Abstract
Objective
To explore gender differences in real-world outcomes after catheter ablation of atrial fibrillation (AF).
Background
Compared to men, women with AF have greater thromboembolic risk and tend to be more symptomatic. Catheter ablation is generally more effective than antiarrhythmic drug therapy alone. However, there is limited data on the influence of gender on AF ablation outcomes.
Methods
We analyzed medical claims of 45 million United States patients enrolled in a variety of employee-sponsored and fee-for-service plans. We identified patients who underwent an AF ablation from 2007 to 2011 and evaluated 30-day safety and one-year effectiveness outcomes.
Results
Of the 21,091 patients who underwent an AF ablation, 7,460 (29%) were female. Women, compared to men, were older (62±11 vs. 58±11 years), had higher CHADS2 (1.2±1.1 vs. 1.0±1.0), higher CHA2DS2-VASc (2.9±1.5 vs. 1.6±1.4), and higher Charlson comorbidity index scores (1.2±1.3 vs. 1.0±1.2)(p<0.001 for all). Following ablation, women had higher risk of 30-day complications of hemorrhage (2.7 vs. 2.0%,p<0.001) and tamponade (3.8 vs. 2.9%,p<0.001). In multivariable analyses, women were more likely to have a re-hospitalization for AF (adjusted HR 1.12,p=0.009), but less likely to have repeat AF ablation (adjusted HR 0.92,p=0.04) or cardioversion (adjusted HR 0.75,p<0.001).
Conclusion
Women have increased hospitalization rates after AF ablation and are more likely to have a procedural complication. Despite the higher rate of hospital admissions for AF after ablation, women were less likely to undergo repeat ablation or cardioversion. These data call for greater examination of barriers and facilitators to sustain rhythm control strategies in women.
Keywords: atrial fibrillation, catheter ablation, disparities, rhythm control, women
1. Introduction
Atrial fibrillation (AF) is the most common sustained arrhythmia in the adult population with estimates that one in four women will develop the arrhythmia at some point in their lifetime.(1) In 2014, female gender was incorporated into risk stratification guidelines for stroke prevention in AF based on the CHA2DS2-VASc score, highlighting the importance of gender in AF management.(2) Not only are women at an increased risk of thromboembolic complications, they tend to be more symptomatic than men, and less likely to respond to pharmacologic therapy.(3–6) Catheter ablation may therefore seem particularly attractive in women. However, there are limited data on the influences of gender on AF ablation procedures. We therefore sought to explore gender influences on long-term outcomes of catheter ablation of AF using data from multiple insurance health plans throughout the United States.
2. Methods
We analyzed data from the Truven Health MarketScanR Commercials Claims and Encounters and Medicare Supplemental Databases (Truven Health Analytics Inc., Ann Arbor, MI). This data source contains de-identified medical and pharmacy claims data on inpatient, outpatient, and prescription drug experience of over 45 million enrolled employees, dependents and retirees covered under a variety of fee-for-service (FFS) and managed care health plans, including health maintenance organizations, preferred and exclusive provider organizations, and point-of-service and consumer-directed health plans.(7) Linked datasets include the Inpatient Admissions file, which contains all diagnoses and procedures in the service records related to a hospital admission; the Outpatient Services file, which contains information on encounters and claims for services delivered at a doctor’s office, hospital outpatient facility, emergency room, or other outpatient facility; and the Outpatient Pharmaceutical Claims file, which includes complete records of mail-order or card program prescription drug claims. Medical claims are linked to outpatient prescription drug claims and person-level enrollment information. These data sources have been used extensively in health services research of heart rhythm disorders, including for catheter ablation.(8–10)
We identified all adult patients with non-valvular AF who received a catheter ablation between January 1, 2007 and December 31, 2011 (Figure 1). Patients were required to have a primary diagnosis of AF (International Classification of Diseases, 9th Revision [ICD-9] code 427.31) associated with any inpatient or outpatient encounter as well as a documented catheter ablation procedure (ICD-9 code 37.34 or Current Procedural Terminology, 4th Edition [CPT-4] code 93651). To avoid bias in ascertainment of baseline comorbidities, drug prescriptions and in post-ablation outcomes, we excluded patients without continuous health plan enrollment for at least six months prior and one month after the index ablation procedure date.
