Postbypass arrhythmias: pathophysiology, prevention, and therapy

Incidence of atrioventricular block after isolated coronary artery bypass grafting: a systematic review and pooled-analysis

Background and objectives

Atrioventricular block (AVB) is a serious complication following coronary artery bypass grafting (CABG) surgery, and its high-grade form may necessitate the implantation of a permanent pacemaker (PPM). AVB is associated with increased morbidity and mortality rates. This study aims to estimate the incidence of AVB and subsequent PPM implantation after isolated CABG surgery.

Material and methods

We searched electronic databases of PubMed, Embase, and Scopus from inception to 18 November 2022. Clinical trials and observational studies reporting the incidence of post-CABG AVB or subsequent PPM implantation in adult patients were included. The total incidence for all included outcomes was calculated using the inverse variance method, and the I2 statistic was reported to evaluate the heterogeneity of studies.

Results

A total of 28 studies met the inclusion criteria. Four studies [3 cohorts, 1 randomized controlled trial (RCT)] reported AVB without specifying its type; one (cohort) reported different degrees of AVB, 20 (12 cohorts, 8 RCTs) reported complete heart block (CHB) (or AVB requiring temporary pacing), and nine (8 cohorts, 1 RCT) reported the number of PPM inserted due to AVB. The pooled incidence of AVB, CHB (or AVB requiring temporary pacing), and PPM due to AVB was 1.16%, 1.73%, and 0.58%, respectively. Meta-regression analysis revealed that age, gender, diabetes, hypertension, hyperlipidemia, or smoking were not significantly associated with AVB, CHB, or PPM implantation.

Conclusion

This study highlights the incidence of AVB and the need for PPM implantation following CABG surgery. The findings emphasize the importance of postoperative monitoring and surveillance to improve patient outcomes.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022377181, identifier PROSPERO CRD42022377181.

Sinus node dysfunction and related permanent pacemaker implantation after major cardiac surgeries, systematic review, and meta-analysis

Background

There is no concise evidence or clinical guidelines regarding the incidence of sinus node dysfunction (SND) and permanent pacemaker (PPM) implantation following cardiac surgeries and their management approaches.

Objective

We aim to systematically review current evidence on the prevalence of SND, PPM implantation concerning it, and its risk factors in patients undergoing cardiac surgery.

Method

Four electronic databases (Cochrane Library, Medline, SCOPUS, and Web of Science) were systematically searched for articles regarding SND after cardiovascular surgeries and reviewed by two independent researchers, and a third review in case of discrepancies. Using the random-effects model, a proportion meta-analysis was performed on data regarding PPM implantation. Subgroup analysis was performed for different interventions, and the possible effect of different covariates was evaluated using meta-regression.

Results

From the initial 2012 unique records, 87 were included in the study, and results were extracted. Pooled data from 38,519 patients indicated that the overall prevalence of PPM implantation due to SND after cardiac surgery was 2.87% (95% CI [2.09; 3.76]). The incidence of PPM implantation in the first post-surgical month was 2.707% (95% CI [1.657; 3.952]). Among the four main intervention groups, including valve, maze, valve-maze, and combined surgeries, maze surgery was associated with the highest prevalence (4.93%; CI [3.24; 6.92]). The pooled prevalence of SND among studies was 13.71% (95% CI [8.13; 20.33]). No significant relationship was observed between PPM implantation and age, gender, cardiopulmonary bypass time, or aortic cross-clamp time.

Conclusion

Based on the present report, patients undergoing the maze and maze-valve procedures are at higher risk of post-op SND, whereas lone valve surgery had the lowest prevalence of PPM implantation.

Systematic Review Registration

PROSPERO (CRD42022341896).

New-Onset Atrial Fibrillation After PCI or CABG for Left Main Disease: The EXCEL Trial

BACKGROUND

There is limited information on the incidence and prognostic impact of new-onset atrial fibrillation (NOAF) following percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) for left main coronary artery disease (LMCAD).

OBJECTIVES

This study sought to determine the incidence of NOAF following PCI and CABG for LMCAD and its effect on 3-year cardiovascular outcomes.

