What is the role of high-sensitivity (hs) troponin point of care (POC) testing in diagnosing myocardial infarction in adults with risk factors for coronary artery disease, such as hypertension, diabetes, or hyperlipidemia?

High-Sensitivity Troponin Point-of-Care Testing

Point-of-care high-sensitivity troponin testing has inferior diagnostic performance compared to central laboratory assays and should not be the preferred method for diagnosing myocardial infarction in adults with coronary artery disease risk factors. 1

Central Laboratory vs. Point-of-Care: The Critical Performance Gap

The European Society of Cardiology explicitly states that automated central laboratory assays are preferable to point-of-care tests at this time. 1 The fundamental limitation is clear: the majority of currently available POC troponin tests cannot be considered sensitive or high-sensitivity assays, whereas central laboratory platforms routinely achieve high-sensitivity status (detecting troponin in 50-95% of healthy individuals). 1

Key Performance Deficiencies of POC Testing

The shorter turnaround time advantage of POC tests is counterbalanced by three critical weaknesses: 1

• Lower sensitivity - POC tests miss more cases of myocardial infarction
• Lower diagnostic accuracy - Less reliable for both ruling in and ruling out MI
• Lower negative predictive value - Higher risk of false reassurance when results are negative

The American Heart Association confirms that POC troponin sensitivity is substantially below central laboratory methods, and the rigorous quantitative assay standardization needed for routine diagnosis favors central laboratory testing. 1

Recent Evidence on POC High-Sensitivity Troponin

Despite the guideline recommendations favoring central laboratory testing, emerging research from 2024 demonstrates that newer POC high-sensitivity troponin I assays may achieve acceptable performance when used in validated algorithms. 2 A multi-center study using the Siemens Atellica POC hs-cTnI at baseline and 2 hours identified 53-66% of patients as low risk with a sensitivity of 98.8-98.9% and negative predictive value of 99.9% for index MI. 2

Similarly, a 2022 study showed that a single POC whole-blood hs-cTnI measurement <4 ng/L at presentation achieved a sensitivity of 98.8-98.9% and NPV of 99.5-99.8% for ruling out MI, allowing safe discharge of 18-42% of patients. 3

The Critical Caveat

These newer POC studies used specific validated algorithms with predetermined thresholds and were conducted in controlled research settings. 2, 3 The guideline statements reflect the reality that most POC troponin tests in current clinical use do not meet high-sensitivity criteria and have not been validated in such rigorous protocols. 1

Optimal Diagnostic Approach for High-Risk Patients

For adults with hypertension, diabetes, or hyperlipidemia presenting with suspected acute coronary syndrome:

Measurement Strategy

• Use central laboratory high-sensitivity cardiac troponin (hs-cTnI or hs-cTnT) as the mandatory biomarker 1
• Measure at presentation and 3-6 hours after symptom onset to identify rising and/or falling patterns 1
• Serial testing is critically important in patients with chronic comorbidities like diabetes and renal dysfunction 1

Interpretation Framework

Interpret hs-cTn as a quantitative marker where higher levels indicate greater likelihood of MI: 1, 4

• Elevations >5-fold the upper reference limit (99th percentile) have >90% positive predictive value for acute type 1 MI 1, 4
• Elevations up to 3-fold the upper reference limit have only 50-60% PPV and may represent numerous non-MI conditions 1, 4
• Absolute change criteria are superior to relative change for detecting acute myocardial injury 1

Common Pitfalls in High-Risk Populations

Do not attribute elevated hs-cTn in elderly patients with renal dysfunction to impaired clearance alone - underlying cardiac conditions such as chronic coronary syndromes or hypertensive heart disease are the primary contributors. 1, 4

The differential diagnosis of elevated hs-cTn is broad at lower concentrations and includes: 1, 4

• Tachyarrhythmias
• Heart failure and hypertensive emergencies
• Myocarditis and Takotsubo syndrome
• Pulmonary embolism
• Critical illness and sepsis

In patients with diabetes, impaired renal function, and elevated C-reactive protein, baseline hs-cTn values are independently higher (often exceeding conventional thresholds even in stable states), making serial change measurements essential. 5

Clinical Algorithm

1. Obtain central laboratory hs-cTn at presentation (not POC unless using a validated newer assay with established protocols) 1
2. Repeat at 3-6 hours or use accelerated 0/1h or 0/2h protocols if validated hs-cTn assays are available 1
3. Look for absolute changes (e.g., ≥7 ng/L change for hs-cTnT from baseline of 14 ng/L) rather than percentage changes 1
4. Consider the clinical context - the magnitude and rapidity of troponin rise helps differentiate type 1 MI from other causes 1
5. In high-risk patients with chronic elevations, focus on the delta change rather than absolute values alone 1, 5