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Characteristics of isolated atrial flutter versus atrial flutter combined with atrial fibrillation
Archives of Cardiovascular Disease (2011) 104, 530—535
CLINICAL RESEARCH
Characteristics of isolated atrial flutter versus atrial flutter combined with atrial fibrillation Caractéristique du flutter isolé versus associé à une fibrillation auriculaire Michael Peyrol ∗, Pascal Sbragia , Laurent Bonello , Samuel Lévy , Franck Paganelli School of Medicine, université de La-Méditerrané, hôpital Nord, Division of Cardiology, chemin des Bourrelys, 13015 Marseille, France Received 20 May 2011; received in revised form 13 July 2011; accepted 29 July 2011
KEYWORDS Atrial fibrillation; Atrial flutter; Characteristics
∗
Summary Background. — Atrial flutter (AFL) and atrial fibrillation (AF) are ‘‘fellow-travellers’’. AF may be a stable, ‘‘isolated’’ rhythm, a bridge between sinus rhythm and AF, or both arrhythmias can coexist. Whether the characteristics of isolated AFL are different from those of patients with AFL combined with AF is still unclear. Aim. — To compare the clinical characteristics of patients with isolated AFL to those of patients with AFL combined with AF, in a series of patients referred for AFL ablation. Methods. — Seventy-six consecutive patients (mean age 66.9 ± 12.2 years; 53 men) with a history of electrocardiogram-documented paroxysmal or persistent AFL, referred for catheter ablation, underwent clinical work-up including bidimensional echocardiogram. Patients were subdivided into group I (44 with isolated AFL) and group II (32 with AFL and a history of AF). Results. — Underlying heart disease was present in 62 patients (81.6%). Hypertension was the most common cardiac disorder (n = 44, 57.9%) and was more prevalent in group II than in group I (75.0% vs 45.5%; P = 0.01). Prevalence of prior cardiac surgery was higher in group I (22.7% vs 6.3%; P = 0.04). AFL was persistent in 35 group I patients and 17 group II patients (79.5% vs 53.1%; P = 0.01). Class I or III antiarrhythmic drug use was more frequent in group II (84.4% vs 45.5%; P = 0.001). Conclusion. — This study showed significant differences between patients with isolated AFL and those with AFL combined with AF, in the prevalence of underlying heart disease and the use of antiarrhythmic medication, which were higher when both atrial arrhythmias were combined. In
Abbreviations: AF, atrial fibrillation; AFL, atrial flutter; ECG, electrocardiogram. Corresponding author. Fax: +34 91 96 89 79. E-mail address: [email protected] (M. Peyrol).
1875-2136/$ — see front matter © 2011 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.acvd.2011.07.003
Characteristics of atrial flutter with/without atrial fibrillation
531
turn, the history of cardiac surgery (including atriotomy), was more common in patients with isolated AFL than in those with AFL combined with AF. © 2011 Elsevier Masson SAS. All rights reserved.
MOTS CLÉS Flutter atrial ; Fibrillation atriale ; Anticoagulation orale ; Cardiopathie
Résumé Introduction. — Une relation étroite existe entre flutter atrial (FLA) et fibrillation atriale (FA). Le FLA peut être une arythmie cardiaque « isolé » et stable, mais aussi un rythme transitoire entre rythme sinusal et FA. Ces deux troubles du rythme peuvent par ailleurs coexister chez le même patient. L’existence d’une différence de caractéristiques cliniques des patients avec FLA isolé de ceux avec FLA et FA associés n’a pas été précédemment étudiée. Nous avons comparé ces deux populations dans une série de patients adressés pour ablation de FLA. Méthode et résultats. — Soixante-seize patients (53 hommes et 23 femmes) avec un âge moyen de 66,9 ± 12,2 ans et un FLA paroxystique ou persistent documenté par ECG, adressés pour ablation endocavitaire de FLA ont bénéficié d’un examen clinique complet incluant une échocardiographie bidimensionnelle. Les patients étaient répartis en deux groupes : groupe I (44 patients) dans lequel les patients avaient un FLA isolé et groupe II (32 patients) dans lequel les patients avaient également un antécédent de FA. Une cardiopathie sous-jacente était présente chez 62 patients (81,6 %). L’hypertension artérielle était l’anomalie la plus fréquente, retrouvée chez 44 patients (57,9 %) et était plus fréquente dans le groupe II que dans le groupe I (75,0 % versus 45,5 % ; p = 0,01). La prévalence d’un antécédent de chirurgie cardiaque avec atriotomie était supérieure dans le groupe I que dans le groupe II (22,7 % versus 6,3 % ; p = 0,04). Le FLA était persistent chez 35 patients du groupe I et 17 patients du groupe II (79,5 % versus 53,1 % ; p = 0,01). La prescription de traitement antiarythmique de classe I ou III était plus fréquente dans le groupe II que dans le groupe I (84,4 % versus 45,5 % ; p = 0,001). Les caractéristiques cliniques des deux groupes étudiés étaient comparables par ailleurs. Conclusion. — Cette étude rapporte des différences cliniques significatives entre les patients avec FLA isolé et ceux avec FLA et FA associés en termes de prévalence de cardiopathie sousjacente et de prescription de traitement antiarythmique qui étaient supérieures quand les deux troubles du rythme étaient combinés. En revanche, un antécédent de chirurgie cardiaque avec cicatrice d’atriotomie était plus fréquent chez les patients avec FLA isolé que chez les patients avec FLA et FA associés. © 2011 Elsevier Masson SAS. Tous droits réservés.
