umu.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Atrial fibrillation after cardiac surgery: an analysis of risk factors, mechanisms, and survival effects
Umeå University, Faculty of Medicine, Surgical and Perioperative Sciences, Surgery.
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Despite the recent improvements in surgical techniques and postoperative patient care, atrial fibrillation (AF) remains the most frequent complication after cardiac surgery. Although postoperative AF is often regarded as a benign clinical condition, this arrhythmia has significant adverse effects on patient recovery and postoperative survival. Its exact pathophysiology has not yet been elucidated. The present thesis aims to analyze AF risk factors and their interaction, pre-existing histological explanatory alterations of the atrium, the AF impact on postoperative survival and the compliance of a prophylactic drug regimen.

Methods: During a 10-year period, consecutive cardiac surgery cases with complete data on AF occurrence and postoperative survival were extracted. All patients were operated on for coronary or valvular surgery, with cardiopulmonary bypass (CPB). Hospital and long-term survival data were obtained from Swedish population registry. Study I) Isolated coronary artery bypass grafting (CABG, n=7056), aortic valve replacement (n=690) and their combination (n=688) were considered. Independent AF risk factors and AF effects on early and 1 year mortality were investigated. Study II) Patients affected by postoperative AF among isolated CABG patients (n=7621), valvular surgeries (n=995) and their combination (n=879) were studied. Long-term survival was obtained and prognostic factors identified. Study III) Seventy patients were randomized to on-pump (n=35) or off-pump (n=35) CABG. Samples from the right atrial appendage were collected and histology was evaluated by means of light and electronic microscopy with reference to preexistent alterations related to postoperative AF. Study IV) Cardiac surgery patients with complete data on smoking status (n=3245) were reviewed. Effects of smoking on AF development and interaction among variables were explored. Study V) CABG patients without clinical contraindications to receive oral sotalol (80 mg twice daily) and magnesium were prospectively enrolled (n = 49) and compared with a matched contemporary control CABG group (n = 844). The clinical compliance to the AF prophylactic drug regimen was tested.

Results: The overall AF incidence was around 26%, subdivided into 23%, 40% and 45% for isolated CABG, valve procedures and their combined surgeries, respectively. Age was the strongest predictor of postoperative AF. Coronary disease superimposed risk factors with reference to myocardial conditions at CPB weaning. Considering the preoperative smoking condition, smokers demonstrated a reduced AF incidence compared to non-smokers (20% versus 27%, p<0.001). An interaction between smoking status and inotropic support was observed: without this interaction smoking conferred a 46% risk reduction of AF (p=0.011). At the histological level, myocyte vacuolization and nuclear derangement represented anatomical independent AF predictors (p=0.002 and p=0.016, respectively). CPB exposure was not associated to postoperative AF nor histological changes. Although, postoperative AF increases the length of hospitalization in all patient groups, it did not affect the hospital survival. However, AF independently impaired the late survival, a phenomenon seen in the CABG group only. With reference to the tested sotalolmagnesium drug regimen, only 55% of CABG patients were compliant to the treatment, with marginal effects on AF occurrence.

Conclusions: In addition to age, details at the CPB weaning period, pre-existing histopathological changes, the hyperadrenergic state and catecholamines are key mechanisms in the pathophysiology of postoperative AF. In particular, the CPB period hides valuable information for timely AF prophylactic stratifications. Further, compliance effects due to patient selection should also be considered in a prophylactic therapy model. Postoperative AF increases late mortality after isolated CABG surgery, but not after valvular procedures. Although the mechanisms are unclear, our results draw the attention to possible AF recurrence after hospital discharge, indicating a strict postoperative surveillance.

Place, publisher, year, edition, pages
Umeå: Kirurgisk och perioperativ vetenskap , 2008. , 40 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1156
Keyword [en]
atrial fibrillation, adult, cardiac surgery, coronary artery bypass grafting, valvular surgery, cardiopulmonary bypass, mortalilty, histology, catecholamines, embolism
National Category
Surgery
Identifiers
URN: urn:nbn:se:umu:diva-1798ISBN: 978-91-7264-580-6 (print)OAI: oai:DiVA.org:umu-1798DiVA: diva2:142003
Public defence
2008-09-25, Sal D, Tandläkarhögskolan, Byggnad 1 D, NUS, Umeå, 13:00 (English)
Opponent
Available from: 2008-09-02 Created: 2008-09-02 Last updated: 2009-06-11Bibliographically approved
List of papers
1. Atrial fibrillation after cardiac surgery: risk factors and their temporal relationship in prophylactic drug strategy decision
Open this publication in new window or tab >>Atrial fibrillation after cardiac surgery: risk factors and their temporal relationship in prophylactic drug strategy decision
2007 (English)In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 129, no 3, 354-362 p.Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE: Postoperative atrial fibrillation (AF) is a vexing problem in cardiac surgery. Our aim was to identify risk factors between surgical procedures, all having cardiopulmonary bypass (CPB) in common, and how AF contributes to early and late mortality.

