More Aggressive Left Atrial Ablation in Elderly Patients does not Increase Procedural Complications and Favorably Impacts Outcomes

DOI: 10.19102/icrm.2011.020304

¹TOBIN LIM, MD, ^1,2JOHN D. DAY, MD, ^1,2J. PETER WEISS, MD, ^1,2BRIAN G. CRANDALL, MD, ¹HEIDI T. MAY, PhD, ¹TAMI L. BAIR, RN, ^1,2JEFFREY S. OSBORN, MD, ¹JEFFREY L. ANDERSON, MD, ¹JOSEPH B. MUHLESTEIN, MD, ¹DONALD L. LAPPÉ, MD, ³SRIJOY MAHAPATRA, MD and ^1,2T. JARED BUNCH, MD

¹Department of Cardiology, Intermountain Medical Center, Murray, UT

²Intermountain Heart Rhythm Specialists, Intermountain Medical Center, Murray, UT

³Division of Cardiovascular Medicine, University of Virginia, Charlottesville, VA

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ABSTRACT. Studies have shown that there has been a dramatic increase in atrial fibrillation (AF) in elderly patients. Fortunately, left atrial ablation to resolve AF in elderly people has good long-term outcomes. However, it remains unclear if the procedure should be modified in elderly people to involve a less aggressive approach that might minimize periprocedural complications. A total of 855 consecutive patients underwent either wide area circumferential ablation (WACA) or WACA plus additional linear lines (WACA-L) for drug refractory AF. Outcome analysis based on ablation type was partitioned into age-based tertiles for comparison. In general, those patients who underwent WACA-L were older, had higher rates of heart failure, and had lower rates of paroxysmal AF. There were no differences in 1-yearAF-free survival rates, which were similar and independent of procedure type across age groups. In the elderly patient cohort there was a non-significant trend towards improved outcomes with WACA-L. There were no observed increases in periprocedural or long-term complications when comparing age groups or procedure types. These data support the use of both WACA and WACA-L as strategies for management of AF in all age groups. Furthermore, we observed no increased risks when more aggressive AF ablation was performed in elderly people.

KEYWORDS. left atrial ablation, elderly, atrial fibrillation.

The authors report no conflicts of interest for the published content.
Manuscript received January 8, 2011, final version accepted February 11, 2011.
Address correspondence to: T. Jared Bunch, MD, Intermountain Heart Rhythm Specialists, Intermountain Medical Center, Eccles Outpatient Care Center, 5169 Cottonwood St, Suite 510, Murray, UT 84157. E-mail: Thomas.bunch@imail.org

Introduction

Atrial fibrillation (AF) is the most common cardiac dysrhythmia, affecting nearly 2.5 million people in the United States alone.¹ Patients are living longer with cardiovascular disease, resulting in an increased incidence of AF and also more persistent or permanent AF.^1,2

Medical management of AF in elderly people poses particular clinical challenges. Age-related physiologic changes make elderly patients more susceptible to drug toxicities and drug–drug interactions. Also, there is a lack of long-term studies in older populations evaluating pharmacologic and non-pharmacologic interventions.^3–5

Radiofrequency (RF) catheter-based pulmonary vein isolation has been shown to be effective in eliminating AF. Worldwide multicenter success rates with RF ablation have been reported to exceed 70% in 2009, and have consistently increased over time.^6,7 What was once thought to be a procedure limited to young patients with paroxysmal AF without structural heart disease⁸ has broadened to encompass persistent, permanent AF in all age groups and across multiple disease states. To date, published outcomes of RF ablation therapies have included a small number of elderly patients. This is in part due to the Atrial Fibrillation Ablation Consensus document's general sense that “very elderly” patients have a “heightened risk for myocardial perforation and thromboembolic complications,” suggesting that age be considered as part of patient selection for RF ablation.⁹ This consensus recommendation was made without recently published observational data that demonstrate no increased risk with age.^10–12

