Coronary artery disease affecting the atrial branches is an independent determinant of atrial fibrillation after myocardial infarction

High Killips Class as a Predictor of New-onset Atrial Fibrillation Following Acute Myocardial Infarction: Systematic Review and Meta-analysis

BACKGROUND

Recent observational studies have shown that patients with higher Killips score (>I) have higher risk of new-onset atrial fibrillation (NOAF) following acute myocardial infarction (AMI), while others drew a neutral conclusion. The ultimate predictive value of high Killips class on NOAF remained obscure.

METHODS

PubMed, Web of Science, China National Knowledge Infrastructure, and the Cochrane Controlled Trials Register Databases were searched until February 2015. Of the 3732 initially identified studies, 5 observational studies with 10,053 patients were analyzed.

RESULTS

The meta-analysis of these studies showed that higher Killips score on admission was associated with higher incidence of NOAF following AMI (odds ratio = 2.29, 95% confidence interval 1.96-2.67, P < 0.00001), while no significant differences exist among individual trials (P = 0.14 and I2 = 43%).

CONCLUSIONS

Killips class >I was associated with the higher opportunity of developing NOAF following AMI.

Obesity and atrial fibrillation: A comprehensive review of the pathophysiological mechanisms and links

Obesity is a worldwide health problem with epidemic proportions that has been associated with atrial fibrillation (AF). Even though the underlying pathophysiological mechanisms have not been completely elucidated, several experimental and clinical studies implicate obesity in the initiation and perpetuation of AF. Of note, hypertension, diabetes mellitus, metabolic syndrome, coronary artery disease, and obstructive sleep apnea, represent clinical correlates between obesity and AF. In addition, ventricular adaptation, diastolic dysfunction, and epicardial adipose tissue appear to be implicated in atrial electrical and structural remodeling, thereby promoting the arrhythmia in obese subjects. The present article provides a concise overview of the association between obesity and AF, and highlights the underlying pathophysiological mechanisms.

Mechanisms of new-onset atrial fibrillation complicating acute coronary syndrome

Atrial fibrillation (AF) is one of the most common arrhythmia complications of acute coronary syndrome (ACS). The incidence of new-onset AF is 2.3-37 %, and it is an important predictor of a patient's morbidity, mortality, and prolonged hospitalization. Various risk factors for the development of new-onset AF after ACS have been identified, including: old age, higher Killip class, relevant history (e.g., hypertension), and enlarged left atrium. Insights into the pathophysiological mechanisms of new-onset AF have been provided by both experimental and clinical investigations and show that new-onset AF is multifactorial, involving atrial ischemia and atrial stretch, inflammation, autonomic nervous system activity, and hormone activation. An understanding of the mechanisms underlying new-onset AF complicating ACS can provide new insight of therapeutic importance.

Structural and Functional Remodeling of the Left Atrium: Clinical and Therapeutic Implications for Atrial Fibrillation

Atrial fibrillation (AF) is the most commonly encountered arrhythmia in clinical practice. Despite advances in our understanding of the pathophysiology of this complex arrhythmia, current therapeutic options remain suboptimal. This review aimed to delineate the atrial structural and functional remodeling leading to the perpetuation of AF. We explored the complex changes seen in the atria in various substrates for AF and the therapeutic options available to prevent these changes or for reverse remodeling. Here we also highlighted the emerging role of aggressive risk factor management aimed at the arrhythmogenic atrial substrate to prevent or retard AF progression.

Atrial coronary artery occlusion during elective percutaneous coronary angioplasty

BACKGROUND

Atrial arteries arise from the right and left circumflex coronary arteries and they may be accidentally occluded during percutaneous coronary angioplasty; however, this complication is not well known. The aim of our study was to analyze the incidence and risk factors of accidental atrial branch occlusion (ABO) during elective angioplasty.

METHODS AND MATERIALS

Clinical records and coronary angiography of 200 patients undergoing elective angioplasty were retrospectively analyzed. Atrial branches were identified and in each vessel we measured the luminal diameter, flow grade, and the location of atherosclerotic plaques. Patients were allocated either into the ABO group if atrial branch flow fell from TIMI grades 2-3 to 0-1 after procedure or in the non-ABO group if TIMI flow was preserved.

RESULTS

Atrial branch occlusion occurred in 43 (21.5%) patients. The atrial branch diameter was larger in non-ABO than in ABO group (1.29mm, SD 0.33 versus 0.97mm, SD 0.22, p=<0.0001). Plaques at atrial branch origin were present in 93% of ABO group, only in 31.8% of non-ABO (p≤0.0001). Predictors of ABO were a cut-off vessel diameter of 1.00mm (ROC 77% sensitivity and 67.5% specificity, p≤0.0001), the presence of atherosclerotic plaque at the ostium of atrial branch and maximal inflation pressure during stenting.

