Citations

Introduction: Exposure to high altitude results in hypobaric hypoxia, leading to physiological changes in the cardiovascular system that may result in dyspnea. Hypoxic simulation testing (HSTs) simulates changes in physiology that occur at a specific altitude. Hypothesis: The use of transthoracic echocardiography (TTE) during HST can detect the raise in right-sided pressures revealing underlying causes of high-altitude dyspnea. Methods: We performed a prospective observational study of consecutive patients with unexplained dyspnea at high altitude who were referred to an aerospace medicine program at a single institution between August 2021 and March 2023. Reduced FiO 2 was administered for 20 minutes to simulate altitude levels specific to patients’ history. TTE images were obtained at baseline and during peak hypoxia to evaluate right ventricular (RV) function, RV systolic pressure, and any possible shunts. Result: The study included 27 patients, with a mean age of 64.7 ±14.4 years and 14 (51.9%) females. No significant abnormalities were seen on baseline TTE and no significant differences in blood pressure and heart rate between baseline and hypoxia simulation were detected. Notably, RV systolic pressure increased at peak hypoxia, while RV systolic function declined as shown by a decrease in S’ wave and TAPSE ( Figure 1 ). Additionally, right to left shunts were present in 19 (70.4%) patients. Of these, four patients (21.1%) had shunts present at baseline with no changes at peak hypoxia, while the severity of shunts increased at peak hypoxia in eight cases (42.1%) and the shunts were only evident during hypoxia in seven patients (36.8%). Conclusion: TTE during HST provides valuable information by revealing the presence of symptomatic, sustained shunts and confirming the decline in RV hemodynamics explaining dyspnea at altitude. Further studies are necessary to establish the optimal clinical role of this physiologic method.

Introduction: An elevated shock index (SI) predicts worse outcomes in multiple clinical arenas. We aimed to determine whether the SI can aid in mortality risk stratification in unselected CICU patients. Methods: We included admissions to the Mayo Clinic from 2007 to 2015 and stratified them based on admission SI, defined as heart rate divided by systolic blood pressure. The primary outcome was in-hospital mortality, and predictors of in-hospital mortality were analyzed using multivariable logistic regression. Results: We included 9,939 unique CICU patients with available data for SI. The mean age was 69 years old (37% female). Median HR, SBP, and shock index for our cohort were 79 beats per minute (BPM), 121 mmHg, and 0.65 BPM/mmHg, respectively. Patients were grouped by SI as follows: < 0.6, 3,973 (40%); 0.6-0.99, 4,810 (48%); and ≥ 1.0, 1,156 (12%). After multivariable adjustment, both HR (adjusted OR 1.06 per 10 BPM higher; CI 1.02-1.10; p-value 0.005) and SBP (adjusted OR 0.94 per 10 mmHg higher; CI 0.90-0.97; p-value < 0.001) remained associated with higher in-hospital mortality. As SI increased there was an incremental increase in in-hospital mortality (adjusted OR 1.07 per 0.1 BPM/mmHg higher, CI 1.04-1.10, p-Value < 0.001). A higher SI was associated with increased mortality across all examined admission diagnoses, including acute coronary syndromes, heart failure, and cardiogenic shock. Conclusions: The SI is a simple and universally available bedside marker that can be used at the time of admission to predict in-hospital mortality in CICU patients across a variety of cardiac conditions.

Background: Catheter ablation for ventricular tachycardia (VT) has been increasingly performed over the past decades. However, the real-world data on the safety profile of this procedure among elderly patients is limited. Objective: This study aimed to evaluate the procedural outcomes and 30-day readmission among those aged 18-64 years versus those aged ≥65 years who underwent catheter ablation of VT. Method: Using the all-payer, nationally representative Nationwide Readmissions Database, our study included patients aged 18 years or older who underwent VT catheter ablation between 2017 and 2020. We divided the patients into non-elderly (18-64 years old) and elderly age groups (≥65 years old). We then analyzed the in-hospital procedural outcome and 30-day readmission between these groups. Results: Our study included 2075 (49.1%) non-elderly patients and 2153 (50.9%) elderly patients who underwent VT ablation. Following the procedure, elderly patients had significantly higher rates of prolonged index hospitalization (≥7 days) (35.5% vs 29.3%, p<0.01), non-home discharge (13.4% vs 6.0%, p<0.01), 30-day readmission (17.0% vs 11.4%, p<0.01), and early mortality (5.5% v 2.4%, p<0.01). The median cumulative cost of hospitalization was significantly higher in the elder groups ($40,230 vs. $37,612, p ≤0.01). There was no significant difference in the procedural complications between the two groups. Through multivariable analysis, the elderly group was associated with significantly higher odds of early mortality (OR: 7.50; CI 1.86 - 30.31, p=0.01), non-home discharge (OR: 2.41; CI: 1.93 - 3.00, p<0.01) and 30-day readmissions (OR: 1.58; CI 1.32 - 1.89, p<0.01). Conclusion: Our study suggests that elderly patients have poorer in-hospital outcome in early mortality, non-home discharge and 30-day readmissions following catheter ablation for VT. There was no significant difference between elderly and non-elderly groups in the procedural complications.

