What is the cause of telemetry findings showing a heart rate of 102-224 bpm in an elderly man with Chronic Obstructive Pulmonary Disease (COPD) and orthostatic syncope?

Diagnosis: Multifocal Atrial Tachycardia (MAT)

The telemetry findings showing a heart rate of 102-224 bpm in this elderly COPD patient with syncope are most consistent with multifocal atrial tachycardia (MAT), making option D the correct answer. 1, 2

Clinical Reasoning

Why MAT is the Most Likely Diagnosis

• COPD is the classic setting for MAT, with exacerbation of chronic obstructive pulmonary disease overwhelmingly represented among patients presenting with this arrhythmia 1, 2

• The heart rate range of 102-224 bpm fits MAT perfectly, as this arrhythmia characteristically shows variable rates due to multiple ectopic atrial foci firing irregularly 2

• MAT occurs most commonly in elderly patients with chronic pulmonary disease who are critically ill due to acute respiratory or cardiac decompensation, exactly matching this clinical scenario 2

• The oxygen saturation of 93% on 4L and bilateral wheezes indicate COPD exacerbation, which is the primary trigger for MAT 1, 2

• Research demonstrates that MAT with rates as low as 90 beats/min (not just >100) is strongly associated with COPD exacerbations (p = 0.00036), supporting the diagnosis even at the lower end of this patient's heart rate range 1

Why Other Options Are Less Likely

Sinus tachycardia with premature contractions (Option A):

• Would not explain the wide heart rate variability from 102-224 bpm 2
• Sinus tachycardia maintains a more consistent rate with occasional interruptions, not the chaotic variability seen here 2

Atrial flutter with rapid ventricular response (Option B):

• Typically shows a more regular atrial rate (usually around 300 bpm with 2:1 or variable block) 3
• The irregular ventricular response pattern and wide rate variability (102-224 bpm) is more consistent with MAT than atrial flutter 2

Ventricular tachycardia with aberrant conduction (Option C):

• The clinical examination shows "regular rate and rhythm" on cardiopulmonary exam, which argues against VT 3
• VT would typically present with hemodynamic instability and wider QRS complexes, not described here 3
• The return to normal sinus rhythm and stable vital signs make sustained VT unlikely 3

Pathophysiological Mechanism

• MAT arises from triggered activity due to increased intracellular calcium stores, produced by the combination of hypokalemia, hypoxia, acidemia, and increased catecholamines—all characteristics commonly found in COPD exacerbations 2

• The mechanism involves multiple ectopic atrial foci firing irregularly, creating the characteristic wide variability in heart rate 2

• COPD and cardiac arrhythmias share common pathophysiological processes and act synergistically as negative prognostic factors 4, 5

Critical Management Considerations

Immediate Actions

• Correct the underlying COPD exacerbation first, as it is common for patients to convert to sinus rhythm spontaneously after treating precipitating causes 2

• Address hypoxia, electrolyte abnormalities (especially hypokalemia and hypomagnesemia), and acidemia, which are the primary triggers for MAT 2

• Avoid digoxin, as MAT is commonly mistaken for atrial fibrillation and inappropriately treated with digoxin, which is known to be ineffective and potentially toxic in MAT patients 2

Common Pitfalls

• Do not confuse MAT with atrial fibrillation—both show narrow ventricular complexes and irregular rates, but MAT requires different management focused on treating the underlying pulmonary disease 2

• The syncope episode requires cardiac evaluation per ACC/AHA guidelines, as continuous ECG monitoring is useful for hospitalized patients with syncope of suspected cardiac etiology 3

• Recognize that mortality in MAT patients is high (38-62%), but this is due to underlying disease processes (COPD exacerbation, respiratory failure) rather than the arrhythmia itself 2

Prognostic Implications

• COPD is significantly associated with increased risks of atrial fibrillation (RR = 1.99), ventricular arrhythmias (RR = 2.01), and sudden cardiac death (RR = 1.68) 5

• Cardiac disease mortality in moderate COPD patients exceeds mortality from respiratory failure, emphasizing the importance of recognizing and managing cardiac complications 4

• Close to 70% of readmissions after COPD hospitalization result from decompensation of other comorbidities, including cardiac arrhythmias 6