METHODS: Patients were reviewed during a 10-year period, comprising coronary artery bypass grafting (CABG, n=7056), aortic valve replacement (AVR, n=690) and their combination (COMB, n=688). The study assessed 43 variables of which pre-/intraoperative data were evaluated for uni/multivariate analysis in relation to AF and type of surgery. Data were reviewed versus hospital and 1-year mortality; the latter being obtained from the Swedish population registry.

RESULTS: The surgery subgroups exhibited obvious differences. The overall incidence of AF was 25.6%, ranging from 22.7% for CABG to 44.0% for COMB procedures. Numerous interaction patterns were seen among the analyzed parameters. In multivariate fashion, age was encountered in all groups, whereas coronary disease superimposed risk factors with reference to myocardial conditions at CPB weaning. Postoperative AF increased the length of hospitalization, whereas it did not affect hospital mortality. In CABG patients only, AF gave rise to increased 1-year mortality (p<0.001).

CONCLUSIONS: In addition to the accepted risk factors of AF, primarily age, we emphasize the importance of considering details at CPB weaning, a correlation that was coronary specific. The weaning period hides valuable information that can be useful for more specific AF-prophylactic strategies. The AF-related increase in late mortality after CABG but not after valve procedures is intriguing, and draws attention to possible AF recurrence during patient follow-up and management.

Keyword
Atrial fibrillation, Adult, Cardiac surgery, Coronary artery bypass grafting, Cardiopulmonary bypass, Embolism
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-22326 (URN)10.1016/j.ijcard.2007.07.123 (DOI)000259564000009 ()18022261 (PubMedID)
Available from: 2009-05-05 Created: 2009-05-05 Last updated: 2017-12-13Bibliographically approved
2. Postoperative atrial fibrillation is associated with late mortality after coronary surgery, but not after valvular surgery
Open this publication in new window or tab >>Postoperative atrial fibrillation is associated with late mortality after coronary surgery, but not after valvular surgery
Article in journal (Refereed) Submitted
Identifiers
urn:nbn:se:umu:diva-3340 (URN)
Available from: 2008-09-02 Created: 2008-09-02Bibliographically approved
3. Relationship between atrial histopathology and atrial fibrillation after coronary bypass surgery
Open this publication in new window or tab >>Relationship between atrial histopathology and atrial fibrillation after coronary bypass surgery
Show others...
2006 (English)In: Journal of Thoracic and Cardiovascular Surgery, ISSN 0022-5223, E-ISSN 1097-685X, Vol. 131, no 6, 1364-1372 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Postoperative atrial fibrillation is common after coronary surgery. The cellular condition of atrial myocytes might play a part in the postoperative development of atrial fibrillation. Our study aimed to investigate whether patients in whom postoperative atrial fibrillation develops show pre-existent alterations in histopathology of the right atrium and how such changes are expressed in relation to the use of cardiopulmonary bypass.

METHODS: Seventy patients undergoing elective coronary revascularization were prospectively randomized to on-pump conventional surgery (conventional coronary artery bypass grafting, n = 35) or off-pump surgery on the beating heart (off-pump coronary artery bypass grafting, n = 35). Samples from the right atrial appendage were immediately collected after opening the pericardium. In the on-pump group samples were also taken after weaning from cardiopulmonary bypass. Focusing on degenerative alterations, histology was studied by means of light microscopy and for confirmation of particular findings by means of electronic microscopy.

RESULTS: Twenty-two (31%) patients had postoperative atrial fibrillation, with the rate not being different between the off-pump coronary artery bypass grafting and conventional coronary artery bypass grafting groups (P = .797). Left atrial enlargement and inotropic requirement were related to atrial fibrillation. Interstitial fibrosis, vacuolization, and nuclear derangement of myocytes were the histologic abnormalities associated with the development of postoperative atrial fibrillation. However, in multivariate analysis fibrosis was confounded by myocyte vacuolization (P = .002) and nuclear derangement (P = .016), representing independent atrial fibrillation predictors. As expected, the conventional coronary artery bypass grafting and off-pump coronary artery bypass grafting groups showed similar histology, but more importantly, no atrial changes were detected in relation to cardiopulmonary bypass exposure in the conventional coronary artery bypass grafting group. Atrial histology showed degenerative changes that correlated with advanced age and left atrial enlargement.