Introduction: The relationship between aortic stenosis (AS) severity, AS-related symptoms, and clinical outcomes is poorly understood. Research Question: Does a history of AS-related symptoms at the time of diagnosis affect clinical outcomes including death and AS-related hospitalization? Methods: Using a combination of natural language processing algorithms and administrative codes, we ascertained physician-assessed AS, AS severity, and AS-related symptoms (chest pain, acute coronary syndrome, syncope, presyncope, orthopnea, dyspnea, PND, and worsening heart failure) in the year prior or up to 60 days after an initial AS diagnosis among 602,821 adults with echocardiograms in a large, integrated health system from 2010-2019. We examined multivariable associations between AS severity and recent AS-related symptoms for the outcomes of death and AS-related hospitalizations using Cox models. Results: Among 40,333 patients identified with incident AS, the majority had recent AS-related symptoms (mild: 80%, mild-moderate: 77%, moderate: 77%, moderate-severe: 85%, and severe AS: 87%). Patients with recent symptoms were older (mean [SD] age 78 [10] vs 75 [11] years; p<0.01), more likely female (51% vs 47%; p<0.01), and had a higher comorbidity burden. In unadjusted analyses, symptom status was a strong discriminator of risk over a median (IQR) of 2.2 (0.8-4.3) years of follow-up ( Figure ). After multivariable adjustment, AS-related symptoms remained strongly associated with death and AS-related hospitalization across the spectrum of AS severity, with moderate symptomatic patients having risk similar to severe asymptomatic patients. Conclusions: The majority of patients diagnosed with AS have recent and/or active AS-related symptoms, which is associated with a significantly increased risk of adverse outcomes. Incorporating symptom status across the individual grades of AS may improve risk stratification beyond AS severity alone.

Introduction: The relative diagnostic and prognostic performance of left ventricular global longitudinal strain (LVGLS) as compared to LV ejection fraction (LVEF), and the role of LVGLS for detecting early stages of LV systolic dysfunction in adults with repaired coarctation of aorta (COA) is unknown. Objective: The purpose of this study was to address these knowledge gaps. Methods: Retrospective cohort study of adults with repaired COA that underwent transthoracic echocardiogram (2003-2020). LV systolic function was assessed using LVEF (derived from volumetric analysis) and LVGLS (derived from speckle-tracking echocardiography). Results: Of the 795 patients (age 36±14 years), mean LVEF and LVGLS were 62±11%, and 21±4%, respectively. The prevalence of LV systolic dysfunction was higher when assessed using LVGLS as compared to LVEF (20% versus 6%, p<0.001). Of 795 patients, 94 (12%) patients died, of which 75 (9%) died from cardiovascular causes. LVGLS provided more robust prognostic power in predicting all-cause mortality as compared to LVEF as evidenced by a higher C -statistic (0.743, 95%CI 0.730-0.755 versus 0.782, 95% CI 0.771-0.792, p<0.001). Furthermore, patients with normal LVEF in the setting of reduced LVGLS had a higher risk of all-cause mortality (as compared to patients with normal LVGLS and LVEF) and were at risk for temporal decline in LVEF during follow-up. Conclusions: These findings suggest that the use of LVGLS for risk stratification can help identify high-risk patients, and provide opportunities for interventions, which would, in turn, improve clinical outcomes. Further studies are required to empirically test these postulates.

