Diagnostic and prognostic utility of cardiac troponin in post-cardiac arrest care

BACKGROUND

Cardiac troponin is routinely tested in the post-cardiac arrest setting, but its utility in identifying ischaemic aetiology and predicting left ventricular systolic dysfunction (LVSD) and survival is not known.

METHODS

In a retrospective single center registry, we identified 145 consecutive patients who had achieved return of spontaneous circulation after cardiac arrest and had undergone serial cardiac troponin T (cTnT) testing, echocardiogram, and expert adjudication of aetiology. Initial and peak cTnT were evaluated for assessing ischaemic aetiology, LVSD, and survival to discharge using area under the receiver operating characteristic curve (AUROC).

RESULTS

Mean age was 61 ± 14 years and 71% were men. Of the 145 arrests, 19% had an ischaemic aetiology, 68% had LVSD post-arrest, and 55% survived to discharge. All patients had a positive initial cTnT at 0.01 ng/mL (clinical cut-off). Even at higher cut-offs of 10×, 100× and 1000×, initial cTnT performed poorly (AUROC 0.57, 0.56, and 0.56) and peak cTnT performed modestly (AUROC 0.55, 0.61, and 0.62) as diagnostic tests for ischaemic aetiology. Similarly, even at higher cut-offs, initial (AUROC 0.60, 0.62, 0.55) and peak (AUROC 0.57, 0.61, and 0.62) cTnT performed poorly to modestly at predicting LVSD. The test performed poorly for predicting survival to discharge (AUROC for all <0.6).

CONCLUSIONS

At both current and several-fold higher thresholds, cTnT does not perform sufficiently well to guide clinical decision-making or predict patient outcomes. Routine post-cardiac arrest testing of cTnT should be reevaluated.

An AI-Based Heart Failure Treatment Adviser System

Management of heart failure is a major health care challenge. Healthcare providers are expected to use best practices described in clinical practice guidelines, which typically consist of a long series of complex rules. For heart failure management, the relevant guidelines are nearly 80 pages long. Due to their complexity, the guidelines are often difficult to fully comply with, which can result in suboptimal medical practices. In this paper, we describe a heart failure treatment adviser system that automates the entire set of rules in the guidelines for heart failure management. The system is based on answer set programming, a form of declarative programming suited for simulating human-style reasoning. Given a patient's information, the system is able to generate a set of guideline-compliant recommendations. We conducted a pilot study of the system on 21 real and 10 simulated patients with heart failure. The results show that the system can give treatment recommendations compliant with the guidelines. Out of 187 total recommendations made by the system, 176 were agreed upon by the expert cardiologists. Also, the system missed eight valid recommendations. The reason for the missed and discordant recommendations seems to be insufficient information, differing style, experience, and knowledge of experts in decision-making that were not captured in the system at this time. The system can serve as a point-of-care tool for clinics. Also, it can be used as an educational tool for training physicians and an assessment tool to measure the quality metrics of heart failure care of an institution.

Abstract 281: Contemporary Epidemiology of Atrial Fibrillation Among Medicare Beneficiaries, 2004-2013

Background: Atrial fibrillation (AF) is the most common dysrhythmia in clinical practice, and is a significant contributor to morbidity and mortality. Prior reports have projected a large increase in AF burden over time. A contemporary assessment of epidemiology is needed to assess if an emphasis of prevention strategies over the last decade has been effective in alleviating this risk.

Methods: We used a 5% national sample of all Medicare beneficiaries in the US from 2002 through 2013 to construct a longitudinal cohort of 2.3 million fee-for-service Medicare beneficiaries administratively followed for ≥2 years using claims data. Trends in incident and prevalent AF were assessed for 2004 through 2013. Using ICD-9 codes, encounters with AF were identified from inpatient, outpatient, and physician claims. AF during the first 2 years of entry into the cohort was defined as pre-existing AF. Incident AF was defined as having either 1 inpatient claim with a diagnosis of AF or 2 outpatient or physician claims with AF. Calendar-year prevalence comprised pre-existing and incident AF for the respective years as well as those with incident AF in preceding years. Age-adjusted time trends were assessed using Poisson regression.

Results: Between 2002 and 2013, 219,570 patients had incident AF. At incidence, mean age was 79 years, 55% were women, and 92% and 5% were white and black, respectively. Age-adjusted AF incidence decreased by 0.4/1000 per year between 2004 (20/1000) and 2013 (17/1000). While incidence declined for white men and women (P<.05), it has remained unchanged for black men and women (Figure). Proportion of incident events in the outpatient setting increased from 26% to 40%. One-year mortality was 9%, and remained unchanged throughout the study period. Over this period, the overall prevalence of AF decreased by 0.9/1000 per year (p<.05), however, there was a relative increase in AF prevalence among black men.

Conclusions: Between years 2004 and 2013, the overall incidence and prevalence of AF among a 5% sample of Medicare beneficiaries stabilized. There were, however, differences across racial groups, with a slight decline in incidence among white men and women, which was not observed in black men and women.

Novel Biomarkers of Subclinical Cardiac Dysfunction in the General Population

PURPOSE OF REVIEW

Recognition of subclinical myocardial dysfunction offers clinicians and patients an opportunity for early intervention and prevention of symptomatic cardiovascular disease. We review the data on novel biomarkers in subclinical heart disease in the general population with a focus on pathophysiology, recent observational or trial data, and potential applicability and pitfalls for clinical use.

