Management of Coronary No-Reflow in the Catheterization Lab
Intracoronary vasodilators should be administered as first-line therapy for coronary no-reflow that occurs during primary or elective PCI. 1
Understanding No-Reflow Phenomenon
No-reflow is characterized by inadequate myocardial reperfusion despite successful reopening of the epicardial infarct-related artery. It occurs in approximately 10-40% of patients undergoing reperfusion therapy for STEMI 1. This phenomenon results from:
- Downstream microvascular embolization of thrombotic or atheromatous debris
- Reperfusion injury
- Microvascular disruption
- Endothelial dysfunction
- Inflammation
- Myocardial edema 1
Diagnosis of No-Reflow
No-reflow is diagnosed when:
- Post-procedural TIMI flow is <3, or
- TIMI flow is 3 but myocardial blush grade (MBG) is 0 or 1, or
- ST resolution within 4 hours of the procedure is <70% 1
The TIMI flow grading system includes:
- TIMI 0: No antegrade flow
- TIMI 1: Contrast passes beyond obstruction but "hangs up"
- TIMI 2: Slower flow than normal vessels
- TIMI 3: Normal flow 1
Management Algorithm
First-Line Treatment
Intracoronary vasodilators 1, 2:
- Adenosine (70-100 μg/kg/min or incremental doses of 100-200 μg)
- Verapamil (100-200 μg increments)
- Nitroprusside (50-100 μg increments)
- Nicorandil
- Papaverine
Administration technique 3, 4:
- Inject distally in the epicardial artery to minimize systemic effects
- Use high-velocity injection through an intracoronary perfusion catheter
- For nitroprusside: start with 50-100 μg and increase up to 1000 μg as needed
Second-Line Treatment
- GPIIb/IIIa inhibitors 1, 2:
- Abciximab (0.25 mg/kg bolus followed by 0.125 μg/kg/min infusion for 12-24h)
- Has been shown to improve tissue perfusion 1
Mechanical Approaches
- Thrombus aspiration if visible thrombus burden 2
- Optimize stent deployment if PCI has been performed 2
- Ensure adequate anticoagulation during the procedure 2
Important Considerations
- No-reflow can cause prolonged myocardial ischemia, severe arrhythmias, and critical hemodynamic deterioration 1
- It is associated with significantly increased risk of clinical complications 1
- Reversing no-reflow has a favorable effect on left ventricular remodeling 1
- Emergency CABG is unlikely to improve perfusion in the setting of no-reflow and may be harmful 1
Clinical Pitfalls and Caveats
- Prophylactic injections of vasodilators may be considered prior to balloon inflation, particularly in vein graft interventions 4
- The no-reflow phenomenon typically develops within the first 2 hours of reperfusion 5
- In patients with cardiogenic shock, routine PCI of a non-infarct artery at the time of primary PCI should not be performed due to higher risk of death or renal failure 1
- When using nitroprusside, careful monitoring is required as it can induce unlimited blood pressure reduction 3
- No double-blind, randomized trials have been conducted to determine the appropriate dosage of these agents 6
By following this algorithm and understanding the pathophysiology of no-reflow, interventional cardiologists can effectively manage this complication and potentially improve patient outcomes.