Early atrial arrhythmias in acute myocardial infarction. Role of the sinus node artery

Acute atrial infarction: a relatively neglected and under-recognized entity in clinical practice

BACKGROUND

Electrocardiograms (ECGs) and angiographic features indicative of acute atrial infarction (AAI) often go unnoticed and are under-recognized in clinical practice.

METHODS

In this retrospective observational study, we analyzed the data of 3981 out of 9803 patients (40.61%) who were referred to our hospital for angiography and/or percutaneous coronary intervention due to acute coronary syndrome (ACS). These patients were diagnosed with acute ST segment elevation myocardial infarction (AMI) affecting the inferior, posterior, and/or right ventricular regions.

RESULTS

Of the 3981 patients, 270 (6.78%) had involvement of the main coronary atrial branch meeting the angiographic criteria for AAI. Among the 270 patients identified, the right coronary artery was diagnosed as the infarct-related artery (IRA) in 187 patients (group R), while the left circumflex artery was the IRA in 83 patients (group L). The incidence of PR-segment deviation was similar between the two groups (65.2% in group R vs. 66.3% in group L, p = 0.870), as was occurrence of atrial tachyarrhythmia (67.4% vs. 55.4%, p = 0.059). The prevalence of P wave morphology abnormalities (29.9% vs. 49.4%, p = 0.005) and sinus bradycardia or arrest (25.1% vs. 66.3%, p < 0.001) was significantly lower in Group R than in Group L.

CONCLUSION

Acute atrial infarction represents a distinct yet frequently overlooked clinical entity. Clinicians should consider the potential for atrial arrhythmias, thromboembolism, hemodynamic instability, and atrial rupture when diagnosing AAI.

Association of lipopolysaccharide with new-onset atrial fibrillation in ST-segment elevation myocardial infarction

Background

Lipopolysaccharide (LPS) is related to various cardiovascular diseases. However, the relationship between LPS and new-onset atrial fibrillation (NOAF) after ST-segment elevation myocardial infarction (STEMI) has yet to be elucidated. This study aimed to evaluate the impact of LPS on NOAF in STEMI patients.

Methods

This was a single-center retrospective observational study including 806 patients diagnosed with STEMI. LPS levels were determined using a commercial ELISA kit. NOAF was characterized by postadmission AF with the absence of any prior history of AF.

Results

A total of 806 participants were enrolled, with 752 individuals in the non-AF group (93.3%) and 54 individuals in the AF group (6.7%). Multivariable analysis showed that LPS (OR = 1.047; 95% CI: 1.029-1.065, P < 0.001) was an independent risk marker for NOAF. The analysis of the ROC demonstrated that LPS had an AUC of 0.717 in predicting NOAF. When LPS was added to the conventional model, the ability of the risk model to discriminate and reclassify NOAF was improved significantly (IDI 0.053, P = 0.001; NRI 0.510, P < 0.001).

Conclusion

Elevated LPS is associated with an increased risk of NOAF in STEMI patients. The integration of LPS can improve the ability to predict NOAF in STEMI patients.

The role of miR1 and miR133a in new-onset atrial fibrillation after acute myocardial infarction

BACKGROUND

The development of new-onset atrial fibrillation (NOAF) after acute myocardial infarction (AMI) is a clinical complication that requires a better understanding of the causative risk factors. This study aimed to explore the risk factors and the expression and function of miR-1 and miR-133a in new atrial fibrillation after AMI.

METHODS

We collected clinical data from 172 patients with AMI treated with emergency percutaneous coronary intervention (PCI) between October 2021 and October 2022. Independent predictors of NOAF were determined using binary logistic univariate and multivariate regression analyses. The predictive value of NOAF was assessed using the area under the receiver operating characteristic (ROC) curve for related risk factors. In total, 172 venous blood samples were collected preoperatively and on the first day postoperatively; the expression levels of miR-1 and miR-133a were determined using the polymerase chain reaction. The clinical significance of miR-1 and miR-133a expression levels was determined by Spearman correlation analysis.

RESULTS

The Glasgow prognostic score, left atrial diameter, and infarct area were significant independent risk factors for NOAF after AMI. We observed that the expression levels of miR-1 and miR-133a were significantly higher in the NOAF group than in the non-NOAF group. On postoperative day 1, strong associations were found between miR-133a expression levels and the neutrophil ratio and between miR-1 expression levels and an increased left atrial diameter.

CONCLUSIONS

Our findings indicate that the mechanism of NOAF after AMI may include an inflammatory response associated with an increased miR-1-related mechanism. Conversely, miR-133a could play a protective role in this clinical condition.

Hypertension and Arrhythmias: A Clinical Overview of the Pathophysiology-Driven Management of Cardiac Arrhythmias in Hypertensive Patients

Because of demographic aging, the prevalence of arterial hypertension (HTN) and cardiac arrhythmias, namely atrial fibrillation (AF), is progressively increasing. Not only are these clinical entities strongly connected, but, acting with a synergistic effect, their association may cause a worse clinical outcome in patients already at risk of ischemic and/or haemorrhagic stroke and, consequently, disability and death. Despite the well-known association between HTN and AF, several pathogenetic mechanisms underlying the higher risk of AF in hypertensive patients are still incompletely known. Although several trials reported the overall clinical benefit of renin–angiotensin–aldosterone inhibitors in reducing incident AF in HTN, the role of this class of drugs is greatly reduced when AF diagnosis is already established, thus hinting at the urgent need for primary prevention measures to reduce AF occurrence in these patients. Through a thorough review of the available literature in the field, we investigated the basic mechanisms through which HTN is believed to promote AF, summarising the evidence supporting a pathophysiology-driven approach to prevent this arrhythmia in hypertensive patients, including those suffering from primary aldosteronism, a non-negligible and under-recognised cause of secondary HTN. Finally, in the hazy scenario of AF screening in hypertensive patients, we reviewed which patients should be screened, by which modality, and who should be offered oral anticoagulation for stroke prevention.

