High-frequency QRS analysis to supplement ST evaluation in exercise stress electrocardiography: Incremental diagnostic accuracy and net reclassification.

BACKGROUND: Exercise stress electrocardiography (ECG) alone is underutilized in part due to poor diagnostic accuracy. High-frequency QRS analysis (HF-QRS) is a novel tool to supplement ST evaluation during stress ECG. We compared the diagnostic accuracy and net reclassification of HF-QRS analysis compared with ST evaluation for substantial myocardial ischemia by exercise SPECT myocardial perfusion imaging (MPI). METHODS AND RESULTS: Exercise SPECT MPI was performed in 257 consecutive eligible patients (mean age 59 ± 12, 67% male). An ischemic HF-QRS pattern was defined as a ≥ 1 µV absolute reduction and a ≥ 50% relative reduction of the root-mean-square of the 150-250 Hz band signal in ≥ 3 leads. Left ventricular ischemia of ≥ 10% on SPECT MPI was the diagnostic standard for substantial myocardial ischemia. HF-QRS analysis demonstrated incremental diagnostic value to ST evaluation plus clinical risk factors (AUC 0.804 vs 0.749, P < .0001). A HF-QRS + ST -analysis strategy identified 92.3% of subjects with substantial ischemia and no abnormality in 59.9% of the cohort. No cardiac events occurred in patients without substantial ischemia identified by HF-QRS analysis. CONCLUSIONS: In this prospective analysis, exercise stress ECG with HF-QRS analysis identified any and substantial ischemia with high diagnostic accuracy and may allow more than half of referred patients to safely avoid imaging.

Reduced field of view single-shot spiral perfusion imaging.

PURPOSE: To develop a single-shot spiral perfusion pulse sequence with outer-volume suppression (OVS) to achieve whole-heart coverage with a short temporal footprint of 10 ms per slice location. METHODS: A highly accelerated single-shot variable density spiral pulse sequence with an integrated OVS module for reduced field of view (rFOV) perfusion imaging with 2 mm spatial resolution was developed and evaluated in simulations, phantom experiments and in clinical patients with (n = 8) or without (n = 8) OVS. Images were reconstructed by block low-rank sparsity with motion guidance (BLOSM) and graded by two cardiologists on a 5-point scale (1, excellent; 5, poor). RESULTS: Simulation and phantom results showed that OVS effectively suppressed the signal outside the desired field of view (FOV). Clinical patient data demonstrated high quality perfusion images with rFOV. The average image quality scores of full FOV cases and rFOV cases were 3.1 ± 0.64 and 2.3 ± 0.46, respectively, (P = 0.02) from cardiologist 1 and 2.5 ± 0.54 and 1.8 ± 0.47, respectively, (P = 0.04) from cardiologist 2, showing superior image quality for the rFOV images compared with the full FOV images. CONCLUSION: A single-shot spiral perfusion sequence that uses OVS and BLOSM performs perfusion imaging with a very short temporal footprint per image supporting whole-heart coverage with good image quality. Magn Reson Med 79:208-216, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Quantitative cardiovascular magnetic resonance perfusion imaging identifies reduced flow reserve in microvascular coronary artery disease.

BACKGROUND: Preliminary semi-quantitative cardiovascular magnetic resonance (CMR) perfusion studies have demonstrated reduced myocardial perfusion reserve (MPR) in patients with angina and risk factors for microvascular disease (MVD), however fully quantitative CMR has not been studied. The purpose of this study is to evaluate whether fully quantitative CMR identifies reduced MPR in this population, and to investigate the relationship between epicardial atherosclerosis, left ventricular hypertrophy (LVH), extracellular volume (ECV), and perfusion. METHODS: Forty-six patients with typical angina and risk factors for MVD (females, or males with diabetes or metabolic syndrome) who had no obstructive coronary artery disease by coronary angiography and 20 healthy control subjects underwent regadenoson stress CMR perfusion imaging using a dual-sequence quantitative spiral pulse sequence to quantify MPR. Subjects also underwent T1 mapping to quantify ECV, and computed tomographic (CT) coronary calcium scoring to assess atherosclerosis burden. RESULTS: In patients with risk factors for MVD, both MPR (2.21 [1.95,2.69] vs. 2.93 [2.763.19], p < 0.001) and stress myocardial perfusion (2.65 ± 0.62 ml/min/g, vs. 3.17 ± 0.49 ml/min/g p < 0.002) were reduced as compared to controls. These differences remained after adjusting for age, left ventricular (LV) mass, body mass index (BMI), and gender. There were no differences in native T1 or ECV between subjects and controls. CONCLUSIONS: Stress myocardial perfusion and MPR as measured by fully quantitative CMR perfusion imaging are reduced in subjects with risk factors for MVD with no obstructive CAD as compared to healthy controls. Neither myocardial hypertrophy nor fibrosis accounts for these differences.

