Circulation: Cardiovascular Imaging最新文献

Background: The relative flow reserve (RFR) derived from quantitative myocardial perfusion imaging is the ratio of absolute myocardial perfusion in a stenotic to normally perfused area and is considered the noninvasive equivalent of fractional flow reserve (FFR). In patients with prior coronary artery disease (CAD), detecting hemodynamically significant CAD using hyperemic myocardial blood flow (hMBF) is complicated by diffuse CAD and microvascular disease. In these patients, RFR may improve the diagnostic performance of myocardial perfusion imaging. Therefore, we studied the diagnostic value of RFR over hMBF in patients with prior CAD.

Methods: The PACIFIC-2 trial (functional stress imaging to predict abnormal coronary FFR) included symptomatic patients with prior myocardial infarction and/or percutaneous coronary intervention who prospectively underwent [¹⁵O]H₂O positron emission tomography perfusion imaging and invasive coronary angiography with 3-vessel FFR. RFR was assessed using positron emission tomography in an overall cohort incorporating all trial patients, and an optimal cohort of patients with angiographic 1- or 2-vessel disease (diameter stenosis ≥50%) and a nonstenotic reference vessel (diameter stenosis <30%). RFR was calculated as the ratio between the lowest to highest regional hMBF (overall cohort), or the lowest hMBF of a stenotic to the reference area (optimal cohort). Position emission tomography-derived flow indices were referenced by invasive FFR (≤0.80 deemed hemodynamically significant).

Results: The overall cohort included 187 patients (63±9.3 years, 36 [19%] female), and the optimal cohort 80 patients (62±9.6 years, 19 [24%] female). Significant CAD was present in 87 (47%) and 43 (54%) patients, respectively. Correlations between RFR and FFR were 0.42 and 0.52 (P<0.001 for both). C statistics for hMBF and RFR were comparable in the overall (0.81 versus 0.78; P=0.288) and the optimal cohort (0.79 versus 0.82; P=0.512).

Conclusions: RFR proves clinically applicable, even without specific patient selection and knowledge of the coronary anatomy. However, RFR does not outperform absolute hyperemic myocardial perfusion for detecting FFR-defined significant CAD in patients with prior CAD and recurrence of symptoms.

Background: Multisystem Inflammatory Syndrome in Children is characterized by high rates of acute cardiovascular involvement with rapid recovery of organ dysfunction. However, information regarding long-term sequelae is lacking. We sought to characterize the systolic function and myocardial tissue properties using cardiac magnetic resonance (CMR) imaging in a multicenter observational cohort of patients with Multisystem Inflammatory Syndrome in Children.

Methods: In this observational cohort study, comprising 32 centers in North America, CMR studies were analyzed by a core laboratory to assess ventricular volumetric data, tissue characterization, and coronary involvement.

Results: A total of 263 CMRs from 255 patients with Multisystem Inflammatory Syndrome in Children were analyzed. The mean patient age was 11.4±4.4 years. Most studies were performed at 3 months (33%) or 6 months (45%) after hospitalization. Left ventricular dysfunction was present in 17 (6.7%) of the first CMRs and was never worse than mild. Dysfunction was observed in 4/7 (57%) patients at admission, 5/87 (6.9%) patients at 3 months, and 6/129 (4.6%) patients imaged either at 6 months or 1 year post-hospitalization. Late gadolinium enhancement was present in 2 (0.8%) patients, 1 at 3 months and another at 6 months following hospitalization. Coronary artery dilation was present in 13 of the 174 (7.5%) patients. Nine patients met the Lake Louise criteria for myocarditis (3.5%) at the time of CMR.

Conclusions: In this largest published multiinstitutional longitudinal CMR evaluation of confirmed patients with Multisystem Inflammatory Syndrome in Children, the prevalence of ventricular dysfunction and myocardial tissue characterization abnormalities on medium-term follow-up was low. However, a small number of patients had mild residual abnormalities at 6 months and 1 year following hospitalization.

Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT05287412.

Background: Left ventricular ejection fraction (LVEF) is an essential tool for heart failure (HF) assessment but is limited by load dependence. Additional tools are needed to risk-stratify normal LVEF populations. We aimed to assess the prognostic value of systolic blood pressure-indexed left ventricular end-systolic volume ratio, or cardiac contractility index (CCI).

Methods: In a prospective observational cohort study of people newly diagnosed with HF, we defined characteristics and outcomes associated with LVEF and CCI, including after stratification into HF with reduced ejection fraction or HF with preserved ejection fraction. We used UK Biobank to assess whether CCI is associated with subclinical myocardial dysfunction and incident HF.

Results: In people with HF, mortality increased over tertiles of declining CCI (P<0.001). Within the HF with preserved ejection fraction group, below-median CCI was associated with distinct clinical characteristics and an all-cause mortality risk approximately twice that of those with above median CCI (observed event rate 17.3/100 patient-years versus 8.8/100 patient-years; P<0.001), similar to those with HF with reduced ejection fraction. Modeled as continuous variables, there was a curvilinear relationship between mortality across the detected range of CCI, while there was no clear association with mortality risk across a wide range of LVEF (20%-55%). In UK Biobank for participants without HF and normal LVEF, below-median CCI was associated with ≈33% increased risk of incident HF (adjusted hazard ratio, 1.33 [1.01-1.75]; P=0.043). Decreasing CCI was also associated with lower myocardial contractility defined using global radial and circumferential strain.

Conclusions: CCI is a simple, noninvasive, relatively afterload-independent method to stratify HF risk in populations with normal LVEF. Its simplicity means CCI could be applied to existing clinical trial data sets or used be as an inclusion criterion in future randomized controlled trials.

Heart failure with preserved ejection fraction (HFpEF) is a complex syndrome characterized by left ventricular diastolic dysfunction, elevated filling pressures, and normal ejection fraction (left ventricular ejection fraction ≥50%) in the absence of an underlying disease process. Its prevalence is increasing, driven by an aging population and rising comorbidities including obesity, diabetes, and hypertension. Given the benefit of emerging HFpEF therapies, such as glucagon-like peptide-1 inhibitors, early and accurate diagnosis is critical to improve outcomes. The diagnosis of HFpEF, however, can be challenging to make, and clinical practice relies heavily on echocardiographic evidence of diastolic dysfunction. There is a need for additional noninvasive diagnostic strategies to facilitate earlier HFpEF diagnosis to improve clinical outcomes. Emerging evidence suggests that cardiac magnetic resonance (CMR) imaging may have clinical value in enhancing HFpEF diagnosis and prognosis. Moreover, CMR tissue characterization by parametric mapping sequences (T1/T2 mapping and extracellular volume quantification) makes CMR a powerful tool for evaluating HFpEF mimickers, specific diseases that cause the clinical syndrome of heart failure in the setting of normal ejection fraction, which may confound HFpEF diagnosis. Finally, novel imaging sequences, such as magnetic resonance spectroscopy, diffusion tensor imaging, and elastography, are being developed to characterize metabolism and hemodynamics in vivo and may provide insight into HFpEF pathophysiology. The diagnostic and prognostic values of CMR-derived indices of diastolic dysfunction and the use of CMR to distinguish between HFpEF and its mimickers, as well as the use of novel CMR sequences in HFpEF, are reviewed herein.