physiology has been gained from studies on LV tissues in animal models or atrial tissues in human studies, findings are often generalised across cardiac regions. Given that fundamental differences in anatomical structure, physiological function and metabolic demands exist between the LV and left atrium (LA), this study aimed to compare mitochondrial bioenergetics between LV and LA tissues from healthy rat hearts. Using high-resolution respirometry coupled with fluorimetry, we assessed mitochondrial respiration, ATP production and hydrolysis, and reactive oxygen species (ROS) production rates. Protein expression of mitochondrial respiratory complexes and antioxidant enzymes was quantified using western blotting. Our results showed that per tissue mass, LV tissues exhibited greater mitochondrial OXPHOS respiration, ATP production and hydrolysis rates, ROS production rate, and higher protein levels of mitochondrial complexes and antioxidant enzymes, consistent with higher citrate synthase activity as a marker of mitochondrial content. However, when normalised to mitochondrial content, LV tissues exhibited lower OXPHOS respiration and ATP production, expression of mitochondrial complexes and antioxidant proteins compared to LA. This study provides new insights into chamber-specific differences in mitochondrial function under physiological conditions, suggesting the importance of considering regional mitochondrial profiles in studies of cardiac mitochondrial function in health and disease.

Background: Epicardial adipose tissue is associated with prevalent and incident atrial fibrillation (AF). The mechanism for this association has been at least partially attributed to fatty atrial infiltration, or lipomatous metaplasia (LM), of the left atrium (LA). Objective: The purpose of this study was to quantitate the extent of LA LM using contrast enhanced computed tomography (CECT) and to examine its association with intracardiac electrogram characteristics using high density electroanatomic mapping in patients referred for AF ablation. Methods: The retrospective cohort included consecutive patients who underwent CECT and LA high-density mapping (Pentaray, Biosense Webster) prior to AF ablation between January 2021- 2023. Univariable associations were examined using nonparametric tests. The association of bipolar voltage amplitude and mid-LA myocardial CECT image intensity (&lt; 0 Hounsfield units indicative of LM, ADAS 3D software), at each electroanatomic map point, was examined using a mixed effects linear regression model clustered by patient. Results: The cohort consisted of 34 patients with mean age 66.4 ± 9.5 years, BMI of 31.7 ± 9.5 kg/m2, left atrial volume index (LAVI) 38.0 ± 8.1 mL, and EF 51 ±13%. Of all patients, 41% were female, 65% had persistent AF, 74% had hypertension, 41% had coronary disease, 12% had diabetes, 33% had sleep apnea, and 15% had prior stroke or TIA. LM was detected among 53% of patients (95% CI 36-69%), and was unassociated with age, BMI, LAVI, AF type, sex, diabetes, sleep apnea, or hypertension. Bipolar voltage was associated with CECT attenuation (-0.2 mV/ Hounsfield unit, P&lt;0.001), but was unassociated with LM. Conclusions: LA LM was prevalent in a small cohort of patients undergoing AF ablation and was unassociated with traditional risk factors and voltage mapping. Additional studies are warranted to refine the understanding of LM as an atrial myopathy.

