From the Guidelines
Moderate ST segment depression on an electrocardiogram (EKG) is a significant finding that suggests myocardial ischemia and requires prompt medical evaluation, as it is associated with a high risk of death at 6 months, with the degree of ST depression showing a strong relationship to outcome. This finding is crucial, especially if accompanied by chest pain, shortness of breath, or other cardiac symptoms, as it could indicate coronary artery disease or an ongoing heart attack 1. The management of such patients typically includes aspirin (325mg chewed immediately), rest, oxygen if needed, and possibly nitroglycerin (0.4mg sublingual) for chest pain. Further management depends on the clinical context and may include blood tests for cardiac enzymes, additional cardiac imaging, and possibly cardiac catheterization.
Key Considerations
- The depth of ST depression suggests significant ischemia that shouldn't be ignored, even in the absence of symptoms.
- The presence of ST depression on the presenting ECG portends the highest risk of death at 6 months, 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.
- Dynamic risk modeling, which accounts for the evolution of risk as patients pass through their disease process, is a new frontier in modeling that may provide more sophisticated, adaptive, and individually predictive modeling of risk in the future.
Clinical Implications
- Patients with moderate ST segment depression should undergo thorough cardiac evaluation to determine the underlying cause and appropriate treatment strategy, which might include medications, lifestyle changes, or interventional procedures.
- Renal impairment, recognized as an additional high-risk feature in patients with acute coronary syndrome (ACS), should be considered in the management of these patients, as it is associated with increased bleeding risks, higher rates of heart failure and arrhythmias, and may not enjoy the same magnitude of benefit with some therapies observed in patients with normal renal function 1.
- The use of newer, more aggressive therapies such as low-molecular-weight heparin (LMWH), platelet GP IIb/IIIa inhibition, and an invasive strategy may be beneficial in patients with unstable angina/non-ST-elevation myocardial infarction (UA/NSTEMI), particularly those with increasing risk score 1.
From the Research
Significance of Moderate ST Segment Depression on an EKG
- Moderate ST segment depression on an electrocardiogram (EKG) is a significant finding that can indicate acute coronary syndromes (ACS), including non-ST-segment elevation myocardial infarction (NSTEMI) and unstable angina 2, 3, 4, 5, 6.
- ST segment depression is typically seen in patients with subendocardial ischemia secondary to subocclusion of the epicardial artery, distal embolization to small arteries, or supply/demand mismatch 3.
- The EKG should be read along with the clinical assessment of the patient, and comparison to previous EKGs and subsequent EKGs can add to the diagnosis and interpretation in difficult cases 3.
- Moderate ST segment depression can also be secondary to nonischemic etiologies, such as left ventricular hypertrophy, cardiomyopathies, and digitalis therapy 5.
- The significance of ST segment depression can be classified into different EKG patterns, including ST depression, negative T wave, and even normal EKG, which need to be better defined in future studies to correlate them with the severity and extent of ischemia 6.
Clinical Implications
- Patients with moderate ST segment depression should be evaluated for ACS, and elevated troponin levels without ST-segment elevation on EKG suggest non-ST-segment elevation ACS 2, 4.
- Coronary angiography with percutaneous or surgical revascularization is recommended for patients with ACS, including those with moderate ST segment depression 2, 4.
- Other important management considerations include initiation of dual antiplatelet therapy and parenteral anticoagulation, statin therapy, beta-blocker therapy, and sodium-glucose cotransporter-2 inhibitor therapy 4.