A Young Man with Recurrent Paroxysmal Tachyarrhythmia

A 32-year-old man presents with an episode of rapid heartbeat and the sensation that his heart is “jumping around his chest.” This episode came on abruptly while preparing to go to work in the morning. The patient reported no shortness of breath or chest pains. He does not have symptoms suggestive of syncope or near syncope. This is the third such episode within the last 6 months. 

After the first time, the patient went to the emergency room and was told he had suffered an episode of atrial fibrillation (AF), which was acutely medicated and resolved. He was told to abstain from alcohol and caffeine, but required no further therapy. 

About 2 months ago, despite complete compliance regarding caffeine and alcohol, a similar episode ensued but resolved spontaneously before he saw his physician. Subsequently, a thyroid evaluation was normal and a cardiac echo was negative for structural abnormality.

History

The patient is otherwise healthy with no history of heart or lung disease. He takes no chronic medications. He works for a financial firm doing stock analysis.

Physical examination

Physical examination reveals a healthy-appearing man. Vital signs reveal a pulse of 160 beats per minute, which was too rapid to assess regularity. Blood pressure was 90/60 mm Hg without postural change. He is not diaphoretic and room air pulse oximetry is 98% oxygen saturated. Chest is clear. Heart reveals a tachycardia at 160 per minute to 170 per minute without gross murmurs. The remainder of the physical exam is normal.

Laboratory Tests

Urgently measured hemogram and metabolic panel are all normal. EKG reveals a narrow QRS complex tachycardia at 160 per minute to 170 per minute, which is irregular. Cardiac troponins are normal.

Which of the following is the optimal treatment strategy for this patient?

A. Administer adenosine 6 mg intravenously.
B. Administer either verapamil or diltiazem intravenously.
C. Initiate an appropriate rate control and oral anticoagulation regimen, and arrange for elective radiofrequency ablation.
D. Administer urgent electrical cardioversion followed by elective pacemaker insertion.

(Answer and discussion on next page)

Correct Answer: C, Initiate an appropriate rate control and oral anticoagulation regimen, and arrange for elective radiofrequency ablation.

This case illustrates 2 major and common situations encountered with cardiac arrhythmias: the initial evaluation of a patient presenting with an acute, symptomatic supraventricular tachyarrhythmia and the management of patients with AF—the most common cardiac arrhythmia, with a lifetime risk of 20%.¹

Symptomatic Tachyarrhythmia

The first issue is acute evaluation and management of any symptomatic tachyarrhythmia. Clinical status, ventricular rate, and QRS characteristics determine initial diagnostic and therapeutic considerations.² 

The first determinant should be wide complex versus narrow QRS complex tachycardias. The wide QRS tachycardias carry a more dangerous differential diagnosis, including ventricular tachycardia and torsade de pointes that can degenerate into even more malignant and life-threatening arrhythmias. Adenosine can actually worsen these and should not be given in this situation. Cardioversion should be considered early on in such cases. 

For narrow complex tachycardias, as was seen in our patient, adenoside 6 mg intravenously is usually the initial maneuver of choice. Adenosine blocks atrioventricular nodal conduction and will slow most such tachycardias. This often stabilizes the situation and reduces symptoms, as well as allowing more precise identification of the supraventricular tachycardia.² 

Thereafter, more specific therapy can be tailored to the arrhythmia present. Our patient had sustained abrupt onset arrhythmia twice prior to this episode and paroxismal atrial fibrillation (PAF) had been identified. 

Differential Diagnosis

It is reasonable to assume that the administration of adenosine (Answer A) is not incorrect, but Answer C is the more complete answer. The patient had reasonable and stable blood pressure and few symptoms related to heart rate. Thus, he was not unstable and cardioversion; Answer D was not indicated here. Intravenous verapamil and diltiazem also block the atrioventricular node but are longer acting and are associated more with hypotension and thus, are not first choice agents,³ especially in a case with borderline hypotension as in our patient. Therefore, Answer B is incorrect.

