Acute ST-segment myocardial infarction-evolution of treatment strategies

The commonest cause of acute myocardial infarction involves the rupture or erosion of vulnerable athero- sclerotic plaques followed by aggregation of platelets and subsequent thrombus formation, leading to par- tial or complete epicardial coronary arterial occlusion. Over the last 25 years, advancement in therapeutic options for acute myocardial infarction has resulted in substantial improvement in morbidity and mortal- ity. As a result, the absolute risk reduction of in-hos- pital deaths for patients presenting with STEMI has been on the decline in the last decade. The focus of the treatment for acute myocardial infarction invol- ves achieving epicardial and microvascular patency, prevention of recurrent ischaemic events while bal- ancing the risk of bleeding. This involves antiplatelet and antithrombotic therapies or fibrinolytic agents when timely performance of primary percutaneous coronary intervention is not possible. We review the evolution of treatment strategies for STEMI that has contributed to the improvement in patient outcome.Dennis T. L. Wong, Rishi Puri, Peter J. Psaltis, Stephen G. Worthley, Matthew I. Worthle

Acute ST-segment myocardial infarction—Evolution of treatment strategies

The commonest cause of acute myocardial infarction involves the rupture or erosion of vulnerable athero- sclerotic plaques followed by aggregation of platelets and subsequent thrombus formation, leading to par- tial or complete epicardial coronary arterial occlusion. Over the last 25 years, advancement in therapeutic options for acute myocardial infarction has resulted in substantial improvement in morbidity and mortal- ity. As a result, the absolute risk reduction of in-hos- pital deaths for patients presenting with STEMI has been on the decline in the last decade. The focus of the treatment for acute myocardial infarction invol- ves achieving epicardial and microvascular patency, prevention of recurrent ischaemic events while bal- ancing the risk of bleeding. This involves antiplatelet and antithrombotic therapies or fibrinolytic agents when timely performance of primary percutaneous coronary intervention is not possible. We review the evolution of treatment strategies for STEMI that has contributed to the improvement in patient outcome.Dennis T. L. Wong, Rishi Puri, Peter J. Psaltis, Stephen G. Worthley, Matthew I. Worthle

Appropriate indications for computed tomography coronary angiography

Computed tomography coronary angiography (CTCA) has been shown in multicentre trials to be reliable in ruling out significant coronary artery disease (CAD). It is used most appropriately in symptomatic patients with low to intermediate pretest probability of CAD. It should not be used in asymptomatic subjects, patients with known significant CAD or patients with a high pretest probability of CAD. The radiation dose of CTCA was previously two to three times that of invasive coronary angiography but with modern protocols, it is similar or lower. Patients generally need to be in sinus rhythm, tolerate Β-blockers and nitrates, have a heart rate < 65 beats per minute, be able to hold their breath for 10 seconds, and have normal renal function.Gary Y H Liew, Michael P Feneley and Stephen G Worthle

Safety and efficacy of a multi-electrode renal sympathetic denervation system in resistant hypertension: The EnligHTN I trial

Aims: Catheter-based renal artery sympathetic denervation has emerged as a novel therapy for treatment of patients with drug-resistant hypertension. Initial studies were performed using a single electrode radiofrequency catheter, but recent advances in catheter design have allowed the development of multi-electrode systems that can deliver lesions with a pre-determined pattern. This study was designed to evaluate the safety and efficacy of the EnligHTN ™ multi-electrode system. Methods and results: We conducted the first-in-human, prospective, multi-centre, non-randomized study in 46 patients (67% male, mean age 60 years, and mean baseline office blood pressure 176/96 mmHg) with drug-resistant hypertension. The primary efficacy objective was change in office blood pressure from baseline to 6 months. Safety measures included all adverse events with a focus on the renal artery and other vascular complications and changes in renal function. Renal artery denervation, using the EnligHTN™ system significantly reduced the office blood pressure from baseline to 1, 3, and 6 months by -28/10, -27/10 and -26/10 mmHg, respectively (P &amp;lt; 0.0001). No acute renal artery injury or other serious vascular complications occurred. Small, non-clinically relevant, changes in average estimated glomerular filtration rate were reported from baseline (87 ± 19 mL/min/1.73 m2) to 6 months post-procedure (82 ± 20 mL/min/1.73 m2). Conclusion: Renal sympathetic denervation, using the EnligHTN™ multi-electrode catheter results in a rapid and significant office blood pressure reduction that was sustained through 6 months. The EnligHTN™ system delivers a promising therapy for the treatment of drug-resistant hypertension. © The Author 2013

End-stage renal failure is associated with impaired coronary microvascular function

Abstract Not AvailableAdam J. Nelson, Benjamin K. Dundon, Stephen G. Worthley, James D. Richardson, Rishi Puri, Dennis T.L. Wong, Patrick T. Coates, Randall J. Faull and Matthew I. Worthle

Cardiac flow component analysis

In a chamber of the heart, large-scale vortices are shown to exist as the result of the dynamic blood flow and unique morphological changes of the chamber wall. As the cardiovascular flow varies over a cardiac cycle, there is a need for a robust quantification method to analyze its vorticity and circulation. We attempt to measure vortex characteristics by means of two-dimensional vorticity maps and vortex circulation. First, we develop vortex component analysis by segmenting the vortices using an data clustering algorithm before histograms of their vorticity distribution are generated. The next stage is to generate the statistics of the vorticity maps for each phase of the cardiac cycle to allow analysis of the flow. This is followed by evaluating the circulation of each segmented vortex. The proposed approach is dedicated to examining vortices within the human heart chamber. The vorticity field can indicate the strength and number of large-scale vortices in the chamber. We provide the results of the flow analysis after vorticity map segmentation and the statistical properties that characterize the vorticity components. The success of the cardiac measurement and analysis is illustrated by a case study of the right atrium. Our investigation shows that it is possible to utilize a data clustering algorithm to segment vortices after vorticity mapping, and that the vorticity and circulation analysis of a chamber vorticity can provide new insights into the blood flow within the cardiovascular structure.Kelvin K.L. Wong, Jiyuan Tu, Richard M. Kelso, Stephen G. Worthley, Prashanthan Sanders, Jagannath Mazumdar, Derek Abbot

Coronary atheroma composition predicts endothelial dysfunction in non-ST segment myocardial infarction: novel insights with radiofrequency (iMAP) intravascular ultrasonography (IVUS)

Poster abstract TCT-648Abstract not availableRishi Puri, Stephen J. Nicholls, Danielle M. Brennan, Jordan Andrews, Gary Y. Liew, Angelo Carbone, Barbara Copus, Adam J. Nelson, Samir R. Kapadia, E. Murat Tuzcu, John F. Beltrame, Stephen G. Worthley, Matthew I. Worthle

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 nonablation (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 &gt;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. © 2018 Kataoka et al