Atrial Branch Coronary Artery Stenosis as a Mechanism for Atrial Fibrillation

BACKGROUND

The etiology of atrial fibrillation (AF) is multifactorial and incompletely understood.

OBJECTIVE

Evaluate the association between coronary artery disease (CAD) affecting atrial tissue and AF.

METHODS

Patients from a single center with obstructive CAD during cardiac catheterization (1/12007-12/1/2013) were included in a matched case-control analysis, based on the presence or absence of new-onset AF within 12 months post-catheterization. Quantitative measurements of stenosis severity were performed for sinoatrial (SA) nodal artery, atrioventricular (AV) nodal artery, and right intermediate atrial artery (RIAA), as well as the right coronary, left circumflex, and left anterior descending proximal to the take-off for each atrial-level artery. A multivariable logistic regression model identified factors associated with AF.

RESULTS

Among 1,794 patients, 115 (6%) developed AF within 1-year post-catheterization. The matched cohort included 110 patients with and 110 patients without AF within 12 months post-catheterization. Higher odds of AF at 1 year were associated with increasing lesion stenosis severity in the RIAA (OR 1.41 per 10% increase >50%, 95% CI 1.01-1.97, p=0.047) and AV nodal artery (OR 1.58 per 10% increase >50%, 95% CI 1.00-2.49, p=0.050). Odds of AF diagnosis during the year post-catheterization increased with the number of atrial arteries with >50% lesion (OR 1.53 for each additional artery, 95% CI 1.08-2.15, p=0.015).

CONCLUSIONS

Among patients with obstructive CAD, disease of the AV nodal artery and RIAA, as well as higher burden of CAD within all arteries supplying blood flow to the atrial myocardium were associated with higher odds of new-onset AF at 1 year.

Acute atrial ischemia associates with early but not late new-onset atrial fibrillation in STEMI patients treated with primary PCI: relationship with in-hospital outcomes

BACKGROUND

New-onset atrial fibrillation (NOAF), both early (EAF) or late (LAF), may complicate ST-segment elevation myocardial infarction (STEMI). The mechanisms underlying EAF or LAF are poorly described. We investigated atrial branch occlusion and EAF or LAF onset in STEMI patients undergoing primary percutaneous coronary intervention.

METHODS

This was a retrospective cohort study including 155 STEMI patients. Patients were divided into 3 groups: sinus rhythm (SR), EAF, or LAF. Clinical characteristics, angiographic features including occlusion of atrial branches, namely ramus ostia cavae superioris (ROCS), atrio-ventricular node artery (AVNA), right intermediate atrial artery (RIAA), and left intermediate atrial artery, were assessed. We also investigated in-hospital adverse events (AEs) and death.

RESULTS

Mean age was 63.8±11.9 years; 78.7% were men. NOAF was detected in 22 (14.2%) patients: 10 (6.4%) EAF and 12 LAF (7.7%). Compared to EAF, LAF patients were older (p=0.013), with higher GRACE risk score (p=0.014) and Killip class (p=0.015), depressed ejection fraction (p=0.007), elevated filling pressures (p=0.029), higher C-reactive protein (p=0.014) and more with thrombolysis in myocardial infarction flow <3 (p=0.015). Compared to SR, EAF was associated with higher prevalence of occluded ROCS (p=0.010), AVNA (p=0.005), and RIAA (p<0.001). Moreover, EAF patients had more frequently ≥2 diseased atrial branches than SR (19.5%, p<0.001) and LAF (25%, p<0.030) patients. LAF patients had a higher in-hospital AEs (p=0.019 vs SR; p=0.029 vs EAF) and death (p=0.004 vs SR).

CONCLUSIONS

The occlusion of atrial branches is associated with EAF but not LAF following STEMI. LAF patients had worse in-hospital AEs and mortality.

The relation between the atrial blood supply and the complexity of acute atrial fibrillation

Background

Patients with a history of myocardial infarction and coronary artery disease (CAD) have a higher risk of developing AF. Conversely, patients with atrial fibrillation (AF) have a higher risk of developing myocardial infarction, suggesting a link in underlying pathophysiology. The aim of this study was to assess whether coronary angiographic parameters are associated with a substrate for AF in patients without a history of AF.

Methods

During cardiac surgery in 62 patients (coronary artery bypass grafting (CABG;n = 47), aortic valve replacement (AVR;n = 9) or CABG + AVR (n = 6)) without a history of clinical AF (age 65.4 ± 8.5 years, 26.2% female), AF was induced by burst pacing. The preoperative coronary angiogram (CAG) was assessed for the severity of CAD, and the adequacy of atrial coronary blood supply as quantified by a novel scoring system including the location and severity of right coronary artery disease in relation to the right atrial branches. Epicardial mapping of the right atrium (256 unipolar electrodes) was used to assess the complexity of induced AF.

