A Unique Incident Presentation of Cardiac Involvement in Mitochondrial Myopathy

Document Type

Conference Proceeding

Publication Date

11-7-2023

Publication Title

Circulation

Abstract

Case: A 68 year old female with mitochondrial myopathy (MT-TK subset) and no significant cardiac history presented with shortness of breath and palpitations for 1 day. Initial vitals were HR 152, BP 174/102, RR 31, SpO2 83% on RA. Imaging showed pulmonary congestion, EKG showed new onset atrial flutter with RVR, and 2D echo showed a new drop in EF to 15% with global hypokinesis. BNP was elevated (861 pg/ml). Other labs including serial troponins were unremarkable. Patient was started on diuresis, nitroglycerin infusion, and anticoagulation. RVR persisted despite iv metoprolol, digoxin, and esmolol infusion. Cardioversion was planned but TEE revealed a LAA thrombus. Finally on day 3 of hospitalization, patient spontaneously converted to sinus rhythm. Amiodarone was added for rhythm control. Notably, a repeat 2DE showed improvement in EF to 35%, concerning for tachycardia induced cardiomyopathy. GDMT was started and patient was discharged in a stable condition. A month later patient successfully underwent cavotricuspid isthmus ablation and pulmonary vein isolation.

Discussion: The heart is critically dependent on mitochondrial oxidative phosphorylation and is one of the most frequently affected organs in mitochondrial disorders (MIDs). Cardiac involvement (CI) can be structural (myocardium, coronary arteries, pericardium, aortic root), functional (impulse generation/ conduction, arrhythmias) or both. Since almost half of the cardiac ATP is used to maintain ion channel homeostasis, mitochondria is a key player in arrhythmogenesis. It is crucial to avoid conditions that may create a high metabolic demand (fever, stress) and drugs that may interfere with enzymes involved in mitochondrial metabolism (such as metformin, propofol, valproic acid, erythromycin). Antioxidants and respiratory chain cofactors are commonly used for supportive management, however benefits are inconsistent. Interventions targeted towards definite control, like ablation should be considered early. Additionally, a comprehensive cardiac evaluation is important at diagnosis considering the progressive nature of MIDs. At present, there is no targeted treatment and further studies are needed to explore mitochondria as a potential therapeutic target in arrhythmias.

Volume

148

Issue

Suppl 1

First Page

A17574

Comments

American Heart Association Scientific Sessions, November 11-13, 2023, Philadelphia, PA

DOI

10.1161/circ.148.suppl_1.17574

Link to Full Text

Share

COinS