Microvascular Dysfunction in Patients with Idiopathic Dilated Cardiomyopathy: Quantitative Assessment with Phase Contrast Cine MR Imaging of the Coronary Sinus.

PURPOSE: The purposes of this study were to compare global coronary flow reserve (CFR) between patients with idiopathic dilated cardiomyopathy (DCM) and risk-matched controls using cardiac MRI (CMR), and to evaluate the relationship between global CFR and CMR left ventricular (LV) parameters. METHODS: Twenty-six patients with DCM and 26 risk-matched controls who underwent comprehensive CMR examination, including stress-rest coronary sinus flow measurement by phase contrast (PC) cine CMR were retrospectively studied. LV peak global longitudinal, radial, and circumferential strains (GLS, GRS, and GCS) were determined by feature tracking. RESULTS: Patients with DCM had significantly lower global CFR compared with the risk-matched controls (2.87 ± 0.86 vs. 4.03 ± 1.47, P = 0.001). Among the parameters, univariate linear regression analyses revealed significant correlation of global CFR with LV end-diastolic volume index (r = -0.396, P = 0.045), LV mass index (r = -0.461, P = 0.018), GLS (r = -0.558, P = 0.003), and GRS (r = 0.392, P = 0.047). Multiple linear regression analysis revealed GLS as the only independent predictor of global CFR (standardized ß = -0.558, P = 0.003). CONCLUSION: Global CFR was significantly impaired in patients with idiopathic DCM and independently associated with LV GLS, suggesting that microvascular dysfunction may contribute to deterioration of LV function in patients with idiopathic DCM.

Combined Assessment of Stress Myocardial Perfusion Cardiovascular Magnetic Resonance and Flow Measurement in the Coronary Sinus Improves Prediction of Functionally Significant Coronary Stenosis Determined by Fractional Flow Reserve in Multivessel Disease.

BACKGROUND: Recent studies using stress-rest perfusion cardiovascular magnetic resonance (CMR) demonstrated a close correlation between myocardial ischemia and reduced fractional flow reserve (FFR). However, its diagnostic concordance may be reduced in patients with multivessel disease. We sought to evaluate the concordance of adenosine stress-rest perfusion CMR for predicting reduced FFR, and to determine the additive value of measuring global coronary flow reserve (CFR) in the coronary sinus in multivessel disease. METHODS AND RESULTS: Ninety-six patients with angiographic luminal narrowing >50% underwent comprehensive CMR study and FFR measurements in 139 coronary vessels. FFR <0.80 was considered hemodynamically significant. Global CFR was quantified as the ratio of stress-rest coronary sinus flow measured by phase-contrast cine CMR. In 25 patients with single-vessel disease, visual assessment of perfusion CMR yielded high diagnostic concordance for predicting flow-limiting stenosis, with the area under receiver operating characteristic curve of 0.93 on a per-patient basis. However, in 71 patients with multivessel disease, perfusion CMR underestimated flow-limiting stenosis, resulting in the reduced area under receiver operating characteristic curve of 0.74. When CFR of <2.0 measured in the coronary sinus was considered as global myocardial ischemia, combined assessment provided correct reclassifications in 7 patients with false-negative myocardial ischemia, and improved the diagnostic concordance to 92% sensitivity and 73% specificity with the area under receiver operating characteristic curve of 0.88 (95% confidence interval, 0.80%-0.97%, P=0.002). CONCLUSIONS: Visual analysis of stress-rest perfusion CMR has limited concordance with FFR in patients with multivessel disease. Multiparametric CMR integrating stress-rest perfusion CMR and flow measurement in the coronary sinus is useful for detecting reduced FFR in multivessel disease.

Native T1 Mapping and Extracellular Volume Mapping for the Assessment of Diffuse Myocardial Fibrosis in Dilated Cardiomyopathy.