Results

There was no association between the adequacy of right atrial coronary blood supply on preoperative CAG and AF complexity parameters. Multivariable analysis revealed that only increasing age (B0.232 (0.030;0.433),p = 0.03) and the presence of 3VD (B3.602 (0.187;7.018),p = 0.04) were independently associated with an increased maximal activation time difference.

Conclusions

The adequacy of epicardial right atrial blood supply is not associated with increased complexity of induced atrial fibrillation in patients without a history of clinical AF, while age and the extent of ventricular coronary artery disease are.

New-Onset Atrial Fibrillation in St-Segment Elevation Myocardial Infarction: Predictors and Impact on Therapy And Mortality

Backgrund

New-onset atrial fibrillation complicating acute myocardial infarction represents an important challenge, with prognostic significance.

Objective

To study the incidence, impact on therapy and mortality, and to identify predictors of development of new-onset atrial fibrillation during hospital stay for ST-segment elevation myocardial infarction.

Methods

We studied all patients with ST-elevation myocardial infarction included consecutively, between 2010 and 2017, in a Portuguese national registry and compared two groups: 1 - no atrial fibrillation and 2 - new-onset atrial fibrillation. We adjusted a logistic regression model data analysis to assess the impact of new-onset atrial fibrillation on in-hospital mortality and to identify independent predictors of its development. A p value < 0.05 was considered significant.

Results

We studied 6325 patients, and new-onset atrial fibrillation was found in 365 (5.8%). Reperfusion was successfully accomplished in both groups with no difference regarding type of reperfusion. In group 2, therapy with beta-blockers and angiotensin-conversion enzyme (ACE) inhibitors/angiotensin receptor blockers (ARBs) was less frequent, 20.6% received anticoagulation at discharge and 16.1% were on triple therapy. New-onset atrial fibrillation was associated with more in-hospital complications and mortality. However, it was not found as an independent predictor of in-hospital mortality. We identified age, prior stroke, inferior myocardial infarction and complete atrioventricular block as independent predictors of new-onset atrial fibrillation.

Conclusion

New-onset atrial fibrillation remains a frequent complication of myocardial infarction and is associated with higher rate of complications and in-hospital mortality. Age, prior stroke, inferior myocardial infarction and complete atrioventricular block were independent predictors of new onset atrial fibrillation. Only 36.7% of the patients received anticoagulation at discharge.

Procedural-related coronary atrial branch occlusion during primary percutaneous coronary intervention for ST-segment elevation myocardial infarction and atrial arrhythmias at follow-up

OBJECTIVES

To evaluate the frequency of procedural-related atrial branch occlusion in ST-segment elevation myocardial infarction (STEMI) patients and its association with atrial arrhythmias at 1-year follow-up.

BACKGROUND

Atrial ischemia due to procedural-related coronary atrial branch occlusion in elective percutaneous coronary intervention (PCI) has been associated with atrial arrhythmias. Its role in a STEMI scenario is unknown.

METHODS

STEMI patients treated with primary PCI were classified according to the loss or patency of an atrial branch at the end of the procedure. The occurrence of atrial arrhythmias was documented on 24-hr Holter-ECG at 3 and 6 months or on ECG during 1-year follow-up visits.

RESULTS

Of 900 patients, 355 (age 61 ± 12 years, 79% male) underwent primary PCI involving the origin of an atrial branch. Procedural-related coronary atrial branch occlusion was observed in 18 (5%) individuals). During 1-year follow-up, 33% of patients with procedural-related atrial branch occlusion presented atrial arrhythmias, as compared with 55% in those with a patent atrial branch (p = .088). Age, no previous history of myocardial infarction, and a reduced flow in the culprit vessel were the only independent correlates of atrial arrhythmias.

CONCLUSIONS

The frequency of procedural-related atrial branch occlusion during primary PCI is low (5%) and is not associated with increased frequency of atrial arrhythmias at 1-year follow-up.

Contemporary practice pattern of permanent pacing for conduction disorders in inferior ST-elevation myocardial infarction

BACKGROUND

Currently, there is no clear consensus regarding the optimal waiting period before permanent pacemaker implantation in patients with conduction disorders following an inferior myocardial infarction.

HYPOTHESIS

We aimed to elucidate the contemporary practice pattern of pacing, especially the timing of pacemaker implantation, for sinoatrial node and atrioventricular (AV) conduction disorders following an inferior ST-elevation myocardial infarction (STEMI).

METHODS

Using the National Inpatient Sample database from 2010 to 2014, we identified patients with a primary diagnosis of inferior STEMI. Primary conduction disorders were classified into: (a) high-degree AV block (HDAVB) consisting of complete AV block or Mobitz-type II second-degree AV block, (b) sinoatrial node dysfunction (SND), and (c) no major conduction disorders.

RESULTS

Among 66 961 patients, 2706 patients (4.0%) had HDAVB, which mostly consisted of complete AV block (2594 patients). SND was observed in 393 patients (0.6%). Among the 2706 patients with HDAVB, 267 patients (9.9%) underwent permanent pacemaker. In patients with HDAVB, more than one-third (34.9%) of permanent pacemakers were placed within 72 hours after admission. The median interval from admission to permanent pacemaker implantation was 3 days (interquartile range; 2-5 days) for HDAVB vs 4 days (3-6 days) for SND (P < .001). HDAVB was associated with increased in-hospital mortality, whereas SND was not.

CONCLUSIONS

In patients who developed HDAVB following an inferior STEMI, only one in 10 patients underwent permanent pacemaker implantation. Despite its highly reversible nature, permanent pacemakers were implanted relatively early.

