VIRSTA Score: what it is and why it matters

The VIRSTA score is a clinical prediction rule used in patients with Staphylococcus aureus bacteremia (SAB) to estimate the likelihood of infective endocarditis (IE) and help decide how urgently echocardiography should be performed. It was developed to support early risk stratification within the first 48 hours after SAB is identified.

Why this score is important

IE is one of the most serious complications of SAB. In prospective studies, about 10% to 20% of SAB episodes are complicated by infective endocarditis, yet the diagnosis can be difficult because classic signs may be absent at presentation. Echocardiography, especially transesophageal echocardiography (TEE), is a key diagnostic test, but it is not practical to perform urgently in every patient without some method of prioritization.

The VIRSTA score was created to address that problem. In the original multicenter French study, the investigators aimed to quantify IE risk early in the course of SAB and identify patients who should undergo urgent echocardiography. They concluded that patients with a VIRSTA score of 3 or higher should be strongly prioritized for echocardiography.

What the VIRSTA score includes

The score uses 10 clinical and microbiologic variables, each weighted according to its association with IE. External validation papers describe the variables as follows:

• cerebral or peripheral emboli
• meningitis
• permanent intracardiac device or previous infective endocarditis
• intravenous drug use
• preexisting native valve disease
• persistent bacteremia on follow-up blood culture
• vertebral osteomyelitis
• community or non-nosocomial healthcare-associated acquisition
• severe sepsis or shock
• C-reactive protein elevation

These factors reflect the biology of IE: embolic phenomena, persistent bacteremia, underlying cardiac substrate, and metastatic infection all increase suspicion that bacteremia is not just transient bloodstream infection but part of an endovascular focus.

How to interpret it

In practice, the most widely used cutoff is:

• Score < 3: lower risk of IE
• Score ≥ 3: higher risk of IE, with echocardiography prioritized

That threshold comes from the original derivation study and has been used in later validations.

Strengths of the score

A major strength of VIRSTA is its high negative predictive value (NPV). In a prospective external validation study from the Netherlands that compared VIRSTA with the POSITIVE and PREDICT scores, only VIRSTA achieved an NPV of at least 98%, which the investigators considered the safety threshold for ruling out endocarditis. In that cohort, VIRSTA had 98.9% sensitivity and 99.3% NPV.

This is why many clinicians view VIRSTA as particularly useful when the question is: “Can this SAB patient safely avoid TEE?” Among available scores, VIRSTA appears best suited for identifying a truly low-risk group.

Limitations

The main tradeoff is specificity. In the same Dutch validation study, 70.9% of patients were classified as high risk by VIRSTA, which means many patients still end up in the echocardiography pathway. In other words, VIRSTA is good at not missing IE, but it may label a large share of patients as needing further workup.

That limitation has shown up in more recent cohorts as well. A 2024 prospective Asian cohort found that VIRSTA performed better than PREDICT in that setting, and a score <3 had a 97.5% NPV, but the score still needs to be interpreted alongside local practice patterns and bedside judgment.

Place in current practice

Recent European guidance emphasizes echocardiography in SAB and supports risk-stratified use of imaging tools in this setting. The 2023 ESC endocarditis guideline highlights the importance of multimodal imaging and includes updated diagnostic pathways for IE.

So, the VIRSTA score should be seen as a triage tool, not a replacement for clinical assessment. A low score can help identify patients at low risk, but a high score does not by itself diagnose IE. Final decisions should still consider blood culture persistence, prosthetic material, metastatic infection, murmur, imaging findings, and the patient’s overall clinical picture.

Bottom line

The VIRSTA score is one of the best-validated tools for estimating IE risk in S. aureus bacteremia. Its main value is in identifying patients with a very low probability of endocarditis when the score is below 3. Its weakness is that many patients are still classified as high risk, so it does not eliminate the need for careful clinical decision-making. Used properly, it helps clinicians prioritize echocardiography while reducing the chance of missing a dangerous diagnosis.

References

1. Tubiana S, Duval X, Alla F, et al. The VIRSTA score, a prediction score to estimate risk of infective endocarditis and determine priority for echocardiography in patients with Staphylococcus aureus bacteremia. Journal of Infection. 2016;72(5):544-553.
2. van der Vaart TW, Prins JM, Soetekouw R, et al. Prediction Rules for Ruling Out Endocarditis in Patients With Staphylococcus aureus Bacteremia. Clinical Infectious Diseases. 2022;74(8):1442-1449.
3. Peinado-Acevedo JS, Hurtado-Guerra JJ, Hincapie-Osorno C, et al. Validation of VIRSTA and PREDICT scores to determine the priority of echocardiography in patients with Staphylococcus aureus bacteremia. Clinical Infectious Diseases. 2021;73:e1151-e1157.
4. Papadimitriou-Olivgeris M, et al. The LAUsanne STAPHylococcus aureus ENdocarditis score and other risk scores for infective endocarditis in SAB. 2022 review discussing VIRSTA variables and score structure.
5. Ngiam JN, et al. Performance of Risk Scores in Predicting Infective Endocarditis in Patients with Staphylococcus aureus Bacteraemia in a Prospective Asian Cohort. Journal of Clinical Medicine. 2024.
6. European Society of Cardiology. 2023 ESC Guidelines for the management of endocarditis.