METHODS

In the EXCEL (Evaluation of XIENCE Versus Coronary Artery Bypass Surgery for Effectiveness of Left Main Revascularization) trial, 1,905 patients with LMCAD and low or intermediate SYNTAX scores were randomized to PCI with everolimus-eluting stents versus CABG. Outcomes were analyzed according to the development of NOAF during the initial hospitalization following revascularization.

RESULTS

Among 1,812 patients without atrial fibrillation on presentation, NOAF developed at a mean of 2.7 ± 2.5 days after revascularization in 162 patients (8.9%), including 161 of 893 (18.0%) CABG-treated patients and 1 of 919 (0.1%) PCI-treated patients (p < 0.0001). Older age, greater body mass index, and reduced left ventricular ejection fraction were independent predictors of NOAF in patients undergoing CABG. Patients with versus without NOAF had a significantly longer duration of hospitalization, were more likely to be discharged on anticoagulant therapy, and had an increased 30-day rate of Thrombolysis In Myocardial Infarction major or minor bleeding (14.2% vs. 5.5%; p < 0.0001). By multivariable analysis, NOAF after CABG was an independent predictor of 3-year stroke (6.6% vs. 2.4%; adjusted hazard ratio [HR]: 4.19; 95% confidence interval [CI]: 1.74 to 10.11; p = 0.001), death (11.4% vs. 4.3%; adjusted HR: 3.02; 95% CI: 1.60 to 5.70; p = 0.0006), and the primary composite endpoint of death, MI, or stroke (22.6% vs. 12.8%; adjusted HR: 2.13; 95% CI: 1.39 to 3.25; p = 0.0004).

CONCLUSIONS

In patients with LMCAD undergoing revascularization in the EXCEL trial, NOAF was common after CABG but extremely rare after PCI. The development of NOAF was strongly associated with subsequent death and stroke in CABG-treated patients. Further studies are warranted to determine whether prophylactic strategies to prevent or treat atrial fibrillation may improve prognosis in patients with LMCAD who are undergoing CABG. (Evaluation of XIENCE Versus Coronary Artery Bypass Surgery for Effectiveness of Left Main Revascularization [EXCEL]; NCT01205776).

Red blood cells treated with the amustaline (S-303) pathogen reduction system: a transfusion study in cardiac surgery

BACKGROUND

Nucleic acid-targeted pathogen inactivation technology using amustaline (S-303) and glutathione (GSH) was developed to reduce the risk of transfusion-transmitted infectious disease and transfusion-associated graft-versus-host disease with red blood cell (RBC) transfusion.

STUDY DESIGN AND METHODS

A randomized, double-blind, controlled study was performed to assess the in vitro characteristics of amustaline-treated RBCs (test) compared with conventional (control) RBCs and to evaluate safety and efficacy of transfusion during and after cardiac surgery. The primary device efficacy endpoint was the postproduction hemoglobin (Hb) content of RBCs. Exploratory clinical outcomes included renal and hepatic failure, the 6-minute walk test (a surrogate for cardiopulmonary function), adverse events (AEs), and the immune response to amustaline-treated RBCs.

RESULTS

A total of 774 RBC unis were produced. Mean treatment difference in Hb content was -2.27 g/unit (95% confidence interval, -2.61 to -1.92 g/unit), within the prespecified equivalence margins (±5 g/unit) to declare noninferiority. Amustaline-treated RBCs met European guidelines for Hb content, hematocrit, and hemolysis. Fifty-one (25 test and 26 control) patients received study RBCs. There were no significant differences in RBC usage or other clinical outcomes. Observed AEs were within the spectrum expected for patients of similar age undergoing cardiovascular surgery requiring RBCs transfusion. No patients exhibited an immune response specific to amustaline-treated RBCs.

CONCLUSION

Amustaline-treated RBCs demonstrated equivalence to control RBCs for Hb content, have appropriate characteristics for transfusion, and were well tolerated when transfused in support of acute anemia. Renal impairment was characterized as a potential efficacy endpoint for pivotal studies of RBC transfusion in cardiac surgery.

