Related Experiment Video
Updated: May 12, 2026
In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography
Published on: February 16, 2016
TIMI myocardial perfusion grade and ST segment resolution: association with infarct size as assessed by single photon
Brad G Angeja1, Madhavi Gunda, Sabina A Murphy
1Department of Medicine, the University of California, San Francisco, USA.
Insights
Early indicators of blood flow, like TIMI myocardial perfusion grade (TMPG) and ST-segment resolution, correlate with smaller infarct sizes after acute myocardial infarction treatment.
Area of Science:
- Cardiology
- Medical Imaging
- Thrombolytic Therapy
Background:
- TIMI myocardial perfusion grade (TMPG) and ST-segment resolution assess perfusion post-thrombolysis for acute myocardial infarction.
- These measures are linked to patient mortality.
- Their association with infarct size, measured by SPECT, was investigated.
Purpose of the Study:
- To determine if TMPG and ST-segment resolution correlate with infarct size.
- To explore the relationship between early perfusion markers and myocardial damage.
Main Methods:
- Utilized data from the LIMIT AMI trial.
- Compared early 90-minute TMPG and ST-segment resolution with SPECT-derived infarct size (Technetium-99 m Sestamibi uptake).
- Analyzed infarct size based on TMPG (0-3) and ST resolution categories.
Main Results:
- Larger infarct sizes were observed with lower TMPG scores (0-1) compared to higher scores (2-3) (median 13% vs. 7%, P=0.004).
- Patients with no or incomplete ST resolution had larger infarcts than those with complete resolution (median 15% or 11% vs. 6%, P=0.0001).
- The association between TMPG and infarct size remained significant even when stratified by ST resolution.
Conclusions:
- Early restoration of tissue-level perfusion may be linked to reduced infarct size.
- These findings suggest a pathophysiological basis for the association between early perfusion markers and long-term survival after acute myocardial infarction.
Background:
The TIMI myocardial perfusion grade (TMPG) and ST-segment resolution both reflect perfusion and are associated with mortality after thrombolysis for acute myocardial infarction. We hypothesized that these measures would also be associated with infarct size by single photon emission computed tomography (SPECT). Methods and Results- In the LIMIT AMI trial (Limitation of Myocardial Injury following Thrombolysis in Acute Myocardial Infarction) of lytic monotherapy versus lytic plus rhuMAb CD18, early 90-minute TMPG (n=221) and ST segment resolution (n=242) were compared with subsequent SPECT Technetium-99 m Sestamibi, measuring the percentage of the left ventricle with no Sestamibi uptake. Infarct sizes were larger with TMPG 0 or 1 (a closed or stained myocardium) than with TMPG 2 or 3 (open myocardium, median 13% versus 7%, P=0.004). Infarcts were also larger in patients with no ST segment resolution (median 15%) or incomplete resolution (11%) than in those with complete resolution (6%, overall P=0.0001). The difference in infarct size by TMPG persisted when stratified by category of ST resolution.
Conclusions:
There may be a pathophysiological link between early restoration of tissue-level perfusion and reduced subsequent infarct size that may partially explain why these early angiographic and electrocardiographic measures are associated with long-term survival.