Background: Atrial tachycardias (AT) after radiofrequency ablation (RFA) of atrial fibrillation (AF) may utilize Bachmann’s bundle (BB). Due to their epicardial location, these ATs remain poorly understood. Objective: To describe the electrophysiologic and anatomic basis of BB-related ATs. Methods: The region of BB was defined as the anterior left atrium (LA) immediately outside the right superior pulmonary vein. A BB-dependent AT was defined as an arrhythmia that originated from [focal] or involved the BB region [reentrant], and if it terminated during RFA. Results: Among 1611 patients with persistent AF undergoing ablation, 32 patients (2%) (age 69±9, male n=22, LA size 47±6 mm, ejection fraction, 55±13%) with BB ATs were included. Twenty-six (90%) had undergone prior ablation for persistent AF (average, 2.0±1.3 procedures). The mechanism of BB ATs was focal (n=7, 22%) or macro-reentry (n=25,78%). RFA eliminated all focal, and ultimately reentrant ATs in 15 of the 32 patients, RFA was required at the right atrial (RA) projections of BB among 8 of the latter patients. The electrogram at the successful site was devoid of local voltage in 4 patients. In 8 patients with redo procedure, recurrent BB-AT was found in 5 (63%). After 2.3±1.4 years follow-up, 22 of the 32 patients (69%) remained free of atrial arrhythmias. Conclusion: The region of BB bundle may be responsible for focal and reentrant tachycardias which were encountered in 2% of patients following RFA of persistent AF. Given its epicardial location, sequential ablation from the LA and RA may be required, even at sites that might be devoid of local voltage. Allowing for multiple procedures, freedom from recurrent arrhythmias was attained in the majority of patients.

Background: Coronary artery calcium (CAC) computed tomography (CT) is widely used for atherosclerotic cardiovascular risk assessment but is not routinely utilized for predicting incident heart failure (HF). Deep learning now enables automated extraction of cardiac morphometrics from CAC CT. We evaluated whether chamber and myocardial volumes derived from CAC CT improve HF risk prediction beyond traditional factors. Methods: We analyzed 23,452 adults who underwent CAC CT without prior HF at Houston Methodist. Cardiac chambers (left atrium, right atrium, left and right ventricles) and myocardium were segmented using a validated pre-trained deep learning model (TotalSegmentator). Time-to-incident HF was modeled using Cox proportional hazards models. Model 1 included age, sex, race/ethnicity, and CAC score. Model 2 added chamber and myocardial volumes modeled flexibly using penalized splines. Discrimination was evaluated with Harrell’s C-index, and model improvement assessed by likelihood ratio test. Results: Over 32,730 person-years of follow-up (median 0.79 years), 330 participants developed HF (incidence rate: 10.1 per 1,000 person-years). Model 2 significantly improved discrimination over Model 1 (C-index: 0.789 vs. 0.706; ΔC = +0.083; p &lt; 2×10 -16 ) . Subgroup C-indices for Model 2 were: Male 0.806, Female 0.793, White 0.804, Black 0.742, and Hispanic 0.734. Compared to the lowest tertile of predicted risk, the highest tertile had a markedly increased risk of HF (HR: 8.25 [95% CI: 5.47–12.44]; p &lt; 0.001), with a cumulative incidence of 21.8 per 1,000 person-years versus 2.7 in the lowest tertile (Figure). Conclusion: Cardiac chamber and myocardial volumes extracted from CAC CT significantly enhance HF risk prediction beyond traditional risk factors. The model performs well across sex and racial/ethnic subgroups and supports the potential for equitable, opportunistic HF risk stratification using existing imaging.

Introduction/Background: Retrograde aortic valve crossing is a fundamental step in transcatheter aortic valve replacement (TAVR). With the expansion of TAVR programs, rare but challenging cases of failure to cross the valve may arise. Alternate access routes, while helpful, may still prove ineffective in select anatomies or re-operative valves. Research Question: What are the alternative strategies when retrograde crossing of the aortic valve fails during TAVR, and can a transseptal approach provide a viable solution in anatomically complex or previously operated patients? Goals/Aims: To describe a case of bioprosthetic valve-in-valve TAVR complicated by inability to cross the aortic valve via both transfemoral and transcarotid retrograde approaches, requiring an unconventional transseptal antegrade solution. Case Presentation: A 73-year-old male with prior type A aortic dissection repair and a 27 mm bioprosthetic aortic valve (Magna) presented with progressive dyspnea. Echo revealed severe valve stenosis (mean gradient 40 mmHg, AVA 0.6 cm, EF 55–60%). After surgical turndown, valve-in-valve TAVR was pursued. Despite multiple attempts by three experienced operators, retrograde valve crossing failed via transfemoral and left carotid routes, even with a stiff wire support. A transseptal puncture was then performed under TEE and fluoroscopic guidance using the VersaCross system. A balloon catheter and wire were passed antegrade from the left atrium through the left ventricle and across the aortic valve into the descending aorta. The wire was snared retrogradely via the carotid sheath, establishing rail access. This enabled retrograde valve crossing and delivery of a 26 mm Sapien Resilia valve. Management/Outcome: The valve was deployed successfully after balloon valvuloplasty under rapid pacing. TEE confirmed optimal position with a mean post-deployment gradient of 4 mmHg and no paravalvular leak. The patient remained stable and experienced no procedural complications. Conclusion: Although rare, failure to cross the aortic valve retrogradely can occur, particularly in patients with prior complex aortic surgery. When standard retrograde and alternate access routes fail, a transseptal antegrade approach may offer a safe and effective bailout strategy. Familiarity with this technique can be critical for heart teams managing complex valve-in-valve scenarios in high-risk patients.

