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Transient myocardial ischaemia after acute myocardial infarction
1Department of Cardiology, Royal Liverpool Hospital.
Insights
Transient myocardial ischemia becomes more common and silent after myocardial infarction. Episodes later in recovery are linked to increased heart rate and oxygen demand, suggesting different implications.
Area of Science:
- Cardiology
- Internal Medicine
- Clinical Research
Background:
- Acute myocardial infarction (MI) is a leading cause of mortality.
- Transient myocardial ischemia can occur post-MI and impact prognosis.
- Understanding the evolution of ischemia is crucial for patient management.
Purpose of the Study:
- To investigate the prevalence and characteristics of transient myocardial ischemia.
- To compare early and late ischemic episodes following acute MI.
- To assess the association of ischemia with myocardial oxygen demand.
Main Methods:
- Ambulatory ST-segment monitoring was performed in 203 patients with recent acute MI.
- Monitoring occurred at two time points: early (average 6.4 days) and late (average 38 days) post-MI.
- Characteristics of transient ischemic episodes, including symptoms and heart rate, were analyzed.
Main Results:
- Transient ST-segment depression was significantly more prevalent during late monitoring (32%) compared to early monitoring (14%).
- The majority of transient ischemia episodes (over 85%) were silent, with 80% of patients experiencing only silent episodes.
- Late transient ischemia was associated with higher heart rates and a diurnal pattern, indicating increased myocardial oxygen demand.
Conclusions:
- Transient myocardial ischemia increases in frequency and is more often silent in the early months after acute MI.
- Late-onset ischemia exhibits distinct characteristics, suggesting a potential link to increased myocardial oxygen demand.
- Dissimilarities between early and late ischemic episodes may imply different pathophysiologies and prognostic significance.
Abstract:
The prevalence and characteristics of transient myocardial ischaemia were studied in 203 patients with recent acute myocardial infarction by both early (6.4 days) and late (38 days) ambulatory monitoring of the ST segment. Transient ST segment depression was much commoner during late (32% patients) than early (14%) monitoring. Most transient ischaemia (greater than 85% episodes) was silent and 80% of patients had only silent episodes. During late monitoring painful ST depression was accompanied by greater ST depression and tended to occur at a higher heart rate. Late transient ischaemia showed a diurnal distribution, occurred at a higher initial heart rate, and was more often accompanied by a further increase in heart rate than early ischaemia. Thus in the first 2 months after myocardial infarction transient ischaemia became increasingly common and more closely associated with increased myocardial oxygen demand. Because transient ischaemic episodes during early and late ambulatory monitoring have dissimilar characteristics they may also have different pathophysiologies and prognostic implications.