RECENT FINDINGS

High-sensitivity cardiac troponin and natriuretic peptide assays are powerful markers of subclinical cardiac disease. Elevated levels of these biomarkers signify subclinical cardiac injury and hemodynamic stress and portend an adverse prognosis. Novel biomarkers of myocardial inflammation, fibrosis, and abnormal contraction are gaining momentum as predictors for incident heart failure, providing new insight into pathophysiologic mechanisms of cardiac disease. There has been exciting growth in both traditional and novel biomarkers of subclinical cardiac injury in recent years. Many biomarkers have demonstrated associations with relevant cardiovascular outcomes and may enhance the diagnostic and prognostic power of more conventional biomarkers. However, their use in "prime time" to identify patients with or at risk for subclinical cardiac dysfunction in the general population remains an open question. Strategic investigation into their clinical applicability in the context of clinical trials remains an area of ongoing investigation.

Predictors of Death in Adults With Duchenne Muscular Dystrophy-Associated Cardiomyopathy

Background

Duchenne muscular dystrophy (DMD) is frequently complicated by development of a cardiomyopathy. Despite significant medical advances provided to DMD patients over the past 2 decades, there remains a group of DMD patients who die prematurely. The current study sought to identify a set of prognostic factors that portend a worse outcome among adult DMD patients.

Methods and Results

A retrospective cohort of 43 consecutive patients was followed in the adult UT Southwestern Neuromuscular Cardiomyopathy Clinic. Clinical data were abstracted from the electronic medical record to generate baseline characteristics. The population was stratified by survival to time of analysis and compared with characteristics associated with death. The DMD population was in the early 20s, with median follow‐up times over 2 years. All the patients had developed a cardiomyopathy, with the majority of the patients on angiotensin‐converting enzyme inhibitors (86%) and steroids (56%), but few other guideline‐directed heart failure medications. Comparison between the nonsurviving and surviving cohorts found several poor prognostic factors, including lower body mass index (17.3 [14.8–19.3] versus 25.8 [20.8–29.1] kg/m², P<0.01), alanine aminotransferase levels (26 [18–42] versus 53 [37–81] units/L, P=0.001), maximum inspiratory pressures (13 [0–30] versus 33 [25–40] cmH₂O, P=0.03), and elevated cardiac biomarkers (N‐terminal pro‐brain natriuretic peptide: 288 [72–1632] versus 35 [21–135] pg/mL, P=0.03].

Conclusions

The findings demonstrate a DMD population with a high burden of cardiomyopathy. The nonsurviving cohort was comparatively underweight, and had worse respiratory profiles and elevated cardiac biomarkers. Collectively, these factors highlight a high‐risk cardiovascular population with a worse prognosis.

Abstract 118: Physician Specific Practice Patterns and 30-day Heart Failure Readmission Rates: Is One Way Better Than the Other?

Background: Heart failure (HF) admissions place a significant burden on hospital resource utilization. Management of inpatient HF remains heterogeneous, from daily diuresis to discharge strategies. We sought to evaluate if specific physician practices were associated with two important contributors to resource utilization, readmission and length of stay (LOS).

Methods: Physician-specific discharges, LOS, and 30-day readmission rates from 7/1/2015-6/30/2016 were extracted from the EHR. Patients with “shock” as the primary diagnostic code were excluded. We created a survey to assess HF management strategies that was administered to all cardiologists and hospitalists at our institution; physicians were blinded to LOS and readmission data. Many factors potentially impacting LOS and discharge decisions were queried, including physical examination, medication use and kidney function.

Results: We received 62 of 69 (90%) survey responses – 26 cardiologists and 36 hospitalists. Overall, 52% (32 of 62) were male with a median 7 years in practice [IQR 3-13]. We tracked HF utilization metrics in 58 physicians, encompassing 753 patient discharges in the preceding year. Total 30-day readmission rate was 17.0% (128 of 753). No significant differences were seen in discharge practices between readmission rate tertiles. Median of the median LOS was 4.7 days (IQR 4.0-5.8), and physicians above median LOS were compared to physicians below median LOS. Point estimates suggest physicians with lower median LOS targeted a daily net diuresis goal greater than 3L (40% vs 11% for those above median LOS, p = 0.1), and were less likely to hold beta blockers (17% vs 37%, p = 0.1) or to consider 24 hours of inpatient oral diuretics prior to discharge to be “very important” (16% vs 56%, p < 0.01). The pooled readmission rate of physicians below median LOS was not significantly different than those above median LOS (14.5% vs 16.2%, p = 0.6).

Conclusions: We identified three specific HF management patterns that may be associated with lower LOS without a concomitant increase in 30-day readmission: (1) more aggressive daily diuresis, (2) continuation of beta blockade, and (3) not delaying discharge to observe 24 hours of an oral diuretic regimen. Further studies are warranted to confirm and quantify the impact of these changes on resource utilization.

Multiple aneurysms of the internal thoracic artery

Nontraumatic aneurysms of the internal thoracic artery are rare. We report a case where multiple aneurysms of the right internal thoracic artery presented as an asymptomatic density on the chest radiograph. Operative findings and pathology are reviewed.