Early ventricular tachyarrhythmias after coronary artery bypass grafting surgery: Is it a real burden?

BACKGROUND

The prevalence of ventricular dysrhythmias (VD) [ventricular premature beats (VPBs), ventricular couplets (Vcouplets), ventricular runs (Vruns)] after coronary artery bypass grafting (CABG) has so far not been examined. The goal of this study is to examine characteristics of VD and whether they precede ventricular tachyarrhythmias (VTA) during a postoperative follow-up period of 5 days using continuous rhythm registrations. In addition, we determined predictive factors of VD/VTA.

METHODS

Incidences and burdens of VD/VTA were calculated in patients (N=105, 83 male, 65±9 years) undergoing primary, on-pump CABG. Independent risk factors were examined using multivariate analysis.

RESULTS

VPBs, Vcouplets, and Vruns occurred in respectively 100%, 82.9%, and 48.6% with corresponding burdens of 0.05%, 0%, and 0%. Sustained ventricular tachycardia (VT) and ventricular fibrillation (VF) did not occur in our cohort. Independent risk factors for VD included male gender, mitral valve insufficiency, hyperlipidemia, and age ≥60 years.

CONCLUSIONS

VD are common in patients with coronary artery disease after CABG. Despite high incidences of these dysrhythmias, corresponding burdens are low and sustained VT or VF did not occur. Incidences were highest on the first postoperative day and diminished over time.

Risk factors and clinical outcomes of arrhythmias in the medical intensive care unit

BACKGROUND

The clinical impact of arrhythmias on the continuum of critical illness is unclear, and data in medical intensive care units (ICU) is lacking. In this study, we distinguish between different types of arrhythmias and evaluate if their distinction is of clinical importance based on ICU length of stay and mortality outcomes.

METHODS

We performed a retrospective analysis of 215 patients in a community-based teaching hospital medical ICU. Variables gathered include sociodemographic data, arrhythmias identified and interpreted by the study team, and admission diagnoses coded into clinical mediator categories based on theorized common risk pathways. Univariable and multivariable Poisson regression models were used to identify risk factors for developing arrhythmias by type, prolonged length of stay, and hospital mortality.

RESULTS

Significant arrhythmia was detected in 28.8 % of subjects with most new arrhythmia events developing within the first 3 days of ICU stay. Acute myocardial ischemia and acute kidney injury at the time of ICU admission were associated with an increased risk of developing supraventricular arrhythmias (SVA) (RR = 2.02; 95 % CI 1.08-3.78 and RR = 1.93; 95 %CI 1.09-3.37, respectively). SVA in the first 3 days of ICU stay was associated with an increased risk of prolonged ICU stay (RR = 1.47; 95 % CI 1.09-1.97). After controlling for clinical mediators, development of SVA was not independently associated with in-hospital mortality. No mediators significantly increased the risk of developing ventricular arrhythmias (VA). VA were not associated to prolonged ICU stay but were associated with increased risk of hospital mortality (RR = 1.93; 95 % CI 1.18-3.15).

CONCLUSIONS

It is important to distinguish between supraventricular and ventricular arrhythmias for outcomes in the medical ICU setting. Developing a new VA increases the risk of in-hospital mortality independently. Developing a new SVA increases the risk of having a prolonged ICU stay but does not appear to increase in-hospital mortality independently. These findings suggest that the development of a VA should be considered an independent morbid event and not necessarily the end result of a complicated clinical course, while a new SVA may be considered a cardiac complication of the disease continuum which may add complexity to an ICU stay.

The impact of race and postoperative atrial fibrillation on operative mortality after elective coronary artery bypass grafting

OBJECTIVE

Black patients are less likely to develop postoperative atrial fibrillation (POAF) following coronary artery bypass grafting (CABG) than whites. However, the influence of race and POAF on operative mortality has not been examined. The objective of this study was to determine the influence of race and POAF on operative mortality after CABG.

METHODS

Patients undergoing elective CABG between 1992 and 2011 were included. Operative mortality was compared between patients with and those without new-onset POAF by race. Relative risk (RR) and 95% confidence intervals (CI) were computed using Poisson (robust variance estimates) and log-binomial regression models.

