Accepted Manuscript

The case of the furtive finding: atypical atrial flutter

Jeffrey Paulsen, MD Gagan Singh, MD Uma Srivatsa, MBBS Ezra A. Amsterdam, MD

PII: S0002-9343(14)00642-1

DOI: 10.1016/j.amjmed.2014.07.018

Reference: AJM 12619

To appear in: The American Journal of Medicine

Received Date: 11 February 2014

Revised Date: 24 July 2014

Accepted Date: 24 July 2014

Please cite this article as: Paulsen J, Singh G, Srivatsa U, Amsterdam EA, The case of thefurtive finding: atypical atrial flutter, The American Journal of Medicine (2014), doi: 10.1016/j.amjmed.2014.07.018.

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The Case of the Furtive Finding: Atypical Atrial Flutter

Submission 14-218

Jeffrey Paulsen, M.D.

Gagan Singh, M.D.

Uma Srivatsa, M.B.B.S.

Ezra A. Amsterdam, M.D.

University of California Davis Health System

Department of Internal Medicine

Division of Cardiovascular Medicine

Correspondence to:

Jeffrey Paulsen, M.D.

Division of Cardiovascular Medicine

4860 Y Street, Suite 2860

Sacramento, CA 95817

Funding Source: Not applicable

Conflicts of Interest: None

Verification Statement: All of the above authors were involved in the writing of the

manuscript

Article Type: ECG Image of the Month

Key Words: atrial flutter, atrial fibrillation, atypical flutter, post-operative

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ECG of the Month

The case of the furtive finding: atypical atrial flutter

Julia H. Indik, MD, PhD, Section Editor

Jeffrey Paulsen, MD, Gagan Singh, MD, Uma Srivatsa, MBBS, Ezra A. Amsterdam, MD

Division of Cardiovascular Medicine, Department of Internal Medicine, University of

California Davis Health System, Sacramento, CA.

The corresponding author is Jeffrey Paulsen, MD, Division of Cardiovascular Medicine,

4860 Y Street, Suite 2860, Sacramento, CA, 95817.

E-mail address: Jeffrey.paulsen@ucdmc.ucdavis.edu

PRESENTATION

A patient’s arrhythmia was identified only after an electrocardiogram (ECG) lead was

attached directly to an atrial epicardial lead. The 87-year-old man had a history of

paroxysmal atrial fibrillation, coronary artery disease, and severe mitral and tricuspid

regurgitation and was admitted for corrective cardiac surgery. His history included a

cardioembolic stroke 10 months prior to admission, hypertension, and hyperlipidemia. He

underwent coronary artery bypass grafting (CABG) to the right coronary artery,

bioprosthetic mitral valve replacement, tricuspid annulus repair, and a maze cryoablation

or cryomaze procedure.

In addition, temporary atrial and ventricular epicardial leads were placed

intraoperatively for management of potential postoperative bradyarrhythmia. Surgery was

uncomplicated, but on postoperative day 2, the patient’s electrocardiogram (ECG)

revealed a rate of 50 beats per minute, which was interpreted as a junctional rhythm

(Figure 1). Prior to this finding, on postoperative day 1, the patient had likewise been

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found to be in a possible junctional rhythm but with a ventricular rate in the 60s. He had

not been managed on rate- or rhythm-controlling medications pre- or postoperatively.

Cardiology consultation was requested for evaluation and management.

ASSESSMENT

The patient’s ECG showed no clear evidence of atrial activity, a narrow QRS complex

(duration, 90 msec), and regular-appearing rhythm (Figure 1). These findings are

consistent with a junctional rhythm. However, on closer inspection, the R-R interval was

slightly variable, and there was a subtle suggestion of atrial activity, especially in the

anterior precordial leads. Another ECG was obtained with the atrial epicardial lead

connected to lead V1, and this revealed a hidden diagnosis (Figure 2). A review of serial

ECGs obtained over the 2 years prior to the patient’s hospitalization showed that he had

exhibited atrial fibrillation with slow ventricular response, as well as sinus bradycardia

with first-degree atrioventricular nodal block.

DIAGNOSIS

Atrial fibrillation and flutter commonly occur in the early postoperative period following

CABG. Frequencies of 20-45% have been reported. In 1 study, a 27% incidence of

postoperative atrial fibrillation was documented among 2,417 patients undergoing CABG

with or without concurrent valve surgery.1 Occurrence of these post-CABG tachycardias

appears to peak 2-3 days after surgery.2,3 They are also associated with an increased rate

of postoperative stroke and ventricular arrhythmia.1

Atrial flutter is less common than atrial fibrillation and may be more difficult to

identify on a surface ECG, given the potential for regular-appearing ventricular

conduction that is suggestive of sinus rhythm. Diagnosis of atrial flutter may be further

complicated if, as in our patient, the atrial activity is not clearly represented on the

surface ECG. Recognition of an underlying atrial arrhythmia is necessary for appropriate

management in the postoperative setting.