Answer C is the optimal approach—address the PAF that is very likely by history and the fact that the patient’s narrow complex tachycardia is irregular with an effective rate control regimen (usually a beta-blocker), then address definitive management of his PAF. 

Managing Atrial Fibrillation

A long, excellent, and evolving literature has been reviewed over the years in these columns regarding rate versus rhythm control issues and what rate is optimal for AF management. Research continues on this most common arrhythmia and our patient seems to fit the newest strategy for PAF. 

In a recent study,⁴ patients with no prior history of antiarrhythmia drug use who had sustained at least 2 episodes of PAF but with no episode longer than 7 days and had favorable clinical characteristics (left atrial diameter <50 mm; left ventricular ejection fraction >40%; no contraindication to oral anticoagulants and no significant mitral valve disease) were identified. Early radioablation techniques resulted in subtle differences in the “cumulative burden” of AF over a 2-year follow-up period as compared to traditional drug therapy regimens. This included episodes of symptomatic PAF and Holter monitoring for any AF, as well as global quality of life. There were a small but nonsignificant number of procedure-related events (3 pericardial tamponade) balanced by a seemingly greater benefit from radioablation as time passes—85% free of AF with ablation versus 71% free of AF with drugs. 

Arrhythmia-free intervals seemed to benefit patients even more as time from procedure accrued >2 years. It must be emphasized that this more aggressive approach should be reserved for younger patients with symptomatic PAF without other major heart disease, which for now is a minority of AF patients. 

Durability of response and true reduction in morbidity and mortality will require additional follow-up and more numbers.⁵ For now, however, a young, otherwise healthy but symptomatically bothered patient with frequent PAF episodes seems an optimal candidate for this technique.

Outcome of the Case

Upon correlating the prior history, current syndrome, and EKG findings, immediate propanolol was administered with a reduction within hours of heartrate to 100 beats per minute with confirmation of AF. Metroprolol was substituted and on day 3, sinus rhythm was restored. 

The patient and his physicians believed that he was a good candidate for radiofrequency ablation and he underwent an anticoagulant/transesophageal echocardiogram protocol for thrombosis prophylaxis, followed by an uneventful radiofrequency ablation at day 30. At 18 months, he is well, on no cardiac medications, and has not had a recurrence of PAF.

Take-Home Message

In patients presenting with acute tachyarrhythmia syndromes, initial evaluation should focus on ventricular response rate, as well as determining regularity and wide versus narrow QRS complex morphology. Rapidity versus chronicity of onset also is helpful in the initial differential diagnosis. 

Adenosine lowers the rates of most cases and allows more accurate initial EKG analysis, but should not be used in wide complex cases. Electrical cardioversion should be reserved for unstable cases and/or situations where adenosine fails.

When PAF is the cause, a variety of rate and rhythm control strategies are effective. In selected cases, the use of early radiofrequency ablation seems able to definitively lessen the subsequent burden of AF with a reasonable risk/benefit ratio compared to drug regimens.

Ronald Rubin, MD, is a professor of medicine at Temple University School of Medicine and chief of clinical hematology in the department of medicine at Temple University Hospital, both in Philadelphia. 

References:

1.Magnani JW, Rienstra M, Lin H, et al. Atrial fibrillation: current knowledge and future directions in epidemiology and genomics. Circulation. 2011;124:1982-1993.

2.Link MS. Evaluation and initial treatment of supraventricular tachycardia. N Eng J Med. 2012;367:1438-1448.

3.Oakes RS, Badger TJ, Kholmovski EG, et al. Detection and quantification of left atrial structural remodeling with delayed-enhancement magnetic resonance imaging in patients with atrial fibrillation. Circulation. 2009;119:1758-1767.

4.Nielsen JC, Johannessen A, Raatikainen P, Hindricks G, et al. Radiofrequency ablation as initial therapy in paroxysmal atrial fibrillation. N Eng J Med. 2012;367:1587-1595.

5.Stevenson WG, Albert CM. Catheter ablation for paroxysmal atrial fibrillation. N Eng J Med. 2012;367:1648-1649.