Introduction: Haemophilus influenzae is a rare cause of native valve infective endocarditis. We present a case of double valve endocarditis with initial focal neurologic findings and subsequent progression to cardiogenic shock requiring emergent surgical intervention. Description of Case: A 41-year-old male with a history of hypertension presented with headache, dizziness, and blurred vision, with rapid progression to global aphasia. Initial neurologic imaging revealed a subarachnoid hemorrhage of the left posterior, frontal, and parietal sulci. Transthoracic echocardiogram showed a bicuspid aortic valve with moderate aortic and mitral regurgitation and a 2.5cm mobile mitral valve vegetation. Digital subtraction angiography identified multiple pseudoaneurysms and a 2mm mycotic aneurysm. His intra-procedural course was complicated by acute hypoxic respiratory failure requiring emergent intubation and SCAI-C valvular cardiogenic shock. His course was further complicated by acute respiratory distress syndrome requiring lung-protective ventilation and stress-dose steroids. Transesophageal imaging revealed a new aortic root vegetation with worsening severe aortic regurgitation and mitral regurgitation. He remained febrile despite negative blood cultures and empiric antimicrobial treatment. A Karius Spectrum panel detected ceftriaxone-sensitive Haemophilus influenzae . Despite maximal inotropic support, antibiotics, and ventilator settings, he remained in refractory valvular shock and hypoxic respiratory failure. Emergent surgical intervention with Commando procedure additionally revealed an abscess extending into the aorto-mitral curtain, and the mitral valve, aortic valve and root, left atria, and left ventricular outflow tract was replaced and reconstructed.His post-operative course was complicated by high degree AV block requiring a leadless pacemaker and was discharged nine days later to acute rehabilitation. ` Discussion Haemophilus influenzae is culture-negative microbe that is a rare cause of double valve endocarditis. Karius testing allowed for identification and targeted antimicrobial therapy. However, despite maximal supportive therapy, correction of acute severe valvular cardiogenic shock required urgent surgery. The Commando procedure can be used for treatment of native double valve endocarditis and aorto-mitral curtain reconstruction.This case reinforces the essential role of a multidisciplinary care team in improving outcomes in critically ill patients.

