When to perform cardiac catheterization in a patient with atrial fibrillation (AF) and rapid ventricular response (RVR) presenting with mild ST segment depression and elevated troponin levels indicating myocardial injury?

From the Guidelines

In the setting of mild ST segment depression with atrial fibrillation with rapid ventricular response (RVR) and a troponin of 70, an early invasive strategy within 24 hours is recommended if the patient has a diagnosis of NSTEMI suggested by the diagnostic algorithm or dynamic ST/T-segment changes suggesting ongoing ischemia 1. The first priority should be to control the rapid heart rate with medications such as beta-blockers (metoprolol 5mg IV every 5 minutes up to 15mg) or calcium channel blockers (diltiazem 0.25mg/kg IV over 2 minutes). Once the heart rate is controlled, reassess the ECG changes and troponin levels. If ST depression resolves with rate control, cardiac catheterization may be deferred and a non-invasive stress test can be scheduled after stabilization. However, if the patient has a history of coronary artery disease, multiple cardiac risk factors, or if troponin levels continue to rise despite adequate rate control, proceeding to cardiac catheterization within 24 hours is reasonable, as suggested by the 2020 ESC guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation 1. The elevated troponin in this context may be due to either demand ischemia from the rapid heart rate or from acute coronary syndrome, and distinguishing between these causes is crucial for appropriate management, with prompt coronary angiography being the mainstay of diagnosis and management of patients at high risk for ACS, particularly those with an ischemic pattern on ECG 1. Some key points to consider in the management of these patients include:

• The presence of ST-segment depression >1 mm in ≥6 leads additional to ST-segment elevation in aVR and/or V1 is a very high-risk criterion that warrants an immediate invasive strategy 1
• The GRACE risk score >140 is a high-risk criterion that warrants an early invasive strategy within 24 hours 1
• The use of other modalities in the evaluation of high-risk ACS patients, particularly modalities with a significant time penalty, is limited 1

From the Research

Decision to Send for Cardiac Catheterization

When considering sending a patient for cardiac catheterization due to mild ST segment depression in the setting of atrial fibrillation with rapid ventricular rate (RVR) and a troponin level of 70, several factors must be taken into account.

• The presence of ST-segment depression during rapid atrial fibrillation is not always predictive of obstructive coronary artery disease (CAD) 2.
• However, another study found that ST-segment depression during rapid AF had 88.0% sensitivity and 75.6% specificity in predicting the presence of CAD, with a positive predictive value of 50.0% and a negative predictive value of 95.8% 3.
• The relationship between ST-segment depression and coronary artery disease is complex, and the decision to proceed with cardiac catheterization should be based on a comprehensive evaluation of the patient's clinical presentation, medical history, and other diagnostic test results.

Considerations for Cardiac Catheterization

In patients with atrial fibrillation and RVR, the primary goal is to achieve rate control and prevent complications such as heart failure or thromboembolism.

• The choice of rate control agent, such as metoprolol or diltiazem, does not significantly influence sustained rate control success 4.
• However, the presence of ST-segment depression may be associated with a higher risk of adverse cardiac events, including heart failure hospitalization and major adverse cardiovascular events (MACE) 5.

Diagnostic Value of ST-Segment Depression

The diagnostic value of ST-segment depression in patients with atrial fibrillation is not well established.

• One study found that resting ST segment depression was associated with a higher prevalence of severe coronary disease in patients without prior myocardial infarction 6.
• However, the presence of ST-segment depression during rapid atrial fibrillation is not always indicative of obstructive CAD, and other diagnostic tests, such as coronary angiography, may be necessary to confirm the diagnosis 2, 3.