Introduction Atrial flutter (AFL) and atrial fibrillation (AF) are considered to be ‘‘fellow-travellers’’ and to share similar clinical contexts. AFL may be a stable, ‘‘isolated’’ rhythm, a bridge between sinus rhythm and AF, or both arrhythmias can coexist in the same patient. Among patients referred for catheter ablation of AFL, the prevalence of AF before ablation in current literature ranged from 24% to 62% [1—7]. The followup of patients who underwent successful ablation of the cavotricuspid isthmus for isolated AFL showed occurrence of AF in up to 70% of cases [8]. Long-term administration of class I or III antiarrhythmic agents in patients with AF may promote the conversion of AF into AFL in 12.8% to 22.4% of cases [9,10]. Newly discovered AF has been detected in 8% of patients after AFL ablation, early (< 6 months) after the procedure [11]. Clinical characteristics of patients with AF have been previously described in a number of population-based studies [12—14]. Multivariable analysis from the Framingham Heart Study showed that age, male sex, hypertension, congestive heart failure, diabetes and valve disease were independent risk factors for the development of AF [12,14]. Arrhythmogenic substrates and mechanisms underlying the presence of common AFL are better understood than those of AF
and catheter ablation therapy of AFL has been proposed as a first-line treatment because of the limited efficacy of pharmacological therapy and the good results that it achieves. Surprisingly, studies on the clinical characteristics of patients with AFL are scarce. In a population-based study, independent clinical risk factors for AFL development were found to be heart failure and chronic obstructive pulmonary disease, with relative risks being 3.5 and 1.9, respectively. AFL was found to be 2.5 times more frequent in men than in women [15]. Whether the characteristics of patients with isolated AFL differ from those of patients with AFL combined with AF is still unclear. The aim of this study was to compare the clinical characteristics of patients with isolated AFL to those of patients with AFL combined with AF, in a series of patients referred for AFL ablation.
Methods From 1 January 2005 to 30 April 2007, 76 consecutive patients with electrocardiogram (ECG)-documented AFL lasting more than 30 seconds were referred to our institution for catheter ablation. The information provided by the clinical and biological work-up was prospectively collected
532 but the analysis was retrospective. Excluded from the study were patients with recent (< 1 month) cardiac surgery, acute pulmonary embolism, pulmonary infection, hyperthyroidism or prior left atrial ablation for the treatment of AF. All patients underwent M mode and bidimensional echocardiogram. ECG diagnosis of AF was made according to Bellet’s definition [16]. AFL was diagnosed when the surface ECG showed highly regular atrial tachycardia greater than 240 beats per minute, with continuous wave and the typical ‘‘sawtooth’’ pattern in the inferior leads. The atrial rate of AFL had to be greater than 200 beats per minute in patients on class I or class III antiarrhythmic agents [13]. Common AFL was defined on the ECG as having negative flutter waves (F waves) in the inferior leads (II, III and VF) and positive F waves in lead V1. The surface ECG of uncommon AFL was defined as having positive F waves in the inferior leads and negative F waves in lead V1. The type of AFL was defined according to the classification described for AF: paroxysmal when the arrhythmia was self-terminating within 7 days and persistent when lasting for more than 7 days [17]. Patients without detectable underlying heart disease or a detectable cause were labelled as having ‘‘lone AFL’’. Patients were subdivided into two groups based on the absence or presence of a clinical history and/or of the ECG record of AF. Group I included patients with no history of AF and group II included patients with both AFL and a history of ECG-documented AF (duration > 30 seconds). Clinical characteristics and the use of antiarrhythmic and anticoagulant medications were recorded. ECG (and, when indicated, 24-hour ECG ambulatory recording) and bidimensional echocardiographic findings were reviewed. Hypertension was diagnosed when blood pressure at rest was greater than 140/90 mmHg (or, in a treated patient, by the use of antihypertensive medication). Coronary artery disease was diagnosed when a documented history of myocardial infarction and/or coronary revascularization was present, or if one or more significant (> 70%) obstructive lesion(s) were present on a coronary angiogram. Diagnosis of valvular heart disease was made in patients with moderate to severe valvular regurgitation or on the evidence of mitral stenosis.
Statistical analysis Results are reported as mean ± standard deviation or number and percentage, as applicable. Qualitative clinical characteristics of patients were examined using Fisher’s exact test or the Khi-square test. The t test was used for quantitative values. A P value less than 0.05 was considered to be statistically significant. All analyses were performed using Microsoft Excel (Microsoft Corporation, Redmond, WA, USA) and SPSS (SPSS Inc., Chicago, IL, USA).
