What is TIMI Flow Grade used for?

TIMI Flow Grade is the standard angiographic metric for assessing coronary artery perfusion during cardiac catheterization. It is used to document the severity of coronary occlusion before intervention and to confirm restoration of flow after reperfusion therapy (thrombolytics or PCI). Achieving TIMI 3 (normal flow) is the primary angiographic endpoint of STEMI reperfusion.

What is the difference between TIMI 2 and TIMI 3 flow?

TIMI 2 flow means contrast penetrates the stenosis and fills the distal vessel completely, but opacification is slower than a normal (non-culprit) coronary artery. TIMI 3 flow means contrast fills and clears the distal vessel at the same rate as a normal artery — considered complete, normal flow. Clinically, TIMI 3 after primary PCI is associated with substantially lower 30-day mortality than TIMI 2, making the distinction prognostically important.

How does TIMI Flow Grade relate to myocardial blush grade?

TIMI Flow Grade assesses epicardial artery flow on the angiogram. Myocardial Blush Grade (MBG) assesses microvascular perfusion — whether contrast actually reaches the capillary bed. A patient can have TIMI 3 epicardial flow but MBG 0 (no blush), indicating microvascular obstruction or "no-reflow." Both metrics together provide a more complete picture of reperfusion success.

Can TIMI flow grade be applied to non-STEMI situations?

Yes. TIMI Flow Grade was originally developed in the context of thrombolytic therapy trials for STEMI but is now applied universally during diagnostic and interventional catheterization regardless of ACS type. It provides a common language for describing coronary flow in stable angina, NSTEMI, and STEMI cases alike.

Is TIMI 0 always a complete blockage?

TIMI 0 means there is no antegrade flow beyond the point of occlusion — no contrast passes the culprit lesion to opacify the distal vessel. This is consistent with total occlusion but does not always mean the vessel is irreversibly occluded; thrombus, spasm, or a critical stenosis can all produce TIMI 0, some of which are reversible with intervention.

What is the clinical significance of achieving TIMI 3 flow?

Multiple trials, including GUSTO-I, demonstrated that TIMI 3 flow at 90 minutes is associated with a 30-day mortality of approximately 4%, compared with approximately 8% for TIMI 0/1 flow. The survival benefit is proportional: TIMI 3 > TIMI 2 > TIMI 0/1. This is why reperfusion strategies — primary PCI or thrombolytics — aim specifically for TIMI 3 as the angiographic endpoint.

TIMI Flow Grade

Select the observed angiographic characteristics to identify the TIMI Flow Grade (0–3) and review its clinical significance in ACS and interventional cardiology.

Select Angiographic Finding

Click the description that best matches your observation.

Select an angiographic finding on the left to view the TIMI Flow Grade and clinical details.

All Grades at a Glance

Grade	Label	Key Feature	Approx. 30-Day Mortality
0	No Perfusion	No contrast beyond occlusion	~8–12%
1	Penetration Without Perfusion	Contrast passes, distal bed not filled	~8–12%
2	Partial Perfusion	Distal vessel fills but flow is slow	~6–7%
3	Complete Perfusion	Brisk flow, normal filling and clearance	~4%

Mortality estimates based on GUSTO-I trial data for STEMI reperfusion cohorts. Rates vary by era, institution, and patient population.

Summary

TIMI (Thrombolysis in Myocardial Infarction) Flow Grade is a four-level angiographic scale — 0 through 3 — that quantifies coronary artery perfusion during cardiac catheterization. Grade 0 indicates complete occlusion with no flow beyond the culprit lesion; Grade 3 indicates normal flow with complete and prompt filling of the distal vessel. Restoring TIMI 3 flow is the primary goal of reperfusion therapy in STEMI and is independently associated with improved 30-day and one-year survival. This reference tool helps clinicians and trainees quickly identify and interpret each grade from angiographic observations.

How it works

Click the angiographic description that best matches your observation in the cath lab or on review of the angiogram.
The corresponding TIMI Flow Grade (0–3) is highlighted with a full description and clinical significance panel.
Review the associated outcomes context, including published mortality differentials between grades.
Use the comparison table at the bottom to see all four grades side by side.
Click "Reset" to clear the selection for the next case.

Use cases

Interventional cardiology reference for real-time cath lab grade assignment during primary PCI.
STEMI and NSTEMI case review to document pre- and post-intervention TIMI flow grades.
Medical education and cardiology board preparation — USMLE, ABIM, and interventional cardiology fellows.
Quality assurance audit to benchmark TIMI 3 achievement rates after reperfusion therapy.
Multidisciplinary team discussions on residual flow and decisions about staged procedures.
Research data collection for ACS registries requiring standardized flow classification.

Frequently Asked Questions

Last updated: 2026-06-18 · Reviewed by Nham Vu