The optimal treatment strategy for RF catheter ablation remains an evolving and elusive goal. The general sense that elderly patients may be at heightened risk for periprocedural complications may imply that a less aggressive approach be utilized. This logical approach without supportive data may actually disservice elderly people who often present with coexistent cardiovascular disease and persistent/chronic AF.¹³ In order to examine age-based procedural strategy risk, we examined RF catheter ablation undertaken in a wide spectrum of AF patients based on the outcomes of two approaches: wide area circumferential ablation (WACA) or a more aggressive approach of WACA plus additional linear lines in the left atrium (WACA-L) for drug refractory AF. We used three age categories: <50, 50–75, >75 years of age.

Methods

Patient population

Patients who underwent pulmonary vein isolation ablation for drug refractory AF, from March 2005 to November 2008, were included and enrolled in a prospective database at the time of their ablation procedure. Of note, this time period represented a change in the ablative paradigm, including the use of the irrigated-tip catheter technology beginning in December of 2005. Our RF ablation approach has been previously described in detail.^14,15

Ablation endpoints

The primary endpoint of the procedure was complete antral isolation with loss of all local atrial electrograms within both pulmonary vein antra as well as along all ablative lines. Entrance block into the pulmonary vein was confirmed by placing a circular mapping catheter in the pulmonary vein orifice with assessment of local electrograms during left atrial pacing. If AF was not terminated after ablation and these subsequent steps described above, sinus rhythm was restored by transthoracic cardioversion. A cavotricuspid isthmus ablation was performed in all patients with bidirectional block confirmed. Additional linear ablation was performed based upon the electrophysiologist's preference, but typically reflected stage of disease, if prior ablation had been performed, or inducibility of atypical atrial flutter after ablation of the standard lesions was complete. After sinus rhythm was restored the pulmonary veins and linear lines were checked for block. Retargeting of complex fractionated electrograms was typically not performed.

Follow-up

Each patient was followed through telephone contact, clinic follow-up visits (1 week, 3 months, 6 months, 12 months), and communication with the patient's primary referring physician. Patients received electrocardiograms at each clinic visit. Auto-triggered AF event monitors were used for 2- to 4-week intervals at 6 and 12 months following ablation to document recurrences after a 3-month blanking period. The electrocardiogram database that spans the entire Intermountain Health Care database was also searched for any documented AF recurrences missed by the other methods. The procedure was deemed to be a “Success” after one or more ablation attempts if they had no documented symptomatic or asymptomatic episodes of AF and no concurrent antiarrhythmic drugs were required after the 3-month blanking period.

Statistical analysis

The total population was separated into two groups for comparison: those who received WACA and those who received WACA-L. Continuous variables were reported as mean ± standard deviation, and comparisons between groups were based on a two-sample t-test (parametric). Categorical variables were summarized as percentages, and group comparisons were based on the chi-square statistic and Fisher's exact test. Survival rates free of AF were estimated using the Kaplan–Meier product limit method. A p-value <0.05 was considered statistically significant.

Results

Between arch 2005 and November 2008, out of a total 908 patients, 855 underwent WACA (n = 160) or WACA-L (n = 748) for drug refractory AF. In these two groups, an older population was seen in the WACA-L (66.0 ± 9.8) versus WACA (60.5 ± 12.3), p<0.0001. Fifty-three of the 908 patients underwent focal RF ablation outside the pulmonary veins only, without WACA. The basic demographics with the associated comparative analysis between ablation strategies are listed in Table 1. More patients with paroxysmal AF underwent WACA than WACA-L (88.1% versus 47.7%, respectively, p<0.0001). WACA-L patients were more likely to have congestive heart failure (40.9% versus 19.4%, p<0.0001), higher levels of BNP236.5 (108–471) versus 96 (44–193) pg/nl, p<0.0001) and have no significant differences in coronary artery disease (10.2% versus 13.1%, p = 0.27). Although more patients received WACA-L, in general there was no age-based difference in strategy use across the three age groups studied (Figure 1).