Results The study included 76 patients with AFL who fulfilled the inclusion criteria. There were 53 men (69.7%) and 23 women (30.3%), with a mean age of 66.9 ± 12.2 years (range 33—90 years), as shown in Table 1. The mean time from the first
M. Peyrol et al. episode of AFL to present clinical evaluation was 76 ± 55 days (range 0—240 months). Underlying heart disease was present in 62 patients (81.6%) and included hypertension in 44 patients (57.9%), ischaemic cardiomyopathy in 15 patients (19.7%), valvular heart disease in 10 patients (13.2%), four of whom had rheumatic valve disease and dilated cardiomyopathy in seven patients (9.2%). History of cardiac surgery (including atriotomy) was present in 12 patients (15.8%). AFL occurred 3—43 months after cardiac surgery. None of these 12 patients experienced AFL perioperatively or had documented AFL prior to surgery. Chronic obstructive lung disease was diagnosed in 12 patients (15.8%). Fourteen patients (18.4%) were classified as having ‘‘lone AFL’’. Among 62 patients with detectable heart disease, 15 were in New York Heart Association class I (24.2%), 24 in class II (38.7%), nine in class III (14.5%) and 14 in class IV (22.4%). A history of thromboembolic event was present in eight patients (10.5%). In no patient was an embolic event the presenting symptom of AFL. Common predisposing factors to thromboembolism were not more common in patients with a history of embolic events than in those without. Hypertension was significantly more common in group II than in group I (75.0% vs 45.5%; P = 0.01). Prior cardiac surgery (including atriotomy) was significantly more frequent in group I than in group II (22.7% vs 6.3%; P = 0.04). The remaining clinical characteristics of the two groups did not differ significantly. As shown in table 2, AFL on the ECG was of the common type in 59 patients (77.6%) and of the uncommon type in 17 (22.4%). The mean AFL cycle length was 244 ± 43.7 ms (range 200 to 300 ms) and did not significantly differ between group I and group II (239.3 ± 36.2 vs 253.1 ± 55.7 ms; P = 0.40). AFL was paroxysmal in 24 patients (31.6%) and persistent in the remaining 52 (68.4%). There was more persistent AFL in group I than in group II (79.5% vs 53.1%; P = 0.01). Among the 12 patients with prior cardiac surgery, AFL was paroxysmal in 10 (83%). AFL was of the common type in eight patients and of the uncommon type in the remaining four patients. Mean left ventricular ejection fraction and mean left atrial anteroposterior diameter measured on echocardiogram were 56.3 ± 12.4% (range 20% to 70%) and 45.1 ± 6.8 mm (range 30 to 59 mm), respectively. There were no significant differences in these echocardiographic variables between the two groups, as shown in table 2. Antiarrhythmic drug therapy and anticoagulant therapy at the time of hospitalization are summarized in table 3. Anticoagulant drug therapy included vitamin K antagonists in 65 patients (85.5%). Clopidogrel was associated with vitamin K antagonists in seven patients (9.2%) and with vitamin K antagonists plus aspirin in one patient with recent (< 1 month) coronary angioplasty. At the time of the hospitalization, 47 patients (61.8%) were treated with either a class Ic sodium channel blocker or amiodarone. Twenty patients in group I and 27 patients in group II were on antiarrhythmic drugs aimed at preventing arrhythmia recurrences. Prescription of these agents was significantly more frequent in group II patients than in group I patients (45.5% vs 84.4%; P = 0.001). Twenty-two patients (29.0%) were receiving heart rate control agents, such as beta-blockers in 17 patients (22.4%) and non-dihydropyridine calcium channel blockers in five patients (6.6%), with no significant differences between the two groups.
Characteristics of atrial flutter with/without atrial fibrillation Table 1
533
Clinical characteristics of patients. Total population (n = 76)
Age (years) Male/female ratio (n/n) Body weight (kg) Height (cm) Systolic BP (mmHg) Diastolic BP (mmHg) NYHA functional class I II III IV
Isolated AFL (n = 44)
AFL combined with AF (n = 32)
P
66.9 ± 12.2
66.7 ± 12.5
67.2 ± 12.1
0.86
53/23
31/13
22/10
0.34
75.6 ± 13.8
76.5 ± 13.7
74.4 ± 14.1
0.64
168.5 ± 7.7
169.7 ± 6.5
166.7 ± 8.9
0.11
132 ± 14
132 ± 15
133 ± 13
0.71
70 ± 10
69 ± 10
72 ± 9
0.80
2.34 ± 1.09 15 (24.2) 24 (38.7) 9 (14.5) 14 (22.4)
2.30 ± 1.00 9 (20.5) 21 (47.7) 6 (13.6) 8 (18.2)
2.41 ± 1.21 10 (31.3) 8 (25.0) 5 (15.6) 9 (28.1)
0.67
Underlying heart disease Hypertension Coronary artery disease Dilated cardiomyopathy Non-rheumatic heart disease Rheumatic heart disease Lone AFL
62 44 15 7 10 4 14
(81.6) (57.9) (19.7) (9.2) (13.2) (5.3) (18.4)
Predisposing or associated factors Prior cardiac surgery Bronchopulmonary disease Prior embolic events
12 (15.8) 14 (18.4) 8 (10.5)
33 20 8 5 5 2 11
(75.0) (45.5) (18.6) (11.4) (11.6) (4.5) (25.0)
10 (22.7) 9 (20.5) 2 (4.5)
29 24 7 2 5 2 3
* * * *
(90.6) (75.0) (21.9) (6.3) (15.6) (6.3) (9.4)
0.08 0.01 0.72 0.69 0.73 0.91 0.08
2 (6.3) 5 (15.6) 6 (18.8)
0.04 0.59 0.06
Data are mean ± standard deviation or number (%), unless otherwise indicated. AF: atrial fibrillation; AFL: atrial flutter; BP: blood pressure; NYHA: New York Heart Association. * Not significant.
