Samuel Sidharta

Confirmation of the Intracoronary Near-Infrared Spectroscopy Threshold of Lipid-Rich Plaques That Underlie ST-Segment–Elevation Myocardial Infarction

Objective—In a previous exploratory analysis, intracoronary near-infrared spectroscopy (NIRS) found the majority of culprit lesions in ST-segment–elevation myocardial infarction (STEMI) to contain a maximum lipid core burden index in 4 mm (maxLCBI4mm) of >400. This initial study was limited by a small sample size, enrollment at a single center, and post hoc selection of the maxLCBI4mm ≥400 threshold. This study was designed a priori to substantiate the ability of NIRS to discriminate STEMI culprit from nonculprit segments and to confirm the performance of the maxLCBI4mm ≥400 threshold. Approach and Results—At 2 centers in the United States and Sweden, 75 STEMI patients underwent intracoronary NIRS imaging after establishing thrombolysis in myocardial infarction 3 flow, but before stenting. Blinded core laboratory analysis defined the culprit segment as the 10-mm segment distal to the proximal angiographic culprit margin. The remaining vessel was divided into contiguous 10-mm nonculprit segments. The maxLCBI4mm of culprit segments (median [interquartile range]: 543 [273–756]) was 4.4-fold greater than nonculprit segments (median [interquartile range]: 123 [0–307]; P<0.001). Receiver-operating characteristic analysis demonstrated that maxLCBI4mm differentiated culprit from nonculprit segments with high accuracy (c-statistic=0.83; P<0.001). A threshold maxLCBI4mm ≥400 identified STEMI culprit segments with a sensitivity of 64% and specificity of 85%. Conclusions—This study substantiates the ability of NIRS to accurately differentiate STEMI culprit from nonculprit segments and confirms that a threshold maxLCBI4mm ≥400 is detected by NIRS in the majority of STEMI culprits.

Tissue injury characterization by pre-contrast T1 mapping post myocardial infarction

Background Myocardial scar and edema can be assessed by late gadolinium enhancement (LGE) and T2W cardiac magnetic resonance (CMR) respectively, but each has important limitations. T1-mapping has emerged as an alternative method to characterize acute ischemic injury and contemporary mapping sequences make this clinically feasible. We assessed the T1 relaxation time in myocardial segments exhibiting varying degrees of ischemic injury in patients after acute MI. Methods T2W, T1-mapping (using Shortened Modified LookLooker Inversion recovery sequence) and LGE imaging was performed 24-72 hours after MI on a 1.5T scanner. Assessment of acute segmental damage, in a 16-segment AHA model, was performed on matched short axis slices. Mean segmental T1 values were calculated for infarcted, adjacent/edema, microvascular obstruction (MVO) or remote segments as defined by LGE. Results

The Innocent Bystander: Papillary Fibroelastoma

The Innocent Bystander: Papillary Fibroelastoma Andrew Li, MBBS, FHKCP, Shah M. Azarisman, MBBS, MMED, Karen S. L. Teo, MBBS, PhD, Matthew I. Worthley, MBBS PhD, Samuel Sidharta, MBBS, Timothy Glenie, MBBS, FRACP, Luay Samaraie, MBBS, FRACP, SK Chua, MBBS, MMED, Timothy J. Bailie, MBBS, FRACP, Robert Stuklis, FRACS, Stephen G. Worthley, MBBS, PhD Cardiovascular Research Centre and the Department of Medicine and the Department of Surgery, Royal Adelaide Hospital, University of Adelaide, Adelaide, South Australia, Australia, Department of Internal Medicine, International Islamic University Malaysia, Kuantan, Pahang, Malaysia, and the Department of Medicine, Ruttonjee Hospital, Wan Chai, Hong Kong.

Serial changes in vessel walls of renal arteries after catheter-based renal artery denervation: insights from volumetric computed tomography analysis