Figure 1.
Cohort Selection Diagram
Clinical covariates
Baseline comorbidities were determined using comorbidity-specific ICD-9 codes up to one year prior to the catheter ablation date, based on the Agency for Healthcare Research and Quality (AHRQ) Clinical Classification System. We additionally assessed comorbidity using the Charlson and Selim Comorbidity Indices using validated methods.(11) CHADS2 and CHA2DS2- VASc scores were calculated by summing the component comorbidities. Pharmacological therapies received in the 120 days prior to AF ablation were ascertained using the MarketScanR Outpatient Pharmaceutical Claims file.
Procedural Complications
We ascertained 30-day post-procedural complications based on hospital discharge diagnoses or procedure codes that would be used to manage a complication (e.g. pericardiocentesis). This approach has been previously applied to AF treatment studies using the same data source.(8,12) One-year clinical outcomes were similarly ascertained and included hospitalization for AF, cardioversion (inpatient or outpatient), or repeat catheter ablation of AF. For the endpoint of AF hospitalization, we considered any inpatient encounter associated with a primary diagnosis for AF, which occurred after the initial inpatient or outpatient AF ablation procedure. We evaluated cause-specific hospitalization for acute coronary syndrome or myocardial infarction, heart failure, supraventricular tachycardia, ventricular arrhythmia, syncope, stroke or transient ischemic attack, and intracranial hemorrhage.
Statistical analysis
We compared differences in baseline characteristics and 30-day complications between females and males using t-tests for continuous variables and chi-squared tests for categorical variables. Cox proportional hazards regression was used to examine the association between gender and each outcome at one year (hospitalization for AF, cardioversion, repeat catheter ablation of AF), while adjusting for potential confounders. We included the following baseline covariates in multivariate models: age, sex, Charlson Comorbidity Index score, CHF, hypertension, diabetes, stroke/TIA, prior MI, anemia, peripheral artery disease (PAD) or vascular disease, year of ablation, insurance plan, and receipt of concomitant drug therapies (warfarin, dabigatran, clopidogrel, Class I and Class III anti-arrhythmic drugs, amiodarone, beta blockers, and calcium channel blockers). The Cox model assumption of proportional hazards was found to be valid by using the Schoenfeld test. We also used the Kaplan-Meier method and Log-rank tests to calculate differential probability of event-free survival using the composite endpoint of AF hospitalization, cardioversion, or repeat AF ablation within one year.
The study was approved by the local Institutional Review Board. All analyses were performed using SAS, version 9.1 (Cary, NC) and STATA, version 11.0 (College Station, TX). The funding agencies were not involved in any way with study design, data analysis, interpretation of results, or manuscript preparation.
3. Results
We identified 21,091 patients with an index AF ablation meeting inclusion criteria. Although procedure volume increased from over the study period (2007–2011), 30% of the ablations were performed in women, and this proportion did not substantively change over the observation period. At the time of catheter ablation, women, compared to men, were older (62±11 vs. 58±11 years, p<0.001), and had higher CHADS2 (1.2±1.1 vs. 1.0±1.0, p<0.001), CHA2DS2-VASc scores (2.9±1.5 vs. 1.6±1.4, p<0.001) and Charlson comorbidity index scores (1.2±1.3 vs. 1.0±1.2, p<0.001) (Table 1). Women, compared to men, also had a higher prevalence of hypertension (66.2% vs 61.8%, p<0.001), diabetes (22.8% vs 20.7%, p<0.001), prior stroke or transient ischemic attack (TIA) (5.7% vs 3.5%, p<0.001), and anemia (13.6% vs 8.2%, p<0.001) but had a lower prevalence of prior myocardial infarction (4.5% vs 5.6%, p<0.001). There was no significant difference in prevalence of heart failure (33.4% vs 33.6%, p=NS) or chronic kidney disease (8.0% vs 7.4%, p=NS).
Table 1.