First-pass myocardial perfusion imaging with whole-heart coverage using L1-SPIRiT accelerated variable density spiral trajectories.

PURPOSE: To design and evaluate two-dimensional (2D) L1-SPIRiT accelerated spiral pulse sequences for first-pass myocardial perfusion imaging with whole heart coverage capable of measuring eight slices at 2 mm in-plane resolution at heart rates up to 125 beats per minute (BPM). METHODS: Combinations of five different spiral trajectories and four k-t sampling patterns were retrospectively simulated in 25 fully sampled datasets and reconstructed with L1-SPIRiT to determine the best combination of parameters. Two candidate sequences were prospectively evaluated in 34 human subjects to assess in vivo performance. RESULTS: A dual density broad transition spiral trajectory with either angularly uniform or golden angle in time k-t sampling pattern had the largest structural similarity and smallest root mean square error from the retrospective simulation, and the L1-SPIRiT reconstruction had well-preserved temporal dynamics. In vivo data demonstrated that both of the sampling patterns could produce high quality perfusion images with whole-heart coverage. CONCLUSION: First-pass myocardial perfusion imaging using accelerated spirals with optimized trajectory and k-t sampling pattern can produce high quality 2D perfusion images with whole-heart coverage at the heart rates up to 125 BPM. Magn Reson Med 76:1375-1387, 2016. © 2015 International Society for Magnetic Resonance in Medicine.

Cardiometabolic biomarker patterns associated with cardiac MRI defined fibrosis and microvascular dysfunction in patients with heart failure with preserved ejection fraction.

Introduction: Heart failure with preserved ejection fraction (HFpEF) is a complex disease process influenced by metabolic disorders, systemic inflammation, myocardial fibrosis, and microvascular dysfunction. The goal of our study is to identify potential relationships between plasma biomarkers and cardiac magnetic resonance (CMR) imaging markers in patients with HFpEF. Methods: Nineteen subjects with HFpEF and 15 age-matched healthy controls were enrolled and underwent multiparametric CMR and plasma biomarker analysis using the Olink® Cardiometabolic Panel (Olink Proteomics, Uppsala, Sweden). Partial least squares discriminant analysis (PLS-DA) was used to characterize CMR and biomarker variables that differentiate the subject groups into two principal components. Orthogonal projection to latent structures by partial least squares (OPLS) analysis was used to identify biomarker patterns that correlate with myocardial perfusion reserve (MPR) and extracellular volume (ECV) mapping. Results: A PLS-DA could differentiate between HFpEF and normal controls with two significant components explaining 79% (Q2 = 0.47) of the differences. For OPLS, there were 7 biomarkers that significantly correlated with ECV (R2 = 0.85, Q = 0.53) and 6 biomarkers that significantly correlated with MPR (R2 = 0.92, Q2 = 0.32). Only 1 biomarker significantly correlated with both ECV and MPR. Discussion: Patients with HFpEF have unique imaging and biomarker patterns that suggest mechanisms associated with metabolic disease, inflammation, fibrosis and microvascular dysfunction.

Functional and Economic Impact of INOCA and Influence of Coronary Microvascular Dysfunction.

OBJECTIVES: This study sought to better characterize the quality of life and economic impact in patients with symptoms of ischemia and no obstructive coronary disease (INOCA) and to identify the influence of coronary microvascular dysfunction (CMD). BACKGROUND: Patients with INOCA have a high symptom burden and an increased incidence of major adverse cardiac events. CMD is a frequent cause of INOCA. The morbidity associated with INOCA and CMD has not been well-characterized. METHODS: Sixty-six patients with INOCA underwent stress cardiac magnetic resonance with calculation of myocardial perfusion reserve (MPR); MPR 2.0 to 2.4 was considered borderline-reduced (possible CMD) and MPR <2.0 was defined as reduced (definite CMD). Subjects completed quality of life questionnaires to assess the morbidity and economic impact of INOCA. Questionnaire results were compared between INOCA patients with and without CMD. In addition, logistic regression was used to determine the predictors of CMD within the INOCA population. RESULTS: The prevalence of definite CMD was 24%. Definite or borderline CMD was present in 59% (MPR ≤2.4). Patients with INOCA reported greater physical limitation, angina frequency, and reduced quality of life compared to referent stable coronary artery disease and acute myocardial infarction populations. In addition, Patients with INOCA reported frequent time missed from work and work limitations, suggesting a substantial economic impact. No difference was observed in reported symptoms between INOCA patients with and without CMD. Glomerular filtration rate and body-mass index were significant predictors of CMD in multivariable regression analysis. CONCLUSIONS: INOCA is associated with high morbidity similar to other high-risk cardiac populations, and work limitations reported by Patients with INOCA suggest a substantial economic impact. CMD is a common cause of INOCA but is not associated with increased morbidity. These results suggest that there is significant symptom burden in the INOCA population regardless of etiology.

