Influence of Age on the Diagnosis of Myocardial Infarction

Abstract

Background: The 99th centile of cardiac troponin, derived from a healthy reference population, is recommended as the diagnostic threshold for myocardial infarction, but troponin concentrations are strongly influenced by age. Our aim was to assess the diagnostic performance of cardiac troponin in older patients presenting with suspected myocardial infarction. Methods: In a secondary analysis of a multicenter trial of consecutive patients with suspected myocardial infarction, we assessed the diagnostic accuracy of high-sensitivity cardiac troponin I at presentation for the diagnosis of type 1, type 2, or type 4b myocardial infarction across 3 age groups (<50, 50–74, and ≥75 years) using guideline-recommended sex-specific and age-adjusted 99th centile thresholds. Results: In 46 435 consecutive patients aged 18 to 108 years (mean, 61±17 years), 5216 (11%) had a diagnosis of myocardial infarction. In patients <50 (n=12 379), 50 to 74 (n=22 380), and ≥75 (n=11 676) years, the sensitivity of the guideline-recommended threshold was similar at 79.2% (95% CI, 75.5–82.9), 80.6% (95% CI, 79.2–82.1), and 81.6% (95% CI, 79.8–83.2), respectively. The specificity decreased with advancing age from 98.3% (95% CI, 98.1–98.5) to 95.5% (95% CI, 95.2–95.8), and 82.6% (95% CI, 81.9–83.4). The use of age-adjusted 99th centile thresholds improved the specificity (91.3% [90.8%–91.9%] versus 82.6% [95% CI, 81.9%–83.4%]) and positive predictive value (59.3% [57.0%–61.5%] versus 51.5% [49.9%–53.3%]) for myocardial infarction in patients ≥75 years but failed to prevent the decrease in either parameter with increasing age and resulted in a marked reduction in sensitivity compared with the use of the guideline-recommended threshold (55.9% [53.6%–57.9%] versus 81.6% [79.8%–83.3%]. Conclusions: Age alters the diagnostic performance of cardiac troponin, with reduced specificity and positive predictive value in older patients when applying the guideline-recommended or age-adjusted 99th centiles. Individualized diagnostic approaches rather than the adjustment of binary thresholds are needed in an aging population.

Letter by Chen et al Regarding Article, “Influence of Age on the Diagnosis of Myocardial Infarction”

“…We read with great interest the study of “Influence of Age on the Diagnosis of Myocardial Infarction” by Lowry et al 1 The authors found that cardiac troponin concentrations above the recommended sex-specific 99th percentile are common in older patients, affecting nearly half of those >90 years of age, and no approach achieved parity in the diagnosis between older and younger patients with specificity and positive predictive value (PPV) reducing with advancing age, regardless of the threshold adopted.…”

Letter by Gibson and McEvoy Regarding Article, “Influence of Age on the Diagnosis of Myocardial Infarction”

“…We commend Lowry et al on their recent retrospective analysis of age-adjusted, sex-specific 99th percentile upper reference limits for high-sensitivity (hs) troponin-I in the High-STEACS (High-Sensitivity Troponin in the Evaluation of Patients With Acute Coronary Syndrome) trial. 1,2 The authors found that, compared with currently recommended sex-specific 99th percentile upper reference limits, the use of age-adjusted, sex-specific 99th percentile upper reference limits improved specificity (91.3% versus 82.6%) and positive predictive value (59.3% versus 51.5%) for myocardial infarction (MI) diagnosis in older adults. However, these improvements come at the cost of a significant reduction in sensitivity.…”

Response by Lowry et al to Letter Regarding Article, “Influence of Age on the Diagnosis of Myocardial Infarction”

“…We wish to thank Chen et al and Gibson et al for their thoughtful appraisal of our recent article, in which we evaluated the impact of age on the diagnostic performance of high-sensitivity cardiac troponin for myocardial infarction. 1…”

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We wish to thank Chen et al and Gibson et al for their thoughtful appraisal of our recent article, in which we evaluated the impact of age on the diagnostic performance of high-sensitivity cardiac troponin for myocardial infarction. 1 Chen et al highlight the importance of considering renal function when interpreting elevated cardiac troponin concentrations in older people. Two of every 5 patients with suspected myocardial infarction and renal impairment have cardiac troponin concentrations above the 99th centile upper reference limit.

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“…We adjudicated the diagnosis in 48 282 consecutive patients on the basis of all clinical information, investigations, and serial high-sensitivity cardiac troponin measurements to provide confidence in the distinction of myocardial infarction from injury. 1 We would highlight that, in patients with suspected acute coronary syndrome, the use of a presentation cardiac troponin concentration to identify patients at high or low probability of myocardial infarction, facilitating early rule-out or rule-in, is an established and internationally recognized component of diagnostic pathways.…”