OBJECTIVES: The purpose of this study was to examine the histological correlation of native myocardial T1 and extracellular volume fraction (ECV) measurement at 3-T for the assessment of diffuse pathological changes in the myocardial tissue, including myocardial fibrosis and extracellular space in dilated cardiomyopathy (DCM). BACKGROUND: Cardiac magnetic resonance T1 techniques allow the quantification of diffuse myocardial fibrosis. However, there are no definitive head-to-head studies of native T1 versus ECV for the detection, quantification, and characterization of pathological changes in the myocardial tissue in DCM by using histological samples for confirmation. METHODS: A total of 36 subjects with DCM (31 men, mean age 56 ± 16 years) underwent pre- and post-contrast T1 mapping as well as late gadolinium enhancement (LGE) cardiac magnetic resonance at 3-T. Biopsy samples were used for the quantification of collagen volume fraction using picrosirius red staining and an extracellular space component from hematoxylin and eosin-stained myocardium. RESULTS: Nonischemic LGE was observed in 14 of 36 patients. Although patients with LGE had significantly greater biopsy-proven collagen volume fraction than those without LGE (21 ± 12% vs. 11 ± 8%; p < 0.01), there was substantial overlap of collagen volume fraction values between patients with and without LGE. Both native T1 value and ECV were similarly and significantly associated with biopsy-proven collagen volume fraction (r = 0.77 and r = 0.66, respectively; p < 0.05). Furthermore, ECV had a strong correlation with the biopsy-proven extracellular space component (r = 0.86), whereas native T1 had only a moderate correlation (r = 0.55). Interobserver and intraobserver reproducibility for native T1 and ECV were 0.89, 0.95, 0.96, and 0.98, respectively. CONCLUSIONS: Native T1 exhibited comparable ability as ECV measurement in the detection and quantification of histological collagen volume fraction, with high reproducibility, and therefore diffuse myocardial fibrosis in DCM may be reliably assessed by native T1 mapping without the administration of gadolinium contrast agent. In addition, cardiac magnetic resonance-derived ECV showed excellent agreement with histological extracellular space.

Detection of diminished response to cold pressor test in smokers: assessment using phase-contrast cine magnetic resonance imaging of the coronary sinus.

PURPOSE: The purposes of this study were to evaluate the reproducibility for measuring the cold pressor test (CPT)-induced myocardial blood flow (MBF) alteration using phase-contrast (PC) cine MRI, and to determine if this approach could detect altered MBF response to CPT in smokers. MATERIALS AND METHODS: After obtaining informed consent, ten healthy male non-smokers (mean age: 28±5 years) and ten age-matched male smokers (smoking duration ≥5 years, mean age: 28±3 years) were examined in this institutional review board approved study. Breath-hold PC cine MR images of the coronary sinus were obtained with a 3T MR imager with 32 channel coils at rest and during a CPT performed after immersing one foot in ice water. MBF was calculated as coronary sinus flow divided by the left ventricular (LV) mass which was given as a total LV myocardial volume measured on cine MRI multiplied by the specific gravity (1.05 g/mL). RESULTS: In non-smokers, MBF was 0.86±0.25 mL/min/g at rest, with a significant increase to 1.20±0.36 mL/min/g seen during CPT (percentage change of MBF (∆MBF (%)); 39.2%±14.4%, p<0.001). Inter-study reproducibility for ∆MBF (%) measurements by different MR technologist was good, as indicated by the intraclass correlation coefficient of 0.93 and reproducibility coefficient of 10.5%. There was no significant difference between smokers and non-smokers for resting MBF (0.85±0.32 mL/min/g, p=0.91). However, ∆MBF (%) in smokers was significantly reduced (-4.0±32.2% vs. 39.2±14.4%, p=0.011). CONCLUSION: PC cine MRI can be used to reproducibly quantify MBF response to CPT and to detect impaired flow response in smokers. This MR approach may be useful for monitoring the sequential change of coronary blood flow in various potentially pathologic conditions and for investigating its relationship with cardiovascular risk.

Improving drug adherence using fixed combinations caused beneficial treatment outcomes and decreased health-care costs in patients with hypertension.

We enrolled 196 patients with hypertension who were already being treated with free-drug combinations of angiotensin-II receptor blocker (ARB) and amlodipine. The free-drug combinations of ARB and amlodipine were replaced with the same dose of the fixed-dose combinations. The average home blood pressure (BP) in all patients receiving fixed-dose combinations was significantly lower than those receiving free-drug combinations (131 ± 10/75 ± 8 vs. 136 ± 11/77 ± 9 mm Hg, P < .01) accompanied with increasing drug adherence. After lowering BP by fixed-dose combinations, the costs for medications decreased by 31% over the 3 months.