Advances in valve replacement

Aortic valve replacement is becoming more common with almost 5,000 aortic valve replacements being carried out on the NHS in England between April 2011 and April 2012. Transcatheter aortic valve implantation (TAVI) is an established alternative to surgical valve replacement in the management of calcified severe aortic stenosis in those with co-morbidities or adverse features (advanced age, impaired left ventricular function), or in those where open surgery may be associated with unfavourable technical features, such as previous sternotomy with a patent internal mammary graft, porcelain aorta or previous thoracic radiation, rendering the operative field hostile. A large body of experience and evidence exists predominantly for two commonly used TAVI devices; namely the balloon-expandable Edwards Sapien Valve (ESV) (Edwards Lifesciences Ltd, Irvine, California, US) and the self-expanding Medtronic CoreValve (MCV) (Medtronic Inc, Minneapolis, Minnesota, US). Although the fundamental principle behind the two valves is similar, both involving a stent with three bioprosthetic cusps (leaflets) deployed within a calcified native aortic valve, the specific design features and potential indications are different. That said, studies have not shown a difference in mortality between the two valve types.

Patients may undergo cardiac catheterizationn to confirm a diagnosis of heart disease as well as treating and replacing a faulty valve.Whilst it can seem a daunting procedure for patients, it’s reassuring for them to know that cardiac catheterization has been around since the early 1940s with the advent of catheter-based interventions, pioneered by Andreas Gruentzig in the late 1970s. Since then, there has been considerable progress in the refinement and expansion of these techniques.

Continuing Education is important to keep physicians up to speed in the ever-changing world of invasive and non-invasive cardiac techniques. With this in mind Radcliffe Cardiology’s website is a good source of information for continuing education and includes many articles as well as round table discussions on TAVI and other procedures.

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Drug-eluting balloons more successful than other treament in coronary restenosis

Drug-Eluting Balloons (DEBs) are conventional semi-compliant angioplasty balloons covered with an antirestenotic drug which is released into the vessel wall during inflation of the balloon, usually at nominal pressures with a specific minimal inflation time. The active substance on the Drug-Eluting Balloons should be lipophilic enough to have a high absorption rate through the vessel wall to compensate for the short period of contact between the inflated balloon and the vessel wall itself, and to maintain a sustained effect once released.

Percutaneous treatment of complex coronary lesions, such as small-vessel heart disease, diabetes and long diffuse disease, remain hampered by suboptimal results, even with the use of drug-eluting stents (DES). The DEB is an interesting emerging device in the field of heart disease that optimises clinical outcomes in these specific lesions. The DEB may become a viable alternative treatment option for the inhibition of coronary restenosis and subsequent revascularisation, as it allows local release of a high-concentration antirestenotic drug, paclitaxel, into the coronary vessel without using a metal scaffold or durable polymers.

Several studies have already shown promising and consistent results in the treatment of in-stent restenosis. The DEB has demonstrated its added value compared with certain DES. Inspired by these results, an increasing number of studies have been started in different coronary lesion subsets to explore the value of the DEB in a broader range of lesions. It will be interesting for cardiology associates to see whether the DEB will find more indications beyond in-stent restenosis treatment. Moreover, will all DEBs offer the same added value, or will there be differences in efficacy among the DEBs produced by the various manufacturers? As was the case in the development of DES, now the puzzle pieces have to be put together for DEB. Potentially more good news on the horizon for cardiology associates.

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Safer alternatives to conventional coronary artery bypass (CCAB)

Adverse clinical consequences associated with conventional coronary artery bypass graft

surgery have largely been attributed to cardiopulmonary bypass circuit (CPB), hypothermic cardiac arrest, aortic cannulation and cross-clamping. Since the introduction of OPCAB for coronary artery disease, numerous studies have been published to evaluate the impact of OPCAB surgery compared with conventional coronary artery bypass graft surgery. However, subsequent prospective randomised studies and meta-analyses comparing OPCAB and CCAB surgery were performed on low-risk patients or mixed-risk populations. Due to underpowered design for infrequent complications, they usually failed to demonstrate a significant benefit of OPCAB surgery on early mortality and peri-operative major cardiac and cerebrovascular events. In recent years, further efforts have been made to elucidate the meaning of beating-heart concepts for patients with specific extra-cardiac and cardiac risk factors for extracorporeal circulation and cardioplegic arrest.

Several mono- and multicentre studies are currently available for patients with specific cardiac or extra-cardiac co-morbidities. Even if most of them were non-randomised and thus failed to reach American Heart Association (AHA)/American College of Cardiology (ACC) evidence level A, they still allow analysis of interim results for each specific peri-operative risk factor and help to shed light on these cardiology specialties. Particularly multi-risk patients and patients with severely reduced left ventricular function seem to benefit in terms of peri-operative mortality and major morbidity by avoiding cardiopulmonary bypass and cardioplegic arrest. Moreover, for most patients with significant extra-cardiac risk factors the incidence of peri-operative stroke was reduced. Further insight into these cardiology specialties and risk factors are evident in European Cardiology Review, 2007;3(1):126-128.

For those looking for information on electrophysiology, sister electrophysiology journal Arrhythmia & Electrophysiology Review (AER) is a good source of information. The lastest volume 3, Issue one, includes current recommendations for cardiac resynchronisation therapy to the ablation of arrhythmias in adult congenital heart disease. This electrophysiology journal is tri-annual, helping time-pressured general and specialist cardiologists to stay abreast of key advances and opinion in the arrhythmia and electrophysiology sphere.

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CABG or PCI for CAD?

Recent years have seen an ongoing debate as to whether heart surgery using coronary artery bypass graft (CABG) or the non-surgical procedure of percutaneous coronary intervention (PCI) is the most appropriate revascularisation strategy for patients with coronary artery disease (CAD), the most common form of cardiovascular disease. During PCI, a cardiologist feeds a deflated balloon or other device on a catheter from the inguinal femoral artery or radial artery up through blood vessels until they reach the site of blockage in the heart. X-ray imaging is used to guide the catheter threading. At the blockage, the balloon is inflated to open the artery, allowing blood to flow. This is then combined with stenting, whereby a short-wired mesh tube (or stent) is placed at the site of blockage to permanently open the artery. In patients treated with PCI, improvements in technology and antiplatelet therapy coupled with landmark studies have effectively led to the replacement of balloon angioplasty with coronary artery stenting, which is the current preferred method of PCI.

The Synergy between Percutaneous Coronary Intervention with TAXUS and Cardiac Surgery (SYNTAX) study was conducted with the intention of defining the specific roles of each therapy in the management of de novo three-vessel disease or left main CAD. Interim results after 12 months show that PCI leads to significantly higher rates of major adverse cardiac or cerebrovascular events compared with heart surgeryusing CABG (17.8 versus 12.4; p=0.002), largely owing to increased rates of repeat revascularisation. However, CABG was much more likely to lead to stroke. Interestingly, categorisation of patients by severity of CAD complexity according to the SYNTAX score has shown that there are certain patients in whom PCI can yield results that are comparable to, if not better than, those achieved with CABG.  

For the practitioner, the most important message to take away from the SYNTAX study is that patients with three-vessel disease should no longer be treated using a generalised approach, but rather should undergo a careful clinical evaluation and comprehensive assessment of CAD severity, alongside application of the SYNTAX score. This will help practitioners in selecting the most suitable therapy for each individual CAD patient and optimise outcomes for this most common form of cardiovascular disease.

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