Wai-ee Thai

Assessment of mitral valve adaptation with gated cardiac computed tomography: validation with three-dimensional echocardiography and mechanistic insight to functional mitral regurgitation.

Background— Mitral valve (MV) enlargement is a compensatory mechanism capable of preventing functional mitral regurgitation (FMR) in dilated ventricles. Total leaflet area and its relation with closure area measured by 3-dimensional (3D) echocardiography have been related to FMR. Whether these parameters can be assessed with other imaging modalities is not known. Our objectives are to compare cardiac computed tomography (CT)–based measurements of MV leaflets with 3D echocardiography and determine the relationship of these metrics to the presence of FMR. Methods and Results— We used 2 cohorts of patients who had cardiac CT to measure MV total leaflet, closure, and annulus areas. In cohort 1 (26 patients), we validated these CT metrics to 3D echocardiography. In cohort 2 (66 patients), we assessed the relation of MV size with the presence of FMR in 3 populations: heart failure with FMR, heart failure without FMR, and normal controls. Cardiac CT and 3D echocardiography produced similar results for total leaflet (R 2=0.97), closure (R 2=0.89), and annulus areas (R 2=0.84). MV size was the largest in heart failure without FMR compared with controls and patients with FMR (9.1±1.7 versus 7.5±1.0 versus 8.1±0.9 cm2/m2; P<0.01). Patients with FMR had reduced ratios of total leaflet to closure areas and total leaflet to annulus areas when compared with patients without FMR (P<0.01). Conclusions— MV size measured by CT is comparable with 3D echocardiography. MV enlargement in cardiomyopathy suggests leaflet adaptation. Patients with FMR have inadequate adaptation as reflected by decreased ratios of leaflet area and areas determined by ventricle size (annulus and closure areas). These measurements provide additional insight into the mechanism of FMR.

Pulmonary Venous Anatomy Imaging with Low-Dose, Prospectively ECG-Triggered, High-Pitch 128-Slice Dual Source Computed Tomography

Background—The efforts to reduce radiation from cardiac computed tomography (CT) are essential. Using a prospectively triggered, high-pitch dual-source CT protocol, we aim to determine the radiation dose and image quality in patients undergoing pulmonary vein (PV) imaging. Methods and Results—In 94 patients (61±9 years; 71% male) who underwent 128-slice dual-source CT (pitch 3.4), radiation dose and image quality were assessed and compared between 69 patients with sinus rhythm and 25 patients with atrial fibrillation. Radiation dose was compared in a subset of 19 patients with prior retrospective or prospectively triggered CT PV scans without high pitch. In a subset of 18 patients with prior magnetic resonance imaging for PV assessment, PV anatomy and scan duration were compared with high-pitch CT. Using the high-pitch protocol, total effective radiation dose was 1.4 (1.3, 1.9) mSv, with no difference between sinus rhythm and atrial fibrillation (1.4 versus 1.5 mSv; P=0.22). No high-pitch CT scans were nondiagnostic or had poor image quality. Radiation dose was reduced with high-pitch (1.6 mSv) compared with standard protocols (19.3 mSv; P<0.0001). This radiation dose reduction was seen with sinus rhythm (1.5 versus 16.7 mSv; P<0.0001) but was more profound with atrial fibrillation (1.9 versus 27.7 mSv; P=0.039). There was excellent agreement of PV anatomy (&kgr; 0.84; P<0.0001) and a shorter CT scan duration (6 minutes) compared with magnetic resonance imaging (41 minutes; P<0.0001). Conclusions—Using a high-pitch dual-source CT protocol, PV imaging can be performed with minimal radiation dose, short scan acquisition, and excellent image quality in patients with sinus rhythm or atrial fibrillation. This protocol highlights the success of new cardiac CT technology to minimize radiation exposure, giving clinicians a new low-dose imaging alternative to assess PV anatomy.

Aortic Distensibility and its Relationship to Coronary and Thoracic Atherosclerosis Plaque and Morphology by MDCT: Insights from the ROMICAT Trial

BACKGROUND Multi-detector cardiac computed tomography (CT) allows for simultaneous assessment of aortic distensibility (AD), coronary atherosclerosis, and thoracic aortic atherosclerosis. OBJECTIVES We sought to determine the relationship of AD to the presence and morphological features in coronary and thoracic atherosclerosis. METHODS In 293 patients (53 ± 12 years, 63% male), retrospectively-gated MDCT were performed. We measured intraluminal aortic areas across 10 phases of the cardiac cycle (multiphase reformation 10% increments) at pre-defined locations to calculate the ascending, descending, and local AD (at locations of thoracic plaque). AD was calculated as maximum change in area/(minimum area × pulse pressure). Coronary and thoracic plaques were categorized as calcified, mixed, or non-calcified. RESULTS Ascending and descending AD were lower in patients with any coronary plaque, calcified or mixed plaque than those without (all p<0.0001) but not with non-calcified coronary plaque (p ≥ 0.46). Per 1mm Hg(-1) 10(-3) increase in ascending and descending AD, there was an 18-29% adjusted risk reduction for having any coronary, calcified plaque, or mixed coronary plaque (ascending AD only) (all p ≤ 0.04). AD was not associated with non-calcified coronary plaque or when age was added to the models (all p>0.39). Local AD was lower at locations of calcified and mixed thoracic plaque when compared to non-calcified thoracic atherosclerosis (p<0.04). CONCLUSIONS A stiffer, less distensible aorta is associated with coronary and thoracic atherosclerosis, particularly in the presence of calcified and mixed plaques, suggesting that the mechanism of atherosclerosis in small and large vessels is similar and influenced by advancing age.

