From the Guidelines
As a paramedic, the main EKG changes to look for include ST-segment elevation or depression, T-wave inversions, and other signs of ischemia or injury, as these are critical for identifying acute coronary syndrome and guiding immediate treatment decisions 1. When assessing an EKG, it is essential to follow a systematic approach, evaluating rate, rhythm, axis, intervals, and specific abnormalities in each lead.
- Key changes to look for include:
- ST-segment elevation ≥1mm in two contiguous leads, which may indicate STEMI requiring immediate reperfusion therapy
- ST-segment depression or T-wave inversions, which can indicate ischemia or non-ST elevation acute coronary syndrome (NSTE-ACS)
- Other signs of ischemia or injury, such as Q waves or conduction delays For suspected acute coronary syndrome, serial ECGs should be performed to detect potential ischemic changes, especially when clinical suspicion is high or symptoms are persistent 1. It is also important to note that a normal ECG does not exclude ACS, and serial ECGs should be repeated at 15- to 30-minute intervals during the first hour, especially if symptoms recur 1. Understanding these key changes allows for rapid identification of life-threatening conditions and appropriate treatment in the prehospital setting, with the goal of reducing time to reperfusion and improving patient outcomes 1.
From the Research
EKG Changes in Acute Coronary Syndrome
The main EKG changes to look for in patients with acute coronary syndrome include:
- ST segment elevation (STEMI) in patients with active symptoms, usually indicating acute occlusion of an epicardial artery with ongoing transmural ischemia 2
- ST depression in leads V1-V3, indicative of subendocardial ischemia secondary to subocclusion of the epicardial artery, distal embolization to small arteries, or spasm supply/demand mismatch 2
- ST depression in leads other than V1-V3, which may be indicative of subendocardial ischemia or nonischemic etiologies such as left ventricular hypertrophy or cardiomyopathies 2
- QRS complex changes, which can be affected by acute ischemia 2
- T wave changes, which can also be affected by acute ischemia 2
Importance of EKG Interpretation in Paramedicine
EKG interpretation is an essential competency in modern paramedicine, and advanced care paramedics should be able to recognize and interpret various EKG diagnoses or findings, including:
- STEMI 3
- ST segment elevation or depression 3
- Other EKG diagnoses or findings that may impact prehospital care, such as arrhythmias or conduction abnormalities 3
Timing of Medication Administration
The timing of medication administration, such as aspirin and nitroglycerin, can impact patient outcomes in acute coronary syndrome:
- Giving nitroglycerin 10 minutes after aspirin dosing may lead to a greater than 20% reduction in need for additional nitroglycerin and a greater than 7% decrease in subjective pain experienced by the patient 4
- Early upstream antithrombotic therapy administration, including aspirin, ticagrelor, and heparin, may be associated with greater pre-PPCI TIMI flow and less definite acute stent thrombosis in STEMI patients 5