What is the treatment for cardiac arrest due to microvascular (small blood vessel) spasm?

Treatment of Cardiac Arrest Due to Microvascular Spasm

For cardiac arrest caused by microvascular spasm, immediately initiate standard high-quality CPR and ACLS protocols, but avoid or minimize epinephrine administration as it may worsen coronary vasospasm, and instead prioritize vasodilator therapy with intracoronary or intravenous nitroglycerin and calcium channel blockers once return of spontaneous circulation (ROSC) is achieved. 1

Immediate Resuscitation Phase

Standard ACLS Protocol with Critical Modifications

• Begin high-quality chest compressions immediately at 100-120 compressions per minute with depth of at least 2 inches (5 cm), allowing complete chest recoil between compressions 2
• Minimize interruptions in chest compressions to maintain coronary and cerebral perfusion 2
• Apply defibrillator immediately to identify and treat shockable rhythms (VF/pVT) if present 2
• Establish IV/IO access without interrupting chest compressions 3

Critical Caveat Regarding Epinephrine

The use of epinephrine during cardiac arrest from coronary vasospasm may be harmful and can exacerbate the underlying spasm. 1 Two case reports demonstrated that patients with cardiac arrest due to coronary artery spasm who received intravenous epinephrine during resuscitation had persistent hemodynamic instability and diffuse coronary artery spasm on emergent angiography 1. This represents a unique situation where standard ACLS drug protocols may worsen the underlying pathophysiology.

• If the etiology of cardiac arrest is known or strongly suspected to be vasospastic in nature, consider withholding or minimizing epinephrine administration 1
• If epinephrine has already been given and hemodynamics do not improve, strongly suspect worsening vasospasm as the cause 1

Definitive Treatment: Vasodilator Therapy

Nitroglycerin Administration

Nitroglycerin is the first-line vasodilator for coronary vasospasm and should be administered as soon as possible. 3, 1

• For coronary vasospasm, consider nitroglycerin (Class IIa, LOE C) 3
• Intracoronary boluses of nitroglycerin can immediately reverse coronary artery spasm if emergent coronary angiography is available 1
• Intravenous nitroglycerin infusion should be initiated if intracoronary administration is not immediately feasible 1

Calcium Channel Blockers

• Administer intravenous diltiazem or other calcium channel blockers for persistent vasospasm 1
• Calcium channel blockers (diltiazem, verapamil, nifedipine, or amlodipine) are the most appropriate long-term therapy for survivors of cardiac arrest due to coronary spasm 4
• Dosing should be titrated until vasospasm is controlled 4

Benzodiazepines and Alpha-Adrenergic Antagonists

• Consider a benzodiazepine to reduce sympathetic tone 3
• Consider phentolamine (an α-adrenergic antagonist) for additional vasodilation (Class IIb, LOE C) 3
• Do not give α-adrenergic blockers alone (Class III, LOE C) 3

Mechanical Circulatory Support

When Vasodilators Fail

If hemodynamic instability persists despite vasodilator therapy:

• Consider temporary mechanical circulatory support with intra-aortic balloon pump (IABP) 1
• Administer intravenous diltiazem and nitroglycerin under IABP support until hemodynamics improve 1
• Consider extracorporeal life support (ECLS/ECPR) as a rescue treatment when initial therapy is failing, particularly if cardiac arrest occurs during coronary catheterization (weak recommendation, very-low-quality evidence) 3

Diagnostic Confirmation

Emergent Coronary Angiography

• Perform emergent coronary angiography as soon as feasible to confirm vasospasm and guide therapy 1
• Angiography may reveal diffuse spasm of the entire coronary artery system 1
• Intracoronary vasodilators can be administered immediately upon confirmation 1

Post-ROSC Care

Targeted Temperature Management

• Implement targeted temperature management (32-36°C) for comatose survivors for at least 24 hours 3
• Avoid hyperthermia as it worsens neurological outcomes 5

Oxygenation and Ventilation

• Titrate inspired oxygen to achieve arterial oxygen saturation of 94% to avoid oxygen toxicity 3
• Maintain normocarbia (PaCO₂ 40-45 mm Hg or PETCO₂ 35-40 mm Hg) 3
• Avoid hyperventilation as it can decrease cerebral blood flow 3

Hemodynamic Management

• Maintain mean arterial pressure >80 mm Hg or systolic blood pressure >100 mm Hg 5
• Use norepinephrine as the preferred vasopressor if needed for blood pressure support (use cautiously given vasospastic etiology) 5

Long-Term Management

Secondary Prevention

• Initiate calcium channel blocker therapy at a dose determined by titration 4
• Smoking cessation is critical - the one patient who continued smoking had recurrent cardiac arrest despite treatment 4
• All seven patients in one case series were habitual cigarette smokers 4
• Long-term prognosis is favorable with appropriate calcium channel blocker therapy and risk factor modification, with six of seven patients remaining symptom-free at mean follow-up of 58 months 4

Common Pitfalls to Avoid

• Do not reflexively administer standard-dose epinephrine without considering vasospastic etiology - this may worsen the underlying spasm and prevent ROSC 1
• Do not use α-adrenergic blockers alone as they are contraindicated (Class III) 3
• Do not delay emergent coronary angiography if vasospasm is suspected, as direct visualization and intracoronary vasodilator administration may be life-saving 1
• Do not discontinue calcium channel blocker therapy after hospital discharge, as long-term treatment is essential for preventing recurrence 4
• Do not underestimate the importance of smoking cessation counseling, as continued smoking is associated with recurrent events 4