Introduction: Right ventricular (RV) systolic dysfunction and pulmonary hypertension is present in 20% of adults with repaired coarctation of aorta (COA). However, the prognostic value of RV to pulmonary artery (RV-PA) coupling in this population is unknown. Objective: The purpose of this study was to assess the relationship between RV-PA coupling and clinical outcomes (heart failure hospitalization and all-cause mortality) in this population. Methods: Retrospective cohort study of adults with repaired COA and normal RV systolic function defined as RV-free wall strain ≥-24%. RV-PA coupling was assessed using tricuspid annular plane systolic excursion/ RV systolic pressure (TAPSE/RVSP) ratio. Results: Of 509 patients (median age 32 [20-45] years; men 290 [57%]), the average TAPSE and RVSP were 22±5 mm and 33±9 mmHg, respectively, and TAPSE/RVSP ratio was 0.78 (0.56-0.96) mm/mmHg. Of 509 patients, 51 (10%) died and 43 (8%) were hospitalized for heart failure. TAPSE/RVSP was associated with all-cause mortality (hazard ratio 0.82, 95% confidence interval 0.78-0.86, per 0.1 mm/mmHg), and heart failure hospitalization (hazard ratio 0.86, 95% confidence interval 0.79-0.83, per 0.1 mm/mmHg) after adjustment for anatomic lesions, cardiovascular interventions, comorbidities, and echocardiographic indices. The inclusion of TAPSE/RVSP ratio in the risk models improved the prognostic power of the models to predict all-cause mortality (C-statistics difference 0.046, p<0.001), and heart failure hospitalization (C-statistics difference 0.031, p=0.007). Conclusions: TAPSE/RVSP ratio was associated with outcomes in COA patients with normal RV systolic function, suggesting that abnormal RV-PA coupling may be present prior to the onset of overt RV systolic function in this population.

Introduction: Adults with repaired tetralogy of Fallot (TOF) have right atrial (RA) remodeling and dysfunction, and RA function can be measured using speckle-tracking echocardiography. There is limited data about the role of RA strain imaging in risk stratification in this population. Hypothesis: We hypothesized that RA reservoir strain could identify TOF patients at risk of developing atrial arrhythmia. We assessed the relationship between RA reservoir strain and atrial arrhythmias in adults with repaired TOF to test this hypothesis. Methods: Retrospective cohort study of adults with repaired TOF, and no prior history of atrial arrhythmias. Atrial arrhythmia was defined as atrial fibrillation, atrial flutter/atrial tachycardia, and categorized as new onset versus recurrent atrial arrhythmias. Results: We identified 426 patients (age 33±12 years; males 208 (49%)) that met the inclusion criteria. The mean RA reservoir, conduit, and booster strains were 34±11%, 20±9%, and 15±12%, respectively. Of 426 patients, 73 (17%) developed new-onset atrial arrhythmias (atrial flutter/tachycardia n=42; atrial fibrillation n=31); annual incidence 1.9%. RA reservoir strain was associated with new-onset atrial arrhythmias (adjusted HR 0.95, 95% CI 0.93-0.97) after multivariable adjustment. Of 73 patients with new-onset atrial arrhythmia, 41 (56%) had recurrent atrial arrhythmia (atrial flutter/tachycardia n=18; atrial fibrillation n=23); annual incidence 11.2%. Similarly, RA reservoir strain was associated with recurrent atrial arrhythmias (adjusted HR 0.92, 95% CI 0.88-0.96) after multivariable adjustment. Conclusions: RA strain indices can identify patients at risk for atrial arrhythmias, and this can, in turn, be used to guide the type/intensity of therapy in such patients.

