Nonpharmacologic rate control of postoperative atrial fibrillation in the canine sterile pericarditis model.

INTRODUCTION: Postoperative atrial fibrillation (POAF) is common following open heart surgery, and is associated with significant morbidity. Medications used for ventricular rate control of POAF may not be effective in controlling rapid ventricular rates during the postoperative period because of increased sympathetic tone. The purpose of this study was to develop nonpharmacologic rate control of POAF by atrioventricular node (AVN) fat pad stimulation using clinically available temporary pacing wires in the canine sterile pericarditis model. METHODS: We studied 10 sterile pericarditis dogs in the closed-chest state on postoperative days 1-3. The AVN fat pad stimulation (amplitude 2-15 mA; frequency 20 Hz; pulse width 0.03-0.2 ms) was performed during sustained POAF (>5 min). We measured ventricular rate and inefficient ventricular contractions during sustained POAF and compared it with and without AVN fat pad stimulation. Also, the parameters of AVN fat pad stimulation to achieve a rate control of POAF were measured over the postoperative days. RESULTS: Eleven episodes of sustained POAF were induced in 5/10 sterile pericarditis dogs in the closed-chest state on postoperative days 1-2. During POAF, the AVN fat pad stimulation decreased the ventricular rate from 178 ± 52 bpm to 100 ± 8 bpm in nine episodes. Nonpharmacologic rate control therapy successfully controlled the ventricular rate and eliminated inefficient ventricular contractions during POAF for the duration of the AVN fat pad stimulation. The AVN fat pad stimulation output remained relatively stable over the postoperative days. CONCLUSION: During sustained POAF, nonpharmacologic rate control by AVN fat pad stimulation effectively and safely controlled rapid ventricular rates throughout the postoperative period.

Understanding Phantom Shocks in Implantable Cardioverter-Defibrillator Recipients.

Phantom shocks in implantable cardioverter-defibrillator (ICD) recipients create a complex nexus between cardiac treatment and psychological distress. These sensations, mimicking therapeutic shocks without device activation, deeply affect patients' functionality and well-being. Heightened anxiety, depression, and hopelessness predispose individuals to these occurrences, posing significant challenges. This article delves into the intricate nature of phantom shocks, highlighting subtle clinical cues to differentiate them from genuine therapy shocks. Through a case study of a 75-year-old male with recurrent ICD shocks, diagnosed eventually with phantom shocks, the interplay between psychological distress and physical sensations is underscored. Urgent intervention to address the patient's anxiety and depression using psychotherapy and antidepressants became imperative. The case underscores the immense psychological toll of phantom shocks, exacerbating fear, hopelessness, and post-traumatic stress disorder (PTSD). Despite treatment attempts, their impact persisted, leading to a shift to comfort-focused care. While research identifies factors such as education levels and prior therapy, predicting and managing phantom shocks remains challenging. This article stresses the need for clinician vigilance, urging proactive identification and tailored interventions to mitigate the profound effects of phantom shocks. The current research landscape lacks comprehensive strategies, necessitating further exploration and targeted therapies to restore patient well-being. In conclusion, comprehensive understanding and specialized care for phantom shocks in ICD recipients, addressing both cardiac and psychological aspects, are imperative. Early recognition and tailored interventions offer promise in alleviating their adverse effects, reinstating patient control, and improving their quality of life.

Wide QRS Complex Transient Pattern in a Patient With Severe COVID-19.

This case report describes a patient in their 60s with shortness of breath who tested positive for COVID-19.

Outcomes of coronary artery bypass grafting in patients with heart failure with a midrange ejection fraction.