Background: During exercise, the right ventricle (RV) is subjected to proportionally greater increases in wall stress given its larger size, lower resting pressure and thinner walls compared to the left ventricle (LV). There is limited understanding in how the RV remodels to habitual, long term aerobic exercise. Based on previous studies, the LV remodels proportionally to exercise intensity while the left atrium (LA) remodels in proportion to exercise duration. In a prospective study, we evaluated the effects of 2 years of high intensity aerobic exercise training on RV remodeling in sedentary, healthy middle-aged adults. Methods: Sixty-one (48% male) healthy sedentary middle-aged participants (53±5 years) were randomized to either high-intensity aerobic exercise (n=33) or yoga (n=28). RV size was measured using 2D echocardiographic assessment at 0, 10, and 24 months, using the maximal transversal dimension in the basal one third of the RV inflow at end diastole. At 0 and 24 months, central venous pressure (CVP) was obtained under preload manipulation using normal saline (NS) rapid infusion across 3 conditions: baseline, NS15 mg/kg, and NS 30ml/kg. RV compliance was calculated as the slope of RV size/CVP across conditions. Results: Twenty-eight participants (46% male) completed the study in the high intensity aerobic exercise group. In these subjects, RV size increased 9.6% between 0 months and 24 months (Pre: 3.1±0.3 cm, 10 months: 3.4±0.2 cm, Post: 3.4±0.2 cm, p-value 4.40 x 10 -7 ). RV compliance did not change between 0 and 24 months (Pre: 0.046±0.02 cm/mmHg, Post: 0.042±0.03 cm/mmHg, p-value 0.514). Twenty-five participants (44% male) completed the study in the yoga group. Two subjects had unanalyzable images. RV size increased 9.3% between 0 months and 24 months (Pre: 2.9±0.3 cm, 10 months: 3.1±0.3 cm, Post: 3.2±0.3 cm, p-value 1.41 x 10 -7 ). RV compliance did not change between 0 and 24 months (Pre: 0.052±0.03 cm/mmHg, Post: 0.061±0.04 cm/mmHg, p-value 0.329). There were no differences in change in RV compliance between groups (p-value 0.258). Conclusions: In previously healthy sedentary adults, 2 years of high intensity aerobic exercise training increased RV size while having no effect on RV compliance. This data suggests that although RV remodeling occurs, there is no change in material stiffness properties, unlike what occurs in LV remodeling with long duration aerobic exercise.

Introduction: Arterio-venous (AV) gradients across tissue beds provide insights into the metabolic activity by measuring the net uptake or release of lipids and metabolites. In the heart, these gradients can reflect real-time changes in myocardial substrate utilization in disease states like atrial fibrillation (AF). Aims: We aimed to explore the lipidomic and metabolic alterations due to acute rhythm changes in AF patients. Methods: Blood samples were collected from the left atrium (LA), coronary sinus (CS), and the vein of Marshall (VOM) during AF ablation procedures, representing the arterial and venous sides of the whole myocardial and atrial tissue, respectively. Samples were collected in the presenting rhythm (SR or AF), after which patients were either cardioverted or underwent AF induction before any ablation delivery. Sampling was repeated 5 minutes after the onset of the new rhythm (Panel A). Blood samples were analyzed for lipid species and metabolites using the Sciex Lipidyzer system and LC-MS metabolite analysis, respectively. Results: We analyzed 16 arterio-venous blood samples (8 in AF, 8 in SR) to measure 1,561 lipid species across 18 lipid classes and 29 metabolites, including those specific to the heart and atria. Oxygen saturation in the VOM was lower in AF (median 53%, IQR 40–58%) compared to SR (58%, IQR 46–68%; P=0.021), indicating greater oxygen extraction in AF by the atria (Panel B). However, there was no significant difference in oxygen saturation in the CS samples: AF (median 56%, IQR 44–63%) and SR (median 57%, 42– 62%; P=0.1). Differences in AV gradients between AF and SR were assessed in both whole-heart and atrial-specific samples. In whole-heart samples, there was a general balance between lipid import and export. However, atrial-specific samples showed a clear shift toward net lipid import in AF (Panel C). For metabolites, we found a mismatch between atrial and ventricular metabolism in AF. Specifically, glucose, valine, and isoleucine showed net export from the whole heart, but net import at the atrial level (Panel D). Conclusion: Atrial-specific metabolic alterations, characterized by increased lipid and amino acid uptake, altered glucose utilization, and increased oxygen extraction were observed with AF compared to SR. These findings point to an acute metabolic shift, with increased energetic demand in atrial tissue, and potential atrial–ventricular metabolic desynchrony during AF.