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Clinical Impact of Postoperative vs. Nonoperative Atrial Fibrillation
Quick Takes
- In this cohort study investigating the risk of adverse outcomes in postoperative atrial fibrillation (AF) versus nonoperative AF, rates of subsequent stroke/TIA and all-cause mortality did not differ significantly.
- 13% of all patients with AF in the cohort had postoperative AF. Although AF recurrence was lower in postoperative versus nonoperative AF, reoccurrence affected >50% of patients within the postop AF group, supporting the notion that these patients are at risk for future episodes of AF, and refuting the concept that the condition may be transient, benign, or unmasked only by the uniquely provocative environment of surgery.
- Despite a higher prevalence of CHA2DS2-VASc score ≥2, the postoperative AF group received anticoagulation (AC) later and less frequently than did the nonoperative AF group, raising the possibility that these patients might benefit from earlier, more proactive AC therapy.
Study Questions:
Does risk for stroke/transient ischemic attack (TIA), subsequent arrhythmia, and all-cause mortality differ among patients whose atrial fibrillation (AF) is first observed during or within 30 days of noncardiac surgery compared to patients whose initial AF diagnosis occurs outside of the perioperative setting?
Methods:
Among patients residing in Olmstead County, Minnesota represented in the Rochester Epidemiology Project database, all cases of AF between January 1, 2000–December 31, 2013 were identified. Cases were dichotomized as first onset during or within 30 days of noncardiac surgery (postoperative AF) versus first onset outside the perioperative period (nonoperative AF). Comorbidity indicators (CHADS2, CHA2DS2-VASc, Charlson Morbidity Index) were collected, and information on anticoagulation (AC) prescription was tabulated when available. All AF cases were manually validated by clinically trained personnel. To determine cumulative risk of stroke/TIA, subsequent arrhythmia, and all-cause mortality, an adjusted proportional hazards model using propensity scoring and inverse probability weighting was constructed to account for differences in baseline comorbidity factors and AC use.
Results:
A total of 4,231 patients with AF were identified: 550 (13%) with postoperative AF and 3,681 (87%) with nonoperative AF. Although age and sex distribution were similar between postoperative versus nonoperative AF groups (73.3 vs. 72.3 years, 52.0% vs. 52.5% male), several comorbidity factors (including CHA2DS2-VASc score) were higher in postoperative AF.
Outcomes in all patients, within the mean 6.3-year follow-up period:
- 486 had ischemic stroke or TIA,
- 2,462 had ≥1 subsequent AF event, and
- 2,565 died.
In the unadjusted model, and inverse-probability weighted model accounting for age, sex, and Charlson Comorbidity Index, 5-year risks were as follows:
Stroke/TIA was similar in postoperative versus nonoperative AF:
- 11.0% vs. 10.5% (absolute risk difference [ARD] 0.5 [-2.3 to 3.3]) in the unadjusted model
- 11.9% vs. 11.8% (ARD 0.1 [-2,9 to 3.1]) in the adjusted model
Subsequent AF was lower in postoperative versus nonoperative AF:
- 51.1% vs. 63.3% (ARD -12.2 [-16.8 to -7.6]) in the unadjusted model
- 51.3% vs. 64.7% (ARD -13.4 [-17.8 to -9.0]) in the adjusted model
All-cause mortality was similar or higher in postoperative versus nonoperative AF:
- 45.5% vs. 39.9% (ARD 5.6 [1.9 to 9.3]) in the unadjusted model
- 41.6% vs. 39.2% (ARD 2.4 [-0.3 to 5.1]) in the adjusted model
Data on use of outpatient anticoagulation became available in patients enrolled in or after 2004, and analysis of this subpopulation revealed the following:
- Markedly less frequent use of AC in postoperative versus nonoperative AF: 25.1% (20.7, 39.2) vs. 39.2% (33.9, 44.8) within 30 days of AF diagnosis; 37.1% (35.3, 39.0) vs. 50.9% (48.8, 52.8) within 1 year of AF diagnosis.
- Among patients having stroke/TIA, lesser use of AC at the time of event if AF was postoperative versus nonoperative: 9 of 46 (19.6%) vs. 114 of 297 (38.4%).
- Time from first AF diagnosis to first AC use was longer after postoperative versus nonoperative AF (median 37 vs. 13 days).
- Only 50.4% of patients with postoperative AF and CHA2DS2-VASc score of ≥2 received AC.
Conclusions:
In this cohort, postoperative AF carried a similar rate of ischemic stroke, TIA, and all-cause mortality compared to nonoperative AF during a mean 6.3-year follow-up period, underscoring its clinical significance. Although postoperative AF carried a lower rate of subsequent AF events, recurrence rate was still substantial (>50%) in this group, refuting the notion that the condition is benign or transient in nature. Data from a subgroup indicate that use of therapeutic AC was employed later and more infrequently after postoperative AF versus nonoperative AF onset.
Perspective:
This study highlights the prognostic value of postoperative AF in alerting clinicians to risk of future adverse thrombotic events, and suggests that the AF often reoccurs, and is no less morbid than nonoperative AF. These findings suggest that therapeutic AC, antiarrhythmic therapy, and outpatient rhythm monitoring should be considered earlier and more frequently in the postoperative AF population.
Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Cardiac Surgery, Geriatric Cardiology, Invasive Cardiovascular Angiography and Intervention, Prevention, Anticoagulation Management and Atrial Fibrillation, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Cardiac Surgery and Arrhythmias, Interventions and Vascular Medicine
Keywords: Anti-Arrhythmia Agents, Anticoagulants, Arrhythmias, Cardiac, Atrial Fibrillation, Cardiac Surgical Procedures, Comorbidity, Geriatrics, Ischemic Attack, Transient, Ischemic Stroke, Outpatients, Perioperative Period, Risk, Secondary Prevention, Stroke, Thrombosis, Vascular Diseases
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