Novel phase-based noise reduction strategy for quantification of left ventricular function and mass assessment by cardiac CT: comparison with cardiac magnetic resonance.

BACKGROUND Tube current modulation in retrospective ECG gated cardiac computed tomography (CT) results in increased image noise and may reduce the accuracy of left ventricular (LV) ejection fraction (EF) and mass assessment. OBJECTIVE To examine the effects of a novel CT phase-based noise reduction (NR) algorithm on LV EF and mass quantification as compared to cardiac magnetic resonance (CMR). METHODS In 40 subjects, we compared the LV EF and mass between CT and CMR. In a subset of 24 subjects with tube current modulated CT, the effect of phase-based noise reduction strategies on contrast-to-noise ratio (CNR) and the assessment of LV EF and mass was compared to CMR. RESULTS There was excellent correlation between CT and CMR for EF (r=0.94) and mass (r=0.97). As compared to CMR, the limits of agreement improved with increasing strength of NR strategy. There was a systematic underestimation of LV mass by CT compared to CMR with no NR (-10.3±10.1g) and low NR (-10.3±12.5g), but was attenuated with high NR (-0.5±8.3g). Studies without NR had lower CNR compared to low and high NR at both the ES phase and ED phase (all p<0.01). CONCLUSIONS A high NR strategy on tube current modulated functional cardiac CT improves correlation of EF compared to CMR and reduces variability of EF and mass evaluation by increasing the CNR. In an effort to reduce radiation dose with tube current modulation, this strategy provides better image quality when LV function and mass quantification is needed.

Steroid Exposure, Acute Coronary Syndrome, and Inflammatory Bowel Disease: Insights into the Inflammatory Milieu

BACKGROUND Steroids are anti-inflammatory agents commonly used to treat inflammatory bowel disease. Inflammation plays a critical role in the pathophysiology of both inflammatory bowel disease and acute coronary syndrome. We examined the relationship between steroid use in patients with inflammatory bowel disease and acute coronary syndrome. METHODS In 177 patients with inflammatory bowel disease (mean age 67 years, 75% male, 44% Crohns disease, 56% ulcerative colitis), we performed a 1:2 case-control study matched for age, sex, and inflammatory bowel disease type, and compared 59 patients with inflammatory bowel disease with acute coronary syndrome to 118 patients with inflammatory bowel disease without acute coronary syndrome. Steroid use was defined as current or prior exposure. Acute coronary syndrome was defined as myocardial infarction or unstable angina, confirmed by cardiac biomarkers and coronary angiography. RESULTS In patients with inflammatory bowel disease, 34% with acute coronary syndrome had exposure to steroids, vs 58% without acute coronary syndrome (P < .01). Steroid exposure reduced the adjusted odds of acute coronary syndrome by 82% (odds ratio [OR] 0.39; 95% confidence interval [CI], 0.20-0.74; adjusted OR 0.18; 95% CI, 0.06-0.51) in patients with inflammatory bowel disease, 77% in Crohns disease (OR 0.36; 95% CI, 0.14-0.92; adjusted OR 0.23; 95% CI, 0.06-0.98), and 78% in ulcerative colitis (OR 0.41; 95% CI, 0.16-1.04; adjusted OR 0.22; 95% CI, 0.06-0.90). There was no association between other inflammatory bowel disease medications and acute coronary syndrome. CONCLUSIONS In patients with inflammatory bowel disease, steroid use significantly reduces the odds of acute coronary syndrome. These findings provide further mechanistic insight into the inflammatory processes involved in inflammatory bowel disease and acute coronary syndrome.

Preprocedural Imaging for Patients with Atrial Fibrillation and Heart Failure

Various electrophysiological procedures and device implantation has been shown to improve morbidity and mortality in patients with atrial fibrillation (AF) and patients with heart failure (HF). Noninvasive cardiac imaging is used extensively in the preprocedural patient selection and for procedural guidance. In this review, we will discuss the application of preprocedural cardiac imaging in patients with AF prior to pulmonary vein and left atrial ablation as well as insertion of left atrial occluder device. We also discuss the role of noninvasive cardiac imaging in the selection of appropriate HF patients for device therapy as well as their use in guiding implantation of biventricular pacemaker for cardiac resynchronization therapy by assessing left ventricular ejection fraction, coronary venous anatomy, mechanical dyssynchrony and myocardial scar. We describe new research associated with preprocedural imaging in these patient cohorts.

