Microvascular Dysfunction in Nonischemic Cardiomyopathy: Insights From CMR Assessment of Coronary Flow Reserve
试验速览
- 阶段
- 4 期
- 状态
- 终止
- 入组人数
- 31
- 试验地点
- 1
- 主要终点
- Prevalence of Microvascular Dysfunction (MVD) by a CMR Measurement of Whole-heart (Global) Perfusion Reserve Ratio in Patients With Hypertrophic Cardiomyopathy, Non-ischemic Cardiomyopathy, and Controls.
研究概览
简要总结
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.
详细描述
Coronary microvascular dysfunction (MVD) has been implicated as an important marker of cardiac risk and has been thought to directly contribute to the pathogenesis of a wide variety of cardiomyopathies. For instance, MVD is believed to cause ischemia (with reduction in coronary flow reserve) in patients with hypertrophic cardiomyopathy (HCM) despite the presence of angiographically normal epicardial coronary arteries. The implication is that MVD in HCM may lead to the ventricular arrhythmias, sudden death, and heart failure. Similarly, patients with idiopathic dilated cardiomyopathy (IDCM) have blunted coronary flow reserve, which appears to be independently associated with poor prognosis.
Several etiologic mechanisms have been proposed to explain the occurrence of MVD, including structural and functional abnormalities1:
- increased microvascular resistance due to reduced vascular luminal caliber.
- reduced density of microvessels associated with replacement scarring.
- inappropriate vasoconstrictor responses.
- inadequate vasodilator responses.
Unfortunately, these mechanisms are difficult to study in humans since no technique currently allows the direct visualization of the coronary microcirculation in vivo. Thus, MVD has been largely studied using non-invasive imaging techniques, such as positron emission tomography (PET) or single photon emitted computed tomography (SPECT).
Although these methods have provided insight into MVD, much remains unknown. For example, even the prevalence of MVD in patients with various types of cardiomyopathy is unclear, with different studies showing widely different rates.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Basic Science
- 盲法
- Single (Outcomes Assessor)
盲法说明
The reader of the CMR scan will be blinded to the stress agent used.
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •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.
排除标准
- •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
研究组 & 干预措施
Hypertrophic cardiomyopathy
干预措施: Regadenoson (Drug)
Hypertrophic cardiomyopathy
干预措施: Adenosine (Drug)
Non-ischemic dilated cardiomyopathy
干预措施: Regadenoson (Drug)
Non-ischemic dilated cardiomyopathy
干预措施: Adenosine (Drug)
Control
干预措施: Regadenoson (Drug)
Control
干预措施: Adenosine (Drug)
结局指标
主要结局
Prevalence of Microvascular Dysfunction (MVD) by a CMR Measurement of Whole-heart (Global) Perfusion Reserve Ratio in Patients With Hypertrophic Cardiomyopathy, Non-ischemic Cardiomyopathy, and Controls.
时间窗: The prevalence of MVD will be determined based on the findings at the time of the scan on Day 1 of the study.
Prevalence of microvascular dysfunction as determined by the CMR measure of global perfusion reserve ratio (GPR) in each these patient groups. MVD was considered present when either GPR was \<2.0 or regional stress perfusion abnormalities were present. In order to calculate this ratio, coronary sinus flow was measured twice: 1. prior to the the administration of adenosine/regadenoson 2. during the administration of adenosine/regadenoson GPR is a ratio of coronary sinus flow during the administration adenosine/regadenoson divided by the baseline coronary sinus flow measured prior to the administration. Regional perfusion abnormalities will be assessed at the time of adenosine/regadenoson administration.
次要结局
- CMR Measurement of Global Perfusion Reserve Ratio(The global perfusion ratio will be calculated from the measurements obtained at the time of the scan on Day 1 of the study.)
- The Association Between Global Perfusion Reserve (GPR) Ratio and Regional Myocardial Scarring.(Both global perfusion ratio and the presence of regional scarring will be determined/measured from the images obtained during the scan on Day 1 of the study.)