Comparison of Magnetic Resonance Analysis of Myocardial Scarring With Biomarker Release Following S-T Elevation Myocardial Infarction

Clinically Acquired High Sensitivity Cardiac Troponin T is a Poor Predictor of Reduced Left Ventricular Ejection Fraction After ST Elevation Myocardial Infarction: A National Cohort Study-ANZACS-QI 65

OBJECTIVE

Cardiac troponins (cTn) have been used historically to estimate infarct size in ST elevation myocardial infarction (STEMI). Within a resource constrained health care environment, cTn could therefore be used for prioritisation of patients for cardiac imaging, in particular echocardiography. We aimed to determine how useful routinely collected cTn would be in predicting significant left ventricular (LV) impairment.

METHODS

All patients in the All New Zealand Acute Coronary Syndrome Quality Improvement (ANZACS-QI) registry with their first episode of STEMI between January 2013 and November 2018, who had high sensitivity troponin T measured, were included. We excluded patients with no left ventricular ejection fraction (LVEF) assessment, known LV dysfunction, or prior myocardial infarction.

RESULTS

In total, 3,698 patients were included in the analysis. A higher mean hsTnT (admission and peak) was seen in patients with more severely impaired LV function but there was significant overlap in the range of hsTnT between the different LVEF categories. Cardiac troponins demonstrated poor discriminative ability to either predict or exclude significant LV impairment (LVEF <40%). At an optimal cutpoint of 3,405 ng/L, peak hsTnT had a sensitivity of 56.5% (95% confidence interval [CI] 42-62%), a specificity of 65.3% (95% CI 62-79%) and an area under the receiver operating curve of 0.62 (95% CI 0.60-0.64).

CONCLUSION

This is the largest study comparing clinically measured troponin levels and LV function in patients presenting with STEMI. A definite, but weak, association was seen between peak troponin and the degree of LV dysfunction, with significant overlap in troponin levels between levels of myocardial dysfunction. Routinely acquired troponin is not suitable for clinical use as a method of prioritising patients for cardiac imaging.

Lack of Relationship between Fibrosis-Related Biomarkers and Cardiac Magnetic Resonance-Assessed Replacement and Interstitial Fibrosis in Dilated Cardiomyopathy

The relationship between circulating fibrosis-related molecules and magnetic resonance-assessed cardiac fibrosis in dilated cardiomyopathy (DCM) is poorly understood. To compare circulating biomarkers between DCM patients with high and low fibrosis burdens, we performed a prospective, single-center, observational study. The study population was composed of 100 DCM patients (87 male, mean age 45.2 ± 11.8 years, mean ejection fraction 29.7% ± 10.1%). Replacement fibrosis was quantified by means of late gadolinium enhancement (LGE), whereas interstitial fibrosis was assessed via extracellular volume (ECV). Plasma concentrations of cardiotrophin-1, growth differentiation factor-15, platelet-derived growth factor, procollagen I C-terminal propeptide, procollagen III N-terminal propeptide, and C-terminal telopeptide of type I collagen were measured. There were 44% patients with LGE and the median ECV was 27.7%. None of analyzed fibrosis serum biomarkers were associated with the LGE or ECV, whereas NT-proBNP was independently associated with both LGE and ECV, and troponin T was associated with ECV. None of the circulating fibrosis markers differentiated between DCM patients with and without replacement fibrosis, or patients stratified according to median ECV. However, cardiac-specific markers, such as NT-proBNP and hs-TnT, were associated with fibrosis. Levels of circulating markers of fibrosis seem to have no utility in the diagnosis and monitoring of cardiac fibrosis in DCM.

Correlations between clinical and laboratory findings and prognostically unfavorable CMR-based characteristics of acute ST-elevation myocardial infarction

Aim To evaluate factors associated with unfavorable predictive characteristics of ST-segment elevation acute myocardial infarction (STEMI) as per data of magnetic resonance imaging (MRI).Material and methods The study included 52 patients with STEMI who underwent a primary percutaneous coronary intervention (pPCI). Contrast-enhanced cardiac MRI was performed for all patients on days 3-7. Delayed contrast-enhancement images were used for assessing infarct size, presence of microvascular obstruction (MVO) areas, and heterogeneity zones.Results Multifactorial analysis showed that independent predictors of MVO were type 2 diabetes mellitus (DM) (relative risk (RR) 1.9, confidence interval (CI): 1.1-3.26, р=0.012), increased levels of brain natriuretic peptide (BNP) (RR 2.04, CI: 1.39-2.99, р=0.004) and creatine kinase (CK) (RR 2.06, CI: 0.52-0.80, р=0.02), and infarct size (IS) (RR 2.81; CI: 1.38-5.72, р=0.0004). Construction of ROC curves provided the quantitative values of study indexes, at which the risk of MVO increased. For BNP, this value was ≥276 pg/ml (sensitivity, 95.7 %; specificity, 37.9 %); for CK ≥160 U/l (sensitivity, 74.1 %; specificity, 61.9 %); and for IS ≥18.8 % (sensitivity, 79.3 %; specificity, 69.6 %). Correlation analysis of risk factors for increased size of the heterogeneity zone showed significant correlations of the heterogeneity zone size with older age of patients (r=0.544, р&lt;0.0001), higher concentrations of BNP (r=0.612, р&lt;0.0001), CK (r=0.3, 95 % CI: 0.02-0.5, р=0.03), and C-reactive protein (CRP) (r=0.59, CI: 0.3-0.7, р=0.0001). Increased levels of CK (r=0.53, 95 % CI: 0.29-0.70, р=0.0001) and BNP (r=0.55, 95 % CI: 0.28-0.70, p=0.0003) significantly correlated with increased IS.Conclusion Risk of MVO formation as per MRI data increased in the presence of type 2 DM and IS ≥18.8 % (р&lt;0.05). Formation of MVO in patients with STEMI was associated with increased levels of BNP ≥276 pg/ml and CK ≥160 U/l (р&lt;0.05). Increased levels of BNP, CK, and CRP were associated with a larger size of heterogeneity zone according to data of the correlation analysis. A larger heterogeneity zone was more typical for older patients. Increased levels of CK and BNP were also associated with larger IS. The correlation analysis did not show any significant interactions between the size of heterogeneity zone, IS, and MVO size (р&gt;0.05).