Periprocedural and long-term complications, and adverse events are listed in Table 2. There were five deaths (4, 55–75; 1>75 years) and four strokes (1<55; 2, 55–75; 1>75 years) as seen in Table 2. One death occurred during the ablative procedure due to pulseless electrical activity. Autopsy results revealed advanced amyloid heart disease. The other four deaths were more than 30 days after the procedure (hemorrhagic stroke, complications of pulmonary hypertension, gastrointestinal (GI) bleed, one unknown cause). Details regarding these adverse outcomes have been previously reported.¹⁵ Of the patients with stroke, one was hemorrhagic, in the setting of an elevated international normalized ratio (INR), whereas the other three occurred in the setting of a therapeutic INR, two of which had recurrent AF. Of these three latter events, no symptoms persisted beyond 3 weeks. The average CHADS2 score was 2.8 (p = 0.20). The patient with the GI bleed had endoscopy, which showed no evidence of an esophageal fistula or erosion. The patient died in the operating room despite attempts to reverse the anticoagulation and find the bleeding source. Given the general low events across all age groups and treatment strategies, we did not observe a significant increase in any of these endpoints based upon procedural type or age group. However, in aggregate, adverse events were more common with WACA-L.

Kaplan–Meier survival curves illustrating no differences in 1-year survival free of AF rates based on ablative procedure type are illustrated in Figure 2a–c. For those patients <55 years (Figure 2a), the 1-year survival rates free of AF are 82.6% (WACA) and 84.9% (WACA-L), and encircling only, p = 0.24. For patients 55–75 years (Figure 2b), the 1-year survival rates free of AF are 84.1% (WACA) and 80.3% (WACA-L), p = 0.38, Finally, for patients >75 years (Figure 2c), the 1-year survival rates free of AF are 71.4% (WACA) and 81.9 % (WACA-L), p = 0.24. Across all age groups, the 1-year survival rates free of AF are 82.9% (WACA) and 81.8% (WACA-L), p = 0.52.

Discussion

Catheter ablation is an effective treatment for AF across a broad spectrum of underlying cardiovascular diseases and age groups. Although on average patients who received WACA-L were older, had more heart failure, had higher baseline levels of BNP, and more likely were in chronic AF, the overall success rate between the two ablation strategies was similar. These outcomes suggest in part that the more aggressive approach (WACA-L) reduces the impact that adverse baseline demographics have in affecting long-term therapy outcomes.

In this age-based comparison, increasing the aggressiveness of the procedure did not correlate with an increase in adverse outcomes. Additionally, WACA-L had a non-significant trend for better freedom from AF rates at 1 year that was most apparent in the age >75 cohort. These findings with WACA-L in elderly people were not surprising as these patients have higher rates of coexistent cardiovascular disease and are more often in chronic AF.¹³ Furthermore, our findings suggest that age alone should not be used to determine RF procedural approach and that this decision should largely be based on other factors such as type of AF and additional cardiac disease.

The prevalence of AF increases with age. Ablative therapy has traditionally been withheld from “very elderly” patients largely based on guideline recommendations⁹ and with the assumption that risks are higher than those observed in younger patients. Additionally, success rates of RF ablative therapy for AF occurring in elderly patients have not been firmly established. Currently, RF ablation is frequently withheld despite the fact that with advancing age the frequency of symptomatic episodes of AF increase with age and antiarrhythmic drugs are poorly tolerated.^3–5 Our results added to others^10–12 establish that successful ablation of AF in elderly patients can be achieved.

We previously observed in very elderly patients that they often required additional days of hospitalization after the procedure.¹³ The most common reason for the longer hospital stay was fluid overload management. A more aggressive approach with an irrigated-tip catheter that requires additional ablation and catheter movement will directly impact this prior observation in that elderly patients with cardiovascular disease have higher rates of renal insufficiency.^16,17 Our data herein show an incremental risk of renal insufficiency in elderly patients who present for ablation.