BACKGROUND: Coronary artery bypass grafting (CABG) improves survival in patients with heart failure and severely reduced left ventricular systolic function (LVEF). Limited data exist regarding adverse cardiovascular event rates after CABG in patients with heart failure with midrange ejection fraction (HFmrEF; LVEF > 40% and < 55%). METHODS: We analyzed data on isolated CABG patients from the Veterans Affairs national database (2010-2019). We stratified patients into control (normal LVEF and no heart failure), HFmrEF, and heart failure with reduced LVEF (HFrEF) groups. We compared all-cause mortality and heart failure hospitalization rates between groups with a Cox model and recurrent events analysis, respectively. RESULTS: In 6533 veterans, HFmrEF and HFrEF was present in 1715 (26.3%) and 566 (8.6%) respectively; the control group had 4252 (65.1%) patients. HFrEF patients were more likely to have diabetes mellitus (59%), insulin therapy (36%), and previous myocardial infarction (31%). Anemia was more prevalent in patients with HFrEF (49%) as was a lower serum albumin (mean, 3.6 mg/dL). Compared with the control group, a higher risk of death was observed in the HFmrEF (hazard ratio [HR], 1.3 [1.2-1.5)] and HFrEF (HR, 1.5 [1.2-1.7]) groups. HFmrEF patients had the higher risk of myocardial infarction (subdistribution HR, 1.2 [1-1.6]; P = .04). Risk of heart failure hospitalization was higher in patients with HFmrEF (HR, 4.1 [3.5-4.7]) and patients with HFrEF (HR, 7.2 [6.2-8.5]). CONCLUSIONS: Heart failure with midrange ejection fraction negatively affects survival after CABG. These patients also experience higher rates myocardial infarction and heart failure hospitalization.

An Evaluation of Phase Analysis to Interpret Atrial Activation Patterns during Persistent Atrial Fibrillation for Targeted Ablation.

BACKGROUND: Phase analysis has been used to identify and localize atrial fibrillation (AF) sources for targeted ablation. We previously demonstrated that repetitive wannabe reentry (incomplete reentry) often generated an apparent stable rotor using phase analysis. The misinterpretation caused by phase analysis using atrial electrograms (AEGs) may result from detecting inaccurate time points at phase inversion (π to -π) in the instantaneous phase waveform converted from AEG. The purpose of this study was to evaluate the accuracy of phase analysis to detect atrial activations recorded from the high-density mapping of AF in patients with persistent and long-standing persistent (LSP) AF. METHODS AND RESULTS: During open heart surgery, we recorded activation from both atria simultaneously using 512 electrodes in 7 patients with persistent and LSP AF. The phase analysis was compared to manual measurements during 4 s of data. For the accuracy of activation sequence maps, a successful recording site was defined as having ≤4 mismatched activation times during the 4 s. In all AF episodes, the accuracy of the phase analysis was only 82% of the total number of activation times due to either activation time differences (14.7%), under-sensing (2.7%), or over-sensing (0.6%). Only 67.9% of the total recording sites met the requirement of a successful recording site by phase analysis. In unsuccessful recording sites, AEG characteristics were relatively irregular cycle length (CL), complex AEG, and double potential AEG. CONCLUSION: The phase analysis was less accurate in recording sites with a relatively irregular CL, complex AEG, or double potential AEG. As a result, phase analysis may lead to the misinterpretation of atrial activation patterns during AF. A visual review of the original AEG is needed to confirm the detected AF sources of phase analysis before performing targeted ablation.

Anticoagulation in new-onset postoperative atrial fibrillation: An analysis from the Society of Thoracic Surgeons Adult Cardiac Surgery Database.

Background: New-onset postoperative atrial fibrillation (POAF) is the most common complication after cardiac surgery and is associated with increased long-term stroke and mortality. Anticoagulation has been suggested as a potential therapy, but data on safety and efficacy are scant. Objectives: To determine the association between anticoagulation for POAF and long-term outcomes. Methods: Adult patients with POAF after isolated coronary artery bypass surgery (CABG) were identified through the Society of Thoracic Surgeons Adult Cardiac Surgery Database and linked to the Medicare Database. Propensity-matched analyses were performed for all-cause mortality, stroke, myocardial infarction, and major bleeding for patients discharged with or without anticoagulation. Interaction between anticoagulation and CHA2DS2-VASc score was also assessed. Results: Of 38,936 patients, 9861 (25%) were discharged on oral anticoagulation. After propensity score matching, discharge anticoagulation was associated with increased mortality (hazard ratio [HR] 1.16, 95% confidence interval [CI] 1.06-1.26). There was no difference in ischemic stroke between groups (HR 0.97, 95% CI 0.82-1.15), but there was significantly higher bleeding (HR 1.60, 95% CI 1.38-1.85) among those discharged on anticoagulation. Myocardial infarction was lower in the first 30 days for those discharged on anticoagulation, but this effect decreased over time. The incidence of all complications was higher for patients with CHA2DS2-VASc scores ≥5 compared to patients with scores of 2-4. Anticoagulation did not appear to benefit either subgroup. Conclusion: Anticoagulation is associated with increased mortality after new-onset POAF following CABG. There was no reduction in ischemic stroke among those discharged on anticoagulation regardless of CHA2DS2-VASc score.

