Sudden Cardiac Death After a Normal Stress Test: What Are We Missing?

INTRODUCTION

A patient with a normal stress test, on Apixaban (for prior PE) and aspirin, was recently cleared for work as a heavy vehicle driver by a cardiologist. Yet, he suffered a fatal myocardial infarction (MI) shortly after pulling over his Road Train Truck due to a mechanical issue.

How does this happen? How reliable is stress testing in predicting future cardiac events? What should we consider beyond standard assessments? This case prompts an important discussion for General Physicians (GPs), Cardiologists, and other healthcare providers on how to identify patients at risk for sudden cardiac death despite seemingly normal test results.

The Limitations of a Normal Stress Test

Exercise stress testing is widely used to detect obstructive coronary artery disease (CAD). However, it primarily identifies flow-limiting stenosis and may miss vulnerable plaques prone to rupture, which are often the cause of sudden MI’s.

What the Data Says:

• The annual mortality and cardiac event rate after a normal exercise stress test is <1% over 5 years. (PubMed)

• The cardiac death and nonfatal MI rate is ~0.5% per year despite a normal stress test. (PMC)

While these numbers suggest a low risk, they are not zero. For high-risk individuals, a normal stress test may provide false reassurance.

What Could Have Been Done Differently?

1. Beyond Stress Testing: The Role of Coronary CT Angiography (CCTA)

• While calcium scoring (CAC) measures overall plaque burden, it does not differentiate between stable vs. unstable plaques.

• Coronary CT angiography (CCTA) provides direct visualization of coronary anatomy and can identify non-obstructive, high-risk plaques (e.g., low-attenuation plaques).

• Who might benefit from CCTA?

• Patients with high CAC scores

• Those with multiple cardiovascular risk factors

• High-stakes professions (e.g., pilots, heavy vehicle operators)

However, CCTA is not without risks:

• Radiation exposure (though low with modern scanners)

• Allergic reactions to contrast agents

• Overdiagnosis and incidental findings leading to unnecessary interventions

Despite these concerns, in select patients, CCTA may provide critical insights beyond stress testing.

2. Aggressive Risk Factor Management Regardless of Test Results

• A normal stress test should not delay or prevent intensive cardiovascular risk management.

• LDL lowering with high-dose statins (or PCSK9 inhibitors in very high-risk cases) should be considered for individuals with high CAC or known atherosclerosis—even if asymptomatic.

3. Occupational Considerations: Should We Be More Cautious?

• A normal stress test does not mean “zero risk”, especially for individuals operating heavy machinery or working in safety-critical roles.

• Would CCTA or even invasive angiography have changed management in this patient? Possibly.

Key Takeaways for GPs, Cardiologists, and General Physicians

✅ A normal stress test does not rule out future cardiac events. It primarily detects flow-limiting CAD, not vulnerable plaques.

✅ CCTA can identify high-risk plaques missed by stress testing and may be appropriate for select patients, especially those in high-risk professions, like Road Train Truck Drivers, Pilots etc. (An Australian plane from Quantas made an emergency landing in Sydney after the pilot experienced chest pain mid air)

✅ Risk factor management should be aggressive regardless of stress test results. Statins, lifestyle changes, and LDL targets matter.

✅ Occupational fitness decisions should consider the limitations of stress testing. A broader assessment may be needed in safety-critical professions.

Revised Conclusion

This case highlights some limitations of conventional cardiac testing and underscores the need for a more nuanced, patient-centered approach to cardiovascular risk assessment. While stress testing remains a valuable tool, it may miss high-risk patients with non-obstructive coronary disease or vulnerable plaques that can lead to sudden cardiac events.

Incorporating Coronary CT Angiography (CCTA) into clinical practice can be particularly beneficial for the following patient groups:

• High coronary artery calcium (CAC) score with unclear implications or risk profile

• Patients with multiple cardiovascular risk factors (e.g., diabetes, hypertension, smoking, family history)

• Patients in high-risk occupations (e.g., pilots, truck drivers, machinery operators) where sudden cardiac events could have life-threatening consequences

• Patients with unexplained chest pain or discomfort, despite a normal stress test

• Those who remain symptomatic or have ongoing risk after management with statins or other therapies

By identifying patients at higher risk for adverse events, CCTA may provide critical insights, enabling more targeted interventions to prevent future MIs and sudden cardiac death.

Ultimately, a combination of advanced imaging, aggressive risk factor management, and clinical judgment will be necessary to optimize patient care and improve long-term outcomes.

Paul Alexander Wolf