The RF ablation approach for AF continues to evolve and be modified. In most patients a tailored approach is required based upon multiple clinical factors. Although isolation of the pulmonary veins remains the cornerstone of the approach, most patients with persistent AF, severe left atrial enlargement, heart failure, and diastolic heart disease need additional linear ablation. These ablation lines are similar to those advocated with the Cox Maze III procedure.^9,18–21 The characteristics that drive the need for more aggressive ablation continues to increase in an age- and age-independent manner in the community.²² Coupled with an aging population, this and other data herein that suggest safety with aggressive ablation approaches in elderly people are vital to understanding the approach and utility of RF ablation strategies for the population in general.

Study limitations

The major limitation to this study as well as other observation studies with ablation is that these patients were selected for the procedure. Therefore, they likely represent a healthier population in general, particularly as we examined an underserved population such as elderly people. Nonetheless, the large patient population and consecutive study design minimize this limitation. In addition, patients were assessed for recurrent AF based upon symptoms, routine clinic visits, auto- and symptom-triggered AF event monitors, and standard electrocardiograms for asymptomatic patients. Subclinical periods of paroxysmal AF between follow-up visits may have been missed. This is further compounded by the fact that elderly patients may have more episodes of asymptomatic AF.²³ The latter limitation we tried to minimize through the frequent use of auto- and symptom-triggered event monitors. Finally, many older patients with AF have other medical comorbidities and may be referred for other interventions such as AV node ablation and/or pacemaker implantation. This latter limitation highlights the need for studies that examine efficacy and risk in novel populations and approaches.

Conclusion

Catheter ablation for AF in elderly patients can be performed with efficacy and risk profiles that are similar to those observed in younger patients. Our results suggest that patients who received WACA-L were older and had more coexistent heart disease. Furthermore, survival free of AF tended to be better in those who received WACA-L than WACA alone. Ablation strategies used for determining intervention type (WACA or WACA-L) should be independent of age and rather be made based on AF type. In fact, given the potential for drug therapy intolerance with age, coupled with the documented tendency for increased frequency and severity of AF that also occur with age, ablative therapy should be considered early in the management strategy of these patients.

