In terms of radiologic findings, bilateral pneumonia (75 of 82 patients [91.5%] vs 236 of 334 patients [70.7%]) and multiple mottling and ground-glass opacity (53 [64.6%] vs 15 [4.5%]) were more prevalent in patients with than those without cardiac injury (both P < .001, Table 1).

CMR (day 7) showed a recovery of systolic function (from 52% by CTA to 64% by CMR), although with persistence of a mild hypokinesia at basal and mid left ventricular segments; at the same sites, diffuse myocardial oedema, determining wall pseudo-hypertrophy, was observed on short T1 inversion recovery (STIR) sequences (Panel D) and confirmed by T1 and T2 mapping (average native T1 = 1188 ms, normal value <1045; average T2 = 61 ms, normal value <50). Late gadolinium enhancement sequences demonstrated absence of detectable myocardial scar/necrotic foci.

Chest radiography was repeated on day 4 and showed no thoracic abnormalities. Transthoracic echocardiography, performed on day 6, revealed a significant reduction of LV wall thickness (interventricular septum, 11 mm; posterior wall, 10 mm), an improvement of LVEF to 44%, and a slight decrease of pericardial effusion (maximum, 8-9 mm). At the time of submission, the patient was hospitalized with progressive clinical and hemodynamic improvement.

Transthoracic echocardiography revealed normal left ventricular (LV) dimensions with an increased wall thickness (interventricular septum, 14 mm, posterior wall, 14 mm) and a diffuse echo-bright appearance of the myocardium. There was diffuse hypokinesis, with an estimated LV ejection fraction (LVEF) of 40%. There was no evidence of heart valve disease. Left ventricular diastolic function was mildly impaired with mitral inflow patterns, with an E/A ratio of 0.7 and an average E/e′ ratio of 12. There was a circumferential pericardial effusion that was most notable around the right cardiac chambers (maximum, 11 mm) without signs of tamponade. Cardiac magnetic resonance imaging (MRI) confirmed the increased wall thickness with diffuse biventricular hypokinesis, especially in the apical segments, and severe LV dysfunction (LVEF of 35%) (Video 1 and Video 2). Short tau inversion recovery and T2-mapping sequences showed marked biventricular myocardial interstitial edema. Phase-sensitive inversion recovery sequences showed diffuse late gadolinium enhancement extended to the entire biventricular wall (Figure 2). The myocardial edema and pattern of late gadolinium enhancement fulfilled all the Lake Louise criteria for the diagnosis of acute myocarditis.6 The circumferential pericardial effusion was confirmed, especially around the right cardiac chambers (maximum, 12 mm).

Cardiac magnetic resonance imaging showed increased wall thickness with diffuse biventricular hypokinesis, especially in the apical segments, and severe left ventricular dysfunction (left ventricular ejection fraction of 35%). Short tau inversion recovery and T2-mapping sequences showed marked biventricular myocardial interstitial edema, and there was also diffuse late gadolinium enhancement involving the entire biventricular wall. There was a circumferential pericardial effusion that was most notable around the right cardiac chambers. These findings were all consistent with acute myopericarditis.