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Rapid strategy can identify acute MI within 1 hour
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Use of an algorithm incorporating baseline high-sensitivity cardiac troponin T and absolute changes within 1 hour led to safe rule-in and rule-out of acute MI in three of four patients.
The results come from an analysis of the ongoing APACE study. Researchers evaluated 1,320 patients who presented to an ED with suspected acute MI at six centers in three countries from June 2009 to June 2013. All patients underwent routine clinical assessment and high-sensitivity cardiac troponin T levels were measured upon presentation and at 1, 2, 3 and 6 hours.
The researchers applied the novel 1-hour algorithm using high-sensitivity cardiac troponin T measurement, which classified patients according to the following categories:
- rule-out for acute MI: baseline high-sensitivity troponin T less than 12 ng/L and absolute change less than 3 ng/L;
- rule-in: baseline troponin T of at least 52 ng/L or absolute change of at least 5 ng/L within first hour; or
- observational zone: patients who fulfilled neither of these criteria.
The algorithm was validated against the final diagnosis.
In 17.3% of patients, acute MI was the final diagnosis.
Based on the algorithm, 59.5% of patients were classified as rule-out for acute MI, 16.4% were classified as rule-in and 24.1% were classified in the observational zone. Of those classified in the observational zone, 18.6% were diagnosed with acute MI. Cumulative 30-day mortality was 0% in the rule-out group, 1.6% in the observational group and 1.9% in the rule-in group.
In the rule-out zone, the sensitivity was 99.6% and the negative predictive value for acute MI was 99.9%. In the rule-in zone, the sensitivity was 95.7% and the positive predictive value was 78.2%. The negative and positive predictive values of the algorithm were significantly higher compared with those for standard interpretation of high-sensitivity cardiac troponin T incorporating a single cutoff of 14 ng/dL at presentation (P < .05; sensitivity, 92.1%; negative predictive value, 98.1%; positive predictive value, 48.4%).
“Our findings extend and corroborate previous work with high-sensitivity cardiac troponin as well as recent pilot data obtained for the 1-hour algorithm,” Tobias Reichlin, MD, from the department of internal medicine, University Hospital, Basel, Switzerland, and colleagues wrote. … “The medical implications of accelerated rule-in include more rapid initiation of antiplatelet, anticoagulant and anti-ischemic medication, as well as more rapid transfer to coronary angiography and, if feasible, coronary revascularization. The medical implications of accelerated rule-out include more rapid relief of patient anxiety and more rapid identification of an alternative cause of acute chest pain without the need for continued rhythm monitoring. The clinical application of the high-sensitivity cardiac troponin T 1-hour algorithm may also lead to substantial economic benefits.” – by Adam Taliercio
Disclosure: Reichlin reports receiving grants, personal fees and nonfinancial support from Roche Diagnostics while conducting the study.
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