Cardiac Troponin T Threshold Predicts Mortality After PCI

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Elevations in the biomarker cardiac troponin T can potentially predict mortality 3 months after percutaneous coronary intervention (PCI), according to a study published online July 22, 2014, ahead of print in Circulation: Cardiovascular Interventions. However, a specific threshold may be more useful for modifying guidelines and forming a universal definition of periprocedural MI than affecting practice, researchers say. 

Methods
Abhiram Prasad, MD, of the University of London (London, England), and colleagues evaluated 5,268 consecutive patients undergoing non-emergent PCI at the Mayo Clinic (Rochester, MN) between November 2000 and October 2009. All patients reported baseline preprocedural cardiac troponin T (≤ 0.01 ng/mL) and CK-MB levels (≤ 6.7 ng/mL for men and ≤ 3.8 ng/mL for women) below the upper limit of normal (ULN).
The 43% of patients with postprocedural cardiac troponin T elevation above the ULN were older and more likely to have reduced LVEF, chronic kidney disease, and COPD. Baseline beta-blocker (P = .012) and lipid-lowering therapy (P = .038) use were less common in patients with troponin T elevations compared with those without. Similar patterns were also seen in the 22% of patients with elevated CK-MB values. 


After median follow-up of 65 months, 824 patients died (15.6%) with 32 of those deaths occurring in the first 3 months. Three-month mortality was lower in patients with troponin T elevation than those without at 0.4% vs 0.9%, respectively (P = .01). On multivariate analysis that adjusted for baseline differences, the risk of death increased along with rising biomarker elevation (table 1).

Table 1. Biomarker Elevation and Mortality 3 Months After PCI

 

Adjusted HR (95% CI)a

P Value

Cardiac Troponin T

1.24 (1.08-1.43)

0.003

CK-MB

1.30 (1.05-1.60)

0.018

aPer doubling of level.  

The optimal cutoff for 3-month mortality was identified as 25 x ULN for cardiac troponin T (HR 4.53; 99% CI 1.59-12.9; P < .001) and 5 x ULN for CK-MB (HR 4.31; 99% CI 1.27-14.6; P = .002). 

There was no interaction between creatinine clearance level and the troponin effect on 3-month all-cause death (P = .99) or cardiovascular death ( P = .81). 

Biomarkers the Cause or a Bystander?  

In an email with TCTMD, Dr. Prasad said that mortality “appears to be largely due to adverse baseline and procedural characteristics.” However, he added, “a direct causal link [between biomarker elevation and mortality] cannot be excluded.” 

The findings can help harmonize definitions between cardiac troponin T and CK-MB as well as shape “guidelines for defining periprocedural MI in order to get clarity on which events should be considered significant in clinical trials,” Dr. Prasad commented. 

For practice, however, the message is less clear. The authors conclude in the paper that extending hospitalization solely on the basis of elevated troponin levels is unlikely to actually improve outcomes for most patients. 

“These patients merit closer monitoring and perhaps more intensive secondary prevention over the 3 month time period following PCI,” Dr. Prasad said.

 


Source: 
Herrmann J, Lennon RJ, Jaffe AS, et al. Defining the optimal cardiac troponin T threshold for predicting death caused by periprocedural myocardial infarction after percutaneous coronary intervention. Circ Cardiovasc Interv. 2014;Epub ahead of print.

 

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Disclosures
  • Dr. Prasad reports no relevant conflicts of interest.

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