Abstract 525: Abnormal Left Ventricular Circumferential Strain, Strain Rate and Rotation Parameters Using Speckle Tracking Imaging in Acute Myocarditis as Evidenced on Cardiac Magnetic Resonance Imaging
Acute myocarditis with preserved LVEF are difficult to detect by conventional echocardiography. CMRI is the non-invasive reference standard for diagnosis. Known LV mechanics suggests disease in epi/mid myocardium is likely to effect torsion and circumferential strain. The aim of this study was to determine the presence and extent of abnormal LV circumferential strain (CirS), strain rate (CirSR) and torsion (Tor) with speckle tracking imaging (STI) in myocarditis.
Methods: We enrolled 23 patients with chest pain and elevated troponin levels without coronary artery disease and myocardial infarction. A diagnosis of myocarditis was confirmed on CMRI. Routine and STI echocardiography parameters were measured and compared with 72 healthy aged-matched controls. A positive STI result for myocarditis was defined as having 2 or more measured parameter that was at least 2 standard deviations (SD) from the control population mean.
Results: Twenty (24±9yrs) were diagnosed with myocarditis. Myocarditis patients had decreased basal CirS (p<0.001) and CirSR (p =0.02), an earlier time to peak basal CirS (p <0.001), increased basal rotation rate (RotR) (p =0.003), decreased apical CirS (p =0.006) and CirSR (p=0.006), increased Tor rate (p=0.04) and an earlier time to peak Tor (p=0.004) when compared to controls (see Table⇓). No significant difference in peak torsion or LVEF. STI parameters identified 18 (90%) patients with myocarditis. The measured parameters time to peak Tor and basal CirS were abnormal in 14 (70%) and 10 (50%) patients with myocarditis respectively. Conventional echocardiographic assessment of LV volumes, LVEF and mitral E/A ratio, had abnormal parameters in 6 (30%).
Conclusion: Speckle tracking imaging assessment of acute myocarditis showed abnormalities of CirS, CirSR and rotation, especially time to peak Tor and peak basal CirS. Conventional echocardiographic parameters failed to detect abnormalities in the majority of cases.