Revascularization in ischaemic heart failure with preserved ejection fraction: a nationwide cohort study.

AIMS: Despite the common occurrence of coronary artery disease (CAD) and heart failure (HF) with preserved ejection fraction (HFpEF), there is limited evidence to guide revascularization. METHODS AND RESULTS: We investigated the long-term outcomes of coronary artery bypass grafting (CABG) in patients with HF and significant CAD across the spectrum of ejection fraction, using a large national cohort of patients from the Veteran Affairs (VA) Medical Centers in the US. Patients with HF were stratified into groups, HFpEF, HF with mid-range ejection fraction (HFmrEF), and HF with reduced ejection fraction (HFrEF) and compared to patients with no preoperative HF. We analysed 10 396 patients. Despite an increased hazard in the first year following revascularization, the long-term survival (median follow-up 6.6 years; interquartile range 3.7-10.1) of HFpEF post-CABG was similar to controls (hazard ratio 0.85, 95% confidence interval 0.68-1.06), but survival progressively declined with HFmrEF and HFrEF. Similar trends were seen with recurrent HF hospitalization with lower risk with baseline HFpEF (43.9 ± 6.9/100 patient-years) compared to HFmrEF (65.9 ± 3.8/100 patient-years) and HFrEF (93.4 ± 4.8/100 patient-years). Although HFpEF patients had lower mortality and HF hospitalization post-CABG compared to patients with a lower ejection fraction, they experienced the highest rates of future myocardial infarction. CONCLUSION: Although HFpEF patients with CAD have greater short-term risk post-CABG, their long-term survival is comparable to controls. However, they are at increased risk for HF hospitalizations and myocardial infarction. These data support the safety of CABG in HFpEF patients and suggest continuum of mortality risk for ischaemic HF when stratified by baseline ejection fraction before revascularization.

Hospitalization for Heart Failure in the United States, UK, Taiwan, and Japan: An International Comparison of Administrative Health Records on 413,385 Individual Patients.

BACKGROUND: Registries show international variations in the characteristics and outcome of patients with heart failure (HF), but national samples are rarely large, and case selection may be biased owing to enrolment in academic centers. National administrative datasets provide large samples with a low risk of bias. In this study, we compared the characteristics, health care resource use (HRU) and outcomes of patients with primary HF hospitalizations (HFH) using electronic health records (EHR) from 4 high-income countries (United States, UK, Taiwan, Japan) on 3 continents. METHODS AND RESULTS: We used electronic health record to identify unplanned HFH between 2012 and 2014. We identified 231,512, 10,991, 36,900, and 133,982 patients with a primary HFH from the United States, the UK, Taiwan, and Japan, respectively. HFH per 100,000 population was highest in the United States and lowest in Taiwan. Fewer patients in Taiwan and Japan were obese or had chronic kidney disease. The length of hospital stay was shortest in the United States (median 4 days) and longer in the UK, Taiwan, and Japan (medians of 7, 9, and 17 days, respectively). HRU during hospitalization was highest in Japan and lowest in UK. Crude and direct standardized in-hospital mortality was lowest in the United States (direct standardized rates 1.8, 95% confidence interval 1.7%-1.9%) and progressively higher in Taiwan (direct standardized rates 3.9, 95% CI 3.8%-4.1%), the UK (direct standardized rates 6.4, 95% CI 6.1%-6.7%), and Japan (direct standardized rates 6.7, 95% CI 6.6%-6.8%). The 30-day all-cause (25.8%) and HF (7.2%) readmissions were highest in the United States and lowest in Japan (11.9% and 5.1%, respectively). CONCLUSIONS: Marked international variations in patient characteristics, HRU, and clinical outcomes exist; understanding them might inform health care policy and international trial design.

