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Multiparametric approach to diagnosis of non-Q-wave acute myocardial infarction
C Carpeggiani1, A L'Abbate, P Marzullo
1Institute of Clinical Physiology, National Research Council, Pisa University, Italy.
Insights
Elevated cardiac enzymes are not always necessary to diagnose myocardial necrosis in ischemic heart disease patients with ST-T changes. Multiparametric evaluation reveals necrosis is often present even without significant enzyme increases.
Area of Science:
- Cardiology
- Biochemistry
Background:
- Ischemic heart disease patients with ST-T changes but no Q waves pose diagnostic challenges.
- Conventional enzymatic markers may underestimate myocardial necrosis in these cases.
Purpose of the Study:
- To investigate if elevated cardiac enzymes are essential for diagnosing myocardial necrosis in ischemic heart disease patients with sustained ST-T changes.
- To evaluate the diagnostic utility of a multiparametric approach for detecting myocardial necrosis.
Main Methods:
- Prospective study of 15 angina patients with sustained ST-T changes.
- Assessed serum enzymes, myoglobin, pyrophosphate uptake, echocardiography, perfusion scintigraphy, and ventriculography.
- Utilized electrocardiographic gated microsphere technique.
Main Results:
- Only 40% met acute myocardial infarction criteria based on conventional enzyme levels.
- Myoglobin was positive in 80%, and perfusion defects occurred in 100% of patients.
- Multiparametric assessment showed high prevalence of necrosis indicators (perfusion defects, pyrophosphate uptake, regional dyssynergies).
Conclusions:
- Sustained ST-T changes in ischemic heart disease patients can indicate myocardial necrosis even with normal enzyme levels.
- Conventional enzymatic diagnosis may miss a significant number of non-Q-wave myocardial infarctions.
- A multiparametric approach is crucial for accurate diagnosis and clinical management.
Abstract:
The present study investigated whether the lack of enzyme increase is reason enough to exclude necrosis in patients with ischemic heart disease who develop electrocardiographic sustained ST-T changes in the absence of Q waves. In 15 consecutive patients with angina who developed sustained ST-T changes during hospitalization, the presence of myocardial necrosis was investigated by a prospective multiparametric approach. Serum enzymes and myoglobin, pyrophosphate uptake, 2-dimensional echocardiography, perfusion scintigraphy, left ventriculography and coronary angiography were evaluated. According to creatine kinase and creatine kinase-MB peak at twice the upper normal value, the diagnosis of acute myocardial infarction applied only to 40% of patients. However, myoglobin was positive in 80% and a perfusion defect could be documented by an electrocardiographic gated microsphere technique in 100% of patients. The positivity of myoglobin increased to 100% and of creatine kinase and creatine kinase-MB to 87 and 60%, respectively, when a peak value twice the individual lowest value was considered for positivity. The 100% presence of perfusion defects associated with the high prevalence of both positive pyrophosphate uptake (87%) and regional dyssynergies (87 and 73%, respectively, by left ventriculography and echocardiography) strongly suggest that sustained (greater than or equal to 7 days) ST-T changes in this population were indicative of myocardial necrosis. Thus, by conventional enzymatic approach, diagnosis of non-Q-wave infarction can be missed in a sizable number of patients and present important clinical implications.