Incremental value of cystatin C over conventional renal metrics for predicting clinical response and outcomes in cardiac resynchronization therapy: The BIOCRT study.

BACKGROUND Despite the benefit of CRT in select patients with heart failure (HF), there remains significant need for predicting those at risk for adverse outcomes for this effective but costly therapy. CysC, an emerging marker of renal function, is predictive of worsening symptoms and mortality in patients with HF. This study assessed the utility of baseline and serial measures of cystatin C (CysC), compared to conventional creatinine-based measures of renal function (estimated glomerular filtration rate, eGFR), in predicting clinical outcomes following cardiac resynchronization therapy (CRT). METHODS In 133 patients, we measured peripheral venous (PV) and coronary sinus (CS) CysC concentrations and peripheral creatinine levels at the time of CRT implant. Study endpoints included clinical response to CRT at 6 months and major adverse cardiac events (MACE) at 2 years. RESULTS While all 3 renal metrics were predictive of MACE (all adjusted p ≤ 0.02), only CysC was associated with CRT non-response at 6 months (adjusted odds ratio 3.6, p = 0.02). CysC improved prediction of CRT non-response (p ≤ 0.003) in net reclassification index analysis compared to models utilizing standard renal metrics. Serial CysC > 1mg/L was associated with 6-month CRT non-response and reduced 6-minute walk distance as well as 2-year MACE (all p ≤ 0.04). CONCLUSION In patients undergoing CRT, CysC demonstrated incremental benefit in the prediction of CRT non-response when compared to standard metrics of renal function. Baseline and serial measures of elevated CysC were predictive of CRT non-response and functional status at 6 months as well as long-term clinical outcomes.

Utility of dual-source computed tomography in cardiac resynchronization therapy—DIRECT study

BACKGROUND Dual-source computed tomography (CT) can evaluate left ventricular (LV) dyssynchrony, myocardial scar, and coronary venous anatomy in patients undergoing cardiac resynchronization therapy (CRT). OBJECTIVE We aimed to determine whether dual-source CT predicts clinical CRT outcomes and reduces intraprocedural time. METHODS In this prospective study, 54 patients scheduled for CRT (mean age 63 ± 11 years; 74% men) underwent preprocedural CT to assess their venous anatomy as well as CT-derived dyssynchrony metrics and myocardial scar. Based on 1:1 randomization, the implanting physician had preimplant knowledge of the venous anatomy in half the patients. In blinded analyses, we measured time to maximal wall thickness and inward wall motion to determine (1) CT global and segmental dyssynchrony and (2) concordance of lead location to regional LV mechanical contraction. End points were 6-month CRT response measured using heart failure clinical composite score and 2-year major adverse cardiac events (MACE). RESULTS There were 72% CRT responders and 17% with MACE. Two wall motion dyssynchrony indices-global wall motion and opposing anteroseptal-inferolateral wall motion-predicted MACE (P < .01). Lead location concordant to regions of maximal wall thickness was associated with less MACE (P < .01). No CT dyssynchrony metrics predicted 6-month CRT response (P = NS for all). Myocardial scar (43%), posterolateral wall scar (28%), and total scar burden did not predict outcomes (P = NS for all). Preknowledge of coronary venous anatomy by CT did not reduce implant or fluoroscopy time (P = NS for both). CONCLUSION Two CT dyssynchrony metrics predicted 2-year MACE, and LV lead location concordant to regions of maximal wall thickness was associated with less MACE. Other CT factors had little utility in CRT.

Cardiac Noninvasive Imaging: Chest Radiography, Cardiovascular Magnetic Resonance and Computed Tomography of the Heart

Non-invasive imaging plays an important role in the management of cardiac diseases. While chest radiography forms a standard part of the diagnostic work-up and follow-up of many cardiac patients, evolving technology related to cardiac computed tomography (CT) and cardiovascular magnetic resonance (CMR) imaging have contributed substantially to the diagnosis and prognosis of various cardiac pathologies. This chapter describes chest radiography findings of cardiopulmonary abnormalities and diseases, including recognition of valvular prostheses as well as pericardial and aortic abnormalities. This is followed by a section on cardiac CT and CMR where scan modes and sequences, indications specific to cardiology and safety issues are addressed.

SUPERIORITY OF CORONARY SINUS CARDIAC BIOMARKER SAMPLING OVER PERIPHERAL VENOUS BLOOD FOR PROGNOSTICATION IN CARDIAC RESYNCHRONIZATION THERAPY: THE BIOCRT STUDY

Coronary sinus (CS) blood is obtainable during implantation of cardiac resynchronization therapy (CRT). We aimed to determine whether CS or peripheral venous (PV) biomarkers are predictive of CRT response and major adverse cardiovascular events (MACE) using single and multi-marker strategies. In 73