From the Guidelines
New ST segment depressions on an electrocardiogram (ECG) are a significant risk indicator for mortality and myocardial infarction (MI), and patients with these findings should seek immediate medical evaluation. The presence of new ST depressions often indicates myocardial ischemia, where the heart muscle isn't receiving adequate blood flow. According to the 2012 ACCF/AHA focused update incorporated into the ACCF/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction 1, ST depression on the presenting ECG portends the highest risk of death at 6 months, with the degree of ST depression showing a strong relationship to outcome.
Key Considerations
- New ST depressions require immediate medical attention, and patients should call 911 or go to the nearest emergency department.
- While awaiting medical help, if available and not contraindicated, patients should take 325mg of aspirin chewed (not swallowed whole) 1.
- Healthcare providers will likely perform serial ECGs, cardiac biomarker tests (troponin), and possibly cardiac imaging to determine the cause and severity of the ischemia.
- Treatment depends on the cause but may include antiplatelet therapy (aspirin, P2Y12 inhibitors like clopidogrel), anticoagulants (heparin), nitrates for pain relief, and possibly cardiac catheterization.
Risk Assessment and Management
- The pattern, location, and depth of ST depressions help clinicians determine the severity and location of the ischemia 1.
- Dynamic risk modeling, which accounts for the evolving risk of patients as they pass through their disease process, can provide additional insights for decision-making at key points in care 1.
- Renal impairment is an additional high-risk feature in patients with acute coronary syndrome (ACS), and patients with renal dysfunction require careful consideration of the benefits and risks of different therapies 1.
From the Research
Implications of New ST Segment Depressions
- New ST segment depressions are associated with a poor prognosis in unstable coronary artery disease, indicating severe coronary lesions and a high risk of subsequent cardiac events 2.
- The presence of ST segment depression is associated with a 100% increase in the occurrence of three-vessel/left main disease 2.
- An early invasive strategy substantially decreases death/myocardial infarction in patients with ST segment depression 2.
- ST segment depression can be caused by coronary artery spasm, and bolus intravenous nitroglycerin can be an effective treatment 3.
- ST segment depression can also be found in asymptomatic patients with normal coronary arteries, highlighting the importance of early detection and prevention of cardiovascular events 4.
Diagnostic Value of ST Segment Depression
- The diagnostic value of ST segment depression is decreased in patients receiving beta-blockers, and the use of the delta ST/HR index does not improve test performance 5.
- Reciprocal ST segment depression can be helpful in distinguishing acute myocardial infarction (AMI) from non-AMI causes of ST segment elevation, especially in patients without confounding electrocardiographic patterns 6.
- The presence of ST segment depression is not helpful in distinguishing AMI from non-AMI when considering all patients with ST segment elevation, but it can be valuable in patients without confounding patterns 6.
Clinical Significance of ST Segment Depression
- ST segment depression is a significant predictor of future cardiovascular events, and early detection and prevention are crucial, especially in asymptomatic patients 4.
- The presence of ST segment depression requires further evaluation, including echocardiographic and laboratory examinations, to rule out underlying causes 4.
- Coronary CT can be a useful diagnostic tool in patients with ST segment depression and normal coronary arteries, to rule out coronary artery disease 4.