Table 2
Electrocardiographic and echocardiographic findings. Total population (n = 76)
ECG-based AFL classification Common Uncommon Type of AFL Paroxysmal Persistent
Isolated AFL (n = 44)
AFL combined with AF (n = 32)
P
59 (77.6) 17 (22.4)
35 (79.5) 9 (20.5)
24 (75.0) 8 (25.0)
0.64
24 (31.6) 52 (68.4)
9 (20.5) 35 (79.5)
15 (46.9) 17 (53.1)
0.01
Heart rate (beats per minute)
104.7 ± 32.0
106.5 ± 33.2
102.2 ± 30.7
0.56
AFL cycle length (ms)
244.2 ± 43.7
239.3 ± 36.2
253.1 ± 55.7
0.40
Left ventricular ejection fraction (%)
56.3 ± 12.4
56.9 ± 11.6
55.5 ± 13.7
0.65
Left atrial diameter (mm)
45.1 ± 6.8
44.6 ± 6.7
46.4 ± 6.9
0.22
Data are mean ± standard deviation or number (%). AF: atrial fibrillation; AFL: atrial flutter; ECG: electrocardiogram.
Discussion Our study showed that patients with both AFL and AF (group II) had a significantly higher prevalence of associated heart disease (mainly hypertension) and a higher use of antiarrhythmic medication aimed at prevention of recurrences than those with isolated AFL (group I). Another interesting
finding was the higher prevalence of cardiac surgery (including atriotomy) in the group of patients with isolated AFL (group I). The other clinical characteristics did not differ significantly between groups. A review of current literature showed a paucity of information on the clinical characteristics of isolated AFL compared with AFL combined with AF. The Framingham
534 Table 3
M. Peyrol et al. Antiarrhythmic drug therapy and anticoagulant therapy at the time of admission. Total population (n = 76)
Antiarrhythmic agents Class Ic or III Class Ic Class III Beta-blockers Calcium channel blockers
47 14 33 17 5
Anticoagulant therapy Vitamin K antagonists Aspirin Clopidogrel
(61.8) (18.4) (43.4) (22.4) (6.6)
Isolated AFL (n = 44) 20 5 15 9 3
AFL combined with AF (n = 32)
P
(45.5) (11.4) (34.1) (20.5) (6.8)
27 (84.4) 9 (28.1) 18 (56.3) 9 (20.5) 2 (6.8)
0.001 0.06 0.05 0.64 1
65 (85.5) 11 (14.5) 8 (10.5)
36 (81.8) 11 (14.5) 3 (6.8)
36 (8.8) 5 (15.6) 5 (15.6)
0.33 0.90 0.27
Statins
23 (30.3)
14 (31.8)
14 (31.8)
0.73
Renin-angiotensin antagonists
37 (48.7)
22 (50.0)
15 (46.9)
0.79
Data are number (%). AF: atrial fibrillation; AFL: atrial flutter.
Heart Study report did not provide such information, as patients were enrolled with either AF or AFL diagnosed on 12-lead ECG [12,14]. A population-based study on the incidence and predisposing factors for AFL in the general population in the Marshfield Epidemiologic Study Area database, reported by Granada et al. in 2002, found that heart failure and chronic obstructive pulmonary disease were the two independent factors predisposing to AFL [15]. Clinical history of AF in patients referred for catheter ablation of AFL in the current literature ranged from 24% to 62% [1—7]. In one study, the 29-month follow-up of 333 patients who underwent successful catheter ablation of the cavotricuspid isthmus for the treatment of AFL revealed occurrence of AF in up to 70% of patients [8]. Similarly, Bertaglia et al. [1] found a cumulative probability of AF post AFL ablation of 50%, 58% and 63% over follow-up periods of 2, 3 and 4 years, respectively. Waldo and Feld recently underlined the role of AF as a transitional rhythm in the development of AFL, illustrating the close inter-relationship between these two arrhythmias [18]. Our study found a high prevalence of postoperative AFL (15% of cases). Although only a small percentage of patients who undergo cardiac surgery may develop AFL, the presence of atriotomy scars may constitute a line of conduction block facilitating a re-entrant circuit. Our study also showed a higher prevalence of hypertension in the group of patients with combined AFL and AF, which contrasts with the findings of Vidaillet et al. [19]. However, the differences in clinical characteristics found between isolated AFL and AFL combined with AF do not support a difference in the management of patients with flutter regarding the need for oral anticoagulation.
However, because of the poor response of AFL to antiarrhythmic medications aimed at preventing recurrences and the excellent results of catheter ablation, this strategy is emerging as a first-line therapy. Our study represents a relatively small group of patients and requires confirmation in a larger patient population. The presence of AF was based on ECG recordings and clinical history of AF. It is likely that the presence of AF — particularly asymptomatic AF — may have been underestimated. Even 24-hour ambulatory recording, which was not done systematically in our study, is unable to detect all episodes of silent AF. New monitoring techniques for AF, including implantable diagnostic devices, may help to clarify the prevalence and significance of asymptomatic atrial arrhythmias.
Conclusion This report on the clinical characteristics of patients with AFL undergoing catheter ablation showed that patients with documented AF had a higher prevalence of heart disease (particularly hypertension) and a higher use of antiarrhythmic drug therapy than those with isolated AFL. In turn, those with isolated AFL had a higher prevalence of cardiac surgery (including atriotomy) than those with combined arrhythmias.
Disclosure of interest The authors declare that they have no conflicts of interest concerning this article.
Study limitations Our patient population consisted of patients with AFL referred to our hospital for catheter ablation because of arrhythmia recurrences. Therefore, our results cannot be extrapolated to a larger population of patients with AFL.