Background: Atrial fibrillation (a-fib) occurs in up to 40% of patients after noncardiac surgery and is associated with increased risk of adverse outcomes. Practice guidelines recommend stress testing, including stress echocardiography (SE) to assess for coronary artery disease in selected high-risk patients prior to noncardiac surgery. The utility of using SE findings for predicting postoperative a-fib is unknown. Hypothesis: Myocardial ischemia can contribute to arrhythmogenic potential; other echocardiographic variables are likely associated with a-fib. Findings on SE may identify patients at risk for a-fib after noncardiac surgery. Aims: To determine if certain SE findings predict a-fib following noncardiac surgery. Methods: The study included patients undergoing pharmacological and exercise SE before noncardiac surgery. The primary outcome was a-fib/flutter within 30 days after surgery. Multivariate analysis was adjusted for age, cardiovascular comorbidities, and markers of surgical risk. Results: This analysis included 2,376 patients (mean age 68 +/- 7 years; 60% male); 1,986 patients had no known history of a-fib/flutter. Of these, 48 (2.4%) developed postoperative a-fib/flutter. In multivariate analysis, SE variables associated with development of new a-fib/flutter included left ventricular dilation (OR 2.11, p=0.049), increased left atrial volume (OR 1.19, p=0.045), and increased left ventricular mass index (OR 1.13, p=0.043) on rest images. The presence of ischemia or infarct on stress echocardiogram was not associated with postoperative a-fib/flutter. A total of 390 patients had a history of paroxysmal a-fib/flutter and were in sinus rhythm at the time of surgery. Of these, 90 (23%) experienced recurrent a-fib/flutter within 30 days of surgery. Multivariate analysis did not reveal any SE variables significantly associated with recurrence, including presence of myocardial ischemia or infarct at the time of SE. Conclusions: All SE variables associated with postoperative a-fib following noncardiac surgery are available from resting images alone. Therefore, SE that includes comprehensive resting images may offer benefit in the pre-operative evaluation of selected patients.

Introduction: The consequences of external cardiovascular compression and cardiac displacement from pectus excavatum (PEx) are debated. The complex geometry of the right (RV) and left ventricle (LV) along with distortion from the extrinsic chest deformity pose significant limitations to reliable assessment of LV and RV volumes and function using transthoracic 2D-echocardiography in this population. Hypothesis: A 3D-echocardiography approach can reliably assess the effects of external cardiac compression and the benefits of surgical correction on RV and LV function in PEx patients. Methods: Adult patients undergoing minimally invasive repair of PEx between Oct-2021 and Feb-2023 were included in this prospective study. Intraoperative transesophageal (TEE) 6 beat full volume video loops incorporating LV and RV were captured and compared before and after surgical correction of the PEx. TomTec Software® was used for offline 3D/4D reconstruction ( Figure 1 shows changes in 3D RV and LV shape pre- and post-surgery). Result: The study included 102 patients (mean age of 32.1 ±11.8 years; Haller index 4.9 ±2.5; 60.8% males). Post PEx repair, there was a significant (p<0.001) increase in the 3D RV volumes, RV ejection fraction (EF), RV stroke volume and RV strain ( Figure 1 ). Additionally, there was a significant improvement in 3D LVEF, 3D LV strain (longitudinal and circumferential), LV twist, and torsion ( Figure 1 ). Conclusion: In this PEx cohort, 3D/4D TEE imaging demonstrated significant increases in RV volumes and in RV and LV systolic function after surgical repair. These findings support the negative cardiovascular consequences of PEx compression and benefits of surgical repair.

Background: Increased sympathetic drive resulting in decreased heart rate variability (HRV), has been linked to cardiovascular diseases such as heart failure and myocardial infarction (MI). Dynamic electrophysiological changes due to acute ischemia and chronic MI are known to be pro-arrhythmic. Objective: Evaluate the changes in autonomic tone resulting from substrate remodeling during the development of chronic MI in an in-vivo ovine model. Methods: ECG recordings were collected at baseline, post occlusion and 6 weeks post MI, in young adult sheep (n=16). Time domain, frequency domain and non-linear measures of HRV were evaluated from 10 minutes of ECG data at the 3 time points. RR interval, heart rate, SDRR (standard deviation of the RR intervals), RMSSD (root mean square of successive differences between normal heartbeats), QTc interval, pNN 50 , LF/HF ratio and SD1/SD2 ratio were calculated and compared between baseline, post acute coronary artery occlusion and after 6 weeks of chronic MI. 24-hour telemetry was also performed in an ambulatory animal for 6 weeks to monitor the progression of alterations in the T-wave morphology or duration, i.e. T-wave alternans, a known marker of ventricular tachyarrhythmias, with chronic MI. Results: Chronic MI led to significantly decreased RR interval (Fig.1A) and increased heart rate (Fig.1B), along with a significant prolongation of the QTc interval (Fig.1C). Significant rise was also observed in the SDRR (Fig1D) and LF/HF ratio (Fig1E) indicating a shift towards increased sympathetic tone and reduced parasympathetic drive. In addition to the autonomic changes, a significant rise in T-wave alternans burden (Fig1F) and localized action potential alternans inducibility was observed with progression of MI indicating increased arrhythmogenicity. Conclusion: Skewed autonomic balance is evident in chronic MI and may be closely linked to increased arrhythmogenicity.