Cardiac computed tomography in patients with symptomatic new-onset atrial fibrillation, rule-out acute coronary syndrome, but with intermediate pretest probability for coronary artery disease admitted to a chest pain unit

Background

Atrial fibrillation (AF) and coronary artery disease (CAD) may be encountered coincidently in a large portion of patients. However, data on coronary artery calcium burden in such patients are lacking. Thus, we sought to determine the value of cardiac computed tomography (CCT) in patients presenting with new-onset AF associated with an intermediate pretest probability for CAD admitted to a chest pain unit (CPU).

Methods

Calcium scores (CS) of 73 new-onset, symptomatic AF subjects without typical clinical, electrocardiographic, or laboratory signs of acute coronary syndrome (ACS) admitted to our CPU were analyzed. In addition, results from computed tomography angiography (CTA) were related to coronary angiography findings whenever available.

Results

Calcium scores of zero were found in 25%. Median Agatston score was 77 (interquartile range: 1–270) with gender- and territory-specific dispersal. CS scores above average were present in about 50%, high (> 400)-to-very high (> 1000) CS scores were found in 22%. Overall percentile ranking showed a relative accordance to the reference percentile distribution. Additional CTA was performed in 47%, revealing stenoses in 12%. Coronary angiography was performed in 22% and resulted in coronary intervention or surgical revascularization in 7%. On univariate analysis, CS > 50th percentile failed to serve as an independent determinant of significant stenosis during catheterization.

Conclusions

Within a CPU setting, relevant CAD was excluded or confirmed in almost 50%, the latter with a high proportion of coronary angiographies and subsequent coronary interventions, underlining the diagnostic value of CCT in symptomatic, non-ACS, new-onset AF patients when admitted to a CPU.

Mechanism underlying impaired cardiac pacemaking rhythm during ischemia: A simulation study

Ischemia in the heart impairs function of the cardiac pacemaker, the sinoatrial node (SAN). However, the ionic mechanisms underlying the ischemia-induced dysfunction of the SAN remain elusive. In order to investigate the ionic mechanisms by which ischemia causes SAN dysfunction, action potential models of rabbit SAN and atrial cells were modified to incorporate extant experimental data of ischemia-induced changes to membrane ion channels and intracellular ion homeostasis. The cell models were incorporated into an anatomically detailed 2D model of the intact SAN-atrium. Using the multi-scale models, the functional impact of ischemia-induced electrical alterations on cardiac pacemaking action potentials (APs) and their conduction was investigated. The effects of vagal tone activity on the regulation of cardiac pacemaker activity in control and ischemic conditions were also investigated. The simulation results showed that at the cellular level ischemia slowed the SAN pacemaking rate, which was mainly attributable to the altered Na+-Ca2+ exchange current and the ATP-sensitive potassium current. In the 2D SAN-atrium tissue model, ischemia slowed down both the pacemaking rate and the conduction velocity of APs into the surrounding atrial tissue. Simulated vagal nerve activity, including the actions of acetylcholine in the model, amplified the effects of ischemia, leading to possible SAN arrest and/or conduction exit block, which are major features of the sick sinus syndrome. In conclusion, this study provides novel insights into understanding the mechanisms by which ischemia alters SAN function, identifying specific conductances as contributors to bradycardia and conduction block.

The atherosclerosis of the sinus node artery is associated with an increased history of supra-ventricular arrhythmias: a retrospective study on 541 standard coronary angiograms

Background. The ischemic damage of the sinus node (SN) is a well known cause of cardiac arrhythmias and can be a consequence of any flow abnormality in the sinus node artery (SNA). Accordingly we aimed this retrospective study to: (1) evaluate the suitability of the standard coronary angiography to study the SNA and (2) determine if the percentage of subjects with a positive retrospective history of supra-ventricular arrhythmias (SVA) differs in patients with normal and diseased SNA ascertained at the time of coronary angiography.

Methods and Results. Out of the 541 coronary angiograms reviewed the SNA was visible for its entire course in 486 cases (89.8%). It was found to arise from the right side of the coronary circulation in 266 cases (54.7%) slightly more often than from the left, 219 cases (45.1%). One patient had 2 distinct SNA arising from either side of the coronary circulation. For the second objective, we studied the 333 patients with: (a) coronary artery disease (CAD), (b) properly evaluable SNA and (c) complete clinical history available. In 51 (15.3%) a SNA disease was found, 41.2% of them had a positive SVA history, mainly atrial fibrillation (AF), whereas only 7.4% of patients with a positive history of SVA could be found in the non-SNA diseased. This difference was statistically significant (P < 0.001).

Conclusions. (1) The evaluation of the SNA is feasible in clinical practice during a standard coronary angiography; (2) this may be relevant since angiographically detectable SNA disease was significantly associated with a positive history of SVA.

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.

Atrial fibrillation in acute ST-elevation myocardial infarction: clinical and prognostic features

Atrial fibrillation (AF) is a common arrhythmia in the setting of acute coronary syndrome and acute ST-elevation myocardial infarction (STEMI). This review summarizes recent evidence on the clinical and prognostic significance of pre-existent and new-onset AF in acute STEMI patients and highlights new emerging predictors of AF development in the era of contemporary treatment.