CONCLUSIONS

The occurrence of ABO is frequent after elective angioplasty of right or circumflex coronary arteries in an experienced interventional center. Risk factors were the diameter and the presence of ostial plaques in the atrial branches, and the maximal inflation pressure during stenting.

Myocardial infarction and atrial fibrillation: importance of atrial ischemia

BACKGROUND

Myocardial infarction (MI) is associated with the development of atrial fibrillation (AF). We aimed to characterize the atrial abnormalities because of MI and determine the role of ischemia to the AF substrate.

METHODS AND RESULTS

Forty-four sheep were studied. MI was induced by occlusion of the left circumflex artery (LCX) or left anterior descending artery (LAD). Excluding 11 with fatal arrhythmias, equal groups of animals (LCX; LAD; and sham-operated) underwent sequential electrophysiology study for 45 minutes to determine atrial effective refractory periods, conduction velocity, conduction heterogeneity index, and AF inducibility. Postmortem evaluation was performed with 2,3,5 triphenyl tetrazolium chloride staining. MI resulted in greater left ventricular dysfunction (P<0.05), LA pressure (P<0.0003), and reduction in atrial effective refractory periods (P<0.0001) compared with control. 2,3,5 triphenyl tetrazolium chloride staining demonstrated that the left circumflex artery, and not the LAD, group had atrial infarction. The left circumflex artery group demonstrated the following compared with the LAD or control groups: greater slowing in atrial conduction velocity (P<0.0001 and P<0.001); increased absolute range of conduction phase delay (P<0.001 and P<0.001); increased conduction heterogeneity index (P<0.0001 and P<0.001); greater AF vulnerability (P<0.05 for both); and longer AF duration (P<0.05 for both). LAD group had modest but significant slowing in conduction velocity (P<0.01) but no change in conduction heterogeneity index or AF duration compared with control.

CONCLUSIONS

Left ventricular infarction, which is known to result in atrial stretch, hemodynamic change, and neurohumoral activation, contributes partially to the atrial abnormalities in MI. Atrial ischemia/infarction results in greater atrial electrophysiological changes and propensity for AF forming the dominant substrate for AF in MI.

Acute regional left atrial ischemia causes acceleration of atrial drivers during atrial fibrillation

BACKGROUND

The mechanisms by which acute left atrial ischemia (LAI) leads to atrial fibrillation (AF) initiation and perpetuation remain unclear.

OBJECTIVE

To investigate the electrophysiological mechanisms of AF perpetuation in the presence of regional atrial ischemia.

METHODS

LAI (90-minute ischemia) was obtained in isolated sheep hearts by selectively perfusing microspheres into the left anterior atrial artery. Two charge-coupled device cameras and several bipolar electrodes enabled recording from multiple atrial locations: with a dual-camera setup (protocol 1, n = 10, and protocol 1', n = 4, for biatrial or atrioventricular camera setups, respectively), in the presence of propranolol/atropine (1 μM) added to the perfusate after LAI (protocol 2, n = 3) and after a pretreatment with glibenclamide (10 μM; protocol 3, n = 4).

RESULTS

Spontaneous AF occurred in 41.2% (7 of 17) of the hearts that were in sinus rhythm before LAI. LAI caused action potential duration shortening in both the ischemic (IZ) and nonischemic (NIZ) zones by 21% ± 8% and 34% ± 13%, respectively (pacing, 5 Hz; P<.05 compared to baseline). Apparent impulse velocity was significantly reduced in the IZ but not in the NIZ (-65% ± 19% and 9% ± 18%; P = .001 and NS, respectively). During LAI-related AF, a significant NIZ maximal dominant frequency increase from 7.4 ± 2.5 to 14.0 ± 5.5 Hz (P<.05) was observed. Glibenclamide, an ATP-sensitive potassium current (IKATP) channel blocker, averted LAI-related maximal dominant frequency increase (NIZ: LAI vs glibenclamide 14.0 ± 5.5 Hz vs 5.9 ± 1.3 Hz; P<.05). An interplay between spontaneous focal discharges and rotors, locating at the IZ-NIZ border zone, maintained LAI-related AF.

CONCLUSIONS

LAI leads to an IKATP conductance-dependent action potential duration shortening and spontaneous AF maintained by both spontaneous focal discharges and reentrant circuits locating at the IZ border zone.

Mechanisms of ranolazine's dual protection against atrial and ventricular fibrillation

Coronary artery disease and heart failure carry concurrent risk for atrial fibrillation and life-threatening ventricular arrhythmias. We review evidence indicating that at therapeutic concentrations, ranolazine has potential for dual suppression of these arrhythmias. Mechanisms and clinical implications are discussed.

