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Groarke, John

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Groarke

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Groarke, John
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    The Incidence, Pattern, and Prognostic Value of Left Ventricular Myocardial Scar by Late Gadolinium Enhancement in Patients With Atrial Fibrillation
    (Elsevier BV, 2013) Neilan, Tomas; Shah, Ravi; Abbasi, Siddique Akbar; Farhad, Hoshang; Groarke, John; Dodson, John; Coelho-Filho, Otavio; McMullan, Ciaran Joseph; Heydari, Bobak; Michaud, Gregory F.; John, Roy M.; van der Geest, Rob; Steigner, Michael; Blankstein, Ron; Jerosch-Herold, Michael; Kwong, Raymond
    Objectives We aimed to identify the frequency, pattern, and prognostic significance of left ventricular (LV) late gadolinium enhancement (LGE) in patients with atrial fibrillation (AF). Background There are limited data on the presence, pattern, and prognostic significance of LV myocardial fibrosis in patients with AF. Late gadolinium enhancement during cardiac magnetic resonance (CMR) is a marker for myocardial fibrosis. Methods We studied a consecutive group of 664 patients without known prior myocardial infarction being referred for radiofrequency ablation of AF. CMR was requested to assess pulmonary venous anatomy. Results Overall, 73% were male, with an average age of 56 years, and an ejection fraction of 55±10%. Left ventricular LGE was found in 88 patients (13%). The endpoint was all-cause mortality, and in this cohort we observed 68 deaths over a median follow-up period of 42 months. On univariable analysis, age (HR 1.05, CI 1.03–1.08, LRχ2 15.2, p=0.0001), diabetes (HR 2.39, CI 1.41–4.09, LRχ210.3, p=0.001), a history of heart failure (HR 1.78, CI 1.09–2.91, LRχ2 5.37, p=0.02), left atrial dimension (HR 1.04, CI 1.01–1.08, LRχ2 6.47, p=0.01), presence of LGE (HR 5.08, CI 3.08–8.36, LRχ2 28.8, p<0.0001), and LGE extent (HR 1.15, CI 1.10–1.21, LRχ2 35.6, p<0.0001) provided the strongest association with mortality. The mortality rate was 8.1% per patient-years in patients with LGE vs. 2.3% patients without LGE. In the best overall multivariable model for mortality, age and the extent of LGE were independent predictors of mortality. Indeed, each 1% increase in LGE associated with a 15% increased risk of death. Conclusions In patients with AF, LV LGE is a frequent finding and is a powerful predictor of mortality.
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    Myocardial strain imaging with radial acquisitions (SIRA) reduces tag fading compared to Cartesian sampling
    (BioMed Central, 2014) Hulten, Edward; Shah, Ravi; Abbasi, Siddique; Neilan, Tomas; Feng, Jiazuo; Groarke, John; Waller, Alfonso H; Blankstein, Ron; Kwong, Raymond; Jerosch-Herold, Michael
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    Identifying Early Changes in Myocardial Microstructure in Hypertensive Heart Disease
    (Public Library of Science, 2014) Hiremath, Pranoti; Bauer, Michael; Aguirre, Aaron; Cheng, Hui-Wen; Unno, Kazumasa; Patel, Ravi B.; Harvey, Bethany W.; Chang, Wei-Ting; Groarke, John; Liao, Ronglih; Cheng, Susan
    The transition from healthy myocardium to hypertensive heart disease is characterized by a series of poorly understood changes in myocardial tissue microstructure. Incremental alterations in the orientation and integrity of myocardial fibers can be assessed using advanced ultrasonic image analysis. We used a modified algorithm to investigate left ventricular myocardial microstructure based on analysis of the reflection intensity at the myocardial-pericardial interface on B-mode echocardiographic images. We evaluated the extent to which the novel algorithm can differentiate between normal myocardium and hypertensive heart disease in humans as well as in a mouse model of afterload resistance. The algorithm significantly differentiated between individuals with uncomplicated essential hypertension (N = 30) and healthy controls (N = 28), even after adjusting for age and sex (P = 0.025). There was a trend in higher relative wall thickness in hypertensive individuals compared to controls (P = 0.08), but no difference between groups in left ventricular mass (P = 0.98) or total wall thickness (P = 0.37). In mice, algorithm measurements (P = 0.026) compared with left ventricular mass (P = 0.053) more clearly differentiated between animal groups that underwent fixed aortic banding, temporary aortic banding, or sham procedure, on echocardiography at 7 weeks after surgery. Based on sonographic signal intensity analysis, a novel imaging algorithm provides an accessible, non-invasive measure that appears to differentiate normal left ventricular microstructure from myocardium exposed to chronic afterload stress. The algorithm may represent a particularly sensitive measure of the myocardial changes that occur early in the course of disease progression.
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    Feasibility study of electrocardiographic and respiratory gated, gadolinium enhanced magnetic resonance angiography of pulmonary veins and the impact of heart rate and rhythm on study quality
    (BioMed Central, 2014) Groarke, John; Waller, Alfonso H; Vita, Tomas S; Michaud, Gregory F.; Di Carli, Marcelo; Blankstein, Ron; Kwong, Raymond; Steigner, Michael
    Background: We aimed to assess the feasibility of 3 dimensional (3D) respiratory and ECG gated, gadolinium enhanced magnetic resonance angiography (MRA) on a 3 Tesla (3 T) scanner for imaging pulmonary veins (PV) and left atrium (LA). The impact of heart rate (HR) and rhythm irregularity associated with atrial fibrillation (AF) on image and segmentation qualities were also assessed. Methods: 101 consecutive patients underwent respiratory and ECG gated (ventricular end systolic window) MRA for pre AF ablation imaging. Image quality (assessed by PV delineation) was scored as 1 = not visualized, 2 = poor, 3 = good and 4 = excellent. Segmentation quality was scored on a similar 4 point scale. Signal to noise ratios (SNRs) were calculated for the LA, LA appendage (LAA), and PV. Contrast to noise ratios (CNRs) were calculated between myocardium and LA, LAA and PV, respectively. Associations between HR/rhythm and quality metrics were assessed. Results: 35 of 101 (34.7%) patients were in AF at time of MRA. 100 (99%) patients had diagnostic studies, and 91 (90.1%) were of good or excellent quality. Overall, mean ± standard deviation (SD) image quality score was 3.40 ± 0.69. Inter observer agreement for image quality scores was substantial, (kappa = 0.68; 95% confidence interval (CI): 0.46, 0.90). Neither HR adjusting for rhythm [odds ratio (OR) = 1.03, 95% CI = 0.98,1.09; p = 0.22] nor rhythm adjusting for HR [OR = 1.25, 95% CI = 0.20, 7.69; p = 0.81] demonstrated association with image quality. Similarly, SNRs and CNRs were largely independent of HR after adjusting for rhythm. Segmentation quality scores were good or excellent for 77.3% of patients: mean ± SD score = 2.91 ± 0.63, and scores did not significantly differ by baseline rhythm (p = 0.78). Conclusions: 3D respiratory and ECG gated, gadolinium enhanced MRA of the PVs and LA on a 3 T system is feasible during ventricular end systole, achieving high image quality and high quality image segmentation when imported into electroanatomic mapping systems. Quality is independent of HR and heart rhythm for this free breathing, radiation free, alternative strategy to current MRA or CT based approaches, for pre AF ablation imaging of PVs and LA.