Reversible impairment of coronary flow reserve in acute myocarditis

Correlations between high sensitive troponin I and acute myocarditis extent in cardiac magnetic resonance imaging

PURPOSE

To assess the correlation between high sensitive troponin I (HsTnI) levels and myocardial damage on cardiac magnetic resonance (CMR) represented by late gadolinium enhancement (LGE) percentage in patients diagnosed with myocarditis.

METHODS

Retrospective analysis of consecutive patients who underwent CMR following a suspected diagnosis of acute myocarditis, comparing CMR findings viewed as LGE percentage and HsTnI levels.

RESULTS

Between February 2016 and December 2021, 101 patients underwent CMR for suspected myocarditis in Rambam Medical Center. Seventy-six (75.2%) patients with a documented diagnosis of acute myocarditis in the medical records based on clinical history and lab work were included in the final analysis. The median age was 30 years [interquartile range (IQR) 22,42] and 62 patients (81.6%) were male. Thirty-four patients (44.7%) had a history of fever and 26 (34.2%) had upper respiratory tract symptoms. The median maximal HsTnI was 3935 ng/l (1165,10 380) and the median C-reactive protein (CRP) was 7.97 mg/l (2.35,19.28). The median LGE percentage was 4.65% (2.6,8.5) and ventricular ejection fraction 60% (56.00,64.75).Linear association was found between LGE (%) and maximal HsTnI (ng/l) value with r  = 0.49 ( P  < 0.001). After including only patients in whom the CMR was performed within 5 days of the maximal HsTnI the correlation improved to r  = 0.67 ( P  < 0.001).

CONCLUSIONS

HsTnI is an indicator for myocardial damage extent resulting from inflammation in patients with acute myocarditis.

Coronary Flow Velocity Reserve by Echocardiography: Beyond Atherosclerotic Disease

Coronary flow velocity reserve (CFVR) is defined as the ratio between coronary flow velocity during maximal hyperemia and coronary flow at rest. Gold-standard techniques to measure CFVR are either invasive or require radiation and are therefore inappropriate for large-scale adoption. More than 30 years ago, echocardiography was demonstrated to be a reliable tool to assess CFVR, and its field of application rapidly expanded. Although initially validated to assess the hemodynamic relevance of a coronary stenosis, CFVR by echocardiography was later used to investigate coronary microcirculation. Microvascular dysfunction was detected in many different conditions, ranging from organ transplantation to inflammatory disorders and from metabolic diseases to cardiomyopathies. Moreover, it has been proven that CFVR by echocardiography not only detects coronary microvascular involvement but is also an effective prognostic factor that allows a precise risk stratification of the patients. In this review, we will summarize the many applications of CFVR by echocardiography, focusing on the coronary involvement of systemic diseases.

Segmental cardiac strain assessment by two-dimensional speckle-tracking echocardiography in surviving MIS-c patients: correlations with myocardial flow reserve (MFR) by 13 N-ammonia PET-CT

MIS-c is associated with severe cardiovascular impairment and eventually death. Pathophysiological mechanisms involved in myocardial injury were scarcely investigated and cardiovascular outcomes are uncertain. Autopsy studies suggested that microvascular dysfunction may be relevant to LV impairment. we aimed to evaluate segmental LV longitudinal strain by 2DST echocardiography, as well as myocardial flow reserve (MFR) by 13 N-ammonia PET-CT, in surviving MIS-c patients. each patient generated 34 LV segments for combined 2DST and MRF analysis. MFR was considered abnormal when < 2, borderline when between 2 and 2.5 and normal when > 2.5. From July 2020 to February 2021, six patients were admitted with MIS-c: three males, aged 9.3 (6.6-15.7) years. Time from admission to the follow-up visit was 6.05 (2-10.3) months. Although all patients were asymptomatic and LV EF was ≥ 55%, 43/102 (42.1%) LV segments showed MFR < 2.5. There was a modest positive correlation between segmental peak systolic longitudinal strain and MFR: r = 0.36, p = 0.03 for basal segments; r = 0.41, p = 0.022 for mid segments; r = 0.42, p = 0.021 for apical segments. Median peak systolic longitudinal strain was different among MRF categories: 18% (12%-24%) for abnormal, 18.5% (11%-35%) for borderline and 21% (12%-32%) for normal MFR (p = 0.006). We provided preliminary evidence that surviving MIS-c patients may present subclinical impairment of myocardial microcirculation. Segmental cardiac strain assessment 2DST seems useful for MIS-c cardiovascular follow-up, given its good correlation with 13 N-ammonia PET-CT derived MFR.