High-Sensitivity Cardiac Troponin T Effectively Rules Out, Rules In MI in 1 Hour, in Study

April 13, 2015

BASEL, SWITZERLAND — A novel algorithm that includes measuring high-sensitivity cardiac troponin T (hs-cTnT) levels can safely and effectively rule out acute MI within 1 hour in patients presenting to the emergency department with chest pain, according to a new study[1].

In 1320 patients, a baseline assessment of hs-cTnT coupled with changes in these levels within 60 minutes ruled out acute MI in 59.5% of patients and had a negative predictive value of 99.9%. The use of hs-cTnT "ruled in" an acute MI in 16.4% of the patients with chest pain and had a positive predictive value of 78.2%.

"Taken together, the algorithm allowed for a definite diagnosis after 1 hour in 75.9% of patients (either rule-in or rule-out)," report Dr Tobias Reichlin (Cardiovascular Research Institute, Basel) and colleagues April 13, 2015 in CMAJ.

In addition, the 1-hour algorithm had higher negative and positive predictive values than the standard interpretation of hs-cTnT using a single value, say researchers.

The six-center study, known as the Advantageous Predictors of Acute Coronary Syndromes Evaluation (APACE), follows an initial pilot study that showed the use of hs-cTnT could rule out and rule in an acute MI in three-quarters of chest-pain patients. Like the pilot study, researchers made use of an algorithm that incorporated baseline hs-cTnT levels and absolute changes in the levels within 1 hour. A baseline hs-cTnT value <12 ng/L and a 1-hour change of <3 ng/L were used to rule out acute MI, whereas a baseline hs-cTnT value >52 ng/L and a 1-hour change >5 ng/L was used to rule in acute MI. All other patients who fell outside these ranges were placed in observation.

In this prospective study, 24.1% of patients were placed in observation and 59 of these patients were eventually diagnosed with an acute MI. At 30 days, there were nine deaths. The cumulative 30-day mortality rate was zero, 1.6%, and 1.9%, respectively, in patients who were ruled out for acute MI, ruled in for acute MI, and classified into the observation zone.

"Although the achieved negative predictive value is extremely high, it is important to stress that the high-sensitivity cardiac troponin T 1-hour algorithm should always be used in conjunction with full clinical assessment, including patient history and examination, and 12-lead ECG," write the researchers.

For the 47 patients who were ruled in with an acute MI but who did not truly have an event, the majority of patients had an arrhythmia. In addition, there were six cases of myocarditis, five pulmonary embolisms, three cases of acute heart failure, and three cases of Takotsubo cardiomyopathy, among others. Eleven had noncardiac chest pain.

The study was sponsored by research grants from the Swiss National Service Foundation, the Swiss Heart Foundation, the Cardiovascular Research Foundation Basel, Abbott, Beckman Coulter, BRAHMS, Roche, Siemens, and the University Hospital, Basel. Reichlin reports grants and financial payments from Roche Diagnostics. Disclosures for the coauthors are listed in the article.

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