What is the best management approach for a 39-year-old female with a history of migraines, back pain, and depression, presenting with chest pain, mildly elevated troponin levels, and a diagnosis of MINOCA (Myocardial Infarction with Non-Obstructive Coronary Arteries), possibly triggered by coronary artery spasm or microvascular angina, with a family history of Raynaud's phenomenon?

Management of MINOCA with Suspected Coronary Vasospasm

Switching from metoprolol to diltiazem is the correct therapeutic decision for this patient with MINOCA likely due to coronary vasospasm, and she should be maintained on a calcium channel blocker plus long-acting nitrate as first-line therapy. 1, 2

Confirming the MINOCA Diagnosis

This patient meets formal MINOCA criteria as defined by current guidelines 1:

• Troponin elevation (146 ng/L, above 99th percentile) with clinical evidence of myocardial ischemia 1
• Non-obstructive coronary arteries on angiography (no stenosis ≥50% in major epicardial vessels) 1
• Preserved LVEF and no wall motion abnormalities on echocardiography, excluding Takotsubo syndrome 1
• Negative CT for pulmonary embolism, excluding alternative diagnoses 3

The clinical presentation strongly suggests coronary vasospasm as the underlying mechanism: cold exposure as a trigger, family history of Raynaud's phenomenon (suggesting systemic vasospastic tendency), and history of migraines (which share pathophysiologic overlap with vasospastic disorders) 4, 2, 5.

Optimal Pharmacologic Management

First-Line Therapy: Calcium Channel Blockers

Calcium channel blockers are the cornerstone of treatment for coronary vasospasm and should be prescribed at moderate-to-high doses 1:

• Diltiazem 180-360 mg daily (appropriate choice for this patient) 1
• Alternative options: verapamil 240-480 mg daily or nifedipine 60-120 mg daily 1
• These agents directly prevent coronary smooth muscle contraction and are highly effective at preventing recurrent vasospastic episodes 1, 2

Second-Line Therapy: Long-Acting Nitrates

Add long-acting nitrates to the calcium channel blocker for optimal vasospasm prevention 1, 2:

• Isosorbide mononitrate or isosorbide dinitrate should be prescribed 1
• Patients with very active disease often require combination therapy with both drug classes 1
• Ensure the patient has sublingual nitroglycerin for breakthrough symptoms 1

Why Beta-Blockers Should Be Avoided

Beta-blockers have theoretical adverse potential in vasospastic angina and their discontinuation is appropriate 1:

• Unopposed alpha-receptor stimulation may worsen coronary vasospasm 1
• While clinical evidence is controversial, calcium channel blockers are definitively superior for this indication 1
• The decision to discontinue metoprolol and switch to diltiazem aligns with guideline recommendations 1

Additional Management Considerations

Mandatory Risk Factor Modification

Smoking cessation is absolutely critical if the patient smokes, as smoking is a potent trigger for coronary vasospasm 1. This should be addressed aggressively with pharmacotherapy and counseling.

Migraine Management Requires Caution

CGRP receptor antagonists should be avoided or used with extreme caution in this patient 5:

• Recent case reports document variant angina associated with CGRP antagonists (atogepant) 5
• CGRP is a potent vasodilator, and its blockade may predispose to vasospasm in vulnerable individuals 5
• If migraine prophylaxis is needed, consider alternative agents that don't interfere with vascular tone 5

Consider Advanced Diagnostic Testing

Cardiac MRI should be strongly considered to definitively exclude other MINOCA causes 3:

• CMR can identify the underlying cause in up to 87% of MINOCA cases 3
• This is particularly important given the patient's young age (39 years) and atypical presentation 3
• CMR can detect myocarditis, which must be systematically excluded 3

Prognosis and Follow-Up

The prognosis for vasospastic angina is generally excellent with appropriate medical therapy 1:

• 5-year survival rates of 89-97% in patients with normal or near-normal coronary arteries 1
• Patients with vasospasm superimposed on obstructive CAD have worse outcomes (80% 5-year survival with multivessel disease) 1
• This patient's normal angiography suggests favorable long-term prognosis with adherence to therapy 1

Close monitoring is essential as MINOCA patients have lower survival rates than age-matched healthy individuals, with excess adverse events at both early and late follow-up 1.

Critical Pitfalls to Avoid

• Never attribute troponin elevation solely to a non-cardiac cause without serial measurements and comprehensive evaluation 6
• Do not rely on a single troponin value for diagnosis; approximately 10-15% of acute MI patients may not show initial elevation 6
• Avoid prescribing beta-blockers as primary therapy for suspected vasospastic angina 1
• Screen for and counsel against CGRP antagonist use for migraine management in this patient 5
• Ensure the patient understands that despite "normal" coronary arteries, this is a real cardiac condition requiring lifelong medication adherence 2, 7