Impact of catheter ablation in patients with atrial flutter and concurrent heart failure.

BACKGROUND: No studies assessed impact of atrial flutter (AFL) ablation on outcomes in patients with AFL and concurrent heart failure (HF). OBJECTIVES: To assess the effect of AFL ablation on mortality and HF readmissions in patients with AFL and HF. METHODS: This retrospective cohort study identified 15,952 patients with AFL and HF from the 2016-17 Nationwide Readmissions Database. The primary outcome was a composite of all-cause mortality and/or HF readmission at 1 year. Secondary outcomes included HF readmission, all-cause mortality, and atrial fibrillation (AF) readmission at 1 year. Propensity score match (1:2) algorithm was used to adjust for confounders. Cox proportional hazard regression was used to generate hazard ratios. RESULTS: Of the 15,952 patients, 9889 had heart failure with reduced ejection fraction (HFrEF) and 6063 had heart failure with preserved ejection fraction (HFpEF). In the matched HFrEF cohort (n = 5421), the primary outcome was significantly lower in patients undergoing ablation (HR 0.72, 95% CI 0.61-0.85, P < .001). HF readmission (HR 0.73, 95% CI 0.61-0.89, P = .001), all-cause mortality (HR 0.62, 95% CI 0.46-0.85, P = .003), and AF readmission (HR 0.63, 95% CI 0.48-0.82, P = .001) were also significantly reduced. In the matched HFpEF cohort (n = 2439), the primary outcome was lower in the group receiving ablation but was not statistically significant (HR 0.80, 95% CI 0.63-1.01, P = .065). CONCLUSION: In patients with AFL and HFrEF, AFL ablation was associated with lower mortality and HF readmissions at 1 year. Patients with AFL and HFpEF did not show a similar significant reduction in the primary outcome.

Pre-operative glycaemic control and long-term survival in diabetic patients after coronary artery bypass grafting.

OBJECTIVES: We analysed the Veteran Affairs data to evaluate the association of pre-operative glycated haemoglobin (HbA1c) and long-term outcome after isolated coronary artery bypass grafting (CABG). METHODS: Veterans with diabetes mellitus and isolated CABG (2006-2018) were divided into 4 groups (I: HbA1c <6.5%, II: HbA1c 6.5-8, III 8-10% and IV: HbA1c >10%). The relationship of pre-operative HbA1c and long-term survival was evaluated with a multivariable Cox proportional hazards model and reported as hazard ratios (HR). The cumulative incidence of secondary end-points [myocardial infarction (MI) and repeat revascularization (percutaneous intervention)] for each group was modelled as competing events with cause-specific Cox proportional hazards models. RESULTS: Overall, 16 190 patients (mean age 64.9 years, male 98%; insulin dependent 53%) with diabetes mellitus underwent isolated CABG. We observed 19.4%, 45.4%, 27% and 8.2% patients in groups I, II, III and IV, respectively. Patients with HbA1c >10% were the youngest (mean age 60.9 years) and had high rates of Insulin dependence (78%). In patients with HbA1c >10%, improvement in levels was observed in 76%. The median follow-up observed was 5.8 (3.2-8.8) years. Compared to the study mean HbA1c (7.3%), mortality rate increased with HbA1c levels >8%, and especially with pre-operative HbA1c levels >9%. Compared to patients with HbA1c <8%, HbA1c 8-10% and >10% were associated with increased MI (HR 1.24 and HR 1.39, respectively) and need for reintervention (HR 1.20 and HR 1.24, respectively). CONCLUSIONS: In patients undergoing CABG, pre-operative HbA1c >8% is associated with the increased risk of mortality and adverse cardiac events.

New Insights Into Understanding Rotor Versus Focal Activation in Patients With Persistent Atrial Fibrillation.

