Postoperative atrial fibrillation

Postoperative atrial fibrillation in patients undergoing non-cardiac non-thoracic surgery: A practical approach for the hospitalist

New postoperative atrial fibrillation (POAF) is the most common perioperative arrhythmia and its reported incidence ranges from 0.4 to 26% in patients undergoing non-cardiac non-thoracic surgery. The incidence varies according to patient characteristics such as age, presence of structural heart disease and other co-morbidities, as well as the type of surgery performed. POAF occurs as a consequence of adrenergic stimulation, systemic inflammation, or autonomic activation in the intra or postoperative period (e.g. due to pain, hypotension, infection) in the setting of a susceptible myocardium and other predisposing factors (e.g. electrolyte abnormalities). POAF develops between day 1 and day 4 post-surgery and it is often considered a self-limited entity. Its acute management involves many of the same strategies used in non-surgical patients but the optimal long-term management is challenging because of the limited available evidence. Several studies have shown an association between occurrence of POAF and in-hospital morbidity, mortality, and length of stay. Although, traditionally, POAF was considered to have a generally favorable long-term prognosis, recent data have shown an association with an increased risk of stroke at 1 year after hospitalization. It is unknown, however, whether strategies to prevent POAF or for rate/rhythm control when it does occur, lead to a reduction in morbidity or mortality. This suggests the need for future studies to better understand the risks associated with POAF and to determine optimal strategies to minimize long-term thromboembolic risks. In this article, we summarize the current knowledge on epidemiology, pathophysiology, and short- and long-term management of POAF after non-cardiac non-thoracic surgery with the goal of providing a practical approach to managing these patients for the non-cardiologist clinician.

Use of ivabradine and atorvastatin in emergent orthopedic lower limb surgery and computed tomography coronary plaque imaging and novel biomarkers of cardiovascular stress and lipid metabolism for the study and prevention of perioperative myocardial infarction: study protocol for a randomized controlled trial

Background

The incidence of perioperative myocardial infarction (PMI) globally is known to be around 2 to 3% and can prolong hospitalization, increased morbidity and mortality. Little is known about the pathophysiology and risk factors for PMI. We investigate the presence of elevated novel cardiac markers and preoperative coronary artery plaque through contemporary laboratory techniques to determine the correlation with PMI, as well as studying ivabradine and atorvastatin as protective pharmacotherapies against PMI in the context of orthopedic surgery.

Methods/Design

We aim to enroll 200 patients aged above 60 years who suffer from neck of femur fracture requiring surgery. Patients will be randomized to four arms (no study drugs, atorvastatin only, ivabradine only and ivabradine and atorvastatin). Our primary outcome is incidence of PMI. All patients will receive an electrocardiogram, cardiac echocardiography, measurement of novel cardiac biomarkers and computed tomography (CT) coronary angiography. A telephone interview post discharge will be conducted at 30 days, 60 days and 1 year.

Discussion

We postulate that ivabradine and atorvastatin will reduce the rate and magnitude of PMI following surgery by reducing heart rate and attenuating catecholamine-induced tachycardia postoperatively. Secondly, we postulate that postoperative reduction in heart rate and catecholamine-induced tachycardia with ivabradine will correlate with a reduction in cardiovascular novel biomarkers which will reduce atrial stretch and postoperative incidence of arrhythmia. We aim to demonstrate that treatment with ivabradine and atorvastatin will cause a reduction in the incidence and magnitude of PMI, the benefit of which is derived primarily in patients with greater atherosclerotic burden as measured by higher CT coronary calcium scores.

Trial registration

This study protocol has been listed in the Australia New Zealand Clinical Trial Registry (registration number: ACTRN12612000340831) on 23 March 2012.

Association between preoperative diuretic use and in-hospital outcomes after cardiac surgery

BACKGROUND

There is a paucity of evidence on the association between preoperative diuretics use and outcomes following cardiac surgery. We hypothesized that diuretic use prior to cardiac surgery will be associated with adverse in-hospital clinical outcomes.

METHODS

We evaluated patients undergoing cardiac surgery at a single institution between January 1, 2000, and December 31, 2011. Patients were grouped as follows: isolated coronary artery bypass grafting (CABG) (n = 8759), CABG plus valve surgery (n = 1188), and valve surgery only (n = 2646). A fourth group "All cardiac surgery" is comprised of patients from all three groups. Preoperative diuretic use was defined as patient on any diuretic till the day of surgery. Primary outcome was the incidence of major adverse events (MAEs) defined as the composite of mortality, postoperative renal dysfunction, myocardial infarction, stroke, and new-onset atrial fibrillation (AF). Logistic regression analysis and propensity score matching were performed.

RESULTS

We included 12,593 patients [3546 on diuretic (28%)]. After logistic regression analyses, preoperative diuretic use was associated with an increased risk of the following: (1) MAE among all groups except the concomitant CABG and valve surgery group, (2) AF in "All cardiac surgery" and isolated CABG groups, (3) postoperative renal dysfunction in all groups. After propensity score matching (n = 3050 in each group), preoperative diuretic use was significantly associated with MAE (48% vs. 43%; P < 0.0001), postoperative renal dysfunction (19% vs. 14%; P < 0.0001), and AF (34% vs. 32%; P = 0.03) in the "All cardiac surgery" group.