Typical atrial flutter is referred to as isthmus-dependent because the causative

macro-reentrant circuit travels through the cavotricuspid isthmus—the region of the

lower right atrium between the inferior vena cava and the tricuspid valve.4 The impulse is

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directed around the tricuspid annulus in either a counterclockwise (typical) or clockwise

(reverse typical) direction. Given the fixed anatomy of the re-entry circuit in typical or

reverse typical flutter, the flutter wave morphology tends to be consistent, appearing on

ECG in a distinctive saw-tooth pattern. Similarly, the atrial rate in typical flutter

predictably ranges from 250-350 beats per minute.5

Atypical flutter, which has no common path, has different conduction

characteristics, owing to the dissimilar anatomies of the macro-reentrant circuits.4

Specifically, the ECG will not display the classic saw-tooth pattern. Instead, there is wide

variability in p-wave morphology and rate; and atrial rates are usually, but not always,

faster than 350 beats per minute. Several atypical right-sided atrial flutter patterns have

been described, including partial-isthmus and non-isthmus-dependent circuits. These

atypical patterns may represent as much as 8% of all atrial flutter presentations.6 Left

atrial flutter is by definition atypical, with numerous patterns identified through

electrophysiologic mapping, such as posterior, anterior, and mitral annular reentry.7 Left-

and right-sided septal reentry circuits are also part of the atypical flutter spectrum.8

Idiopathic atypical flutter is quite rare. More frequently, atypical flutter is

iatrogenic, following catheter ablation, and cardiovascular surgery, such as maze, CABG,

and correction of congenital heart disease.9 Post-maze incidence of atrial tachyarrhythmia

has been estimated at greater than 10%, although this figure may underestimate the true

incidence.9,10

MANAGEMENT

The designation of typical versus atypical flutter is important clinically, as management

of the atypical variant is often much more difficult. By contrast, external electrical

cardioversion or catheter ablation can effectively treat typical flutter, with acute success

rates now exceeding 90-95%.4,11

Our patient’s occult atrial flutter, recognized only by epicardial lead assessment,

fulfilled criteria for atypical atrial flutter. Inability to distinguish the arrhythmia on the

surface ECG was likely related to the combination of surgical myocardial edema and

atrial tissue injury from the cryomaze procedure. Following diagnosis, anticoagulation

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therapy was initiated for stroke prophylaxis. The patient continued in atrial flutter with

variable 4-5:1 conduction, which led to a slow ventricular rate.

Nearly 1 week after surgery, the slow rate persisted in the range of 40-50 beats

per minute, and the patient reported associated lightheadedness. A junctional escape

rhythm remained in the differential diagnosis, but in either case, the lack of rate

improvement garnered concern for concomitant atrioventricular nodal conduction

disease. High-grade atrioventricular nodal block has been described as a complication of

valve replacement, especially in the context of prior conduction disease; our patient had a

history of atrial fibrillation with slow ventricular response as well as first-degree AV

block.12

Ultimately, pacemaker implantation was recommended, and this was carried out

on postoperative day 7. The procedure also included cardioversion of atrial flutter to

sinus bradycardia. On postoperative day 10, the patient was discharged in stable

condition. More than 1 year into follow-up, he continues to do well clinically, with

pacemaker interrogation demonstrating occasional paroxysms of atrial flutter. However,

his heart rate is controlled with nearly 100% ventricular pacing.

References

1. Mathew JP, Parks R, Savino JS, et al. Atrial fibrillation following coronary artery

bypass graft surgery: Predictors, outcomes, and resource utilization. Multicenter

Study of Perioperative Ischemia Research Group. JAMA. 1996;276:300-306.

2. Lauer MS, Eagle KA, Buckley MJ, DeSanctis RW. trial fibrillation following

coronary artery bypass surgery. Prog Cardiovasc Dis. 1989;31:367-378.

3. Frost L, Mølgaard H, Christiansen EH, Hjortholm K, Paulsen PK, Thomsen PE.

Atrial fibrillation and flutter after coronary artery bypass surgery: epidemiology,

risk factors and preventive trials. Int J Cardiol. 1992;36:253-261.

4. Dhar S, Lidhoo P, Koul D, Dhar S, Bakhshi M, Deger FT. Current concepts and

management strategies in atrial flutter. South Med J. 2009;102:917-922.

5. Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of

Cardiovascular Medicine. 9th ed. Philadelphia, PA: Elsevier Saunders; 2012:

777-778.

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6. Yang Y, Cheng J, Bochoeyer A, et al. Atypical right atrial flutter patterns.

Circulation. 2001;103:3092-3098.

7. JaÏs P, Shah DC, HaÏssaguerre M, et al. Mapping and ablation of left atrial

flutters. Circulation. 2000;101:2928-2934.

8. Marrouche NF, Natale A, Wazni OM, et al. Left septal atrial flutter:

Electrophysiology, anatomy, and results of ablation. Circulation. 2004;109:2440-

2447.

9. Garan H. Atypical atrial flutter. Heart Rhythm. 2008;5:618-621.

10. Magnano AR, Woollett I, Garan H. Percutaneous catheter ablation procedures for

the treatment of atrial fibrillation. J Card Surg. 2004;19:188-195.

11. Lee KW, Yang Y, Scheinman MM. Atrial flutter: A review of its history,

mechanisms, clinical features, and current therapy. Curr Probl Cardiol.

2005;30:121-167.

12. Gordon RS, Ivanov J, Cohen G, Ralph-Edwards AL. Permanent cardiac pacing

after a cardiac operation: predicting the use of permanent pacemakers. Ann

Thorac Surg. 1998;66:1698-1704.

[Figure Legends]

Figure 1. On postoperative day 2, the patient’s electrocardiogram (ECG) showed

ventricular rhythm, with a heart rate of 50-55 beats per min. Atrial activity was difficult

to discern, though possible subtle atrial activity was detected in the anterior precordial

leads.

Figure 2. An ECG obtained with lead V1 connected to the atrial epicardial lead revealed

atrial flutter with either variable 4:1 to 5:1 atrioventricular conduction versus heart block

with a junctional escape rhythm. The atrial rate in lead V1 was 260 beats per min; arrows

indicate flutter waves.

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