In the cardiovascular device arena, as in so many other medical device fields, success tends to come only after halting progress. In coronary artery disease, for example, an interventional revolution began when angioplasty catheters were introduced to clear blocked arteries in the heart without the need for bypass surgery. However, plaque dissection and elastic recoil caused the vessels to abruptly close again, necessitating the development of stents to prop them open. Physicians soon discovered that bare-metal stents were plagued by high rates of gradual vessel re-closure (restenosis) due to accelerated neoinitimal cell growth inside the stented area, and drug-eluting stents came along to deal with that problem. Today, coronary revascularization procedures produce excellent long-term vessel patency, although not every problem has been solved and the field continues to evolve and improve. Atrial fibrillation (AF) ablation is following a similar path. Earlier versions of radiofrequency (RF) ablation catheters overheated tissue, so the tips were irrigated with saline to achieve a more controlled burn. Irrigation solved one problem but created another – electrophysiologists (EPs) no longer could use temperature measurement at the tissue surface to confirm that they had created adequate ablation lesions during the procedure. So sensors were developed to measure the force with which the ablation probe contacts tissue to give physicians feedback about whether or not they’re creating a competent lesion.
In the case of AF, however, these incremental advancements have so far failed to result in compelling efficacy across all types of disease and patients. The rates of AF elimination following catheter ablation range from 30% to 80%, according to the type of patient and the definition of success, which depends upon whether you include one or more procedures and concomitant anti-arrhythmic drugs. (The single-procedure success rate of Johnson & Johnson’s [J&J’s] market-leading RF catheter ThermoCool, as noted at its FDA panel approval hearing, was only 49%, for example
