How is the efficacy of thrombolysis for ST-Elevation Myocardial Infarction (STEMI) assessed?

From the Guidelines

The efficacy of thrombolysis for ST-elevation myocardial infarction (STEMI) is primarily assessed through clinical, electrocardiographic, and angiographic parameters, with the most recent and highest quality study 1 suggesting that primary PCI is the preferred treatment over thrombolysis due to its superior preservation of myocardium and lower risk of stroke. The assessment of thrombolysis efficacy in STEMI involves several key parameters, including:

• Resolution of chest pain following administration of thrombolytic agents such as alteplase (tPA), reteplase, or tenecteplase
• Electrocardiographic monitoring, with ST-segment resolution of ≥50% within 60-90 minutes of thrombolytic administration considered a positive response
• Reperfusion arrhythmias, such as accelerated idioventricular rhythm, may also indicate successful reperfusion
• For patients who subsequently undergo coronary angiography, TIMI (Thrombolysis In Myocardial Infarction) flow grades assess coronary perfusion, with TIMI grade 3 flow (complete perfusion) representing successful thrombolysis
• Myocardial blush grade and corrected TIMI frame count provide additional angiographic assessment of microvascular perfusion
• Cardiac biomarkers like troponin and CK-MB should be monitored, with earlier peaking and more rapid decline suggesting successful reperfusion
• Long-term efficacy is evaluated through left ventricular function assessment via echocardiography or other imaging modalities, and by monitoring clinical outcomes including mortality, reinfarction rates, and heart failure development According to the study 1, primary PCI is the preferred treatment over thrombolysis, especially in patients presenting 3-12 hours after the onset of chest pain, due to its superior preservation of myocardium and lower risk of stroke. Additionally, the study suggests that rescue PCI is recommended if thrombolysis fails within 45-60 minutes after starting the administration. The study 1 also highlights the importance of timely reperfusion, with the current guidelines strongly recommending reperfusion therapy for patients presenting within 12 hours of symptoms. However, the study 1 is more recent and of higher quality, and its findings should be prioritized in clinical practice. In summary, the efficacy of thrombolysis for STEMI should be assessed using a combination of clinical, electrocardiographic, and angiographic parameters, and primary PCI should be considered the preferred treatment over thrombolysis due to its superior outcomes, as suggested by the most recent and highest quality study 1.

From the FDA Drug Label

The primary endpoint was the rate of TIMI Grade 3 flow at 90 minutes. The results showed that the 40 mg and 50 mg doses were similar to accelerated infusion of Activase in restoring patency. TIMI Grade 3 flow and TIMI Grade 2/3 flow at 90 minutes are shown in Table 3.

The efficacy of thrombolysis for ST-Elevation Myocardial Infarction (STEMI) is assessed by measuring the rate of TIMI Grade 3 flow at 90 minutes, which indicates the restoration of patency in the coronary arteries. The results of the TIMI-10B study showed that tenecteplase doses of 40 mg and 50 mg were similar to accelerated infusion of Activase in restoring patency, as measured by TIMI Grade 3 flow and TIMI Grade 2/3 flow at 90 minutes 2.

From the Research

Efficacy of Thrombolysis for STEMI

The efficacy of thrombolysis for ST-Elevation Myocardial Infarction (STEMI) is assessed through various studies, which have investigated the outcomes of thrombolytic therapy in patients with STEMI.

• The reperfusion rate, which is a key indicator of the efficacy of thrombolysis, has been reported to be high in several studies. For example, a study published in 2016 found that the reperfusion rate was 89.3% at 120 minutes after thrombolysis 3.
• The timing of thrombolysis is also an important factor in determining its efficacy. A study published in 2016 found that the reperfusion rate was significantly higher in patients who received thrombolysis within 6 hours of onset compared to those who received it between 6-12 hours 3.
• The use of thrombolytic agents, such as reteplase, has been shown to be effective in achieving high recanalization rates and low cardiovascular events and bleeding rates 3.
• Adjunctive intracoronary thrombolytic therapy at the time of primary percutaneous coronary intervention (PCI) has been found to improve clinical and myocardial perfusion parameters without increasing the rate of bleeding 4.

Assessment Tools

Several assessment tools have been developed to evaluate the efficacy of thrombolysis for STEMI, including:

• The Thrombolysis in Myocardial Infarction (TIMI) Risk Index, which is a simple risk assessment tool that has been found to be suitable for risk stratification in elderly patients with STEMI undergoing PCI 5, 6.
• The TIMI Risk Index has been found to be an independent predictor of clinical outcomes, such as death and heart failure, in STEMI patients who underwent primary PCI 6.

Outcomes

The outcomes of thrombolysis for STEMI have been found to be favorable in several studies, with low rates of mortality and bleeding events.

• A study published in 2007 found that initial thrombolysis followed by an active early rescue/definitive revascularization strategy could achieve salutary short- and long-term outcomes in patients with STEMI 7.
• A study published in 2021 found that the incidence of acute kidney injury, acute heart failure, in-hospital death, and major adverse cardiac events was significantly higher in patients with higher TIMI Risk Index values 5.
• A study published in 2022 found that the TIMI Risk Index was an independent predictor of clinical outcomes, such as death and heart failure, in STEMI patients who underwent primary PCI 6.