Frequency of Coronary Microvascular Dysfunction and Diffuse Myocardial Fibrosis (Measured by Cardiovascular Magnetic Resonance) in Patients With Heart Failure and Preserved Left Ventricular Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is frequently accompanied by co-morbidities and a systemic proinflammatory state, resulting in coronary microvascular dysfunction (CMD), as well as myocardial fibrosis. The purpose of this study is to examine the relation between myocardial perfusion reserve (MPR) and diffuse myocardial fibrosis in patients with HFpEF using cardiovascular magnetic resonance. A single center study was performed in 19 patients with clinical HFpEF and 15 healthy control subjects who underwent quantitative first-pass perfusion imaging to calculate global MPR. T1 mapping was used to assess fibrosis and to calculate extracellular volume. Spiral cine displacement encoded stimulated echo was used to calculate myocardial strain. Comprehensive 2D echocardiograms with speckle tracking, cardiopulmonary exercise testing, and brain natriuretic peptide levels were also obtained. In patients with HFpEF, mean left ventricular EF was 61% ± 9% and left ventricular mass index 45 ± 12 g/m2. Compared with controls, HFpEF patients had reduced global MPR (2.29 ± 0.64 vs 3.38 ± 0.76, p = 0.002) and VO2 max (16.5 ± 6.8 vs 30.9 ± 7.7 ml/kg min, p <0.001) whereas extracellular volume (0.29 ± 0.04 vs 0.25 ± 0.04, p = 0.02), pulmonary artery systolic pressure (35.4 ± 13.7 vs 22.3 ± 5.4 mm Hg, p = 0.004), and average E/e' (15.0 ± 7.6 vs 8.6 ± 2.0, p = 0.005) were increased. Displacement encoded stimulated echo peak systolic circumferential strain (p = 0.60) as well as echocardiographic derived global longitudinal strain (p = 0.07) were similar between both groups. The prevalence of CMD, defined as global MPR <2.5, in the HFpEF group was 69%. In conclusion, HFpEF patients have a high prevalence of CMD and diffuse fibrosis. These parameters may be useful clinical end points for future therapeutic trials.

Extracellular volume by cardiac magnetic resonance is associated with biomarkers of inflammation in hypertensive heart disease.

OBJECTIVES: Cardiac magnetic resonance (CMR) provides a unique approach to the characterization of hypertensive heart disease (HHD), enabling the measurement of left ventricular mass and expansion of extracellular volume (ECV). Combining plasma biomarkers with CMR could provide potential insights into the pathophysiological mechanisms in ventricular remodelling. METHODS: In this study, we estimated correlations between plasma biomarkers and CMR parameters of HHD. Patients with a history of hypertension with or without left ventricular hypertrophy (LVH) and healthy volunteers (17 hypertensive non-LVH, 13 hypertensive LVH and 11 controls) underwent CMR on a Siemens 1.5T Avanto. T1 mapping was performed before (native T1) and serially after injection of 0.15 mmol/kg gadolinium-DTPA. Mean ECV and left ventricular mass index (LVMI) were determined. Blood samples were obtained and analysed using the Olink CVD 92-plex biomarker panel. RESULTS: Individual groups were compared on the basis of 91 plasma biomarkers using partial least squares discriminant analysis (PLS-DA). ECV and LVMI were correlated with the 91 distinct plasma biomarkers via orthogonal projection to latent structures by partial least square (OPLS) analysis. A two-dimensional PLS-DA explained 49% of the differences between the three groups. OPLS analysis showed that four plasma biomarkers were significantly correlated to both ECV and LVMI, eight were significantly correlated with LVMI only and 11 were significantly correlated to ECV only. CONCLUSION: ECV and LVMI correlate differentially in plasma biomarker patterns. Top predictors of ECV consisted of well established biomarkers of systemic inflammation and metabolic function.

Trapping Dasinuera mali (Diptera: Cecidomyiidae) in apples.

