Myocardial Infarction in the ISCHEMIA Trial: Impact of Different Definitions on Incidence, Prognosis, and Treatment...

Area of Science:

• Cardiology
• Clinical Trials
• Ischemic Heart Disease

Background:

• The ISCHEMIA trial evaluated invasive vs. conservative strategies for stable ischemic heart disease.
• Myocardial infarction (MI) was a frequent component of composite cardiovascular end points.

Purpose of the Study:

• To compare MI type, frequency, and prognosis based on treatment assignment (invasive vs. conservative) and MI definition.
• To analyze the impact of different MI definitions on trial outcomes.

Main Methods:

• ISCHEMIA used two MI definitions: primary (creatine kinase-MB) and secondary (cardiac troponin).
• Procedural MI definitions included elevated biomarkers, ST-segment depression, and coronary dissections.
• Compared MI rates and outcomes between invasive and conservative strategies.

Main Results:

• Procedural MIs were more frequent with the invasive strategy, particularly using the secondary troponin definition (8.2% vs. 2.0%).
• Type 1 MIs were less frequent with the invasive strategy (3.4% vs. 6.9%) and associated with higher cardiovascular death risk.
• The secondary MI definition identified substantially more procedural MIs than the primary definition.

Conclusions:

• Type 1 MI events were more frequent with a conservative strategy and linked to subsequent cardiovascular death.
• Procedural MI rates were higher with an invasive strategy, influenced by the MI definition used.
• The choice of MI definition significantly impacts the assessment of procedural MIs and overall trial outcomes.