Atrial Fibrillation Complicating Acute Coronary Syndromes

Atrial fibrillation frequently complicates myocardial infarction. Patients with atrial fibrillation complicating acute coronary syndrome have increased morbidity and mortality relative to patients that remain in normal sinus rhythm. No studies have identified a mortality benefit to rhythm control compared with rate control in the setting of acute coronary syndrome. Stroke prevention should be pursued with oral anticoagulation therapy, although the majority of patients with atrial fibrillation associated with acute coronary syndrome receive only antiplatelet therapy. There are several novel oral anticoagulant therapies now available, but these agents have not been well studied in combination with dual antiplatelet therapy. Therefore, warfarin as part of triple therapy is the most conservative approach until additional data becomes available.

Arrhythmias in the coronary care unit

Symptomatic sustained cardiac arrhythmias are frequently observed in in the coronary care unit and often lead to hemodynamic compromise, especially in the presence of multisystem disease. The predominant arrhythmias noted in intensive care units are tachyarrhythmias, particularly atrial fibrillation and flutter, and ventricular tachycardia. Bradycardias, arguably less life-threatening than tachyarrhythmias, can arise from sinus node dysfunction or atrioventricular conduction block; transient vagally-mediated bradycardias are frequently encountered as well. Prompt diagnosis of the patient with tachycardia is critical as treatment depends on the accurate diagnosis of tachycardia mechanism. The electrocardiogram remains the most important diagnostic tool for the evaluation of both wide and narrow complex tachycardia. The electrocardiographic diagnosis of wide complex tachycardia is based on evaluation of atrioventricular relationship and QRS morphology while the diagnosis of narrow complex tachycardia is based on the location and morphology of P waves. It is important for critical care specialists to understand the principles of cardiac arrhythmia diagnosis and remain current with the recent advances in the pharmacologic and non-pharmacologic management of patients with arrhythmias.

Atrial fibrillation and death after myocardial infarction: a community study

BACKGROUND

Atrial fibrillation (AF) often coexists with myocardial infarction (MI), yet its prognostic influence is disputed. Prior reports studied the relationship of AF during early hospitalization for acute MI to the risk of death and could not address the timing of AF in relation to the MI (ie, before, during, after). Furthermore, as data come mostly from clinical trials, their applicability to the community is uncertain. The aims of our study were to assess the occurrence of AF among MI patients, determine whether it has changed over time, and quantify its impact and the impact of its timing on mortality after MI.

METHODS AND RESULTS

This was a community-based cohort of 3220 patients hospitalized with incident (first-ever) MI from 1983 to 2007 in Olmsted County, MN. Atrial fibrillation was identified by diagnostic codes and ECG. Outcomes were all-cause and cardiovascular death. Atrial fibrillation before MI was identified in 304 patients, and 729 developed AF after MI (218 [30%] within 2 days, 119 [16%] between 3 and 30 days, and 392 [54%] >30 days post-MI). The cumulative incidence of AF after MI at 5 years was 19% and did not change over the calendar year of MI (the incidence of AF was the same regardless of when the MI occurred). During a mean follow-up of 6.6 years, 1638 deaths occurred. AF was associated with an increased risk of death (hazard ratio [95% confidence interval] 3.77 [3.37 to 4.21]), independently of clinical characteristics at the time of MI and heart failure. This risk differed markedly according to the timing of AF, and was the greatest for AF occurring >30 days post MI (hazard ratio [95% confidence interval] 1.63 [1.37 to 1.93] for AF within 2 days, 1.81 [0.45 to 2.27] for AF between 3 and 30 days, and 2.58 [2.21 to 3.00] for AF >30 days post MI).

CONCLUSIONS

In the community, AF is frequent in the setting of MI. Atrial fibrillation carries an excess risk of death, which is the highest for AF developing >30 days after MI.

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

BACKGROUND

During acute myocardial infarction (MI), the incidence of atrial fibrillation (AF) is 6% to 22%, and its occurrence in this setting is associated with increased short- and long-term morbidity and mortality.

OBJECTIVE

The purpose of this case control study was evaluate the characteristics associated with the development of new-onset AF.

METHODS

Of 2,460 consecutive patients with acute MI, 149 (6%) were identified as having AF within 7 days of MI. After excluding patients with prior AF, previously documented heart failure, reduced left ventricular (LV) ejection fraction, valvular heart disease, LV hypertrophy, AF after coronary artery bypass grafting, or pericarditis; we identified 42 AF patients in whom coronary anatomy was assessed by invasive angiography and cardiac structure and function was evaluated using transthoracic echocardiography. Another 42 patients from the same cohort with MI but no AF matched for age, gender, and LV ejection fraction were studied as controls.

RESULTS

AF patients were more likely to present with an inferior MI (P = .002) but less likely to present with ST-segment elevation MI (P = .02). Univariate associations with AF included indexed left atrial volume (P <.001), LV filling pressure (E/e'; P = .001), right atrial branch disease (P <.001), left atrial branch disease (P = .009), sinoatrial branch disease (P <.001), left main stem disease (P = .02), and time from onset of symptoms to coronary intervention (P = .002). In multivariable analysis, right and left coronary artery atrial branch disease (P = .02) were predictors of AF post-MI.

CONCLUSION

Coronary artery disease affecting the atrial branches is an independent predictor for the development of AF after MI.

Subocclusion of the sinus node artery during coronary angioplasty: arrhythmological considerations

We report the case of a 58-year-old man who developed atrial fibrillation as a result of iatrogenic subocclusion of a diseased sinus node artery, originating from the left circumflex artery (LCx), occurring during LCx stenting, suggestive of an ischemic etiology of sinus node dysfunction.