RESULTS

A total of 1215 (23%) patients developed POAF (white n=1060; black n=155) following CABG (N=5387). Operative mortality differed by POAF status within race category (white POAF: adjusted RR=1.4, 95% CI=0.86-2.2; black POAF: adjusted RR=5.0, 95% CI=1.9-13; Pinteraction=0.0016). Black POAF patients had a 2-fold increased risk of operative death compared with white POAF patients (Padjusted=0.052).

CONCLUSION

POAF was observed to be a stronger predictor of operative mortality in black compared with white patients undergoing elective CABG.

Untreated preoperative depression is not associated with postoperative arrhythmias in CABG patients

PURPOSE

The mechanism by which depression affects postoperative outcome may involve arrhythmias. The purpose of this study was to evaluate whether untreated depression is associated with an increased incidence of postoperative arrhythmias in patients undergoing coronary artery bypass graft surgery (CABG).

METHODS

One hundred seven patients were assessed for signs of depression with the Prime-MD Patient Health Questionnaire (brief PHQ) one week before surgery and subsequently underwent Holter monitoring for 48-72 hr postoperatively. The incidences of atrial fibrillation (AF); supraventricular tachycardia (SVT); ventricular tachycardia (VT), defined as three or more consecutive beats at a cycle length less than 600 msec; ventricular fibrillation (VF); and average heart rate (HR) were recorded in patients with and without signs of depression.

RESULTS

The incidence of preoperative untreated depression was 27% (29/107). Twenty patients had mild depression (brief PHQ score of 5-9), seven patients had moderate depression (a score of 10-14), and two patients had severe depression (a score of 20). The incidences of postoperative AF, SVT, and non-sustained VT in depressed and non-depressed patients were 37.9% vs 35.9%, respectively (P = 0.50), 34.4% vs 52.5%, respectively (P = 0.07), and 17.2% vs 37.1%, respectively (P = 0.04). The average (SD) postoperative HR was similar in both groups [95 (12) beats·min(-1) in depressed patients and 92 (10) beats·min(-1) in non-depressed patients, (P = 0.25)]. Multivariate regression analysis showed that older age, but not depression, was a risk factor for postoperative arrhythmia.

CONCLUSIONS

Preoperative untreated depression is not related to postoperative arrhythmia in the early postoperative period in patients undergoing elective CABG. This trial was registered at clinicaltrials.gov (number: NCT00622024).

Increased left ventricular myocardial mass is associated with arrhythmias after cardiac surgery

OBJECTIVES

The purpose of this study was to investigate whether patients with an elevated left ventricular mass index undergoing cardiac surgery were more likely to experience postoperative atrial and ventricular arrhythmias.

DESIGN

A retrospective analysis.

SETTING

A single tertiary care university hospital.

PARTICIPANTS

One thousand consecutive patients undergoing all types of adult cardiac surgery.

INTERVENTIONS

With institutional review board approval, intraoperative transesophageal echocardiographic images were reviewed by a single reviewer. The left ventricular mass index was calculated using the American Society of Echocardiography-recommended formula. Medical charts were reviewed for the occurrence and type of clinically significant postoperative arrhythmias.

MEASUREMENTS AND RESULTS

Of the patients who had an elevated left ventricular mass index, 47.6% (225/473) developed clinically significant postoperative arrhythmias compared with 38.3% (142/371) of patients with a normal left ventricular mass index (odds ratio [OR] = 1.46; 95% confidence interval [CI], 1.11-1.93; p = 0.007). In the multivariate analysis, this finding remained statistically significant, controlling for the effects of age, weight, sex, surgery type, left ventricular function, functional status, left atrial dimensions, and a history of atrial fibrillation (OR = 1.40; 95% CI, 1.03-1.90 per 100-g/m(2) increase in the left ventricular mass index). An increased left ventricular mass index was also an independent predictor of the separate or combined occurrence of atrial or ventricular arrhythmias.

