Contrasting the potential benefits of early invasive coronary angiography in acute and chronic myocardial injury patterns.

BACKGROUND: In cases of evolving myocardial injury not definitively attributed to coronary ischaemia precipitated by plaque rupture, referral for invasive coronary angiography (ICA) may be influenced by observed troponin profiles. We sought to explore association between early ICA and elevated high-sensitivity troponin T (hs-cTnT) concentrations with and without dynamic changes, to examine if there may be a hs-cTnT threshold associated with benefit from an initial ICA strategy. METHODS: Using published studies (hs-cTnT study n = 1937, RAPID-TnT study n = 3270) and the Fourth Universal Definition of Myocardial Infarction (MI), index presentations of patients with hs-cTnT concentrations 5-14ng/L were classified as 'non-elevated' (NE). Hs-cTnT greater than upper reference limit (14ng/L) were classified as 'elevated hs-cTnT with dynamic change' (encompassing acute myocardial injury, Type 1 MI, and Type 2 MI), or 'non-dynamic hs-cTnT elevation' (chronic myocardial injury). Patients with hs-cTnT <5ng/L and/or eGFR<15mmol/L/1.73m2 were excluded. ICA was performed within 30 days of admission. Primary outcome was defined as composite endpoint of death, MI, or unstable angina at 12 months. RESULTS: Altogether, 3620 patients comprising 837 (23.1%) with non-dynamic hs-cTnT elevations and 332 (9.2%) with dynamic hs-cTnT elevations were included. Primary outcome was significantly higher with dynamic and non-dynamic hs-cTnT elevations (Dynamic: HR: 4.13 95%CI:2.92-5.82; p<0.001 Non-dynamic: HR: 2.39 95% confidence interval [CI]:1.74-3.28, p<0.001). Hs-cTnT thresholds where benefit from initial ICA strategy appeared to emerge was observed at 110ng/L and 50ng/L in dynamic and non-dynamic elevations, respectively. CONCLUSION: Early ICA appears to portend benefit in hs-cTnT elevations with and without dynamic changes, and at lower hs-cTnT threshold in non-dynamic hs-cTnT elevation. Differences compel further investigation.

Troponin elevation pattern and subsequent cardiac and non-cardiac outcomes: Implementing the Fourth Universal Definition of Myocardial Infarction and high-sensitivity troponin at a population level.

BACKGROUND: The Fourth Universal Definition of Myocardial Infarction (MI) differentiates MI from myocardial injury. We characterised the temporal course of cardiac and non-cardiac outcomes associated with MI, acute and chronic myocardial injury. METHODS: We included all patients presenting to public emergency departments in South Australia between June 2011-Sept 2019. Episodes of care (EOCs) were classified into 5 groups based on high-sensitivity troponin-T (hs-cTnT) and diagnostic codes: 1) Acute MI [rise/fall in hs-cTnT and primary diagnosis of acute coronary syndrome], 2) Acute myocardial injury with coronary artery disease (CAD) [rise/fall in hs-cTnT and diagnosis of CAD], 3) Acute myocardial injury without CAD [rise/fall in hs-cTnT without diagnosis of CAD], 4) Chronic myocardial injury [elevated hs-cTnT without rise/fall], and 5) No myocardial injury. Multivariable flexible parametric models were used to characterize the temporal hazard of death, MI, heart failure (HF), and ventricular arrhythmia. RESULTS: 372,310 EOCs (218,878 individuals) were included: acute MI (19,052 [5.12%]), acute myocardial injury with CAD (6,928 [1.86%]), acute myocardial injury without CAD (32,231 [8.66%]), chronic myocardial injury (55,056 [14.79%]), and no myocardial injury (259,043 [69.58%]). We observed an early hazard of MI and HF after acute MI and acute myocardial injury with CAD. In contrast, subsequent MI risk was lower and more constant in patients with acute injury without CAD or chronic injury. All patterns of myocardial injury were associated with significantly higher risk of all-cause mortality and ventricular arrhythmia. CONCLUSIONS: Different patterns of myocardial injury were associated with divergent profiles of subsequent cardiac and non-cardiac risk. The therapeutic approach and modifiability of such excess risks require further research.

Invasive management of acute coronary syndrome: Interaction with competing risks.