Left atrial infarction: a case report and review of the literature

The majority of cardiac related deaths are due to ischemic heart disease, with the most common clinical scenario being severe coronary artery atherosclerosis resulting in left ventricular myocardial infarction. However, infarction of other cardiac chambers does occur, and often has specific clinical associations. We report a case of a 70-year-old man who suffered from left atrial infarction that resulted in a transmural rupture of his left atrium. The patient had a history of rheumatic heart disease, mitral valve stenosis, and severe atherosclerotic coronary artery disease. Four days before death, he underwent mitral valve replacement and left circumflex coronary artery bypass. Two days later, he developed atrial fibrillation. On the day of death, he had decreased mental status, questionable seizure activity, hematemesis, ventricular tachycardia, and eventually asystole. At autopsy, he had significant hemopericardium with a fibrinous pericarditis and bilateral hemothoraces (total blood volume: 1250 mL). A 0.1 to 0.2 cm left atrial transmural defect was identified. The prosthetic mitral valve was free of vegetations, and completely intact. Similarly, the left circumflex artery bypass graft was completely patent and unremarkable. Severe calcific atherosclerosis was of his native left circumflex and left main coronary arteries. Microscopic examination revealed acute myocardial infarction of the left atrium at the rupture site. The anatomy of atrial circulation as well as the pathology and consequences of atrial infarction are discussed.

Post PCI atrial fibrillation

Atrial fibrillation (AF) is a major arrhythmia with a high prevalence among population. AF is not uncommon in the setting of coronary artery disease, including myocardial infarction (MI) and acute coronary syndromes (ACS). Percutaneous coronary interventions (PCI) have significantly improved outcomes of patients with acute MI and acute coronary syndromes. Nevertheless, the AF was reported to occur in patients with MI and ACS undergoing PCI. New onset AF after PCI for MI and ACS, though being infrequent, was associated with worse clinical course and prognosis. The predictive value of AF has tendency to change in parallel with improvements of reperfusion strategies and comprehensive treatment. Observational studies suggest better patency of culprit vessels achieved by PCI was accompanied by improvement in signal-averaged electrocardiography indices of atrial electrophysiological properties and higher rate of restoration of sinus rhythm during primary PCI as compared with thrombolysis. The adequate management of arrhythmia is required to reduce the risk of complications.

Anatomical investigation of the sinus node artery using dual-source computed tomography

BACKGROUND

Few investigators have studied the anatomy of the sinus node artery (SNA) using noninvasive imaging modalities, so the objective of this study was to visualize the in-vivo 3-dimensional anatomical relations of the SNA using dual-source computed tomography (DSCT).

METHODS AND RESULTS

In the 101 patients included in this study, the visualization rate, anatomical type and diameter of the SNA, the distance between the orifice and coronary artery, and the terminal type of SNA were recorded. The visualization rate was 95.2% (96/101). Of 96 patients, 106 SNAs were detected among which 51 (48.1%, 51/106) originated from the right coronary artery, 52 (49.1%, 52/106) from the left circumflex artery, and 3 (2.7%, 3/106) from other branches. There were 3 types of SNA: right (n = 52), left (n = 45), and posterior (n = 9). The distance between the orifice of the right SNA and the right coronary sinus was 14.2+/-15.2 mm, for the left SNA it was 5.5+/-3.5 mm, and for the posterior SNA, 33.7+/-12.8 mm. The average diameter was 1.27+/-0.29 mm. The SNA approached the nodal tissue by 1 of 3 routes: retrocaval (51.5%), precaval (25.2%), or pericaval (22.3%).

CONCLUSION

The SNA can be visualized in vivo using DSCT, which is important for preoperative knowledge of its origin, course, termination, and anatomical type.

Compromised atrial coronary anatomy is associated with atrial arrhythmias and atrioventricular block complicating acute myocardial infarction

BACKGROUND

The relevance of the atrial coronary anatomy in the pathogenesis of atrial arrhythmias and atrioventricular (AV) block complicating acute myocardial infarction (AMI) remains unclear.

OBJECTIVES

We evaluated the location of the infarct-related coronary lesion relative to the principal atrial branches (ie, sinoatrial nodal, AV nodal, left atrial circumflex) in 454 patients with ST-elevation AMI in the CAPTORS II trial.

METHODS

Patients underwent systematic 60-minute postfibrinolytic angiograms, and coronary anatomy was correlated with evidence of atrial arrhythmias and AV block on sequential electrocardiograms.

RESULTS

Patients with either sinoatrial nodal or left atrial circumflex compromise (n = 34) had a higher incidence of "early" (ie, up to 90 minutes postfibrinolysis) atrial arrhythmias vs those without (23.5% vs 7.1%; P = .004). Patients with AV nodal compromise (n = 207) had a higher incidence of "early" AV block vs those without (12.1% vs 3.6%; P = .001).

CONCLUSION

These findings support the etiological role of acute atrial ischemia in the development of early atrial arrhythmias and AV block complicating AMI.

Prognostic significance of new atrial fibrillation and its relation to heart failure following acute myocardial infarction

BACKGROUND

New-onset atrial fibrillation (AF) after acute myocardial infarction (AMI) frequently occurs in association with postinfarction complications, particularly with heart failure (HF).

AIMS

To evaluate whether postinfarction HF is associated with the subsequent development of AF and whether AF independently predicts poorer prognosis.