References

1. Rosamond W, Flegal K, Friday G, et al. Heart disease and stroke statistics–2007 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Circulation 2007; 115:e69–171. [CrossRef] [PubMed]
2. Go AS. The epidemiology of atrial fibrillation, in elderly persons: the tip of the iceberg. Am J Geriatr Cardiol 2005; 14:56–61. [CrossRef] [PubMed]
3. Pandit SV, Jalife J. Aging and atrial fibrillation research: where we are and where we should go. Heart Rhythm 2007; 4:186–187. [CrossRef] [PubMed]
4. Kistler PM, Sanders P, Fynn SP, et al. Electrophysiologic and electroanatomic changes in the human atrium associated with age. J Am Coll Cardiol 2004; 44:109–116. [CrossRef] [PubMed]
5. Chatap G, Giraud K, Vincent JP. Atrial fibrillation in the elderly: facts and management. Drugs Aging 2002; 19:819–846. [CrossRef] [PubMed]
6. Cappato R, Calkins H, Chen S-A, et al. Worldwide survey on the methods, efficacy, and safety of catheter ablation for human atrial fibrillation. Circulation 2005; 111:1100–1105. [CrossRef] [PubMed]
7. Cappato R, Calkins H, Chen S-A, et al. Second worldwide survey on efficacy and safety of catheter ablation for AF. Presented at Boston Atrial Fibrillation Symposium 2009;
8. Shah DC, Haissaguere M, Jais P, et al. Curative catheter ablation of paroxysmal atrial fibrillation in 200 patients: strategy for presentations ranging from sustained atrial fibrillation to no arrhythmias. Pacing Clin Electrophysiol 2001; 24:1541–1548. [CrossRef] [PubMed]
9. Calkins H, Brugada J, Packer DL, et al. HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for personnel, policy, procedures and follow-up. A report of the Heart Rhythm Society (HRS) Task Force on catheter and surgical ablation of atrial fibrillation. Heart Rhythm 2007; 4:816–861. [CrossRef] [PubMed]
10. Corrado A, Patel D, Riedlbauchova L, et al. Efficacy, safety, and outcome of atrial fibrillation ablation in septuagenarians. J Cardiovasc Electrophysiol 2008; 19:807–811. [CrossRef] [PubMed]
11. Zado E, Callans DJ, Riley M, et al. Long-term clinical efficacy and risk of catheter ablation for atrial fibrillation in the elderly. J Cardiovasc Electrophysiol 2008; 19:621–626. [CrossRef] [PubMed]
12. Hsieh MH, Tai CT, Lee SH, et al. Catheter ablation for atrial fibrillation versus atrioventricular junctional ablation plus pacing for elderly patients with medically refractory paroxysmal atrial fibrillation. J Cardiovasc Electrophysiol 2005; 16:457–461. [CrossRef] [PubMed]
13. Bunch TJ, Weiss JP, Crandall BG, et al. Long-term clinical efficacy and risk of catheter ablation for atrial fibrillation in octogenarians. Pacing Clin Electrophysiol 2010; 33:146–152. [CrossRef] [PubMed]
14. Bunch TJ, Day JD. Novel ablative approach for atrial fibrillation to decrease risk of esophageal injury. Heart Rhythm 2008; 5:624–627. [CrossRef] [PubMed]
15. Bunch TJ, Crandall BG, Weiss JP, et al. Warfarin is not needed in low-risk patients following atrial fibrillation ablation procedures. J Cardiovasc Electrophysiol 2009; 20:988–993. [CrossRef] [PubMed]
16. Hage FG, Venkataraman R, Zoghbi GJ, Perry GJ, DeMattos AM, Iskandrian AE. The scope of coronary heart disease in patients with chronic kidney disease. J Am Coll Cardiol 2009; 53:2129–2140. [CrossRef] [PubMed]
17. Martin-Pfitzenmeyer I, Gauthier S, Bailly M, et al. Prognostic factors in stage d heart failure in the very elderly. Gerontology 2009; 55:719–726. [CrossRef] [PubMed]
18. Ernst S, Ouyang F, Lober F, Antz M, Kuck KH. Catheter-induced linear lesions in the left atrium in patients with atrial fibrillation: an electroanatomic study. J Am Coll Cardiol 2003; 42:1271–1282. [CrossRef] [PubMed]
19. Hocini M, Jais P, Sanders P, et al. Techniques, evaluation, and consequences of linear block at the left atrial roof in paroxysmal atrial fibrillation: a prospective randomized study. Circulation 2005; 112:3688–3696. [CrossRef] [PubMed]
20. Jais P, Hocini M, Hsu LF, et al. Technique and results of linear ablation at the mitral isthmus. Circulation 2004; 110:2996–3002. [CrossRef] [PubMed]
21. Pappone C, Manguso F, Vicedomini G, et al. Prevention of iatrogenic atrial tachycardia after ablation of atrial fibrillation: a prospective randomized study comparing circumferential pulmonary vein ablation with a modified approach. Circulation 2004; 110: 3036–3042. [CrossRef] [PubMed]
22. Miyasaka Y, Barnes ME, Gersh BJ, et al. Secular trends in incidence of atrial fibrillation in Olmsted County, Minnesota, 1980 to 2000, and implications on the projections for future prevalence. Circulation 2006; 114:119–125. [CrossRef] [PubMed]
23. Reiffel JA, Schwarzberg R, Murry M. Comparison of autotriggered memory loop recorders versus standard loop recorders versus 24-hour Holter monitors for arrhythmia detection. Am J Cardiol 2005; 95:1055–1059. [CrossRef] [PubMed]