CONCLUSIONS

An elevated left ventricular mass index was a strong independent predictor of clinically significant postoperative atrial and ventricular arrhythmias after adult cardiac surgery. Although prospective validation is required, targeting patients for arrhythmia prophylaxis therapy may be justified in patients with a left ventricular mass index >188 g/m(2).

[Repair of congenital heart disease in an adult with septal defects and pulmonary stenosis: anesthetic management]

A 66-year-old man with complex congenital heart defects (atrial septal defects, with incomplete cor triatriatum, an aneurysmal sac in the membranous septum, ventricular communication and pulmonary valve stenosis) was scheduled for surgery for progressive dyspnea even at rest. During anesthetic induction, effort was made to avoid increased shunting. Surgery consisted of resection of the cor triatriatum membrane, closure of communications with pericardial patches, pulmonary valve replacement, replacement of the root with a porcine root, and pulmonary artery aneurysmorrhaphy. Severely decreased contractility developed while the patient was still in the operating room; inotropic support with adrenaline and dobutamine was required. Extubation was completed in the postoperative recovery unit with no further complications. Echocardiography showed a left-ventricular ejection fraction of 45%. We found few published reports of cases of complex congenital heart disease treated surgically in adulthood. In such cases, cardiac pathophysiology must be carefully considered, and maneuvers that increase systemic resistance or right-ventricular ejection fraction should be avoided. Postoperative pulmonary vascular resistance should be kept as low as possible.

Sympathetic overstimulation during critical illness: adverse effects of adrenergic stress

The term ''adrenergic'' originates from ''adrenaline'' and describes hormones or drugs whose effects are similar to those of epinephrine. Adrenergic stress is mediated by stimulation of adrenergic receptors and activation of post-receptor pathways. Critical illness is a potent stimulus of the sympathetic nervous system. It is undisputable that the adrenergic-driven ''fight-flight response'' is a physiologically meaningful reaction allowing humans to survive during evolution. However, in critical illness an overshooting stimulation of the sympathetic nervous system may well exceed in time and scope its beneficial effects. Comparable to the overwhelming immune response during sepsis, adrenergic stress in critical illness may get out of control and cause adverse effects. Several organ systems may be affected. The heart seems to be most susceptible to sympathetic overstimulation. Detrimental effects include impaired diastolic function, tachycardia and tachyarrhythmia, myocardial ischemia, stunning, apoptosis and necrosis. Adverse catecholamine effects have been observed in other organs such as the lungs (pulmonary edema, elevated pulmonary arterial pressures), the coagulation (hypercoagulability, thrombus formation), gastrointestinal (hypoperfusion, inhibition of peristalsis), endocrinologic (decreased prolactin, thyroid and growth hormone secretion) and immune systems (immunomodulation, stimulation of bacterial growth), and metabolism (increase in cell energy expenditure, hyperglycemia, catabolism, lipolysis, hyperlactatemia, electrolyte changes), bone marrow (anemia), and skeletal muscles (apoptosis). Potential therapeutic options to reduce excessive adrenergic stress comprise temperature and heart rate control, adequate use of sedative/analgesic drugs, and aiming for reasonable cardiovascular targets, adequate fluid therapy, use of levosimendan, hydrocortisone or supplementary arginine vasopressin.

The Impact of New-Onset Atrial Fibrillation on In-hospital Mortality Following Cardiac Surgery

BACKGROUND

The impact of new-onset postoperative atrial fibrillation (NAF) on in-hospital mortality (IHM) following cardiac surgery is unknown.

METHODS

All patients without preoperative atrial fibrillation undergoing isolated coronary artery bypass graft surgery (CABG) and concomitant CABG and valve surgery were identified (n = 7,347). The association between NAF and IHM was determined using logistic regression modeling. Also, propensity score analysis was used to create two matched subgroups of patients with and without NAF (n = 2,015 in each group). The secondary outcomes examined were stroke, myocardial infarction (MI), intra-aortic balloon pump use, GI complications, deep sternal wound infection (DSWI), septicemia, renal failure, and length of stay.