METHODS AND RESULTS

We examined 650 patients with AMI and compared patients with AF (n=320) to those without (n=330). AF patients were classified as either early AF (n=208)-patients who developed AF within 24 h of symptom onset or late AF (n=112)-patients who had AF thereafter. We compared outcomes between these groups, adjusting for differences in baseline characteristics and postinfarction HF. Heart failure was the most important predictor of AF. In most patients, AF occurred secondary to HF. AF patients had poorer outcomes, including higher in-hospital and 7-year mortality. After multivariate adjustment, overall, AF was not an independent predictor of in-hospital [odds ratio (OR)=0.70) and 7-year [relative risk (RR)=1.14] mortality, but late AF remained an independent predictor of 7-year (RR=2.48, 95% confidence interval, 1.26-4.87) mortality.

CONCLUSIONS

Heart failure mostly preceded the occurrence of new-onset atrial fibrillation after acute myocardial infarction, but only late atrial fibrillation was independently related to long-term mortality.

Effects of right coronary artery PTCA on variables of P-wave signal averaged electrocardiogram

BACKGROUND

P-wave signal averaged ECG has been used to detect atrial late potentials that were found in paroxysmal atrial fibrillation. Ischemia is supposed to trigger ventricular late potentials, which indicate an elevated risk for ventricular tachycardia. Preexistent ventricular late potentials measured by ventricular signal averaged ECG is supposed to be eliminated by successful PTCA.

METHODS

We examined the incidence of atrial late potentials in patients with a proximal stenosis of the right coronary artery and new onset of atrial fibrillation. Furthermore, we investigated the anti-ischemic effect of a successful percutaneous transluminal coronary angioplasty.(PTCA) of the right coronary artery. P-wave signal averaged ECG from 23 patients who had a PTCA of the right coronary artery (group A) were compared to age, sex, and disease-matched control subjects (group B) one day before, one day after, and one month after PTCA.

RESULTS

A new appearance of paroxysmal atrial fibrillation was presented in eight patients before PTCA (group A1) of group A. Patients with a stenosis of the right coronary artery had a significantly higher incidence of supraventricular extrasystoles in a 24-hour-Holter ECG (131.1 +/- 45.4 vs 17.1 +/- 18.9, P < 0.0002). The duration of the filtered P wave was longer (124.8 +/- 11.9 vs 118.5 +/- 10.1 ms, P < 0.04) and the root mean square of the last 20 ms (RMS 20) was significantly lower in group A than in group B (2.87 +/- 1.09 vs 3.97 +/- 1.12 micro V, P < 0.01). A successful PTCA caused an increase in RMS 20 (2.87 +/- 1.11 vs 4.19 +/- 1.19 microV, P < 0.02) and a decrease in filtered P-wave duration (124.8 +/- 11.9 vs 118.4 +/- 10.4 ms, P < 0.04). Preexistent atrial late potentials were found among 15 patients before PTCA. After successful PTCA only 3 out of 15 patients were affected (P < 0.0004) after one day, as well as after one month. All patients with a history of atrial fibrillation did not suffer from an arrhythmic recurrence within the following six months after successful PTCA.

CONCLUSION

A stenosis of the right coronary artery is associated with atrial late potentials. A successful PTCA of the right coronary artery eliminates preexistent atrial late potentials and may reduce the risk of atrial fibrillation.

[The clinical management guidelines of the Sociedad Española de Cardiología in acute myocardial infarct]

In the recent years, new possibilities have emerged in the diagnosis and management of acute myocardial infarction with ST segment elevation and its complications. Moreover, a deep transformation has taken place in the health care system organization, particularly in aspects related to care of patients presenting non-traumatic chest pain, both in pre-hospital and hospital areas. All these issues warrant a consensus document in Spain dealing with the role that these important changes should play in the whole management of myocardial infarction patients. This document revises and updates all the main clinical issues of acute myocardial infarction patients from the moment they contact with the health care system outside the hospital until they return home, after staying at the coronary care unit and the general hospitalization ward. All those aspects are considered not only in the uncomplicated myocardial infarction but also in the complicated one. This review also includes a set of recommendations on structural and organisational aspects, mainly referred to the prehospital and emergency levels.

[Incidence, clinical characteristics and prognostic significance of supraventricular tachyarrhythmias in acute myocardial infarction]

OBJECTIVES

The study of incidence and prognostic significance of supraventricular tachyarrhythmias in patients with acute myocardial infarction.

PATIENTS AND METHODS

Prospective study on 1,239 patients consecutively admitted because of a diagnosis of acute myocardial infarction. Clinical characteristics, indexes of myocardial infarction and complications were analysed.

RESULTS

Supraventricular tachyarrhythmias were observed in 116 (9.3%) cases: atrial fibrillation in 96 (7.7%); atrial tachycardia in 15 (1.2%); and atrial flutter in the remaining five cases (0.4%). Patients with supraventricular tachyarrhythmias were older, and presented higher heart rate, lower blood pressure, a higher number of affected leads in ECG, and higher Killip class. A higher creatine kinase peak and a lower left ventricular ejection fraction were associated with the presence of supraventricular tachyarrhythmias. Predictors of supraventricular tachyarrhythmias were: age, systolic blood pressure, number of affected leads in ECG, and congestive heart failure at admission. The following complications were found more frequently in patients with supraventricular tachyarrhythmias: bundle-branch block, complete A-V block, ventricular tachycardia, ventricular fibrillation; heart failure; stroke; and mortality, in-hospital 18.1% vs 11.1% (p < 0.05) and one-year, 38.7% vs 18.4% (p < 0.001). The logistic regression model showed that supraventricular tachyarrhythmias had no independent prognostic value on mortality.