The midge Dasineura mali (Kieffer) (Diptera: Cecidomyiidae) is a significant pest of apples (Malus spp.), and the recent identification of the female sex pheromone is enabling new direct control tactics to be considered. Direct control using male suppression will require knowledge of the frequency of multiple mating, dispersal and colonization rates, and the efficiency of male removal. Males were able to mate up to five times, with a mean of 2.7 times when presented in a 10 female-to-1 male group, designed to simulate male suppression. Male catch in response to the pheromone loading was curvilinear over 4 orders of magnitude from 3 microg to 30 mg on rubber septa. Trapping using a high-dose pheromone lure was combined with oil-based traps similar to the inexpensive New Zealand "Lynfield trap" used for tephritid surveillance, to test male suppression in young orchard blocks at 500 traps per ha. Monitoring traps indicated 96% lower catch in the treated plots compared with control plots, over 137 d. However, a lack of shoot tip infestation in both treated and untreated plots indicated limited colonization and prevented an assessment of potential population suppression. Furthermore, a contribution to these results from communication disruption cannot be ruled out. Replicated transects of frequency of infested shoots from a mature orchard across the adjacent young block confirmed that colonization by ovipositing females was essentially limited to the first 30 m.

Prognostic Value of Myocardial Scarring on CMR in Patients With Cardiac Sarcoidosis.

OBJECTIVES: This study sought to perform a systematic review and meta-analysis to understand the prognostic value of myocardial scarring as evidenced by late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging in patients with known or suspected cardiac sarcoidosis. BACKGROUND: Although CMR is increasingly used for the diagnosis of cardiac sarcoidosis, the prognostic value of CMR has been less well described in this population. METHODS: PubMed, Cochrane CENTRAL, and metaRegister of Controlled Trials were searched for CMR studies with ≥1 year of prognostic data. Primary endpoints were all-cause mortality and a composite outcome of arrhythmogenic events (ventricular arrhythmia, implantable cardioverter-defibrillator shock, sudden cardiac death) plus all-cause mortality during follow-up. Summary effect estimates were generated with random-effects modeling. RESULTS: Ten studies were included, involving a total of 760 patients with a mean follow-up of 3.0 ± 1.1 years. Patients had a mean age of 53 years, 41% were male, 95.3% had known extracardiac sarcoidosis, and 21.6% had known cardiac sarcoidosis. The average ejection fraction was 57.8 ± 9.1%. Patients with LGE had higher odds for all-cause mortality (odds ratio [OR]: 3.06; p < 0.03) and higher odds of the composite outcome (OR: 10.74; p < 0.00001) than those without LGE. Patients with LGE had an increased annualized event rate of the composite outcome (11.9% vs. 1.1%; p < 0.0001). CONCLUSIONS: In patients with known or suspected cardiac sarcoidosis, the presence of LGE on CMR imaging is associated with increased odds of both all-cause mortality and arrhythmogenic events.

Meta-Analysis of Diagnostic Performance of Coronary Computed Tomography Angiography, Computed Tomography Perfusion, and Computed Tomography-Fractional Flow Reserve in Functional Myocardial Ischemia Assessment Versus Invasive Fractional Flow Reserve.

We sought to compare the diagnostic performance of coronary computed tomography angiography (CCTA), computed tomography perfusion (CTP), and computed tomography (CT)-fractional flow reserve (FFR) for assessing the functional significance of coronary stenosis as defined by invasive FFR in patients with known or suspected coronary artery disease (CAD). CCTA has proved clinically useful for excluding obstructive CAD because of its high sensitivity and negative predictive value (NPV); however, the ability of CTA to identify functionally significant CAD has remained challenging. We searched PubMed/Medline for studies evaluating CCTA, CTP, or CT-FFR for the noninvasive detection of obstructive CAD compared with catheter-derived FFR as the reference standard. Pooled sensitivity, specificity, PPV, NPV, likelihood ratios, and odds ratio of all diagnostic tests were assessed. Eighteen studies involving a total of 1,535 patients were included. CTA demonstrated a pooled sensitivity of 0.92, specificity 0.43, PPV of 0.56, and NPV of 0.87 on a per-patient level. CT-FFR and CTP increased the specificity to 0.72 and 0.77, respectively (p = 0.004 and p = 0.0009) resulting in higher point estimates for PPV 0.70 and 0.83, respectively. There was no improvement in the sensitivity. The CTP protocol involved more radiation (3.5 mSv CCTA vs 9.6 mSv CTP) and a higher volume of iodinated contrast (145 ml). In conclusion, CTP and CT-FFR improve the specificity of CCTA for detecting functionally significant stenosis as defined by invasive FFR on a per-patient level; both techniques could advance the ability to noninvasively detect the functional significance of coronary lesions.