Rational sequence toward the diagnosis of myocardial ischemia

Area of Science:

• Cardiology
• Cardiovascular Investigation

Background:

• Advances in understanding myocardial ischemia and ischemic heart disease challenge classical diagnostic methods.
• Myocardial ischemia can be asymptomatic, have non-atherosclerotic causes, and present with normal perfusion during exercise.
• Current diagnostic markers for ischemia often lack sufficient sensitivity and specificity.

Purpose of the Study:

• To identify organic and functional factors causing myocardial ischemia in individual patients.
• To evaluate the role of these factors in cardiac damage, patient performance, and prognosis.
• To address limitations of exercise stress tests in assessing coronary reserve, particularly concerning functional factors like dynamic stenosis.

Main Methods:

• Comparison of cardiac work during ischemia with reference exercise ischemic thresholds.
• Indirect estimation of transient functional increases in coronary resistance.
• Consideration of repeated tests or reference tests during pharmacologic therapy (e.g., nitrates, calcium antagonists).

Main Results:

• Reduction in 'organic' coronary reserve can be overestimated by functional increases in coronary tone (fixed vs. dynamic stenosis).
• Increases in heart rate and/or blood pressure during ischemia do not rule out primary coronary blood flow reduction unless reference values are met.
• The study proposes refined diagnostic strategies considering both fixed and dynamic stenosis components.

Conclusions:

• Classical diagnostic approaches for myocardial ischemia are insufficient due to asymptomatic presentations and complex pathophysiology.
• Accurate diagnosis requires identifying all factors contributing to ischemia, including functional elements.
• Pharmacological interventions and comparative testing methods are crucial for a comprehensive evaluation of coronary reserve and ischemic heart disease.