CONCLUSIONS

The appearance of supraventricular tachyarrhythmias during the acute phase of myocardial infarction is a relatively frequent finding, often associated with older age and larger infarctions. Supraventricular tachyarrhythmias are accompanied by higher short and long-term mortalities, although there is no independent prognostic significance.

Atrial fibrillation in the setting of acute myocardial infarction: the GUSTO-I experience. Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries

OBJECTIVES

We examined the clinical predictors and angiographic and clinical outcomes associated with atrial fibrillation in the setting of acute myocardial infarction (MI).

BACKGROUND

This condition has been studied primarily in prethrombolytic era small trials.

METHODS

We compared baseline clinical characteristics, short-term clinical and angiographic outcomes and 1-year mortality of patients enrolled in the Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries (GUSTO-I) trial with atrial fibrillation on admission electrocardiography (n = 1,026 [2.5%]) or after enrollment (n = 3,254 [7.9%]) and those without atrial fibrillation (n = 36,611 [89.6%]). Univariable and multivariable analyses were used to assess relations between baseline factors and the development of atrial fibrillation.

RESULTS

Patients with any atrial fibrillation more often had three-vessel coronary artery disease and initial Thrombolysis in Myocardial Infarction (TIMI) grade < 3 flow than those without the arrhythmia. In-hospital stroke was increased in patients with atrial fibrillation (3.1% vs. 1.3%, p = 0.0001), mainly ischemic stroke (1.8% vs. 0.5%, p = 0.0001). Significant multivariable predictors of later atrial fibrillation included advanced age, higher peak creatine kinase levels, worse Killip class and increased heart rate. The unadjusted mortality rate was significantly higher at 30 days (14.3% vs. 6.2%, p = 0.0001) and at 1 year (21.5% vs. 8.6%, p < 0.0001) in patients with atrial fibrillation. The adjusted 30-day mortality rate remained significantly higher with any (odds ratio [OR] 1.3, 95% confidence interval [CI] 1.2 to 1.4) or later (OR 1.4, 95% CI 1.3 to 1.5) atrial fibrillation but not with baseline atrial fibrillation (OR 1.1, 95% CI 0.88 to 1.3).

CONCLUSIONS

Atrial fibrillation in the setting of acute MI independently predicts stroke and 30-day mortality. More aggressive treatment strategies in this subgroup may be warranted and deserve further study.

Postoperative cardiac rhythms with superior-septal approach and lateral approach to the mitral valve

BACKGROUND

The superior-septal approach provides an excellent view of the mitral valve and therefore has received considerable interest. However, the safety of this approach is controversial because it requires division of the sinus node artery in most cases.

METHODS

Postoperative cardiac rhythms were analyzed in 152 consecutive patients who underwent mitral valve procedures between January 1992 and February 1995 with a conventional right lateral left atriotomy (group 1, n = 69) or the superior-septal approach (group 2, n = 83). Follow-up ranged from 2 to 38 months, and the mean follow-up was 16.1 months in group 1 and 13.8 months in group 2.

RESULTS

The mortality rate was similar in the two groups (1.4% in group 1 and 1.2% in group 2), and the causes of death were not related to the left atriotomy. At discharge, 96% of the patients in group 1 who were in sinus rhythm preoperatively and 78% of those in group 2 remained in sinus rhythm. At the last follow-up, 88% of these patients in group 1 and 83% in group 2 remained in sinus rhythm. Among the patients in atrial fibrillation or junctional rhythm before operation, 12% in group 1 and 11% in group 2 had regained sinus rhythm at the last follow-up. There were no significant differences in these values.

CONCLUSIONS

Although the incidence of dysrhythmias was higher with the superior-septal approach in the early postoperative period, this approach provides an excellent operative view of the mitral valve and similar results in terms of late postoperative cardiac rhythms as the right lateral left atriotomy.

Importance of the time of onset of supraventricular tachyarrhythmias on prognosis of patients with acute myocardial infarction

It is known that left ventricular (LV) function, severity of coronary artery disease, and the presence of ventricular arrhythmias are major determinants of prognosis in patients surviving an acute myocardial infarction (AMI). However, little is known about the relationship between the time of onset of supraventricular tachyarrhythmias (SVTs) and mortality. Therefore, this study was carried out in a 48-months period on 131 patients with AMI who presented with SVT during hospitalization. Of these, 53 patients (40.5%) had arrhythmia within < 12 h of MI, while 78 patients (59.5%) had arrhythmia between 12 h and 4 days. The arrhythmias studied were atrial fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia. The patients were similar for age, gender, coronary risk factors, creatine kinase-MB peak, cardioversion and LV function. Angiographic features for patients with the < 12-h onset of arrhythmia were: 86.7% of the patients had uniarterial lesions, 8.9% had biarterial lesions, and 4.4% had triarterial lesions. Patients with the 12-h-4-day onset had 16.1%, 53.2%, and 30.6% (p < or = 0.05) of the respective lesions. Inferior wall myocardial infarction was more frequent among patients with the earlier onset (60.4%), while patients with the later onset presented more anterior wall infarctions (50.0%). Only 11.3% of the patients with the earlier onset presented with severe in-hospital congestive heart failure (Killip classes III-IV), versus 62.8% of the patients with the later onset (p < or = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)