In the CCU, the goal for vasopressors and inotropes in cardiogenic shock (CS) is to bridge the patient to definitive therapy (revascularization or MCS) while maintaining organ perfusion without excessively increasing myocardial oxygen demand (MVO2).
1. The First-Line Vasopressor: Norepinephrine
- Why: Lower risk of arrhythmias compared to dopamine (SOAP II trial).
- Action: Predominantly α1 (vasoconstriction) with moderate β1 (inotropy).
- Goal: Maintain MAP ≥ 65 mmHg.
- Caveat: Avoid Epinephrine as a first-line agent if possible; it is associated with higher rates of refractory shock, lactic acidosis, and increased MVO2.
2. Adding Inotropy: Dobutamine vs. Milrinone
If the MAP is stable but cardiac output remains low (cold extremities, rising lactate), add an “inodilator.”
| Agent | Mechanism | Pros | Cons |
| Dobutamine | β1 > β2 agonist | Rapid onset/offset; titratable. | Tachyarrhythmias; increases MVO2. |
| Milrinone | PDE-3 Inhibitor | Works “downstream” of β-blockers; less tachycardia. | Long half-life (hard to “turn off”); significant hypotension; renally cleared. |
- DOREMI Trial (2021): Showed no significant difference in 30-day mortality between the two.
- Clinical Pearl: Choose Milrinone for patients on chronic β-blockers or with pulmonary hypertension/RV failure. Choose Dobutamine for patients with renal impairment or those prone to hypotension.
3. Quick Checklist for Titration
- Is the SVR high? (The “Cold and Wet” patient). Prioritize inotropy and consider afterload reduction (nitroprusside) if BP allows.
- Is there Vasoplegia? (Low SVR despite low CO). Use Norepinephrine + Vasopressin (to spare catecholamine dose).
- Is it “SCAI Stage D/E”? If you are maxing out two pressors/inotropes, pharmacological therapy has likely failed. Escalate immediately to Mechanical Circulatory Support (MCS) (e.g., Impella, IABP, or ECMO).