By Dr. Ibrahim Abuduruk & Dr. Ali Farzad
A 64-year-old male presents to the emergency department complaining of mid-sternal chest pain and dyspnea, associated with vomiting and diaphoresis. An ECG was done (shown above) and is suggestive of acute inferior MI. Vital signs: Afebrile, BP 140/80, HR 90 bpm. The patient is treated with Aspirin and Nitroglycerin, and subsequently becomes hypotensive with a blood pressure of 90/50. What is the ECG finding that is most suggestive of a cause of the patient’s hypotension after treatment with nitroglycerin?
A. Convex ST segment elevation morphology.
B. ST segment depression in V1, with tall R waves and upright T waves
C. ST segment elevation in V1 and ST segment depression in V2.
D. ST segment elevation magnitude in lead II exceeds the magnitude of ST elevation of lead III.
Answer is C!
This ECG has mild inferior ST-segment elevation, and hyperdynamic T-waves that are concerning for an early inferior MI. Additionally, there is ST elevation in V1, which in the presence of inferior MI is diagnostic of right ventricular MI (RVMI). Inferior MI’s comprise about 50% of all MI’s and are typically due to right coronary artery occlusion. Inferior MI’s typically have a better prognosis when compared to anteroseptal MI’s, but complications of inferior MI may include RV infarction (~40% of Inferior MI’s) or
bradycardia caused by AV Blocks (~20% of AV blocks).
Management goals for STEMI include pain control (typically with nitroglycerin), and prompt initiation of medical management with antiplatelet and anticoagulants while arranging for thrombolysis or transfer to cath lab for emergent revascularization. Antiplatelet and anticoagulants should be started depending on institution protocol.
This patient became hypotensive soon after treatment with nitroglycerin. Right ventricular extension of inferior MI must be a strong consideration when patients are hypotensive or have ECG signs of RV involvement. Findings suggestive of RV MI also include:
• ST segment elevation magnitude in lead III greater than ST segment elevation magnitude in lead II
• ST segment elevation in lead V1 with depression of ST segment in V2
• ST segment elevation in V1
• A right-sided ECG, with leads V3R and V4R has the best sensitivity and specificity for RV MI
Isolated Right Ventricular MI are rare, but RV infarction may accompany inferior MI’s and cause clinically significant hypotension. Patients with RV infarction are preload sensitive (due to poor RV contractility) and can develop severe hypotension in response to any preload reducing agents including nitrates.
Take home point:
Consider right ventricular infarction in patients with inferior MI and hypotension or ECG signs of RV involvement. Hypotension in RV infarction is treated with fluid loading and nitrates are contraindicated.