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Characteristics of atrial flutter with/without atrial fibrillation
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CLINICAL RESEARCH
Characteristics of isolated atrial flutter versus atrial flutter combined with atrial fibrillation Caractéristique du flutter isolé versus associé à une fibrillation auriculaire Michael Peyrol ∗, Pascal Sbragia , Laurent Bonello , Samuel Lévy , Franck Paganelli School of Medicine, université de La-Méditerrané, hôpital Nord, Division of Cardiology, chemin des Bourrelys, 13015 Marseille, France Received 20 May 2011; received in revised form 13 July 2011; accepted 29 July 2011
KEYWORDS Atrial fibrillation; Atrial flutter; Characteristics
∗
Summary Background. — Atrial flutter (AFL) and atrial fibrillation (AF) are ‘‘fellow-travellers’’. AF may be a stable, ‘‘isolated’’ rhythm, a bridge between sinus rhythm and AF, or both arrhythmias can coexist. Whether the characteristics of isolated AFL are different from those of patients with AFL combined with AF is still unclear. Aim. — To compare the clinical characteristics of patients with isolated AFL to those of patients with AFL combined with AF, in a series of patients referred for AFL ablation. Methods. — Seventy-six consecutive patients (mean age 66.9 ± 12.2 years; 53 men) with a history of electrocardiogram-documented paroxysmal or persistent AFL, referred for catheter ablation, underwent clinical work-up including bidimensional echocardiogram. Patients were subdivided into group I (44 with isolated AFL) and group II (32 with AFL and a history of AF). Results. — Underlying heart disease was present in 62 patients (81.6%). Hypertension was the most common cardiac disorder (n = 44, 57.9%) and was more prevalent in group II than in group I (75.0% vs 45.5%; P = 0.01). Prevalence of prior cardiac surgery was higher in group I (22.7% vs 6.3%; P = 0.04). AFL was persistent in 35 group I patients and 17 group II patients (79.5% vs 53.1%; P = 0.01). Class I or III antiarrhythmic drug use was more frequent in group II (84.4% vs 45.5%; P = 0.001). Conclusion. — This study showed significant differences between patients with isolated AFL and those with AFL combined with AF, in the prevalence of underlying heart disease and the use of antiarrhythmic medication, which were higher when both atrial arrhythmias were combined. In
Abbreviations: AF, atrial fibrillation; AFL, atrial flutter; ECG, electrocardiogram. Corresponding author. Fax: +34 91 96 89 79. E-mail address: [email protected] (M. Peyrol).
1875-2136/$ — see front matter © 2011 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.acvd.2011.07.003
Characteristics of atrial flutter with/without atrial fibrillation
531
turn, the history of cardiac surgery (including atriotomy), was more common in patients with isolated AFL than in those with AFL combined with AF. © 2011 Elsevier Masson SAS. All rights reserved.
MOTS CLÉS Flutter atrial ; Fibrillation atriale ; Anticoagulation orale ; Cardiopathie
Résumé Introduction. — Une relation étroite existe entre flutter atrial (FLA) et fibrillation atriale (FA). Le FLA peut être une arythmie cardiaque « isolé » et stable, mais aussi un rythme transitoire entre rythme sinusal et FA. Ces deux troubles du rythme peuvent par ailleurs coexister chez le même patient. L’existence d’une différence de caractéristiques cliniques des patients avec FLA isolé de ceux avec FLA et FA associés n’a pas été précédemment étudiée. Nous avons comparé ces deux populations dans une série de patients adressés pour ablation de FLA. Méthode et résultats. — Soixante-seize patients (53 hommes et 23 femmes) avec un âge moyen de 66,9 ± 12,2 ans et un FLA paroxystique ou persistent documenté par ECG, adressés pour ablation endocavitaire de FLA ont bénéficié d’un examen clinique complet incluant une échocardiographie bidimensionnelle. Les patients étaient répartis en deux groupes : groupe I (44 patients) dans lequel les patients avaient un FLA isolé et groupe II (32 patients) dans lequel les patients avaient également un antécédent de FA. Une cardiopathie sous-jacente était présente chez 62 patients (81,6 %). L’hypertension artérielle était l’anomalie la plus fréquente, retrouvée chez 44 patients (57,9 %) et était plus fréquente dans le groupe II que dans le groupe I (75,0 % versus 45,5 % ; p = 0,01). La prévalence d’un antécédent de chirurgie cardiaque avec atriotomie était supérieure dans le groupe I que dans le groupe II (22,7 % versus 6,3 % ; p = 0,04). Le FLA était persistent chez 35 patients du groupe I et 17 patients du groupe II (79,5 % versus 53,1 % ; p = 0,01). La prescription de traitement antiarythmique de classe I ou III était plus fréquente dans le groupe II que dans le groupe I (84,4 % versus 45,5 % ; p = 0,001). Les caractéristiques cliniques des deux groupes étudiés étaient comparables par ailleurs. Conclusion. — Cette étude rapporte des différences cliniques significatives entre les patients avec FLA isolé et ceux avec FLA et FA associés en termes de prévalence de cardiopathie sousjacente et de prescription de traitement antiarythmique qui étaient supérieures quand les deux troubles du rythme étaient combinés. En revanche, un antécédent de chirurgie cardiaque avec cicatrice d’atriotomie était plus fréquent chez les patients avec FLA isolé que chez les patients avec FLA et FA associés. © 2011 Elsevier Masson SAS. Tous droits réservés.