OBJECTIVES: This study was to test the hypotheses that: 1) when using phase analysis, repetitive Wannabe re-entry produces a phase singularity point (i.e., a rotor); and 2) the location of the stable rotor is close to the focal source. BACKGROUND: Recent contact mapping studies in patients with persistent atrial fibrillation (AF) demonstrated that phase analysis produced a different mechanistic result than classical activation sequence analysis. Our studies in patients with persistent AF showed that focal sources sometimes produced repetitive Wannabe re-entry, that is, incomplete re-entry. METHODS: During open heart surgery, we recorded activation from both atria simultaneously using 510 to 512 electrodes in 12 patients with persistent AF. We performed activation sequence mapping and phase analyses on 4 s of mapped data. For each detected stable rotor (>2 full rotations [720°] recurring at the same site), the corresponding activation patterns were examined from the activation sequence maps. RESULTS: During AF, phase singularity points (rotors) were identified in both atria in all patients. However, stable phase singularity points were only present in 6 of 12 patients. The range of stable phase singularity points per patient was 0 to 6 (total 14). Stable phase singularity points were produced due to repetitive Wannabe re-entry generated from a focal source or by passive activation. A conduction block sometimes created a stable phase singularity point (n = 2). The average distance between a focal source and a stable rotor was 0.9 ± 0.3 cm. CONCLUSIONS: Repetitive Wannabe re-entry generated stable rotors adjacent to a focal source. No true re-entry occurred.

Attitudes toward anticoagulation for postoperative atrial fibrillation: A nationwide survey of VA providers.

INTRODUCTION: Postoperative atrial fibrillation (POAF) is a common complication after cardiac surgery. Though often felt to be self-limited, this complication has been associated with increases in both short and long-term stroke and mortality. Several studies have also shown a high rate of AF recurrence. Optimal treatment strategy is not yet defined, and the role of anticoagulation (AC) is unclear. Our objective was to determine provider attitudes toward management of this common complication. METHODS: A survey consisting of 15 multiple choice questions was distributed to providers at Veterans Healthcare Administration hospitals nationwide. RESULTS: The majority of respondents were cardiologists. Practices varied drastically with respect to AC use for patients with POAF who were discharged in normal sinus rhythm. Less variability existed for patients discharged in AF. There was no clear consensus regarding other factors to consider when deciding on AC therapy, including length of episode, or risk factors for stroke such as CHA2 DS2 -VASc score. There was also no consensus on duration of therapy or need for post discharge cardiac monitoring. CONCLUSION: Our data indicate a wide variability in the management of POAF. This reflects conflicting recommendations in the guidelines, as well as a paucity of prospective treatment trials in this field. Nevertheless, a growing evidence base suggests that this complication carries potentially serious long-term morbidity and mortality, and better evidence for its management is needed.

A case report of unusually long episodes of asystole in a severe COVID-19 patient treated with a leadless pacemaker.

BACKGROUND: Experience has been emerging about cardiac manifestations of COVID-19-positive patients. The full cardiac spectrum is still unknown, and management of these patients is challenging. CASE SUMMARY: We report a COVID-19 patient who developed unusually long asystolic pauses associated with atriventricular block (AV) block and atrial fibrillation who underwent leadless pacemaker implantation. DISCUSSION: Asystole may be a manifestation of COVID-19 infection. A leadless pacemaker is a secure remedy, with limited requirements for follow-up, close interactions, and number of procedures in a COVID-19 patient.

Reconsidering the multiple wavelet hypothesis of atrial fibrillation.

BACKGROUND: Moe and Abildskov proposed the multiple wavelet hypothesis of atrial fibrillation (AF) on the basis of observations in the canine vagal nerve stimulation (VNS) AF model. Data from mapping studies in an in vitro canine AF model by Allessie et al (Allessie MA, Lammers WJEP, Bonke FIM, Hollen SJ. Experimental evaluation of Moe's multiple wavelet hypothesis of atrial fibrillation. In: Zipes DP, Jalife J, eds. Cardiac Electrophysiology and Arrhythmias. Orlando, FL: Grune & Stratton; 1985:265-275.) were used to evaluate the Moe/Abildskov hypothesis, which revealed that a critical number of wavelets sustained AF. OBJECTIVE: The purpose of this study was to reassess VNS mapping data using the same methods used by Allessie to evaluate Moe's multiple wavelet hypothesis. METHODS: Using the canine VNS AF model in 6 dogs, 510 unipolar atrial electrograms were recorded simultaneously from both atria. Activation sequence maps were produced from sustained AF during VNS in each dog. Per Allessie, consecutive 10 ms activation windows were analyzed over a period of 300 ms. Repetitive activation analysis was applied to Moe's canine VNS AF model. RESULTS: The number of wavefronts in each AF episode was 0-8 in Allessie's studies measured by sequential atrial mapping and 0-10 in our biatrial simultaneous mapping studies. In both studies, an electrically silent period was observed in each atrium and was reactivated by wavefronts emanating from focal sources. Allessie postulated that an electrically silent atrium was reactivated by a wavefront propagating from the other atrium. However, in our biatrial simultaneous mapping studies, each electrically silent atrium was reactivated by a distinct focal source. CONCLUSION: Data from both studies showed a similar number of wavefronts, similar AF activation patterns, and periods of electrical atrial silence reactivated by focal sources. Also, in our studies, independent focal sources initiated wavefronts reactivating the atria, thereby explaining the mechanism maintaining AF.