RESULTS

NAF developed in 2,047 patients (27.9%). NAF was not an independent predictor of IHM (odds ratio, 0.8; 95% confidence interval, 0.6 to 1.2; p = 0.3). In multivariate analysis, NAF was associated with age >/= 60 years, combined procedures, preoperative MI within 7 days of surgery, COPD, cerebrovascular disease, and male gender. Propensity-adjusted results revealed no difference in IHM between NAF vs no-NAF patients (2.9% vs 3.5%, respectively; Bonferroni-corrected p = 0.99). However, GI complications (4.2% vs 2.1%), DSWI (1.3% vs 0.4%), septicemia (4.0% vs 1.1%), renal failure (7.6% vs 4.3%), and length of stay (8 days vs 6 days) were significantly increased in patients with NAF.

CONCLUSION

NAF following cardiac surgery is not associated with increased IHM.

Do Cardiac Neuropeptides Play a Role in the Occurrence of Atrial Fibrillation After Coronary Bypass Surgery?

BACKGROUND

One of the potential mechanisms to explain the occurrence of postoperative atrial fibrillation (AF) is imbalance of autonomic nervous system tone. The myocardium is innervated not only by cholinergic and adrenergic nerves but also by peptidergic nerves that synthesize and secrete neuropeptides. To investigate the possible role of cardiac neuropeptides in the development of AF after coronary artery bypass grafting (CABG), we analyzed the plasma levels of substance P (SubP), neuropeptide Y (NPY), and angiotensin II (Ang II) in patients who underwent elective on-pump CABG.

METHODS

This prospective study group included 83 consecutive patients scheduled for elective, on-pump CABG. Depressed left ventricular (LV) function (ejection fraction [EF] less than 0.30), concomitant cardiac procedures, history of atrial fibrillation, second or third degree atrioventricular block, implanted pacemaker, postoperative myocardial infarction, use of class I or III antiarrhythmic drug, and hemodynamic deterioration were exclusion criteria. Preoperative and postoperative serum levels of SubP, NPY, and AngII were measured by radioimmunoassay technique.

RESULTS

Postoperative AF occurred in 27 patients (32.5%). Using multivariate logistic regression analyses, only a decrease in SubP level (odds ratio [OR] = 1.87, 95% confidence interval [CI] = 0.767 to 0.99, p = 0.031) and an increase in AngII level (OR = 2.61, 95% CI = 1.002 to 1.021, p = 0.023) after CABG were found to be independently associated with AF. Increased age (p = 0.02), diabetes mellitus (p = 0.023), preoperative use of beta blocker (p = 0.024), proximal right coronary artery involvement (p = 0.024), low preoperative sodium levels (p = 0.023), low LVEF (p = 0.013), and increased mitral E wave deceleration time (p = 0.044) were also associated with AF.

CONCLUSIONS

These results indicate that the increase in AngII and the decrease in SubP after CABG may play a role in the occurrence of postoperative AF. Further studies are needed to define the physiologic and pathologic relevance of these substances at the occurrence of AF in patients who undergo CABG.

Synthesis and biological evaluation of benzopyran analogues bearing class III antiarrhythmic pharmacophores

We have synthesized a series of compounds combining the hydroxy-benzopyran ring of vitamin E with the methylsulfonylaminophenyl group of class III antiarrhythmic drugs, connected through tertiary amine moieties. Evaluation of the antiarrhythmic and antioxidant activity of the new compounds was carried out on isolated rat heart preparations using the non-recirculating Langendorff mode. The new analogues were present, at 10 microM concentration, during ischemia and reperfusion. Selected compounds were further studied by a conventional microelectrode method in order to get insight into their cellular mode of action. The most active compound, N-[4-[2-[[2-(3,4-dihydro-6-hydroxy-2,2,7,8-tetramethyl-2H-1-benzopyran-5-yl)ethyl] methylamine]ethyl]phenyl]methanesulfonamide (19a), reduces premature beats, prolongs QT and QRS intervals during ischemia and reperfusion, and reduces MDA content, leading to a fast recovery of the heart. In addition, it exhibits moderate class III antiarrhythmic action.