Baseline Characteristics
| Female(N=6,137) | Male(N=14,954) | p | |
|---|---|---|---|
| Inpatient/Outpatient Status | 0.001 | ||
| Inpatient | 2,524 (41.1%) | 5,787 (38.7%) | |
| Outpatient | 3,613 (58.9%) | 9,167 (61.3%) | |
|
| |||
| Age, years | 61.9 ± 11.4 | 58.1 ± 10.5 | <0.001 |
|
| |||
| Comorbidity index | |||
| Charlson comorbidity index | 1.2 ± 1.3 | 1.00 ± 1.2 | <0.001 |
| Selim comorbidity index | 2.3 ± 2.3 | 2.5 ± 2.1 | <0.001 |
|
| |||
| CHADS2 score | 1.2 ± 1.1 | 1.0 ± 1.0 | <0.001 |
|
| |||
| CHADS2 score group | <0.001 | ||
| CHADS2 0 | 1,753 (28.6%) | 5,174 (34.6%) | |
| CHADS2 1 | 2,376 (38.7%) | 5,943 (39.7%) | |
| CHADS2 2 | 1,199 (19.5%) | 2,594 (17.4%) | |
| CHADS2 3 | 564(9.2%) | 904 (6.1%) | |
| CHADS2 4 | 174 (2.8%) | 237 (1.6%) | |
| CHADS2 5 | 59 (0.96%) | 87 (0.58%) | |
| CHADS2 6 | 12 (0.20%) | 15 (0.10%) | |
|
| |||
| CHA2DS2-VASc score | 2.9 ± 1.5 | 1.6 ± 1.4 | <0.001 |
|
| |||
| Congestive heart failure | 2,038 (33.2%) | 5,031 (33.6%) | 0.54 |
|
| |||
| Hypertension | 4,061 (66.2%) | 9,246 (61.8%) | <0.001 |
|
| |||
| Diabetes | 1,400 (22.8%) | 3,097 (20.7%) | 0.0007 |
|
| |||
| Prior stroke or transient ischemic attack | 347 (5.7%) | 529 (3.5%) | <0.001 |
|
| |||
| Prior myocardial infarction | 276 (4.5%) | 831 (5.6%) | 0.001 |
|
| |||
| Anemia | 832 (13.6%) | 1,232 (8.2%) | <0.001 |
|
| |||
| Prior bleeding | 733 (11.9%) | 1,676 (11.2%) | 0.13 |
|
| |||
| Peripheral artery disease | 304 (5.0%) | 603 (4.0%) | 0.003 |
|
| |||
| CKD | 489 (8.0%) | 1,104 (7.4%) | 0.14 |
|
| |||
| Region | 0.002 | ||
| Northeast | 771 (13.0%) | 2,187(14.6%) | |
| North Central | 1,763 (28.7%) | 4,075 (27.3%) | |
| South | 2,453 (40.0%) | 5,873 (39.3%) | |
| West | 1,067 (17.4%) | 2,606 (17.4%) | |
| Unknown | 83 (1.3%) | 213 (1.4%) | |
|
| |||
| Ablation Year | 0.03 | ||
| 2007 | 656 (10.7%) | 1,800 (12.0%) | |
| 2008 | 882 (14.4%) | 2,239 (15.0%) | |
| 2009 | 1,103 (18.0%) | 2,569 (17.2%) | |
| 2010 | 1,382 (22.5%) | 3,358 (22.5%) | |
| 2011 | 2,114 (34.5%) | 4,988 (33.4%) | |
|
| |||
| Insurance Plan Type | <0.001 | ||
| Comprehensive | 1087 (17.7%) | 1,599 (10.7%) | |
| EPO | 79 (1.3%) | 204 (1.4%) | |
| HMO | 661 (10.8%) | 1,609 (10.8%) | |
| POS | 346 (5.6%) | 996 (6.7%) | |
| PPO | 3466 (56.5%) | 9,148 (61.2%) | |
| POS with capitation | 23 (0.37%) | 91 (0.61%) | |
| CDHP | 132 (2.2%) | 377 (2.5%) | |
| HDHP | 53 (0.86%) | 193 (1.3%) | |
| Missing | 290 (4.7%) | 737 (4.9%) | |
|
| |||
| Cardiovascular medications | |||
| Aspirin | 20 (0.33%) | 26 (0.17%) | 0.03 |
| Warfarin | 3,475 (56.6%) | 8,599 (57.5%) | 0.24 |
| Dabigatran | 578 (9.4%) | 1,531 (10.2%) | 0.07 |
| Rivaroxaban | 2 (0.03%) | 1 (0.01%) | 0.20 |
| Clopidogrel | 271 (4.4%) | 930 (6.2%) | <0.001 |
| ACE inhibitor or angiotensin receptor blocker | 2,017 (32.9%) | 4,873 (32.6%) | 0.69 |
| Diuretics | 2,082 (33.9%) | 3,585 (24.0%) | <0.001 |
| Niacin or fibrates | 98 (1.6%) | 576 (3.9%) | 0.007 |
| Statins | 1,498 (24.4%) | 4,275 (28.6%) | <0.001 |
|
| |||
| Antiarrhythmic drugs | |||
| All Class I | 1,716 (28.0%) | 3,561 (23.8%) | <0.001 |
| Class III (Sotalol/Dofetilide) | 1,252 (20.4%) | 2,952 (19.7%) | 0.28 |