Aim Radiofrequency ablation of peri-arterial renal autonomic nerves has been studied as a potential therapeutic option for resistant hypertension. While recent clinical trials have reported its efficacy, there is paucity of data addressing the effects of the procedure on renal arteries, such as changes in vessel and lumen areas. Herein, the effect of atheroma burden on renal arteries after renal denervation was assessed using computed tomography (CT) imaging. Materials and methods Serial renal artery CT imaging was conducted in 38 patients from the EnligHTN™ I study, a prospective, multicenter study evaluating the efficacy of the EnligHTN multi-electrode radiofrequency ablation catheter in resistant hypertensive subjects. Cross-sectional images of renal arteries at 1 mm intervals were acquired using commercially available software (3mensio Structural Heart version 5.1). Vessel and lumen areas were manually traced in each image. Vessel wall volume (VWV) and percent vessel wall volume (P-VWV) were calculated. The measurements within the ablation (first 30 mm segments) and the non-ablation (subsequent 30 mm segment after the first bifurcation of renal arteries) zones were compared. Results On serial evaluation, greater increase in P-VWV and VWV was observed in the ablation zone (change in P-VWV, 6.7%±5.1% vs 3.6%±2.8%, P=0.001; change in VWV, 106.3±87.4 vs 23.0±18.2 mm3, P=0.001). Receiver-operating characteristic analysis demonstrated baseline P-VWV in the ablation zone >37.1% as an optimal cutoff value to predict its substantial progression after the procedure (area under the curve=0.88, sensitivity 89.8%, specificity 79.1%). Conclusion Change in vessel wall was greater within the segments receiving renal artery denervation. Baseline VWV predicted its substantial increase after the procedure. These observations suggest that atheroma burden within the renal arteries is a potential contributing factor to vascular changes after renal sympathetic denervation.

Evaluation of human coronary vasodilator function predicts future coronary atheroma progression

Objective Coronary vasodilator function and atherosclerotic plaque progression have both been shown to be associated with adverse cardiovascular events. However, the relationship between these factors and the lipid burden of coronary plaque remains unknown. These experiments focus on investigating the relationship between impaired coronary vasodilator function (endothelium dependent (salbutamol) and endothelium independent (glyceryl trinitrate)) and the natural history of atheroma plaque progression and lipid burden using dual modality intravascular ultrasound (IVUS) and near-infrared spectroscopy (NIRS) imaging. Methods 33 patients with stable chest pain or acute coronary syndrome underwent serial assessment of coronary vasodilator function and intracoronary plaque IVUS and NIRS imaging. Coronary segmental macrovascular response (% change segmental lumen volume (ΔSLV)), plaque burden (per cent atheroma volume (PAV)), lipid core (lipid-rich plaque (LRP) and lipid core burden index (LCBI)) were measured at baseline and after an interval of 12–18 months (n=520 segments). Results Lipid-negative coronary segments which develop into LRP over the study time period demonstrated impaired endothelial-dependent function (−0.24±2.96 vs 5.60±1.47%, P=0.04) and endothelial-independent function (13.91±4.45 vs 21.19±3.19%, P=0.036), at baseline. By multivariate analysis, endothelial-dependent function predicted ∆LCBI (β coefficient: −3.03, 95% CI (−5.81 to −0.25), P=0.033) whereas endothelial-independent function predicted ∆PAV (β coefficient: 0.07, 95% CI (0.04 to 0.10), P<0.0001). Conclusions Epicardial coronary vasodilator function is a determinant of future atheroma progression and composition irrespective of the nature of clinical presentation. Trial registration number ACTRN12612000594820, Post-results.

The relationship between segmental wall shear stress and lipid core plaque derived from near-infrared spectroscopy

BACKGROUND AND AIMS Wall shear stress (WSS) has an important role in the natural history of coronary atherosclerosis. The aim of this study is to investigate the relationship between WSS and the lipid content of atherosclerotic plaques as assessed by near-infrared spectroscopy (NIRS). METHODS We performed serial NIRS and intravascular ultrasound (IVUS) upon Doppler coronary flow guidewire of coronary plaques at baseline and after 12-18 months in 28 patients with <30% angiographic stenosis, who presented with coronary artery disease. Segmental WSS, plaque burden and NIRS-derived lipid rich plaque (LRP) were evaluated at both time-points in 482 consecutive 2-mm coronary segments. RESULTS Segments with LRP at baseline (n = 106) had a higher average WSS (1.4 ± 0.6 N/m2), compared to those without LRP (n = 376) (1.2 ± 0.6 N/m2, p<0.001). In segments without baseline LRP, WSS was higher in those who subsequently developed new LRP (n = 35) than those who did not (n = 341) (1.4 ± 0.8 vs. 1.1 ± 0.6 N/m2, p=0.002). Conversely, in segments with baseline LRP, WSS was lower in those who had regression of lipid content (n = 41) than those who did not (n = 65) (1.2 ± 0.4 vs. 1.6 ± 0.7 N/m2, p=0.007). Segments with the highest tertile of WSS displayed greater progression of LCBI irrespective of baseline lipid content (p<0.001). Multivariate analysis revealed that baseline WSS (p=0.017), PAV (p<0.001) and LCBI (p<0.001) were all independent predictors of change in LCBI over time. CONCLUSIONS Coronary segments with high WSS associate with progression of lipid content over time, which may indicate transformation to a more vulnerable phenotype.

