Novel Clinical Monitoring Approaches for Reemergence of Diphtheria Myocarditis, Vietnam

Abstract

Diphtheria is a life-threatening, vaccine-preventable disease caused by toxigenic Corynebacterium bacterial species that continues to cause substantial disease and death worldwide, particularly in vulnerable populations. Further outbreaks of vaccine-preventable diseases are forecast because of health service disruptions caused by the coronavirus disease pandemic. Diphtheria causes a spectrum of clinical disease, ranging from cutaneous forms to severe respiratory infections with systemic complications, including cardiac and neurologic. In this synopsis, we describe a case of oropharyngeal diphtheria in a 7-year-old boy in Vietnam who experienced severe myocarditis complications. We also review the cardiac complications of diphtheria and discuss how noninvasive bedside imaging technologies to monitor myocardial function and hemodynamic parameters can help improve the management of this neglected infectious disease.

Keywords: Corynebacterium diphtheriae; Vietnam; bacteria; diphtheria; diphtheria myocarditis; hemodynamic monitoring; infectious diseases; toxins; vaccine-preventable diseases.

Figure 1

Global and regional epidemiologic trends in reported cases of diphtheria, 1980–2019. Cases shown are those reported to the World Health Organization and the United Nations Children’s Fund.

Figure 2

The thick pseudomembrane covering the oropharynx of a 7-year-old boy at admission to a local hospital before his diphtheria myocarditis was diagnosed, Vietnam, 2020.

Figure 3

Results of 12-lead electrocardiograms conducted on a 7-year-old boy later diagnosed with diphtheria myocarditis, Vietnam, 2020. A) At hospital admission (day 10 of illness), electrocardiography showed an incomplete right bundle branch block (RSR) in V1–3 with QRS duration of 92 ms), QTc prolongation (519 ms), and ST depression. B) On day 14 of illness, we observed sinus tachycardia with occasional supraventricular premature complexes and T-wave inversion. C) On day 25, we observed widespread T-wave inversion, which persisted even after clinical recovery.

Figure 4

Temporal changes in troponin I levels and ejection fraction measurements during the acute phase of diphtheria myocarditis in a 7-year-old boy, Vietnam, 2020. EF, ejection fraction.

Figure 5

Serial echocardiographic recordings for 7-year-old boy later diagnosed with diphtheria myocarditis, Vietnam, 2020. On day 14 of illness, the M-mode left ventricular ejection fraction decreased to 40% (A) and the E/A ratio was >3.5 (B). At 2-week follow-up after discharge, both left ventricular systolic (C) and diastolic function (D) had recovered.