| Amiodarone | 851 (13.9%) | 2,396 (16.0%) | <0.001 |
|
| |||
| Rate-controlling drugs | |||
| Metoprolol | 1,997 (32.5%) | 4,657 (31.1%) | 0.80 |
| Carvedilol | 356 (5.8%) | 1,175 (7.9%) | <0.001 |
| Atenolol | 467 (7.6%) | 814 (5.4%) | <0.001 |
|
| |||
| Calcium-channel blockers | |||
| Diltiazem | 1,314 (21.4%) | 2,459 (16.4%) | <0.001 |
| Verapamil | 199 (3.2%) | 320 (2.1%) | <0.001 |
Prior to ablation, women were more likely to be treated with rate-control agents (70.6% vs. 63.0%, p<0.001) and class I antiarrhythmic agents (28.0% vs. 23.8%, p<0.001) but less likely to be treated with amiodarone (13.9% vs. 16.0%, p<0.001). Women had similar use of class III antiarrhythmic agents (20.4% vs. 19.7%, P=NS) and oral anticoagulation (66.0% vs. 67.8%, P=NS).
30-day Complications
In the 30 days following the ablation, women had an increased risk of complications, including vascular complications (2.7% vs 2.0%, p<0.001), hematoma or hemorrhage (2.3% vs 1.6%, p<0.001), and perforation or tamponade (3.8% vs 2.9%, p<0.001) (Table 2). Women demonstrated a trend for increased all-cause hospitalization (9.4% vs 8.6%, p=0.07) and stroke or TIA (0.85% vs 0.64%, p=0.09). There were 7 in-hospital deaths (0.07% vs 0.02%, p= NS).
Table 2.
30-Day complications after AF ablation
| 30-Day complications | All patients (N=21,091) | Gender | ||
|---|---|---|---|---|
| Female (N=6.137) | Male (N=14,954) | p | ||
| All-cause hospitalization | 1,868 (8.9%) | 578 (9.4%) | 1,290(8.6%) | 0.07 |
| Vascular complication | 464 (2.2%) | 168 (2.7%) | 296 (2.0%) | 0.0007 |
| Hematoma or hemorrhage | 376 (1.8%) | 139 (2.3%) | 237 (1.6%) | 0.0007 |
| Perforation or tamponade | 661 (3.1%) | 234 (3.8%) | 427 (2.9%) | 0.0003 |
| Pneumothorax or hemothorax | 29 (0.14%) | 8(0.13%) | 21 (0.14%) | 0.86 |
| Stroke or transient ischemic attack | 147 (0.70%) | 52 (0.85%) | 95 (0.64%) | 0.09 |
| Pacemaker implantation | 2 (0.01%) | 1 (0.02%) | 1 (0.01%) | 0.50 |
| Implantable cardioverter defibrillator implantation | 0 (0.0%) | |||
| Congestive heart failure | 116 (0.55%) | 34 (0.55%) | 82 (0.55%) | 0.96 |
| In-hospital Death | 7 (0.03%) | 4 (0.07%) | 3 (0.02%) | 0.11 |
One-year outcomes
In the year following ablation, women were less likely to receive a cardioversion (17% vs 21%; adjusted HR 0.75, p<0.001) or repeat ablation procedure (13% vs 15%; adjusted HR 0.92, p<0.001) (Table 3). However, unadjusted and adjusted risk of one-year all-cause hospitalization was higher in women compared to men (32% vs 27%, p<0.001; adjusted HR 1.14, 95% CI 1.07–1.20, p<0.001) as was risk of hospitalization for AF (13% vs 12%; adjusted HR 1.12, 95% CI 1.03–1.22, p<0.001). In secondary analyses, we found that women were less likely to be re-hospitalized for myocardial infarction (0.7% vs 1.2%, adjusted HR 0.84 95% CI 0.42–0.84, p<0.05) and were more likely to be admitted with congestive heart failure over the following year (2.5% vs 1.8%, adjusted HR 3.45 95% CI 2.68–4.45, p<0.001) (Table 4). Cumulative event-free survival, defined as freedom from AF rehospitalization, was decreased among women compared to men (86.6% vs 89.0%, adjusted HR 0.88, 95% CI 0.78–0.97, p<0.01) as shown in Figure 2.
