A Novel Exercise Testing Algorithm to Diagnose Mitochondrial Myopathy.

A Novel Exercise Testing Algorithm to Diagnose Mitochondrial Myopathy.

Bhatia Rajeev;Cohen BH;McNinch N

Muscle & Nerve

2021

2021-02-03

INTRODUCTION: Oxygen uptake efficiency slope (OUES) is a non-invasive cardiopulmonary exercise testing (CPET) measurement based on oxygen uptake (V&c.dotab;O(2) ) and minute ventilation (V&c.dotab;(E) ) and is a marker of the efficiency of oxygen utilization by the body. However, it has not been studied in mitochondrial disorders. We explored noninvasive CPET parameters including OUES as a way to reliably diagnose mitochondrial myopathy. METHODS: We performed cycle ergometer maximal exercise testing on definite and suspected mitochondrial myopathy subjects (MM-D & MM-S) and their age and sex matched controls. OUES was corrected for body surface area (OUES/BSA) to eliminate the effect of body size. RESULTS: 40 participants [20 mitochondrial myopathy subjects {13 MM-D (6 males; aged 14-64 years) / 7 MM-S (5 males, aged 11-30 years} and 20 controls] completed the study. MM-D subjects showed lower aerobic fitness than controls. OUES/BSA was lower in MM-D subjects suggesting inefficient oxygen utilization. Area under the curve (AUC) and 95% Confidence Interval (CI) for OUES/BSA [0.91 (0.80, 1.00)], Peak V&c.dotab;O(2) % predicted [0.95 (0.86, 1.00)] and V&c.dotab;O(2) /Work slope [0.94 (0.85, 1.00)] showed excellent ability to diagnose mitochondrial myopathy in MM-D subjects. We applied a diagnostic approach based on the above parameters to MM-S subjects and their controls and were able to support or disprove the diagnosis of mitochondrial myopathy. DISCUSSION: We proposed and applied an approach based on the above three CPET parameters to reliably diagnose mitochondrial myopathy and found it to be clinically useful. This article is protected by copyright. All rights reserved.

Cardiopulmonary exercise testing; Mitochondrial myopathy; Oxygen uptake (V&c.dotab;O2); Oxygen Uptake Efficiency Slope (OUES); V&c.dotab;O2 /Work slope

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1097-4598 0148-639X

NEOMED College of Medicine

Department of Pediatrics

Department of Integrative Medical Science

February 2021 List