Introduction Atrial flutter (AFL) and atrial fibrillation (AF) are considered to be ‘‘fellow-travellers’’ and to share similar clinical contexts. AFL may be a stable, ‘‘isolated’’ rhythm, a bridge between sinus rhythm and AF, or both arrhythmias can coexist in the same patient. Among patients referred for catheter ablation of AFL, the prevalence of AF before ablation in current literature ranged from 24% to 62% [1—7]. The followup of patients who underwent successful ablation of the cavotricuspid isthmus for isolated AFL showed occurrence of AF in up to 70% of cases [8]. Long-term administration of class I or III antiarrhythmic agents in patients with AF may promote the conversion of AF into AFL in 12.8% to 22.4% of cases [9,10]. Newly discovered AF has been detected in 8% of patients after AFL ablation, early (< 6 months) after the procedure [11]. Clinical characteristics of patients with AF have been previously described in a number of population-based studies [12—14]. Multivariable analysis from the Framingham Heart Study showed that age, male sex, hypertension, congestive heart failure, diabetes and valve disease were independent risk factors for the development of AF [12,14]. Arrhythmogenic substrates and mechanisms underlying the presence of common AFL are better understood than those of AF
and catheter ablation therapy of AFL has been proposed as a first-line treatment because of the limited efficacy of pharmacological therapy and the good results that it achieves. Surprisingly, studies on the clinical characteristics of patients with AFL are scarce. In a population-based study, independent clinical risk factors for AFL development were found to be heart failure and chronic obstructive pulmonary disease, with relative risks being 3.5 and 1.9, respectively. AFL was found to be 2.5 times more frequent in men than in women [15]. Whether the characteristics of patients with isolated AFL differ from those of patients with AFL combined with AF is still unclear. The aim of this study was to compare the clinical characteristics of patients with isolated AFL to those of patients with AFL combined with AF, in a series of patients referred for AFL ablation.
Methods From 1 January 2005 to 30 April 2007, 76 consecutive patients with electrocardiogram (ECG)-documented AFL lasting more than 30 seconds were referred to our institution for catheter ablation. The information provided by the clinical and biological work-up was prospectively collected
532 but the analysis was retrospective. Excluded from the study were patients with recent (< 1 month) cardiac surgery, acute pulmonary embolism, pulmonary infection, hyperthyroidism or prior left atrial ablation for the treatment of AF. All patients underwent M mode and bidimensional echocardiogram. ECG diagnosis of AF was made according to Bellet’s definition [16]. AFL was diagnosed when the surface ECG showed highly regular atrial tachycardia greater than 240 beats per minute, with continuous wave and the typical ‘‘sawtooth’’ pattern in the inferior leads. The atrial rate of AFL had to be greater than 200 beats per minute in patients on class I or class III antiarrhythmic agents [13]. Common AFL was defined on the ECG as having negative flutter waves (F waves) in the inferior leads (II, III and VF) and positive F waves in lead V1. The surface ECG of uncommon AFL was defined as having positive F waves in the inferior leads and negative F waves in lead V1. The type of AFL was defined according to the classification described for AF: paroxysmal when the arrhythmia was self-terminating within 7 days and persistent when lasting for more than 7 days [17]. Patients without detectable underlying heart disease or a detectable cause were labelled as having ‘‘lone AFL’’. Patients were subdivided into two groups based on the absence or presence of a clinical history and/or of the ECG record of AF. Group I included patients with no history of AF and group II included patients with both AFL and a history of ECG-documented AF (duration > 30 seconds). Clinical characteristics and the use of antiarrhythmic and anticoagulant medications were recorded. ECG (and, when indicated, 24-hour ECG ambulatory recording) and bidimensional echocardiographic findings were reviewed. Hypertension was diagnosed when blood pressure at rest was greater than 140/90 mmHg (or, in a treated patient, by the use of antihypertensive medication). Coronary artery disease was diagnosed when a documented history of myocardial infarction and/or coronary revascularization was present, or if one or more significant (> 70%) obstructive lesion(s) were present on a coronary angiogram. Diagnosis of valvular heart disease was made in patients with moderate to severe valvular regurgitation or on the evidence of mitral stenosis.
Statistical analysis Results are reported as mean ± standard deviation or number and percentage, as applicable. Qualitative clinical characteristics of patients were examined using Fisher’s exact test or the Khi-square test. The t test was used for quantitative values. A P value less than 0.05 was considered to be statistically significant. All analyses were performed using Microsoft Excel (Microsoft Corporation, Redmond, WA, USA) and SPSS (SPSS Inc., Chicago, IL, USA).