Impact of comorbidities on peak troponin levels and mortality in acute myocardial infarction.

OBJECTIVES: To characterise peak cardiac troponin levels, in patients presenting with acute myocardial infarction (AMI), according to their comorbid condition and determine the influence of peak cardiac troponin (cTn) levels on mortality. METHODS: We included patients with the first admission for AMI in the UK. We used linear regression to estimate the association between eight common comorbidities (diabetes mellitus, previous angina, peripheral arterial disease, previous myocardial infarction (MI), chronic kidney disease (CKD), cerebrovascular disease, chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD)) and peak cTn. Peak cTn levels were adjusted for age, sex, smoking status and comorbidities. Logistic regression and restricted cubic spline models were employed to investigate the association between peak cTn and 180-day mortality for each comorbidity. RESULTS: 330 367 patients with ST elevation myocardial infarction and non-ST elevation myocardial infarction were identified. Adjusted peak cTn levels were significantly higher in patients with CKD (adjusted % difference in peak cTnT for CKD=42%, 95% CI 13.1 to 78.4) and significantly lower for patients with COPD, previous angina, previous MI and CHF when compared with patients without the respective comorbidities (reference group) (cTnI; COPD=-21.7%, 95% CI -29.1 to -13.4; previous angina=-24.2%, 95% CI -29.6 to -8.3; previous MI=-13.5%, 95% CI -20.6 to -5.9; CHF=-28%, 95% CI -37.2 to -17.6). Risk of 180-day mortality in most of the comorbidities did not change substantially after adjusting for peak cTn. In general, cTnI had a stronger association with mortality than cTnT. CONCLUSIONS: In this nationwide analysis of patients presenting with AMI, comorbidities substantially influenced systemic concentrations of peak cTn. Comorbid illness is a significant predictor of mortality regardless of peak cTn levels and should be taken into consideration while interpreting cTn both as a diagnostic and prognostic biomarker.

Contemporary Anticoagulation Practices for Postoperative Atrial Fibrillation: A Single Center Experience.

AIMS: Postoperative atrial fibrillation (POAF) is a frequent in-hospital complication after cardiac surgery. Surprisingly, despite its prevalence, management of this condition has not been well studied. One promising approach that has been evaluated in a limited number of studies is use of anticoagulation. However, the trends and patterns of real-world use of anticoagulation in POAF patients has not been systemically investigated. In this study, we aimed to determine real-world patterns of anticoagulation use for patients with POAF. METHODS: We identified 200 patients undergoing coronary artery bypass (CABG) or cardiac valve surgery at University Hospitals Cleveland Medical Center over a 2 year period beginning January 2016 with new onset POAF. We reviewed charts to verify candidacy for inclusion in the study and to extract data on anticoagulation use, adverse outcomes, and CHA2DS2-VASc scores. RESULTS: Anticoagulation use was low after CABG, but high after bioprosthetic valve surgery. The most common anticoagulant used was warfarin. Anticoagulation use was not correlated with CHA2DS2-VASc score or cardioversion. Stroke and mortality were higher among patients not receiving anticoagulation, however, confirmation of this finding in larger randomized studies is warranted. CONCLUSIONS: Anticoagulation use is low after CABG and this practice does not appear to be affected by CHA2DS2VASc score or cardioversion. This differs with previously reported provider attitudes towards management of this condition. Stroke and mortality appear to be elevated for patients not receiving anticoagulation but further investigation is required to confirm this observation.