Microvascular Dysfunction in Nonischemic Cardiomyopathy: Insights From CMR Assessment of Coronary Flow Reserve
Condition: Hypertrophic Cardiomyopathy; Non-ischemic Dilated Cardiomyopathy; Microvascular Ischaemia of Myocardium
MeSH terms: Cardiomyopathies; Cardiomyopathy, Hypertrophic; Cardiomyopathy, Dilated; Ischemia
Intervention: Regadenoson; Adenosine
Intervention description: Microvascular disease will be considered present if regional perfusion defects are observed or global perfusion reserve is reduced. For the assessment of microvascular disease, the adenosine and regadenoson groups will be combined, as the medications are considered interchangeable.; Microvascular disease will be considered present if regional perfusion defects are observed or global perfusion reserve is reduced. For the assessment of microvascular disease, the adenosine and regadenoson groups will be combined, as the medications are considered interchangeable.
Intervention MeSH terms: Adenosine; Regadenoson
Phase: Phase 4
Study type: Interventional
Primary purpose: Basic Science
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Participants undergoing cardiovascular magnetic resonance stress testing will be recruited and randomized to receive either regadenoson or adenosine.
Masking: Single (Outcomes Assessor)
Masking description: The reader of the CMR scan will be blinded to the stress agent used.
Enrollment: 31.0
Sex: All
Minimum age: 18 Years
Healthy volunteers: No

Summary:

      The aim of this study is to assess microvascular function as determined by a cardiovascular
      magnetic resonance measurement of whole-heart (global) perfusion reserve. The goal is to
      determine the prevalence of MVD in two common forms of non-ischemic cardiomyopathy,
      hypertrophic cardiomyopathy (HCM) and idiopathic dilated cardiomyopathy (IDCM). The
      hypothesis that an optimized technique will provide robust detection of MVD and that a
      multifaceted approach will provide new insights into the pathophysiology of MVD, including
      the influence of myocardial scarring upon the presence and severity of MVD.
    

Eligibility criteria:

        Inclusion Criteria:

          -  Men or women aged 18 years or older

        Cardiomyopathy patients

          -  Patients presenting for CMR with the clinical diagnosis of hypertrophic cardiomyopathy
             based on left ventricular wall thickness of at least ≥15 mm in the absence of any
             other cardiac or systemic cause of hypertrophy

          -  Patients presenting for CMR with the clinical diagnosis of idiopathic dilated
             cardiomyopathy based upon left ventricular ejection fraction ≤40%, LV end-diastolic
             diameter ≥55 mm or left ventricular end-systolic diameter ≤45 mm, and the absence of
             coronary stenoses on angiography.

        Control patients

          -  Patients presenting for CMR without evidence of obstructive coronary artery disease
             either by coronary angiography or stress testing.

        Exclusion Criteria:

          -  Decompensated heart failure or hemodynamic instability

          -  Prior coronary revascularization (PCI or CABG) or myocardial infarction (as evidenced
             by previously elevated CPK-MB or troponin levels)

          -  Accelerating angina or unstable angina

          -  Inability to physically tolerate MRI or implanted objects that are MRI incompatible

          -  Inability to provide written informed consent obtained at time of study enrollment.

          -  Severe claustrophobia

          -  Advanced heart block or sinus node dysfunction

          -  Hypersensitivity or allergic reaction to regadenoson or adenosine

          -  Hypotension

          -  Active bronchospasm or history of hospitalization due to bronchospasm

          -  History of seizures

          -  Recent cerebrovascular accident

          -  Use of dipyridamole within the last 5 days

          -  Contraindication to aminophylline

          -  Severe renal insufficiency with estimated glomerular filtration rate <30 ml/min/ 1.73
             m2

          -  Pregnant or nursing