Results The study included 76 patients with AFL who fulfilled the inclusion criteria. There were 53 men (69.7%) and 23 women (30.3%), with a mean age of 66.9 ± 12.2 years (range 33—90 years), as shown in Table 1. The mean time from the first
M. Peyrol et al. episode of AFL to present clinical evaluation was 76 ± 55 days (range 0—240 months). Underlying heart disease was present in 62 patients (81.6%) and included hypertension in 44 patients (57.9%), ischaemic cardiomyopathy in 15 patients (19.7%), valvular heart disease in 10 patients (13.2%), four of whom had rheumatic valve disease and dilated cardiomyopathy in seven patients (9.2%). History of cardiac surgery (including atriotomy) was present in 12 patients (15.8%). AFL occurred 3—43 months after cardiac surgery. None of these 12 patients experienced AFL perioperatively or had documented AFL prior to surgery. Chronic obstructive lung disease was diagnosed in 12 patients (15.8%). Fourteen patients (18.4%) were classified as having ‘‘lone AFL’’. Among 62 patients with detectable heart disease, 15 were in New York Heart Association class I (24.2%), 24 in class II (38.7%), nine in class III (14.5%) and 14 in class IV (22.4%). A history of thromboembolic event was present in eight patients (10.5%). In no patient was an embolic event the presenting symptom of AFL. Common predisposing factors to thromboembolism were not more common in patients with a history of embolic events than in those without. Hypertension was significantly more common in group II than in group I (75.0% vs 45.5%; P = 0.01). Prior cardiac surgery (including atriotomy) was significantly more frequent in group I than in group II (22.7% vs 6.3%; P = 0.04). The remaining clinical characteristics of the two groups did not differ significantly. As shown in table 2, AFL on the ECG was of the common type in 59 patients (77.6%) and of the uncommon type in 17 (22.4%). The mean AFL cycle length was 244 ± 43.7 ms (range 200 to 300 ms) and did not significantly differ between group I and group II (239.3 ± 36.2 vs 253.1 ± 55.7 ms; P = 0.40). AFL was paroxysmal in 24 patients (31.6%) and persistent in the remaining 52 (68.4%). There was more persistent AFL in group I than in group II (79.5% vs 53.1%; P = 0.01). Among the 12 patients with prior cardiac surgery, AFL was paroxysmal in 10 (83%). AFL was of the common type in eight patients and of the uncommon type in the remaining four patients. Mean left ventricular ejection fraction and mean left atrial anteroposterior diameter measured on echocardiogram were 56.3 ± 12.4% (range 20% to 70%) and 45.1 ± 6.8 mm (range 30 to 59 mm), respectively. There were no significant differences in these echocardiographic variables between the two groups, as shown in table 2. Antiarrhythmic drug therapy and anticoagulant therapy at the time of hospitalization are summarized in table 3. Anticoagulant drug therapy included vitamin K antagonists in 65 patients (85.5%). Clopidogrel was associated with vitamin K antagonists in seven patients (9.2%) and with vitamin K antagonists plus aspirin in one patient with recent (< 1 month) coronary angioplasty. At the time of the hospitalization, 47 patients (61.8%) were treated with either a class Ic sodium channel blocker or amiodarone. Twenty patients in group I and 27 patients in group II were on antiarrhythmic drugs aimed at preventing arrhythmia recurrences. Prescription of these agents was significantly more frequent in group II patients than in group I patients (45.5% vs 84.4%; P = 0.001). Twenty-two patients (29.0%) were receiving heart rate control agents, such as beta-blockers in 17 patients (22.4%) and non-dihydropyridine calcium channel blockers in five patients (6.6%), with no significant differences between the two groups.
Characteristics of atrial flutter with/without atrial fibrillation Table 1
533
Clinical characteristics of patients. Total population (n = 76)
Age (years) Male/female ratio (n/n) Body weight (kg) Height (cm) Systolic BP (mmHg) Diastolic BP (mmHg) NYHA functional class I II III IV
Isolated AFL (n = 44)
AFL combined with AF (n = 32)
P
66.9 ± 12.2
66.7 ± 12.5
67.2 ± 12.1
0.86
53/23
31/13
22/10
0.34
75.6 ± 13.8
76.5 ± 13.7
74.4 ± 14.1
0.64
168.5 ± 7.7
169.7 ± 6.5
166.7 ± 8.9
0.11
132 ± 14
132 ± 15
133 ± 13
0.71
70 ± 10
69 ± 10
72 ± 9
0.80
2.34 ± 1.09 15 (24.2) 24 (38.7) 9 (14.5) 14 (22.4)
2.30 ± 1.00 9 (20.5) 21 (47.7) 6 (13.6) 8 (18.2)
2.41 ± 1.21 10 (31.3) 8 (25.0) 5 (15.6) 9 (28.1)
0.67
Underlying heart disease Hypertension Coronary artery disease Dilated cardiomyopathy Non-rheumatic heart disease Rheumatic heart disease Lone AFL
62 44 15 7 10 4 14
(81.6) (57.9) (19.7) (9.2) (13.2) (5.3) (18.4)
Predisposing or associated factors Prior cardiac surgery Bronchopulmonary disease Prior embolic events
12 (15.8) 14 (18.4) 8 (10.5)
33 20 8 5 5 2 11
(75.0) (45.5) (18.6) (11.4) (11.6) (4.5) (25.0)
10 (22.7) 9 (20.5) 2 (4.5)
29 24 7 2 5 2 3
* * * *
(90.6) (75.0) (21.9) (6.3) (15.6) (6.3) (9.4)
0.08 0.01 0.72 0.69 0.73 0.91 0.08
2 (6.3) 5 (15.6) 6 (18.8)
0.04 0.59 0.06
Data are mean ± standard deviation or number (%), unless otherwise indicated. AF: atrial fibrillation; AFL: atrial flutter; BP: blood pressure; NYHA: New York Heart Association. * Not significant.