BACKGROUND: The aim of this study was to characterise the interaction between ACS- and non-ACS-risk on the benefits of invasive management in patients presenting with acute coronary syndrome (ACS). METHODS: Consecutive patients admitted to a tertiary hospital's Cardiac Care Unit in the months of July-December, 2003-2011 with troponin elevation (>30 ng/L) were included. "ACS-specific-risk" was estimated using the GRACE score and "non-ACS-risk" was estimated using the Charlson-Comorbidity-Index (CCI). Inverse-probability-of-treatment weighting was used to adjust for baseline differences between patients who did or did not receive invasive management. A multivariable flexible parametric model was used to characterise the time-varying hazard. RESULTS: In total, 3057 patients were included with a median follow-up of 9.0 years. Based on CCI, 1783 patients were classified as 'low-non-ACS risk' (CCI ≤ 1; invasive management 81%; 12-month mortality 5%), 820 as 'medium-non-ACS risk' (CCI 2-3; invasive management 68%; 12-month mortality 13%), and 468 as 'high-non-ACS risk' (CCI ≥ 4; invasive management 47%; 12-month mortality 29%). After adjustment, invasive management was associated with a significant reduction in one-year overall-mortality in the 'low-risk' and 'medium-risk' groups (HR = 0.38, 95%CI:0.26-0.56; HR = 0.46, 95%CI:0.32-0.67); but not in the 'high-risk' group (HR = 1.02, 95%CI:0.67-1.56). The absolute benefit of invasive management was greatest with higher baseline ACS-risk, with a non-linear interaction between ACS- and non-ACS-risk. CONCLUSIONS: There is a complex interaction between ACS- and non-ACS-risk on the benefit of invasive management. These results highlight the need to develop robust methods to objectively quantify risk attributable to non-ACS comorbidities in order to make informed decisions regarding the use of invasive management in individuals with numerous comorbidities.

Condition-specific Streaming versus an Acuity-based Model of Cardiovascular Care: A Historically-controlled Quality Improvement Study Evaluating the Association with Early Clinical Events.

BACKGROUND: Ensuring optimal evidence translation is challenging when health-service design has not kept pace with developments in care. Differences in patient outcomes were evident when specific cardiac conditions were discordant with the subspecialty of the cardiologists managing their care. We prospectively explored the clinical and health service implications of a "condition-based" redesign in cardiac care delivery, rather than acuity-based, within a tertiary hospital. METHODS: Prospective evaluation of a disease-specific streaming model of care compared to propensity-matched historical controls, among cardiac patients admitted to a tertiary hospital cardiology unit was undertaken. The outcome measures of 30-day death, and readmission for myocardial infarction, cardiac arrhythmia, and heart failure were explored. RESULTS: In total, 2018 patients admitted subsequent to the implementation of the streaming model were compared with 1830 patients admitted prior. The median age was 68.9 years, and 39.5% were female. There was no significant difference in the overall proportion of patients admitted with an acute coronary syndrome, arrthythmia or heart failure, nor their Charlson index before and after streaming. Subsequent to the implementation, there was a reduction in the use of angiography (pre: 35.4% vs. post: 31.2%, p=0.007) and echocardiography (pre: 59.4% vs. post: 55.6%, p=0.007). A reduction in length of length-of-stay was observed in the entire cohort (pre: 2.7 (range: 1.2-5.0) days vs. post: 2.3 (range 1.0-4.5) days, p=0.0003). By 30 days, the propensity-adjusted hazard ratio for major adverse cardiac events and death or any cardiovascular admission was 0.76 (95% C.I. 0.59-0.97, p=0.026). CONCLUSION: Cardiac service redesign that streams cardiac patients by presenting diagnosis into teams designed to treat that condition may provide capacity and productivity gains for health services striving to improve outcome and efficiency.

Gender differences in the relationship between leptin, insulin resistance and the autonomic nervous system.

OBJECTIVES: Leptin, an important hormonal regulator of body weight, has been shown to stimulate the sympathetic nervous system (SNS) in vitro although the physiological relevance remains unclear. Increased SNS activity has been implicated in the pathogenesis of insulin resistance and an increased cardiovascular risk. We have therefore investigated the relationship between leptin, insulin resistance and cardiac autonomic activity in healthy young adults. 130 healthy men and women age 20.9 years were studied. Insulin sensitivity was assessed using the IVGTT and minimal model with simultaneous measures of leptin. Cardiac autonomic activity was assessed using spectral analysis of heart rate variability. RESULTS: Women showed significantly higher fasting leptin, heart rate and cardiac sympathetic activity, and lower insulin sensitivity. Men showed inverse correlations between insulin resistance and heart rate, and between insulin resistance and cardiac sympatho-vagal ratio. Women, in contrast, showed no SNS relationship with insulin resistance, but rather an inverse correlation between leptin and the sympatho-vagal ratio, suggesting that leptin in women is associated with SNS activity. The correlation remained significant after adjustment for BMI and waist-to-hip ratio (beta=-0.33 and p=0.008). CONCLUSION: Insulin resistance and SNS activity appear to be linked, although the relationship showed marked gender differences, and the direction of causality was unclear from this cross-sectional study. Leptin appears to exert a greater effect on the SNS in women, possibly because of their greater fat mass.