Aortic stenosis (AS) is the most common valvular heart disease in industrialised countries with a prevalence of about 5 % in the general population aged greater than 75 years. During the past decade, transcatheter aortic valve replacement (TAVR) has emerged as a valuable, minimally invasive treatment option for patients presenting with symptomatic severe AS, who due to their advanced age and relevant comorbidities are at prohibitive risk for conventional surgery, 1 whereas surgical aortic valve replacement (SAVR) remains the gold standard for the treatment of symptomatic AS in patients with low to moderate surgical risk.2 However, many patients begin to experience AS-related symptoms late in their lives when multiple comorbidities preclude surgery as an option. As a result, before the advent of TAVR, patients considered high-or extreme-risk surgical candidates were once limited to conventional medical therapy. Ever since the first device was deployed in 2002, TAVR has enabled inoperable patients the opportunity to experience survival rates equivalent to their surgical counterparts with considerably less procedural risk.1 Therefore, the number of patients undergoing TAVR has increased steadily, and the complications related to valve implantation have been well defined.The development of atrioventricular (AV) conduction disturbances is one of the most commonly encountered complications associated with TAVR. Between 3 and 6 % of patients undergoing surgical replacement of their aortic valve will develop complete heart block (CHB), 3 while considerably higher rates have been reported in the setting of TAVR in individual studies. 4 In this review, we aim to explore the significance of conduction disturbances preceding and resulting from TAVR. We have focused on data that raise concerns around creating chronic left ventricular (LV) dyssynchrony in this patient population, either as a consequence of creating left bundle branch block (LBBB), or from chronic right ventricular (RV) pacing. Additionally, we reviewed a number of factors that predispose TAVR patients to develop conduction disturbances, and clinical factors that can be used to identify those patients likely to require permanent pacing and alternatively those in whom it may be worth waiting longer prior to committing to permanent pacemaker (PPM) implantation. Shy of unique valve designs, it has become clear there are only modest improvements an operator can make to avoid the complication of heart block and this complication is simply part of the procedure. It is critical to anticipate it and think prospectively about the ideal pacing mode for the individual patient to prevent chronic LV dyssynchrony in those patients at highest risk. Mechanisms of Heart Block Anatomical Relationship of the Cardiac Conduction System and the Aortic RootSince the 16th century when Leonardo da Vinci conducted the first known cadaveric studies of the heart, the aortic root complex has been studied extensively. With the advent of percutaneous valves, there has been renewed interest ...

ImportanceIn patients with severe aortic valve stenosis at intermediate surgical risk, transcatheter aortic valve replacement (TAVR) with a self-expanding supra-annular valve was noninferior to surgery for all-cause mortality or disabling stroke at 2 years. Comparisons of longer-term clinical and hemodynamic outcomes in these patients are limited.ObjectiveTo report prespecified secondary 5-year outcomes from the Symptomatic Aortic Stenosis in Intermediate Risk Subjects Who Need Aortic Valve Replacement (SURTAVI) randomized clinical trial.Design, Setting, and ParticipantsSURTAVI is a prospective randomized, unblinded clinical trial. Randomization was stratified by investigational site and need for revascularization determined by the local heart teams. Patients with severe aortic valve stenosis deemed to be at intermediate risk of 30-day surgical mortality were enrolled at 87 centers from June 19, 2012, to June 30, 2016, in Europe and North America. Analysis took place between August and October 2021.InterventionPatients were randomized to TAVR with a self-expanding, supra-annular transcatheter or a surgical bioprosthesis.Main Outcomes and MeasuresThe prespecified secondary end points of death or disabling stroke and other adverse events and hemodynamic findings at 5 years. An independent clinical event committee adjudicated all serious adverse events and an independent echocardiographic core laboratory evaluated all echocardiograms at 5 years.ResultsA total of 1660 individuals underwent an attempted TAVR (n = 864) or surgical (n = 796) procedure. The mean (SD) age was 79.8 (6.2) years, 724 (43.6%) were female, and the mean (SD) Society of Thoracic Surgery Predicted Risk of Mortality score was 4.5% (1.6%). At 5 years, the rates of death or disabling stroke were similar (TAVR, 31.3% vs surgery, 30.8%; hazard ratio, 1.02 [95% CI, 0.85-1.22]; P = .85). Transprosthetic gradients remained lower (mean [SD], 8.6 [5.5] mm Hg vs 11.2 [6.0] mm Hg; P < .001) and aortic valve areas were higher (mean [SD], 2.2 [0.7] cm2 vs 1.8 [0.6] cm2; P < .001) with TAVR vs surgery. More patients had moderate/severe paravalvular leak with TAVR than surgery (11 [3.0%] vs 2 [0.7%]; risk difference, 2.37% [95% CI, 0.17%- 4.85%]; P = .05). New pacemaker implantation rates were higher for TAVR than surgery at 5 years (289 [39.1%] vs 94 [15.1%]; hazard ratio, 3.30 [95% CI, 2.61-4.17]; log-rank P < .001), as were valve reintervention rates (27 [3.5%] vs 11 [1.9%]; hazard ratio, 2.21 [95% CI, 1.10-4.45]; log-rank P = .02), although between 2 and 5 years only 6 patients who underwent TAVR and 7 who underwent surgery required a reintervention.Conclusions and RelevanceAmong intermediate-risk patients with symptomatic severe aortic stenosis, major clinical outcomes at 5 years were similar for TAVR and surgery. TAVR was associated with superior hemodynamic valve performance but also with more paravalvular leak and valve reinterventions.

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Young platelets were more reactive and, consistent with the irreversible binding of clopidogrel to P2Y12, this effect was more pronounced after treatment with clopidogrel. The reversible binding of ticagrelor to the platelet P2Y12 receptor may be advantageous in patients with a high platelet turnover.