Table 2
Electrocardiographic and echocardiographic findings. Total population (n = 76)
ECG-based AFL classification Common Uncommon Type of AFL Paroxysmal Persistent
Isolated AFL (n = 44)
AFL combined with AF (n = 32)
P
59 (77.6) 17 (22.4)
35 (79.5) 9 (20.5)
24 (75.0) 8 (25.0)
0.64
24 (31.6) 52 (68.4)
9 (20.5) 35 (79.5)
15 (46.9) 17 (53.1)
0.01
Heart rate (beats per minute)
104.7 ± 32.0
106.5 ± 33.2
102.2 ± 30.7
0.56
AFL cycle length (ms)
244.2 ± 43.7
239.3 ± 36.2
253.1 ± 55.7
0.40
Left ventricular ejection fraction (%)
56.3 ± 12.4
56.9 ± 11.6
55.5 ± 13.7
0.65
Left atrial diameter (mm)
45.1 ± 6.8
44.6 ± 6.7
46.4 ± 6.9
0.22
Data are mean ± standard deviation or number (%). AF: atrial fibrillation; AFL: atrial flutter; ECG: electrocardiogram.
Discussion Our study showed that patients with both AFL and AF (group II) had a significantly higher prevalence of associated heart disease (mainly hypertension) and a higher use of antiarrhythmic medication aimed at prevention of recurrences than those with isolated AFL (group I). Another interesting
finding was the higher prevalence of cardiac surgery (including atriotomy) in the group of patients with isolated AFL (group I). The other clinical characteristics did not differ significantly between groups. A review of current literature showed a paucity of information on the clinical characteristics of isolated AFL compared with AFL combined with AF. The Framingham
534 Table 3
M. Peyrol et al. Antiarrhythmic drug therapy and anticoagulant therapy at the time of admission. Total population (n = 76)
Antiarrhythmic agents Class Ic or III Class Ic Class III Beta-blockers Calcium channel blockers
47 14 33 17 5
Anticoagulant therapy Vitamin K antagonists Aspirin Clopidogrel
(61.8) (18.4) (43.4) (22.4) (6.6)
Isolated AFL (n = 44) 20 5 15 9 3
AFL combined with AF (n = 32)
P
(45.5) (11.4) (34.1) (20.5) (6.8)
27 (84.4) 9 (28.1) 18 (56.3) 9 (20.5) 2 (6.8)
0.001 0.06 0.05 0.64 1
65 (85.5) 11 (14.5) 8 (10.5)
36 (81.8) 11 (14.5) 3 (6.8)
36 (8.8) 5 (15.6) 5 (15.6)
0.33 0.90 0.27
Statins
23 (30.3)
14 (31.8)
14 (31.8)
0.73
Renin-angiotensin antagonists
37 (48.7)
22 (50.0)
15 (46.9)
0.79
Data are number (%). AF: atrial fibrillation; AFL: atrial flutter.
Heart Study report did not provide such information, as patients were enrolled with either AF or AFL diagnosed on 12-lead ECG [12,14]. A population-based study on the incidence and predisposing factors for AFL in the general population in the Marshfield Epidemiologic Study Area database, reported by Granada et al. in 2002, found that heart failure and chronic obstructive pulmonary disease were the two independent factors predisposing to AFL [15]. Clinical history of AF in patients referred for catheter ablation of AFL in the current literature ranged from 24% to 62% [1—7]. In one study, the 29-month follow-up of 333 patients who underwent successful catheter ablation of the cavotricuspid isthmus for the treatment of AFL revealed occurrence of AF in up to 70% of patients [8]. Similarly, Bertaglia et al. [1] found a cumulative probability of AF post AFL ablation of 50%, 58% and 63% over follow-up periods of 2, 3 and 4 years, respectively. Waldo and Feld recently underlined the role of AF as a transitional rhythm in the development of AFL, illustrating the close inter-relationship between these two arrhythmias [18]. Our study found a high prevalence of postoperative AFL (15% of cases). Although only a small percentage of patients who undergo cardiac surgery may develop AFL, the presence of atriotomy scars may constitute a line of conduction block facilitating a re-entrant circuit. Our study also showed a higher prevalence of hypertension in the group of patients with combined AFL and AF, which contrasts with the findings of Vidaillet et al. [19]. However, the differences in clinical characteristics found between isolated AFL and AFL combined with AF do not support a difference in the management of patients with flutter regarding the need for oral anticoagulation.
However, because of the poor response of AFL to antiarrhythmic medications aimed at preventing recurrences and the excellent results of catheter ablation, this strategy is emerging as a first-line therapy. Our study represents a relatively small group of patients and requires confirmation in a larger patient population. The presence of AF was based on ECG recordings and clinical history of AF. It is likely that the presence of AF — particularly asymptomatic AF — may have been underestimated. Even 24-hour ambulatory recording, which was not done systematically in our study, is unable to detect all episodes of silent AF. New monitoring techniques for AF, including implantable diagnostic devices, may help to clarify the prevalence and significance of asymptomatic atrial arrhythmias.
Conclusion This report on the clinical characteristics of patients with AFL undergoing catheter ablation showed that patients with documented AF had a higher prevalence of heart disease (particularly hypertension) and a higher use of antiarrhythmic drug therapy than those with isolated AFL. In turn, those with isolated AFL had a higher prevalence of cardiac surgery (including atriotomy) than those with combined arrhythmias.
Disclosure of interest The authors declare that they have no conflicts of interest concerning this article.
Study limitations Our patient population consisted of patients with AFL referred to our hospital for catheter ablation because of arrhythmia recurrences. Therefore, our results cannot be extrapolated to a larger population of patients with AFL.
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