High Cardiac Troponin T Doubles Event Risk


Major Finding: Community-dwelling older adults in the highest quartile for their serum cardiac troponin T level, as measured with a high-sensitivity assay, had a two- to threefold increased risk for new-onset heart failure and for cardiovascular death during a median follow-up of 12 years.

Data Source: The 4,221 unselected U.S. residents age 65 or older (median age of 71) enrolled in the Cardiovascular Health Study.

Disclosures: The study was partially funded by Roche Diagnostics, which markets a high-sensitivity cardiac troponin T assay. Dr. deFilippi said that he has served as a consultant to and has received honoraria and grant support from Roche Diagnostics and from Siemens Healthcare Diagnostics. He has also been a consultant to and received grant support from Critical Diagnostics and BG Medicine.

CHICAGO — Higher serum concentrations of cardiac troponin T independently predicted an increased rate of new-onset heart failure and cardiovascular death in a longitudinal study of more than 4,000 elderly, community-dwelling Americans with a median follow-up of 12 years.

“Measurement of cTnT [cardiac troponin T] may be useful in cardiovascular risk stratification in older adults,” Dr. Christopher R. deFilippi said at the scientific sessions.

Assessing cTnT's role as a risk predictor became possible with the recent availability of high-sensitivity assays. Previous studies using conventional cTnT assays found roughly 4% of the general elderly population had detectable levels; in Dr. deFilippi's new study, 66% of community-dwelling U.S. adults with a median age of 71 had detectable cTnT levels. The high-sensitivity test produces “about a 10-fold increase in the number of people with detectable cTnT; that's what gives us a dynamic range,” said Dr. deFilippi, a cardiologist at the University of Maryland in Baltimore.

Results from two other studies presented at the meeting and a third study published in early December showed similar links between high levels of cTnT and cardiovascular events, cardiac structure, and death (see box).

The consistent findings from all these studies show that cTnT “is a pretty good risk predictor. Cardiac troponin offers a very easy way for a physician to say that a person is at high risk” for new-onset heart failure, cardiovascular death, or other cardiovascular disease events, Dr. deFilippi said in an interview.

“I look at cardiac troponin T as early biochemical evidence of pathology. Finding a high level in a person could be a wake-up call. It gives some of the earliest, direct evidence with a cardiac-specific molecule that pathology is taking place,” independent of traditional risk markers, he said.

“Cardiac troponin T could be the summation of all other risk factors. We use cholesterol level as a motivator, even though it is much less effective for measuring risk,” Dr. deFilippi explained.

Another attractive feature of measuring cTnT is that the evidence collected by Dr. deFilippi and his associates suggest that in some people high levels are reversible, and when levels drop a person's risk drops.

In the analyses so far, the strongest correlation with a lowered serum level of cTnT has been a person's level of activity and exercise, he said.

The high-sensitivity cardiac troponin T test has not yet received marketing approval from the Food and Drug Administration, but is commercially available in Europe.

To examine the prognostic ability of cTnT, Dr. deFilippi and his associates used serum specimens collected from 4,221 community-dwelling Americans aged 65 or older enrolled in the Cardiovascular Health Study.

At baseline, 2,794 (66%) of the participants had a detectable level of cTnT, at least 3 pg/mL, and their median age was 71.

During a median follow-up of almost 12 years, the incidence of heart failure and cardiovascular death tracked along with baseline levels of cTnT. Among the one-third of patients with an undetectable level at baseline the rate of new-onset heart failure during follow-up averaged 1.6% per year. Among people in the highest quintile of cTnT level, greater than 12.9 pg/mL, the incident heart failure rate averaged 6.4% per year. “It's a huge difference,” he said.

In an analysis that adjusted for demographic differences and traditional risk factors including systolic blood pressure, smoking status, serum creatinine, and left ventricular size, people with baseline cTnT levels above the median all had a significantly increased risk for both end points.

The quintile of people with the highest cardiac troponin T level had a 2.5-fold increased risk of new-onset heart failure and a threefold increased risk of cardiovascular death compared with those who had an undetectable level at baseline.

Even when also adjusted for baseline levels of NT-pro brain natriuretic peptide and C-reactive protein, people in the highest quintile for baseline level had about a twofold higher rate of heart failure and cardiovascular death during follow-up, Dr. deFilippi reported.


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