hs-Troponin 0h/1h ESC Algorithm Calculator | NSTEMI Rule-Out

How it Works

Analytical Logic

The 0h/1h algorithm relies on two principles: (1) Baseline concentration correlates with MI probability, and (2) absolute change (kinetics) within 1 hour serves as a surrogate for 3-6 hour changes (e.g., a 6 ng/L 3h-rise suggests a 2 ng/L 1h-rise).

Assay-Specific Cut-offs (ng/L)

Assay Platform	Very Low (0h)	Rule-Out (0h/1h Δ)	Rule-In (0h / 1h Δ)
Roche Elecsys (hs-cTnT)	< 5	< 12 AND Δ < 3	≥ 52 OR Δ ≥ 5
Abbott Architect (hs-cTnI)	< 4	< 5 AND Δ < 2	≥ 64 OR Δ ≥ 6
Siemens Centaur (hs-cTnI)	< 3	< 6 AND Δ < 3	≥ 120 OR Δ ≥ 12
Beckman Access (hs-cTnI)	< 4	< 5 AND Δ < 4	≥ 50 OR Δ ≥ 15

Temporal Requirements

T0: Time of first blood draw at presentation.

T1: Second blood draw exactly 60 minutes (± 10 min) after T0.

Algorithm remains valid regardless of local laboratory turnaround time (TAT).

Origins & History

Developmental History

2011: ESC introduced the 0h/3h algorithm (NPV >98% if 0h/3h <99th percentile + GRACE <140).

2015: 0h/1h algorithm introduced to reduce the "troponin-blind" interval and improve ED efficiency.

Verification: Validated in the APACE cohort (12 EDs, 5 countries) and the randomized RAPID-TnT trial.

Class Recommendation: Class I, Level A (ESC 2020) for 0h/1h; 0h/3h is now Class IIa alternative.

The "Requiem" for Unstable Angina

With the advent of hs-cTn assays (10-fold lower Limit of Detection), many patients previously diagnosed with Unstable Angina (UA) are now correctly identified as NSTEMI. This has led to a reciprocal reduction in UA prevalence.

Clinical Pearls

Predictive Performance

Rule-Out Zone: Safety quantified by NPV >99% and sensitivity >99% for NSTEMI.

Rule-In Zone: Positive Predictive Value (PPV) ~70-75%. Note: 25-30% of rule-ins may be non-MI cardiac injury (Myocarditis, Takotsubo).

Observe Zone: High-risk group; mortality rates at 2 years are comparable to Rule-In patients.

Demographic Variables

Age: Elevated hs-cTn prevalence is 1% at age 40 vs 5.2% at age 65.

Renal Function: Requires careful interpretation as baseline levels are often chronically elevated.

Next Steps

Observe Zone Protocol

Considered "Observe" if meeting neither Rule-In nor Rule-Out criteria.

Mandatory: 3-hour hs-cTn measurement.

Next Steps: Echocardiography, then non-invasive (CCTA/Stress) or invasive (CAG) based on clinical suspicion.

Disposition Strategy

Rule-Out: Candidate for early discharge if pain-free and life-threats (Aortic Dissection/PE) are excluded.

Rule-In: CCU admission, DAPT loading, and early invasive coronary angiography.

hs-Troponin 0h/1h ESC Algorithm

When to Use

Target Population

Exclusion Criteria

How it Works

Analytical Logic

Assay-Specific Cut-offs (ng/L)

Temporal Requirements

Origins & History

Developmental History

The "Requiem" for Unstable Angina

Clinical Pearls

Predictive Performance

Demographic Variables

Next Steps

Observe Zone Protocol

Disposition Strategy

The Evidence

Key Implementation Trials

Literature References

In Recent Clinical News

hs-Troponin 0h/1h ESC Algorithm

When to Use

Target Population

Exclusion Criteria

How it Works

Analytical Logic

Assay-Specific Cut-offs (ng/L)

Temporal Requirements

Origins & History

Developmental History

The "Requiem" for Unstable Angina

Clinical Pearls

Predictive Performance

Demographic Variables

Next Steps

Observe Zone Protocol

Disposition Strategy

The Evidence

Key Implementation Trials

Literature References

In Recent Clinical News