Myocardial viability of the peri-infarct region measured by T1 mapping post manganese-enhanced MRI correlates with LV dysfunction

BACKGROUND

Manganese-enhanced MRI (MEMRI) detects viable cardiomyocytes based on the intracellular manganese uptake via L-type calcium-channels. This study aimed to quantify myocardial viability based on manganese uptake by viable myocardium in the infarct core (IC), peri-infarct region (PIR) and remote myocardium (RM) using T1 mapping before and after MEMRI and assess their association with cardiac function and arrhythmogenesis.

METHODS

Fifteen female swine had a 60-minute balloon ischemia-reperfusion injury in the LAD. MRI (Signa 3T, GE Healthcare) and electrophysiological study (EPS) were performed 4 weeks later. MEMRI and delayed gadolinium-enhanced MRI (DEMRI) were acquired on LV short axis. The DEMRI positive total infarct area was subdivided into the regions of MEMRI-negative non-viable IC and MEMRI-positive viable PIR. T1 mapping was performed to evaluate native T1, post-MEMRI T1, and delta R1 (R1_post-R1_pre, where R1 equals 1/T1) of each territory. Their correlation with LV function and EPS data was assessed.

RESULTS

PIR was characterized by intermediate native T1 (1530.5 ± 75.2 ms) compared to IC (1634.7 ± 88.4 ms, p = 0.001) and RM (1406.4 ± 37.9 ms, p < 0.0001). Lower post-MEMRI T1 of PIR (1136.3 ± 99.6 ms) than IC (1262.6 ± 126.8 ms, p = 0.005) and higher delta R1 (0.23 ± 0.08 s^-1) of PIR than IC (0.18 ± 0.09 s^-1, p = 0.04) indicated higher myocardial manganese uptake of PIR compared to IC. Post-MEMRI T1 (r = -0.57, p = 0.02) and delta R1 (r = 0.51, p = 0.04) of PIR correlated significantly with LVEF.

CONCLUSIONS

PIR is characterized by higher manganese uptake compared to the infarct core. In the subacute phase post-IR, PIR viability measured by post-MEMRI T1 correlates with cardiac function.

High Serum Secreted Frizzled-Related Protein 5 Levels Associates with Early Improvement of Cardiac Function Following ST-Segment Elevation Myocardial Infarction Treated by Primary Percutaneous Coronary Intervention

Aim: Several members of secreted frizzled-related protein (SFRP) are involved in the process of myocardial ischemia-reperfusion injury. However, little is known about the role of SFRP5 in patients with acute ST-segment elevation myocardial infarction (STEMI).

Methods: In this cross-sectional study, 85 patients with first-time anterior STEMI who underwent timely primary percutaneous coronary intervention (PCI) and 35 patients without coronary artery disease (CAD) were enrolled. Serum SFRP5 levels were measured using an enzyme-linked immunosorbent assay kit. Patients with STEMI were divided into low-SFRP5 and high-SFRP5 groups according to their median baseline serum SFRP5 levels. To evaluate cardiac function and structure after infarction, the left ventricular ejection fraction (LVEF) and left ventricular end-diastolic volume (LVEDV) were measured using echocardiography. The associations between changes in LVEF and reduced LVEF (≤ 50%) and clinical variables were determined by univariate and multivariate analyses.

Results: Baseline serum SFRP5 levels were significantly higher in patients with STEMI than in those without CAD (23.3 ng/mL vs 19.8 ng/mL, P = 0.008), although they decreased over time. Also, baseline serum SFRP5 levels were inversely correlated with peak hypersensitive cardiac troponin I (hs-cTnI) levels (r = −0.234, P = 0.025) and peak hypersensitive C-reactive protein (hs-CRP) levels (r = −0.262, P = 0.015). A multivariate linear regression model showed that changes in LVEF were positively correlated with serum SFRP5 levels at baseline (β = 0.249, 95% confidence interval (CI) 0.018–0.245, P = 0.024) and 24 h after admission (β = 0.220, 95% CI 0.003–0.264, P = 0.045). At 3 months, LVEF in patients with high SFRP5 levels was significantly improved over baseline [(60.8 ± 7.1) % vs (56.1 ± 7.5) %, P = 0.001]. LVEF was also significantly higher in patients with high SFRP5 levels than in those with low at the 3-month follow-up [(60.8 ± 7.1) % vs (56.8 ± 8.9) %, P = 0.028]. Consequently, high serum SFRP5 levels at baseline were associated with a decreased risk of reduced LVEF at 3 months, independent of peak hs-cTnI and baseline cardiac function (hazard ratio 0.190, 95% CI 0.036–0.996; P = 0.049).

Conclusions: High serum SFRP5 levels measured during the acute phase of STEMI were significantly associated with promoting myocardial recovery at an early phase following primary PCI, suggesting that SFRP5 is a potential therapeutic target in acute STEMI.