Background: Conventional echocardiography has low sensitivity in detecting patients with myocarditis and normal left ventricular ejection fraction (LVEF). Speckle tracking imaging allows measurement of LV torsion and untwist, an alternative measure of LV function. Abnormalities of these parameters may identify patients with myocardial inflammation.
Method: We consecutively enrolled patients (10 - 45yrs) with chest pain and elevated troponin when ischemia has been excluded on magnetic resonance imaging (MRI) or angiography. All patients had ECG, echocardiography and MRI. Angiography was performed if an ischemic cause was suspected. LV torsion parameters were compared with age-matched controls.
Results: We recruited 10 patients with 1 excluded for poor image quality. Of the 9 patients analyzed, 7 have features of myocarditis on MRI. Patient 1 to 3 had reduced torsion and untwist rate. Patient 1 and 2 on follow up showed recovery of torsion and untwist rate. Patient 4 to 8 had increased basal rotation rate (rotR) and Patient 8 had increased torsion. Details are summarized in a table. Tissue Doppler imaging, LVEF and other measured LV torsion parameters were non-differentiating.
Conclusion: Abnormality in LV torsion, untwist rate or basal rotR identified all patients with myocarditis. Reduction in torsion and untwist rate normalized with patient recovery. Enhanced LV basal rotR and torsion may reflect early compensatory mechanism to maintain LV function in myocarditis with normal LVEF.