CONCLUSION

Preoperative diuretics use is associated with an increased incidence of MAEs after cardiac surgery.

[Perioperative management of atrial fibrillation]

Atrial fibrillation is a frequent complication in the perioperative period. When it appears there is an increased risk of perioperative morbidity due to stroke, thromboembolism, cardiac arrest, myocardial infarction, anticoagulation haemorrhage, and hospital readmissions. The current article focuses on the recommendations for the management of perioperative atrial fibrillation based on the latest Clinical Practice Guidelines on atrial fibrillation by the European Society of Cardiology and the Spanish Society of Cardiology. This article pays special attention to the preoperative management, as well as to the acute perioperative episode. For this reason, the latest recommendations for the control of cardiac frequency, antiarrhythmic treatment and anticoagulation are included.

Efficacy of N-acetylcysteine in preventing atrial fibrillation after cardiac surgery: a meta-analysis of published randomized controlled trials

Background

Atrial fibrillation is a common complication after cardiac surgery. The aim of this study is to evaluate whether N-acetylcysteine (NAC) could prevent postoperative atrial fibrillation (POAF).

Methods

PubMed, Embase and Cochrane Center Register of Controlled Trials were searched from the date of their inception to 1 July 2013 for relevant randomized controlled trials (RCTs), in which NAC was compared with controls for adult patients undergoing cardiac surgery. Outcome measures comprised the incidence of POAF, all-cause mortality, length of intensive care unit (ICU) stay, hospital length of stay, and the incidence of cerebrovascular events. The meta-analysis was performed with the fixed-effect model or random-effect model according to the heterogeneity.

Results

We retrieved ten studies enrolling a total of 1026 patients. Prophylactic NAC reduced the incidence of POAF (OR 0.56; 95% CI 0.40 to 0.77; P < 0.001) and all-cause mortality (OR 0.40; 95% CI 0.17 to 0.93; P = 0.03) compared with controls, but failed to reduce the stay in ICU and overall stay in hospital. No difference in the incidence of cerebrovascular events was observed.

Conclusions

Prophylactic use of NAC could reduce the incidence of POAF and all-cause mortality in adult patients undergoing cardiac surgery. However, larger RCTs evaluating these and other postoperative complication endpoints are needed.

Lone atrial fibrillation - an overview

Atrial fibrillation (AF) sometimes develops in younger individuals without any evident cardiac or other disease. To refer to these patients who were considered to have a very favourable prognosis compared with other AF patients, the term 'lone' AF was introduced in 1953. However, there are numerous uncertainties associated with 'lone' AF, including inconsistent entity definitions, considerable variations in the reported prevalence and outcomes, etc. Indeed, increasing evidence suggests a number of often subtle cardiac alterations associated with apparently 'lone' AF, which may have relevant prognostic implications. Hence, 'lone' AF patients comprise a rather heterogeneous cohort, and may have largely variable risk profiles based on the presence (or absence) of overlooked subclinical cardiovascular risk factors or genetically determined subtle alterations at the cellular or molecular level. Whether the implementation of various cardiac imaging techniques, biomarkers and genetic information could improve the prediction of risk for incident AF and risk assessment of 'lone' AF patients, and influence the treatment decisions needs further research. In this review, we summarise the current knowledge on 'lone' AF, highlight the existing inconsistencies in the field and discuss the prognostic and treatment implications of recent insights in 'lone' AF pathophysiology.

An exploratory study of the patients' sleep patterns and inflammatory response following cardiopulmonary bypass (CPB)

AIMS AND OBJECTIVES

To describe sleep patterns and inflammatory response postCPB, determine sleep pattern changes and inflammatory response over time and explore relationships between sleep and biomarkers of stress and inflammation.

BACKGROUND

Despite the numerous citations of the role of sleep in restoration and health maintenance, a paucity of research exists about this phenomenon in patients undergoing CPB. Specifically, there is no research that has explored correlations between sleep patterns and systemic inflammatory response in adult cardiac surgery patients.

DESIGN

Exploratory, repeated-measures, correlational study.

METHOD

Subjects were recruited from a Midwestern urban hospital. Of the 25 eligible subjects, 16 males and four females completed the study. Wrist actigraphy was used to measure sleep variables. Salivary cortisol and C-reactive protein (C-RP) levels were measured daily. Data were collected during postoperative nights/days 1 through 4 (T1-T4).

