What is the most likely diagnosis for a 71-year-old man with a history of Coronary Artery Disease (CAD) and stent placement, presenting with chest pain, a feeling of heaviness, and tachycardia, with an electrocardiogram showing a saw-tooth pattern of P waves?

Atrial Flutter

The most likely diagnosis is atrial flutter, given the characteristic saw-tooth pattern of P waves on ECG combined with a heart rate of 150 bpm (consistent with 2:1 AV conduction block) in a patient with significant cardiovascular risk factors. 1

Key Diagnostic Features

The ECG finding of a saw-tooth pattern of P waves is pathognomonic for atrial flutter, specifically typical (cavotricuspid isthmus-dependent) atrial flutter. 1 This pattern, combined with the ventricular rate of 150 bpm, strongly suggests 2:1 atrioventricular conduction, which is the most common conduction ratio in untreated atrial flutter (atrial rate typically 250-300 bpm). 1

Clinical Presentation Consistent with Atrial Flutter

• Chest pain and heaviness can occur with atrial flutter due to reduced diastolic filling time and decreased coronary perfusion at rapid ventricular rates, particularly in patients with underlying CAD. 1
• The sensation of heart "racing" corresponds to the tachycardia (HR 150), which patients with atrial flutter commonly report as palpitations. 2, 1
• Anxiety without acute distress is typical—patients are symptomatic but often hemodynamically stable with 2:1 conduction. 1
• The absence of shortness of breath and no edema on examination suggest the patient is currently compensated, though atrial flutter is associated with increased risk of heart failure. 1

Risk Factor Profile

This patient's profile makes atrial flutter highly likely:

• History of CAD with prior stent placement creates atrial remodeling that predisposes to atrial flutter. 1
• Age 71 years places him in the typical demographic for atrial flutter. 1
• 30 pack-year smoking history contributes to cardiovascular disease burden. 3
• Hypertension (BP 142/94) is a shared risk factor with atrial fibrillation and atrial flutter. 1

Critical Distinction from Acute Coronary Syndrome

While this patient has chest pain and CAD history, several features argue against acute MI as the primary diagnosis:

• Regular heart rhythm on examination with saw-tooth P waves indicates an organized atrial arrhythmia, not ventricular tachycardia or other life-threatening arrhythmia. 1
• The chest discomfort is likely demand ischemia from the rapid ventricular rate rather than acute plaque rupture. 4
• Normal initial cardiac enzymes (implied by lack of mention) would help exclude NSTEMI, though serial troponins should still be obtained. 4

Immediate Management Priorities

Since the patient is hemodynamically stable (BP 142/94, no acute distress), the management approach differs from unstable patients:

Acute Rate Control

• Vagal maneuvers are not typically effective for atrial flutter due to the organized macro-reentrant circuit. 2
• Beta-blockers or calcium channel blockers (IV diltiazem or metoprolol) should be used for acute rate control to slow AV nodal conduction. 2, 1
• Avoid adenosine as it may unmask rapid 1:1 conduction and cause hemodynamic compromise. 2

Anticoagulation Assessment

• Stroke risk assessment using CHA₂DS₂-VASc score is essential, as atrial flutter carries similar thromboembolic risk to atrial fibrillation. 1
• Given age >65 and CAD history, this patient likely warrants anticoagulation. 1

Definitive Treatment

• Catheter ablation is first-line therapy for typical atrial flutter, with superior outcomes compared to medical management in terms of recurrence, hospitalization, and quality of life. 1
• Ablation achieves bidirectional conduction block across the cavotricuspid isthmus with high success rates (>90%). 1
• Early cardiology referral for electrophysiology study should be arranged, as medical management with antiarrhythmic drugs has poor efficacy for atrial flutter. 1

Common Pitfalls to Avoid

• Do not assume chest pain equals ACS in the setting of tachycardia—demand ischemia from rapid rates is common in patients with underlying CAD. 4, 1
• Do not use digoxin alone for rate control in atrial flutter, as it is ineffective at controlling ventricular response during activity. 1
• Do not delay anticoagulation while awaiting cardioversion or ablation if stroke risk factors are present. 1
• Do not perform cardioversion without adequate anticoagulation (minimum 3 weeks or TEE to exclude thrombus) unless hemodynamically unstable. 1