Age-Related Differences in the Contribution of Systolic Blood Pressure and Biomarkers to Cardiovascular Disease Risk Prediction: The Atherosclerosis Risk in Communities (ARIC) Study

We sought to determine how biomarkers known to be associated with hypertension-induced end-organ injury complement the use of systolic blood pressure (SBP) for cardiovascular disease (CVD) risk prediction at different ages. Using data from visits 2 (1990 to 1992) and 5 (2011 to 2013) of the Atherosclerosis Risk in Communities (ARIC) study, 3 models were used to predict CVD (composite of coronary heart disease, stroke, and heart failure). Model A included traditional risk factors (TRFs) except SBP, model B-TRF plus SBP, and model C-TRF plus biomarkers (high-sensitivity troponin T [hsTnT] and N-terminal pro-B-type natriuretic peptide [NT-proBNP]). Harrel's C-statistics were used to assess risk discrimination for CVD comparing models B and A and C and B. At visit 2, the addition of SBP to TRF (model B vs model A) significantly improved the C-statistic (∆C-statistic, 95% confidence interval 0.010, 0.007 to 0.013) whereas the addition of hsTnT to TRF (model C vs model B) decreased the C-statistic (∆C-statistic -0.0038, -0.0075 to -0.0001) compared with SBP. At visit 5, the addition of SBP to TRF did not significantly improve the C-statistic (∆C-statistic 0.001, -0.002 to 0.005) whereas the addition of both hsTnT and NT-proBNP to TRF significantly improved the C-statistic compared with SBP (∆C-statistic 0.028, 0.015 to 0.041 and 0.055, 0.036 to 0.074, respectively). In summary, the incremental value of SBP for CVD risk prediction diminishes with age whereas the incremental value of hsTnT and NT-proBNP increases with age.

Abstract 235: Association Between Abnormal Ankle-Brachial Index and Accelerometer-Derived Sedentary and Exercise Time in the Asymptomatic General Population

Objectives: Sedentary behavior is a distinct adverse health risk factor that is independent of physical activity. The association between sedentary behavior, exercise activity and ankle-brachial index (ABI) is not well understood.

Methods: We analyzed data from the National Health and Nutrition Examination Survey (NHANES) 2003-2004. Participants were included if they had ABI testing and at least one day of accelerometer data with exclusion of participants with self-reported anatomical or functional impairments to ambulation. Accelerometer counts reflect the intensity of activity in 1-minute intervals up to seven days for all participants. We used previously established exercise intensity-threshold criteria to quantify moderate-vigorous physical activity time. Sedentary time was defined as <100 counts/minute. We defined abnormal ABI as a value <1.0 (to include borderline values) in either foot. We performed multi-variable adjusted logistic regression analyses with sedentary time and exercise time as the independent variables and abnormal ABI as the dependent variable, adjusting for important risk factors and confounders. In a sensitivity analysis, we restricted the definition of abnormal ABI to <0.95.

Results: We included 1,443 asymptomatic participants (mean age 61 years, 49% female, 55% current/prior smokers). The mean daily sedentary and exercise times in the study population were 454 ± 144 and 17.7 ± 20.3 minutes, respectively. 23.0% had an abnormal ABI (8.7% with ABI <0.9). In the final multivariable model, sedentary time was associated with increased odds of abnormal ABI (p=0.018) while exercise time was associated with reduced odds of abnormal ABI (p=0.003), independent of traditional risk factors and confounders (Figure, continuous variables per 1 standard deviation). Restricting the analysis to abnormal ABI<0.95, sedentary time and exercise time remained significant (p=0.024 and p=0.018, respectively).

Conclusions: Sedentary time is associated with abnormal ABI values independent of exercise activity and other potential confounders in asymptomatic patients in the general population. Prospective studies are warranted to further evaluate the potential etiologic role of activity profiles on the development of peripheral arterial disease.

Elevated troponin I levels in acute liver failure: is myocardial injury an integral part of acute liver failure?

Although rare instances of cardiac injury or arrhythmias have been reported in acute liver failure (ALF), overall, the heart is considered to be spared in this condition. Troponin I, a sensitive and specific marker of myocardial injury, may be elevated in patients with sepsis and acute stroke without underlying acute coronary syndrome, indicating unrecognized cardiac injury in these settings. We sought to determine whether subclinical cardiac injury might also occur in acute liver failure. Serum troponin I levels were measured in 187 patients enrolled in the US Acute Liver Failure Study Group registry, and correlated with clinical variables and outcomes. Diagnoses were representative of the larger group of >1000 patients thus far enrolled and included 80 with acetaminophen-related injury, 26 with viral hepatitis, 19 with ischemic injury, and 62 others. Overall, 74% of patients had elevated troponin I levels (>0.1 ng/ml). Patients with elevated troponin I levels were more likely to have advanced hepatic coma (grades III or IV) or to die (for troponin I levels >0.1 ng/ml, odds ratio 3.88 and 4.69 for advanced coma or death, respectively).

CONCLUSION

In acute liver failure, subclinical myocardial injury appears to occur more commonly than has been recognized, and its pathogenesis in the context of acute liver failure is unclear. Elevated troponin levels are associated with a significant increase in morbidity and mortality. Measurement of troponin I levels may be helpful in patients with acute liver failure, to detect unrecognized myocardial damage and as a marker of unfavorable outcome.

Cardiovascular Biomarkers for Acute Coronary Syndromes Using a Multi-marker Strategy

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