RESULTS

Subjects' sleep onset latency (SOL) median scores (0 minute) were within normal range across time periods, whereas median scores for wake after sleep onset (WASO > 270 minutes), sleep fragmentation index (SFI >51%), total sleep time (<153 minutes) and sleep efficiency index (SEI <36%) fell outside the normal ranges. Changes in the median sleep scores over time, however, were not significant at p > 0·05. Median cortisol levels were within normal range (0·3-0·8 μg/dl) from T1-T4, but the C-RP level peaked at T2 (median = 2370 pg/ml). Strong correlations were found: (1) between SFI-cortisol (rs = 0·82), C-RP (rs = 0·65) - WBC (rs = 0·69); (2) between SEI-C-RP (rs = 0·58); (3) between WASO-WBC (rs = 0·48), WASO and cross-clamp time (rs = 0·50); and (4) between SOL-age (rs = -0·55) at p < 0·05.

CONCLUSIONS

Subjects were severely sleep-deprived with inflammatory response exaggerations warranting further investigations using larger sample sizes.

RELEVANCE TO CLINICAL PRACTICE

This study offers a foundation for developing a conceptual model explaining mechanisms of sleep disturbance and inflammatory response postCPB. This knowledge is crucial for testing sleep-promoting interventions to modulate inflammatory responses essential for preventing complications, and restoring health.

Incidence, severity and perioperative risk factors for atrial fibrillation following pulmonary resection

OBJECTIVES

Postoperative atrial fibrillation (PAF) occurs commonly following pulmonary resection. Our aims were to quantify the incidence and severity of PAF using the Thoracic Morbidity & Mortality classification system, and identify risk factors for PAF.

METHODS

All consecutive patients undergoing pulmonary resection at a single centre (January 2008 - April 2010) were enrolled. PAF was defined as postoperative, electrocardiographically documented and requiring initiation of pharmacological therapy. Univariate and multivariate analyses of risk factors associated with the development of PAF were conducted.

RESULTS

The incidence of PAF was 11.8% (n = 43) of 363 pulmonary resections (open: n = 173; 47.7%; video-assisted: n = 177; 48.8%; converted: n = 13; 3.6%): sublobar (n = 93; 25.6%), lobectomy (n = 237; 65.3%), bilobectomy (n = 7; 1.9%) and pneumonectomy (n = 24; 6.6%). Twenty-eight cases (65.1%) were uncomplicated/transient, and 15 cases (34.9%) were complicated/persistent PAF, defined as lasting for >7 days (40.0%), requiring cardioversion (13.3%), vasopressors (33.3%), in-hospital use of anticoagulants (46.7%) and/or anticoagulants on discharge (26.7%). Patients with PAF had increased mean lengths of hospital stay (10.5 days vs 6.9 days; P = 0.04). Peak onset of PAF occurred 2.5 (standard deviation (SD) ± 1.3) days after pulmonary resection, lasting for 1.8 ± 2.8 (mean, ±SD) days. Multivariate analysis identified (relative risk; 95% confidence interval): age ≥70 years (2.3; 1.1-5.1), history of angioplasty/stents/angina (4.0; 1.4-11.3), thoracotomy (3.6; 1.4-9.3), conversion to open thoracotomy (16.5; 2.2-124.0) and extent of surgery/stage (7.1; 1.0-49.4) as predictors of PAF.

CONCLUSIONS

While the majority of PAF is uncomplicated and transient, one-third of cases lead to persistence or major intervention. Age, coronary artery disease and extent of surgery/stage increase the risk of PAF following pulmonary resection. Identifying patients with elevated risk may lead to targeted prophylaxis to reduce the incidence of PAF.

Loss of proteostatic control as a substrate for atrial fibrillation: a novel target for upstream therapy by heat shock proteins

Atrial fibrillation (AF) is the most common, sustained clinical tachyarrhythmia associated with significant morbidity and mortality. AF is a persistent condition with progressive structural remodeling of the atrial cardiomyocytes due to the AF itself, resulting in cellular changes commonly observed in aging and in other heart diseases. While rhythm control by electrocardioversion or drug treatment is the treatment of choice in symptomatic AF patients, its efficacy is still limited. Current research is directed at preventing first-onset AF by limiting the development of substrates underlying AF progression and resembles mechanism-based therapy. Upstream therapy refers to the use of non-ion channel anti-arrhythmic drugs that modify the atrial substrate- or target-specific mechanisms of AF, with the ultimate aim to prevent the occurrence (primary prevention) or recurrence of the arrhythmia following (spontaneous) conversion (secondary prevention). Heat shock proteins (HSPs) are molecular chaperones and comprise a large family of proteins involved in the protection against various forms of cellular stress. Their classical function is the conservation of proteostasis via prevention of toxic protein aggregation by binding to (partially) unfolded proteins. Our recent data reveal that HSPs prevent electrical, contractile, and structural remodeling of cardiomyocytes, thus attenuating the AF substrate in cellular, Drosophila melanogaster, and animal experimental models. Furthermore, studies in humans suggest a protective role for HSPs against the progression from paroxysmal AF to persistent AF and in recurrence of AF. In this review, we discuss upregulation of the heat shock response system as a novel target for upstream therapy to prevent derailment of proteostasis and consequently progression and recurrence of AF.