CONCLUSIONS: Our study supports the contention that atrial fibrillation after coronary surgery is associated with pre-existing histopathologic changes of the right atrium. Patients randomly allocated to off-pump coronary artery bypass grafting procedures showed a similar rate of atrial fibrillation and a similar relationship to atrial histology as did those exposed to cardiopulmonary bypass. Cardiopulmonary bypass did not cause additional changes in tested histology variables.

Place, publisher, year, edition, pages
Mosby Inc., 2006
Keyword
Aged, Aged; 80 and over, Atrial Fibrillation, Coronary Artery Bypass, Female, Heart Atria, Humans, Male, Middle Aged, Prospective Studies
National Category
Cardiac and Cardiovascular Systems Surgery
Identifiers
urn:nbn:se:umu:diva-22327 (URN)10.1016/j.jtcvs.2006.01.040 (DOI)000238023300028 ()16733171 (PubMedID)
Available from: 2009-05-05 Created: 2009-05-05 Last updated: 2017-12-13Bibliographically approved
4. Are current smokers paradoxically protected against atrial fibrillation after cardiac surgery?
Open this publication in new window or tab >>Are current smokers paradoxically protected against atrial fibrillation after cardiac surgery?
2009 (English)In: Nicotine & tobacco research, ISSN 1462-2203, E-ISSN 1469-994X, Vol. 11, no 1, 58-63 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: The hyperadrenergic condition following surgical stress and inotropic drugs have been identified as leading causes for postoperative atrial fibrillation (AF). Smokers are characterized by higher catecholamine levels and tolerance. We tested the hypothesis that smoking patients are less prone to develop postoperative AF. METHODS: A total of 3,245 coronary artery bypass and valvular procedures were reviewed. Predictors of AF and interaction between variables were explored by multivariable logistic regression. AF-predictive scores were created and validated for goodness of fit, and receiver operating characteristic curves were created. RESULTS: Postoperative AF occurred in 26% of patients. Smokers accounted for 15% of the study population and demonstrated a reduced incidence of postoperative AF compared with nonsmoking individuals (20% vs. 27%, p < .001). Multivariate analysis revealed a significant interaction between smoking status and inotropic support requirement. The AF-protective effect of smoking was confounded by inotropic drugs. However, when we excluded from analysis the patients with inotropic support, smoking conferred a 46% risk reduction of AF (odds ratio [OR] = 0.54, 95% CI = 0.34-0.87, p = .011). In addition, age, valvular surgery, and hypertension were independently associated with AF. Postoperative AF increased the length of hospitalization, without affecting hospital mortality. AF was associated with an increased 1-year mortality (p = .002). DISCUSSION: Current smokers are less prone to develop AF after cardiac surgery. Our data support the hypothesis that hyperadrenergic state and catecholamines are key mechanisms in the pathophysiology of postoperative AF.

Identifiers
urn:nbn:se:umu:diva-22328 (URN)10.1093/ntr/ntn011 (DOI)19246442 (PubMedID)
Available from: 2009-05-05 Created: 2009-05-05 Last updated: 2017-12-13Bibliographically approved
5. The clinical noncompliance of oral sotalol/magnesium for prophylactic treatment of atrial fibrillation after coronary artery bypass grafting.
Open this publication in new window or tab >>The clinical noncompliance of oral sotalol/magnesium for prophylactic treatment of atrial fibrillation after coronary artery bypass grafting.
2007 (English)In: J Card Surg, ISSN 0886-0440, Vol. 22, no 4, 281-286 p.Article in journal (Refereed) Published
Keyword
Administration; Oral, Aged, Anti-Arrhythmia Agents/*administration & dosage/adverse effects, Atrial Fibrillation/*drug therapy/epidemiology, Cardiopulmonary Bypass, Coronary Artery Bypass, Cross-Sectional Studies, Drug Therapy; Combination, Electrocardiography/drug effects, Feasibility Studies, Female, Humans, Magnesium Hydroxide/*administration & dosage/adverse effects, Male, Middle Aged, Postoperative Complications/*drug therapy/epidemiology, Prospective Studies, Selection Bias, Sotalol/*administration & dosage/adverse effects, Statistics as Topic, Treatment Refusal/*statistics & numerical data
Identifiers
urn:nbn:se:umu:diva-10614 (URN)10.1111/j.1540-8191.2007.00408.x (DOI)17661767 (PubMedID)
Available from: 2008-10-07 Created: 2008-10-07Bibliographically approved

Open Access in DiVA

fulltext(1274 kB)382 downloads
File information
File name FULLTEXT01.pdfFile size 1274 kBChecksum SHA-1
ba975869be79af629c1cccf9bca5e1e5a3e833c62d42610a7676253e908e60461afd2726
Type fulltextMimetype application/pdf

By organisation
Surgery
Surgery

Search outside of DiVA

GoogleGoogle Scholar
Total: 382 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 446 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf