Can Monosodium Glutamate (MSG) cause Supraventricular Tachycardia (SVT)?

MSG and Supraventricular Tachycardia: Relationship and Management

There is no strong evidence that monosodium glutamate (MSG) directly causes supraventricular tachycardia (SVT), but MSG can potentially trigger symptoms that may mimic or exacerbate cardiac arrhythmias in susceptible individuals.

Relationship Between MSG and Cardiac Symptoms

• While the 2015 ACC/AHA/HRS guidelines for SVT management do not specifically list MSG as a trigger for SVT 1, there is limited evidence suggesting MSG may cause cardiovascular symptoms in some individuals.

• A case report from 1977 documented ventricular tachycardia (not SVT) in a patient 30 minutes after consuming wonton soup containing MSG, which resolved with lidocaine administration 2. This represents an isolated case rather than established causation.

• A double-blind, placebo-controlled study investigating MSG symptom complex found that symptoms including headache, muscle tightness, numbness/tingling, general weakness, and flushing occurred more frequently after MSG ingestion than placebo in self-identified MSG-sensitive individuals 3. However, this study did not specifically evaluate cardiac arrhythmias.

Pathophysiological Considerations

• The exact mechanism by which MSG might potentially influence cardiac rhythm is not well established. Possibilities include:

  • Autonomic nervous system activation
  • Electrolyte disturbances
  • Individual hypersensitivity reactions

• SVT is typically caused by specific cardiac mechanisms including re-entry circuits, enhanced automaticity, or triggered activity, rather than dietary factors 1.

Management of SVT

If a patient develops SVT (regardless of potential triggers), the 2015 ACC/AHA/HRS guidelines recommend the following approach:

For Acute Management of SVT:

1. Hemodynamically unstable patients:

   • Immediate synchronized cardioversion is recommended 1

2. Hemodynamically stable patients:

   • First-line: Vagal maneuvers (such as modified Valsalva) 1, 4
   • Second-line: Intravenous adenosine (highly effective at 91%) 1, 4
   • Third-line options:
     • IV diltiazem or verapamil (effective in 64-98% of patients) 1
     • IV beta blockers (reasonable alternative) 1

For Long-term Management:

1. Catheter ablation is the most effective therapy for preventing recurrent SVT with success rates of 94-98% 1, 4

2. Pharmacological options if ablation is not feasible:

   • Beta blockers
   • Non-dihydropyridine calcium channel blockers (diltiazem, verapamil)
   • Class IC antiarrhythmic drugs (flecainide, propafenone) in patients without structural heart disease
   • Class III antiarrhythmic drugs (sotalol, amiodarone) in selected cases 1

Recommendations for Patients with Suspected MSG-Triggered Symptoms

• If a patient suspects MSG triggers their cardiac symptoms:

  1. Document episodes with correlation to MSG consumption
  2. Consider ambulatory cardiac monitoring to establish whether true SVT occurs with MSG ingestion
  3. Avoid MSG-containing foods as a precautionary measure
  4. Treat any documented SVT according to standard guidelines

• For patients with confirmed SVT who report MSG sensitivity:

  1. Follow standard SVT management protocols 1
  2. Consider definitive treatment with catheter ablation to eliminate the arrhythmia substrate
  3. Dietary avoidance of MSG may be reasonable but should not replace appropriate medical therapy

Conclusion

While there is an isolated case report of MSG associated with ventricular tachycardia and evidence of MSG causing various symptoms in sensitive individuals, there is insufficient evidence to establish MSG as a direct cause of SVT. Management should focus on standard SVT treatment protocols while considering dietary modifications as an adjunctive measure in patients who report symptom correlation with MSG consumption.