Identification of Carnitine-Responsive Cardiomyopathy

Study Overview
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Brief Summary
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There are some adults with skeletal muscle weakness (called myopathy) and heart muscle weakness (called cardiomyopathy) who have low blood levels of a compound called carnitine as a cause of their problems. Carnitine is very important to energy production in muscles. In fact, there are reports of some people with carnitine deficiency who have developed myopathy and cardiomyopathy that was completely reversed with carnitine treatment. The main objective of our project is to determine the number of patients who have carnitine deficiency as a cause of their myopathy and cardiomyopathy. The investigators will be measuring carnitine levels in 1000 patients with cardiomyopathy and will describe the specific features in all the study patients to see if there are any trends that may help us predict which patients with muscle weakness are at risk of developing low carnitine levels. The investigators will be treating patients with low carnitine levels with carnitine and observing them to see if their cardiomyopathy and their muscle weakness improve. Knowing the exact percentage of myopathy and cardiomyopathy patients with carnitine deficiency may allow for screening of patients in a cheap and targeted way to treat the serious complication of this condition, including heart failure and sudden death.

Detailed Description
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The primary objective of this research is to determine the prevalence of primary and secondary (genetic and acquired) carnitine deficiency in patients with limb girdle weakness and hypertrophic or idiopathic dilated cardiomyopathy where an underlying cause is unknown. Identification and treatment with carnitine may potentially reverse or halt heart failure and skeletal muscle weakness in these patients. Specific aims: To ascertain the prevalence of primary and secondary carnitine deficiency in a population of adults with myopathy and hypertrophic and dilated cardiomyopathy of unknown etiology To describe the demographic and phenotypic characteristics of patients with myopathy and dilated or hypertrophic cardiomyopathy who have primary and secondary carnitine deficiency To measure the motor and cardiovascular response to carnitine supplementation in patients with myopathy, cardiomyopathy and carnitine deficiency

Official Title
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Identification of Carnitine-responsive Cardiomyopathy and Myopathy in Adult Patients With Dilated and/or Hypertrophic Cardiomyopathy and Limb Girdle Weakness.

Conditions
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Carnitine Deficiency

Intervention / Treatment
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* Drug: Carnitine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: An adult patient (>18 years) with a diagnosis of either hypertrophic or dilated cardiomyopathy, for which the underlying etiology of the cardiomyopathy is unknown. Exclusion Criteria: A history of ischemia A documented or suspected infection including HIV A history of severe longstanding hypertension A history of valvular heart disease A history of chemotherapy exposure A history of alcohol abuse Carnitine supplementation at the time of recruitment

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: CarnitineDeficient<br>Patients identified with primary and secondary carnitine deficiency in the cardiomyopathy population will be prescribed with carnitine supplements to assess cardiac muscle function and status. | Drug: Carnitine<br>* Patients who are found to be carnitine deficient will be started on carnitine replacement and their heart function will be monitored on carnitine.<br>* Other names: Carnitor;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Serum Carnitine Concentration | Measurement of free and total serum carnitine concentrations will be performed using isotope-dilution mass spectrometry. | Baseline | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Echocardiographic Measures | Measurements include: Septal diameter Left Ventricular (LV) mass LV ejection fraction LV end-systolic volume LV end-diastolic measure | Baseline, every 6m for up to 2 years | 
| B-Natriuretic Peptide (BNP) | An elevated BNP level is a marker of increased LV filling pressures and LV dysfunction and is highly correlated with severity of, and prognosis in, heart failure. BNP testing is routinely performed at the cardiac clinic at University Health Network to determine treatment response and to assist with risk stratification prognostication in patients with heart failure. | Baseline, every 6m for up to 2 years |