Table 3.
Primary outcomes in one year after initial ablation (N=21,091)
| One year outcome | Gender | # Patients | # Events | Unadjusted Incidence Rate (per 100 person-years) | Unadjusted Hazard Ratio* (95%CI) | p | Adjusted Hazard Ratio*+ (95%CI) | p |
|---|---|---|---|---|---|---|---|---|
| All-cause hospitalization | Female | 6,137 | 1,955 | 46.1 | 1.23 | <0.00 | 1.14 | <.0001 |
|
|
||||||||
| Male | 14,954 | 4,017 | 36.9 | (1.65- | 1 | (1.07–1.20) | ||
|
| ||||||||
| Atrial fibrillation rehospitalization | Female | 6,137 | 825 | 16.8 | 1.14 | 0.001 | 1.12 | 0.009 |
|
|
||||||||
| Male | 14,954 | 1,792 | 14.7 | (1.05- | (1.03–1.22) | |||
|
| ||||||||
| Cardioversion | Female | 6,137 | 1,050 | 22.4 | 0.78 | <.000 | 0.75 | <.0001 |
|
|
||||||||
| Male | 14,954 | 3,203 | 28.9 | (0.73- | 1 | (0.70–0.81) | ||
|
| ||||||||
| Repeat ablation for atrial fibrillation | Female | 6,137 | 805 | 16.2 | 0.90 | 0.008 | 0.92 | 0.04 |
|
|
||||||||
| Male | 14,954 | 2,195 | 18.1 | (0.82- | (0.841- | |||
Reference group is male
Adjusted for age, Charlson Comorbidity Index score, CHF, hypertension, diabetes, stroke/TIA, prior MI, anemia, peripheral artery disease (PAD) or vascular disease, chronic kidney disease, year of ablation, insurance plan, and receipt of concomitant drug therapies (warfarin, dabigatran, clopidogrel, Class I and Class III anti-arrhythmic drugs, amiodarone, beta blockers, and calcium channel blockers)
Table 4.
Secondary outcomes at one year after index ablation (N=21,091)
| Cause of inpatient admission at one year | Gender | Number of Patients | Number of Events | Unadjusted Incidence Rate (per 100 person- years) | Unadjusted Hazard Ratio* (95%CI) | p | Adjusted Hazard Ratio*+ (95%CI) | p |
|---|---|---|---|---|---|---|---|---|
| Myocardial infarction or unstable angina | Female | 6,137 | 44 (0.72%) | 0.82 | 0.63 (0.45–0.88) | 0.006 | 0.59 (0.42–0.84) | 0.003 |
|
| ||||||||
| Male | 14,954 | 172(1.2%) | 1.30 | |||||
|
| ||||||||
| Congestive heart failure | Female | 6,137 | 151 (2.5%) | 2.85 | 1.38 (1.13–1.69) | 0.001 | 3.45 (2.68–4.45) | <0.001 |
|
| ||||||||
| Male | 14,954 | 269(1.8%) | 2.05 | |||||
|
| ||||||||
| Supraventricular tachycardia | Female | 6,137 | 23 (0.37%) | 0.43 | 1.58 (0.93- 2.66) | 0.08 | 1.52 (0.88- 2.62) | 0.14 |
|
| ||||||||
| Male | 14,954 | 36 (0.24% ) | 0.27 | |||||
|
| ||||||||
| Ventricular arrhythmia | Female | 6,137 | 66 (1.08%) | 1.24 | 1.32 (0.98–1.77) | 0.07 | 1.30(0.95–1.77) | 0.44 |
|
| ||||||||
| Male | 14,954 | 124 (0.83%) | 0.94 | |||||
|
| ||||||||
| Stroke or transient ischemic attack | Female | 6,137 | 39 (0.64%) 70 | 0.73 | 1.38 (0.93– 2.03) | 0.11 | 1.18 (0.79–1.79) | 0.42 |
|
| ||||||||
| Male | 14,954 | (0.47%) | 0.53 | |||||
|
| ||||||||
| Intracranial hemorrhage | Female | 6,137 | 14 (0.23%) | 0.26 | 1.50(0.77–2.92) | 0.22 | 1.16 (0.56– 2.42) | 0.68 |
|
| ||||||||
| Male | 14,954 | 23 (0.15%) | 0.17 | |||||
|
| ||||||||
| Syncope | Female | 6,137 | 14 (0.23%) | 0.26 | 1.23 (0.65– 2.34) | 0.52 | 0.95 (0.48–1.92) | 0.89 |
|
| ||||||||
| Male | 14,954 | 28 (0.19%) | 0.21 | |||||
Reference group is male