Impact of Atrial Fibrillation On Cardiovascular Mortality in the Setting of Myocardial Infarction

Atrial fibrillation (AF) commonly occurs in patient with acute myocardial infarction (AMI). Potential triggers for AF development in this setting includes reduced left ventricular function, advanced diastolic dysfunction and mitral regurgitation leading to elevated left atrial pressures and atrial stretch. Other triggering mechanisms include inflammation and atrial ischemia. Multiple studies have shown that AF in patients with is associated with increased mortality. However, whether AF is a risk marker or a causal mediator of death remains controversial. There is relative dearth of data with regard to optimal management of AF in the setting of acute coronary syndromes. Patients with AMI who develop AF are at increased risk of stroke. However, the issue of the most appropriate antithrombotic regimens is complex given the need to balance stroke prevention against recurrent coronary events or stent thrombosis and the risk of bleeding. Presently, 'triple therapy' consisting of dual antiplatelet agents plus oral anticoagulants for 3-6 months or longer has been recommended for patients at moderate-high risk of stroke. Atrial fibrillation (AF), the most common sustained arrhythmia seen in clinical practice, often coincides with acute myocardial infarction (AMI), with a reported incidence ranging between 7% and 21%.[1] The development of atrial fibrillation in the acute phase of AMI may aggravate ischemia and heart failure, lead to clinical instability and adversely affect outcome. In the following we will review the pathophysiology, clinical characteristics and importance, and management of AF occurring in the setting of AMI.

Rescue pulmonary vein isolation for hemodynamically unstable atrial fibrillation storm in a patient with an acute extensive myocardial infarction

Background

New-onset atrial fibrillation in patients hospitalized for an acute myocardial infarction often leads to hemodynamic deterioration and has serious adverse prognostic implications; mortality is particularly high in patients with congestive heart failure and/or a reduced left ventricular ejection fraction. The mechanism of atrial fibrillation in the context of an acute myocardial infarction has not been well characterized and an effective treatment other than optimal medical therapy and mechanical hemodynamic support are expected.

Case presentation

A 71 year-old male with an acute myocardial infarction due to an occlusion of the left main coronary artery was treated with percutaneous coronary intervention. He had developed severe congestive heart failure with a left ventricular ejection fraction of 34%. The systemic circulation was maintained with an intraaortic balloon pump, continuous hemodiafiltration, and mechanical ventilation until atrial fibrillation occurred on day 3 which immediately led to cardiogenic shock. Because atrial fibrillation was refractory to intravenous amiodarone, beta-blockers, and a total of 15 electrical cardioversions, the patient underwent emergent radiofrequency catheter ablation on day 4. Soon after electrical cardioversion, ectopies from the right superior pulmonary vein triggered the initiation of atrial fibrillation. The right pulmonary veins were isolated during atrial fibrillation. Again, atrial fibrillation was electrically cardioverted, then, sinus rhythm was restored. Subsequently, the left pulmonary veins were isolated. The stabilization of the hemodynamics was successfully achieved with an increase in the blood pressure and urine volume. Hemodiafiltration and amiodarone were discontinued. The patient had been free from atrial fibrillation recurrence until he suddenly died due to ventricular fibrillation on day 9.

Conclusions

To the best of our knowledge, this is the first report of pulmonary vein isolation for a rescue purpose applied in a patient with hemodymically unstable atrial fibrillation complicated with an acute myocardial infarction. This case demonstrates that ectopic activity in the pulmonary veins may be responsible for triggering atrial fibrillation in the critical setting of an acute myocardial infarction and thus pulmonary vein isolation could be an effective therapeutic option.

Atrial Fibrillation in Acute Coronary Syndrome

Atrial fibrillation (AF) is a common cardiac arrhythmia occurring in an estimated 2.7 to 6.1 million people in the United States. The risk factors for the development of AF are very similar to those for developing coronary artery disease, and AF is often associated with acute coronary syndrome (ACS) and acute myocardial infarction (MI). Overall, AF complicates approximately 10% of acute infarcts and the incidence rate is comparable between the thrombolytic and percutaneous coronary intervention (PCI) eras. Prior to widespread use of thrombolysis, the incidence of AF during acute MI was as high as 18%. Moreover, AF is a marker for increased long term mortality post infarct. Over the past 20 years, the relative mortality risk for patients with AF post MI has remained around 2.5 times that for patients without AF. The treatment of AF in the setting of MI and ACS is similar to without; however there is often an increased urgency to limiting rapid heart rates which may exacerbate acute ischemia. Cardioversion and IV amiodarone may be utilized more liberally in this setting than otherwise. Anticoagulation is usually required both for the treatment of MI and possible PCI, as well as for cerebral vascular accident prevention from AF-induced thromboembolism. Often patients require triple-therapy for optimal treatment of both conditions, and special considerations for bleeding risk must be analyzed.