Renal sympathetic denervation increases renal blood volume per cardiac cycle: a serial magnetic resonance imaging study in resistant hypertension

Aim Preclinical studies have demonstrated improvements in renal blood flow after renal sympathetic denervation (RSDN); however, such effects are yet to be confirmed in patients with resistant hypertension. Herein, we assessed the effects of RSDN on renal artery blood flow and diameter at multiple time points post-RSDN. Methods and results Patients (n=11) with systolic blood pressures ≥160 mmHg despite taking three or more antihypertensive medications at maximum tolerated dose were recruited into this single-center, prospective, non-blinded study. Magnetic resonance imaging indices included renal blood flow and renal artery diameters at baseline, 1 month and 6 months. In addition to significant decreases in blood pressures (p<0.0001), total volume of blood flow per cardiac cycle increased by 20% from 6.9±2 mL at baseline to 8.4±2 mL (p=0.003) at 1 month and to 8.0±2 mL (p=0.04) 6 months post-procedure, with no changes in the renal blood flow. There was a significant decrease in renal artery diameters from 7±2 mm at baseline to 6±1 mm (p=0.03) at 1 month post-procedure. This decrease was associated with increases in maximum velocity of blood flow from 73±20 cm/s at baseline to 78±19 cm/s at 1 month post-procedure. Notably, both parameters reverted to 7±2 mm and 72±18 cm/s, respectively, 6 months after procedure. Conclusion RSDN improves renal physiology as evidenced by significant improvements in total volume of blood flow per cardiac cycle. Additionally, for the first time, we identified a transient decrease in renal artery diameters immediately after procedure potentially caused by edema and inflammation that reverted to baseline values 6 months post-procedure.

SAFETY AND EFFICACY OF PRO ANP 31-67 IN CARDIORENAL SYNDROME: A FIRST-IN-HUMAN TRIAL

Congestive heart failure (CHF) remains one of the leading causes of cardiovascular death worldwide despite significant therapeutic advances in the management of this highly prevalent pathology. This study is designed to assess the renal and cardiac benefits of pro ANP 31-67 an endogenous linear

Fungal Obstruction of Transcatheter Aortic Valve Replacement Valve

An aged pensioner with a history of exertional dyspnea and severe aortic stenosis underwent uneventful J-type upper hemisternotomy with direct trans-aortic transcatheter aortic valve replacement (TAVR) of a 23-mm Edwards valve. Planned for review at 3 months, she returned 4 weeks early complaining of lethargy with no features of cardiac failure. Echocardiography revealed …

Use of Intravascular Ultrasound in Interventional Cardiology

For the last 60 years, coronary angiography remains the investigation of choice to evaluate coronary artery disease. Coronary angiography, however, only provides a two-dimensional “luminogram” of a three-dimensional arterial structure. As a result, its interpretation is subjected to interobserver variability and may be compounded by vessel overlapping and tortuosity. Intravascular ultrasound (IVUS), on the other hand, is a catheter-based technique which provides a comprehensive assessment of the entire vessel wall, including the extent and distribution of the atherosclerotic plaque. Owing to its high resolution, IVUS has been used extensively in various clinical and research settings. Some of the IVUS diagnostic applications include assessment of angiographically intermediate lesions particularly in the left main coronary artery. The use of IVUS at times may result in redirection of therapeutic management. IVUS is also extremely valuable in guiding percutaneous revascularisation strategies, especially in the case of left main coronary artery disease. It allows detailed pre-intervention evaluation of the target artery as well as post-intervention assessment of procedural outcome. This information is ultimately critical for the clinician to devise an appropriate procedural strategy to optimise clinical outcome. In atherosclerosis research, IVUS has provided a significant insight into the understanding of the natural history of atherosclerosis. The serial IVUS-measured atheroma change has been widely used as a surrogate end point in various pharmacological clinical trials. The development of new IVUS technology, such as virtual histology IVUS or combined IVUS with near-infrared spectroscopy has allowed further characterisation of atherosclerotic plaque, which may ultimately impact cardiovascular outcome.