Adjusted for age, Charlson Comorbidity Index score, CHF, hypertension, diabetes, stroke/TIA, prior MI, anemia, peripheral artery disease (PAD) or vascular disease, chronic kidney disease, year of ablation, insurance plan, and receipt of concomitant drug therapies (warfarin, dabigatran, clopidogrel, Class I and Class III anti-arrhythmic drugs, amiodarone, beta blockers, and calcium channel blockers)
Figure 2.
Survival free from AF rehospitalization.
4. Discussion
We evaluated the 30-day safety and one-year effectiveness outcomes in over 20,000 patients undergoing catheter ablation procedures for AF using medical claims data from a variety of representative healthcare plans throughout the Unites States. We found that gender was significantly associated with certain aspects of the procedure, including the baseline clinical characteristics of the patients, the safety profile, and long-term outcomes. Adjusting for risk factors, women revealed a paradoxical discordance between increased rehospitalizations for AF and decreased subsequent use of cardioversion or repeat ablation. Our data call for greater examination of barriers and facilitators to sustain rhythm control strategies in women with AF.
In agreement with prior studies, we found women undergoing catheter ablation of AF were older with increased comorbidities compared to men.(13–16) This pattern may be indicative of gender influences on the natural history of AF. Population studies, such as Framingham, have demonstrated that new-onset AF tends to occur at an age approximately five years older in women and are more likely to have comorbidities such as hypertension and diabetes at the time of diagnosis.(17,18) Although women display a similar overall prevalence of AF as men,(19) the older age at diagnosis may decrease the likelihood of undergoing catheter ablation. We also found that women were more likely to be treated with Class I antiarrhythmic medications, which may have been driven by a lower prevalence of prior myocardial infarction, a contraindication to this class of medication.
Compared to men, women were found to have a low, but modestly higher, risk of complications within 30 days of the catheter ablation procedures. These findings are consistent with prior studies and confirm the increased procedural risk for women in our large study population, which is representative of most patients receiving AF ablation today. (20) Prior studies have reported 30-day complication rates which range from 5–8% in women, roughly 1–3% higher compared to men.(12,21,22) The higher complication rate seen in women may be partially explained by the increased comorbidity burden. However, due to the low frequency of events, we did not perform multivariate adjustment. Other potential explanations may include differences in pharmacokinetics and body size. For example, women tend to require a lower heparin dose in order to obtain adequate anticoagulation, even after adjusting for weight.(23) Concordantly, women have demonstrated higher activated clotting times (ACT) during catheter ablation procedures. (24) Fortunately, the overall rates of both stroke (<1%) and death (<0.1%) were low and similar between genders.