Stroke and Death Prediction with the Impact of Vascular Disease in Patients with Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia encountered in the U.S. and the growing burden of AF has profound health implications due to the association of AF with an increased risk of stroke, heart failure, and mortality. AF is a significant risk factor for thromboembolic stroke; and also independently increases total mortality in patients with and without cardiovascular disease. Various risk stratification schemes such as CHADS₂ and CHA₂DS₂-VASc have been implemented in clinical practice to determine the risk of cardio-embolic stroke, and need for thrombo-prophylaxis in patients with AF. AF is also closely related to the pathophysiology of other cardiovascular and peripheral vascular disease. Many patients with AF have associated atherosclerosis given that many risk factors for atherosclerosis also predispose to AF. Myocardial infarction (MI) is also closely related to AF and its clinical course is affected by new onset AF. This review elucidates the impact of AF on major adverse cardiovascular events and mortality outcomes in relation to stroke, coronary artery disease and peripheral vascular disease.

Clinical significance of atrial fibrillation after myocardial infarction

Atrial fibrillation (AF) is a common complication of acute myocardial infarction (AMI) and has been associated with increased risk of mortality, heart failure and stroke. In this article, we evaluate a recent publication investigating the relationship between new-onset AF and clinical outcome after AMI in a community-based cohort. This study shows that the occurrence of AF portends increased risk for mortality after AMI. The findings are discussed in the context of current knowledge on the clinical implications and treatment strategies of AF in the setting of acute coronary syndromes.

Activated inflammation is related to the incidence of atrial fibrillation in patients with acute myocardial infarction

OBJECTIVE

The purpose of this study was to investigate the relationship between the new onset of atrial fibrillation (AF) and inflammation in the early phase of acute myocardial infarction (AMI). Background Serial interaction between inflammation and the incidence of AF is not fully understood in the early phase of AMI.

METHODS

Two hundred fifty-nine consecutive patients with AMI were studied. electrocardiogram monitoring was recorded continuously for >7 days. Serial inflammation markers, cardiac enzymes, coronary angiogram and echocardiography were obtained in all patients.

RESULTS

One hundred seventy-six patients were enrolled. AF was present in 24 patients (14%), and occurred on day 2.7 ± 1.4 after admission. Serial measurements of WBC and C-reactive protein (CRP) with/without AF were as follows. WBC levels of day 5-7 were 9.3 ± 3.5 vs. 7.5 ± 2.4 × 10(3)/µL, p=0.04, and CRP levels of day 2-4, 5-7, 8-14 were 12.6 ± 9.4 vs. 4.7 ± 5.3 mg/dL, p<0.001, 12.3 ± 10.4 vs. 5.2 ± 5.2 mg/dL, p=0.01, and 8.5 ± 7.7 vs. 2.7 ± 4.2 mg/dL, p=0.005, respectively. Those were significantly higher in the patients with AF. In multivariate logistic regression analysis, CRP levels of day 2-4 were independently higher in the patients with AF (odds ratio (OR) 1.15, 95% confidence (CI) 1.04-1.27).

CONCLUSION

AF in the early phase of AMI occurs a few days after the onset of AMI, which is independently related to the activated inflammation. AF in this period persists for only a short duration.

Coronary artery disease potentiates response to dofetilide for rhythm control of atrial fibrillation

BACKGROUND

Dofetilide, a class III antiarrhythmic, is one of the few alternatives to amiodarone in patients with atrial fibrillation (AF) and heart failure or coronary artery disease (CAD). While amiodarone has been extensively studied, little is known about predictors of response to dofetilide. We sought to identify clinical parameters associated with dofetilide success in a large cohort of patients with AF.

METHODS/RESULTS

A total of 287 patients with AF started on dofetilide between 2001 and 2008 were included. Dofetilide was deemed "completely effective" if the patient remained on dofetilide at follow-up and had no recurrences of AF clinically or by electrocardiogram. Dofetilide efficacy was analyzed in relation to clinical variables relevant to AF and AF recurrence. After a follow-up of 10.2 ± 7.7 months, 54.7% of the patients remained on dofetilide and it was completely effective in 26.8%. The discontinuation rate during initial hospitalization was 13.3% from excessive QT prolongation and one patient with torsades de pointes (successfully treated). A history of CAD was the only univariate predictor of efficacy (odds ratio [OR] 2.27, 95% confidence interval [CI] 1.29-4.01, P < 0.05). CAD remained the only significant factor associated with efficacy of dofetilide in a multivariate regression model (OR 2.01, 95% CI 1.11-3.70, P < 0.05, n = 270). The overall efficacy of dofetilide in patients with CAD was 41.1%, compared to 23.5% in those without CAD (P < 0.05).

CONCLUSIONS

In this large cohort of patients with AF, underlying coronary disease was significantly associated with dofetilide success. This finding may have utility for clinical decisions regarding initiation of dofetilide.