With respect to gender differences with longer-term procedural success, prior studies have not revealed consistent findings.(13,14,25–27). Several studies have reported that women have a higher recurrence rate after the ablation procedure(13,14) (25) while other studies have found no significant difference between men and women.(26,27) Our study, which is the largest AF ablation study examining procedural outcomes by gender in the United States, found that women were significantly more likely to be re-hospitalized with AF within one-year after an ablation procedure but less likely to undergo cardioversion or repeat ablation. Although the nature of the claims data does not allow for evaluation of any AF recurrence, our findings, in context, may be indicative of potential barriers to optimal or sustained rhythm control strategies in women. For example, women are more likely than men to report having delayed care due to non-medical barriers, including time logistics and cost. (28) Furthermore, women are more likely to have their cardiac symptoms and risk of heart disease downplayed by their doctors; (29) and are less likely to receive implantable defibrillators. (30) In the case of atrial fibrillation, there is evidence that women exhibit a delayed referral pattern compared to men and fail more antiarrhythmic medications before proceeding to catheter ablation.(15,16) Delaying the time to ablation could promote a higher AF or comorbidity burden at the time of ablation which may have resulted in increased electrical and structural remodeling. However, it is unclear from our data if women were less likely to be offered rhythm-control strategies, or if women were more likely to decline the procedures. The underlying motivations driving clinical decision-making are complex and may vary by gender.(31) For example, a single-center study from Japan suggested women were more likely to refuse catheter ablation.(14) In context, these data highlight the importance of communication between patients and clinicians to ensure that fears, motivations, and perspectives of patients and caregivers are adequately addressed in order to deliver optimal and patient-centered care.
Our study has several significant limitations. First, we used de-identified administrative claims data. Although claims data has the advantages of performing large-scale analyses across multiple health care systems or payers, claims-based ascertainment of ablation procedures and outcomes may be imperfect. AF ablation ascertainment based on procedural and diagnosis could lead to misclassification and inappropriate inclusion of other ablations, such as atrial tachycardia (AT), which tend to be more prevalent in women, although cohort inclusion was conditioned upon a concurrent AF diagnosis.(32,33) However, because AF ablation is has higher risk than AT or SVT procedures, (34) this misclassification would bias complication risk in women toward the null. Second, unidentified confounders and covariates influencing patient outcomes such as repeat ablation or cardioversion, such as frailty or body mass index, may not be identified. Third, we are unable to measure differences in AF recurrence, AF burden, or quality of life, which are the key endpoints used in randomized trials of ablation. Fourth, we are unable to classify AF severity (e.g. paroxysmal vs. persistent), AF duration prior to ablation, heart failure severity, or ejection fraction from administrative data. The ICD-10 medical classification system has separate diagnoses codes for AF severity and may prove useful for future work. Finally, while the baseline differences and outcomes provide insight, the clinical circumstances or patient preferences associated with care cannot be identified. However, these findings provide the rationale for other study designs that may allow more granular and qualitative examination of these issues.
CONCLUSION
In 21,091 patients undergoing catheter ablation of AF across the U.S., women, compared to men, were older, with increased comorbidity burden, and had a low, but modestly increased risk of procedural complications. Adjusting for risk factors, women who underwent catheter ablation revealed a paradoxical discordance between increased rehospitalizations for AF and decreased subsequent use of cardioversion or repeat ablation. These data call for greater examination of barriers and facilitators to sustain rhythm control strategies in women.
Perspectives.
Competency in Medical Knowledge
Similar to stroke risk, women with atrial fibrillation have a low, but modestly higher rate of procedural complications in the 30 days following AF ablation.
Translational Outlook
The higher risk of 30-day complications in women may be mitigated by improved patient selection or tailoring aspects of the procedure to minimize complication rates. Additionally, a greater examination of barriers and facilitators of care and use of shared-decision making tools could help to minimize potential disparities in care and ensure that treatment decisions are in alignment with the clinical evidence and patient preferences.
Acknowledgments
Funding/Support:
Dr. Kaiser is supported by a grant from the National Heart, Lung and Blood Institute (1T32Hl098049). Dr. Turakhia is supported by a Veterans Health Services Research & Development Career Development Award (CDA09027-1), an American Heart Association National Scientist Development Grant (09SDG2250647), a VA Health Services and Development MERIT Award (IIR 09-092), the Gilead Sciences Cardiovascular Scholars Program, and the Stanford Center for Health Research on Women and Sex Differences in Medicine
ABBREVIATIONS
- AF
atrial fibrillation
- CPT
current procedural terminology
- FFS
fee-for-service
- HR
hazard ratio
- ICD-9
International Classification of Diseases, 9th Revision
- TIA
transient ischemic attack
Footnotes
Disclosures: There are no conflicts of interest to report.
References
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