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Highlights from Transcatheter Therapeutics 2017 12 January 2018BCS Editorial By: Conor McQuillan
As the latest TCT (Transcatheter Therapeutics) conference draws to a close the interventional community is left pondering treatment strategies for patients based on the latest clinical trials. In this editorial we review the evidence presented at TCT which is most likely to influence contemporary practice.
CULPRIT-SHOCK was the first big trial which may challenge current guidelines. The recently updated 2017 European Society of Cardiology (ESC) guidelines on the management of acute myocardial infarction upgraded their recommendation for complete revascularisation in patients with acute MI and shock from class III to class IIa.1 However, CULPRIT-SHOCK randomised 706 patients across 83 European centres with multivessel coronary artery disease, acute MI and shock to either culprit lesion only PCI (with the option of staged revascularisation) or immediate multivessel PCI. The composite primary endpoint (death or renal replacement therapy) was lower in the culprit only PCI group (45.9% vs 55.4%, RR 0.83, P=0.01), driven by a reduction in 30-day mortality.2 Time to haemodynamic stabilisation, peak troponin level and duration of catecholamine therapy did not differ between the two groups. It is speculated that higher contrast doses in the multivessel PCI group may have exacerbated acute left ventricular volume overload and contributed to a negative effect on myocardial contractility and recovery. Nevertheless, this study contradicts current guidelines and is likely to change revascularisation strategy for some patients.
The quality-of-life sub-study of the EXCEL trial (PCI vs CABG in patients with left main coronary disease) prospectively analysed the effects of revascularisation from the patient’s perspective. 1788 of the 1905 patients recruited to EXCEL were included in the sub-study which assessed QOL at baseline, 1, 12 and 36 months using the Seattle angina questionnaire and Rose dyspnoea scale. Both PCI and CABG improved QOL significantly from baseline. Unsurprisingly PCI was associated with a better QOL at 1 month compared to CABG, however this was largely attenuated by 12 months.3
Double kissing crush was superior to a provisional strategy for treating left main stem bifurcations according to the investigators in the DKCRUSH-V trial. 482 patients with distal left main bifurcation disease (Medina 1,1,1 or 0,1,1) were randomised to DKCRUSH or provisional strategy. Target lesion failure was more common with a provisional strategy (10.7% vs 5.0%, P=0.02), as was myocardial infarction, stent thrombosis and clinically driven target lesion revascularisation. Side branch pre-dilatation was high in the provisional group at 39.7% and proximal optimisation technique was lower in the provisional group (98.9% vs 99.2%) which may have influenced the outcomes.4 Certainly a DKCRUSH strategy should be considered when treating distal left main bifurcation disease and the EBC left main trial which is to be published in 2018 may shed further light on this.
Drug eluting balloons (DEB) are a reasonable alternative to further drug eluting stent (DES) implantation when treating in-stent restenosis (ISR) according to the DARE trial investigators. A total of 278 patients with ISR were randomised to DEB with a paclitaxel eluting balloon vs stenting with Xience everolimus eluting DES. Although the DES group had a better immediate result, 6-month follow up showed no difference in minimal lumen diameter and this translated to no difference in target lesion revascularisation at 12 months.5 DEB therefore is a reasonable strategy for treating ISR and negates the need for further metal.
The future of bioresorbable vascular scaffolds (BVS) suffered a further setback with results from the ABSORB II 4-year follow-up. Rates of stent thrombosis were significantly higher with BVS (3.0% vs 0.0%, P=0.03) although no new stent thrombosis was reported during 3 to 4 year follow up, the time in which BVS are expected to be fully resorbed.6 There was also a trend toward increased target lesion failure with BVS compared to Xience DES (11.5% vs 6.0%, P=0.06) but this did not reach statistical significance. Although a downturn of events were noted beyond the 3-year period where BVS are resorbed, operators and manufacturers remain sceptical and this is reflected in Abbotts’s decision to stop selling BVS.
Investigators of the REVASC trial aimed to demonstrate a benefit of CTO PCI on LV function by comparing segmental wall thickening and LV volumes using cardiac MRI in patients randomised to either CTO PCI or medical therapy. In this small study of 205 patients with either clinical or functional evidence of ischaemia, CTO PCI failed to improve regional or global LV function compared to medical therapy where CTO PCI success was 99% (following the second procedure).7
Operator radiation exposure in the cath lab could be reduced by the routine use of the RADPAD (a sterile, disposable, lead free shield) which is draped over the patient. The RECAP trial randomised 766 patients undergoing coronary procedures to RADPAD, NOPAD or SHAMPAD. Operator exposure was reduced by 20% with use of the RADPAD. Interestingly, use of the SHAMPAD correlated with a 43% higher relative radiation exposure compared to NOPAD which may represent operator behaviour in the presence of a PAD.8 This study supports the routine use of RADPAD as an adjunctive radioprotective device in the cath lab.
Further weight was added to the efficacy of DES over bare metal stents (BMS) with shorter dual antiplatelet therapy (DAPT) in the SENIOR trial. Investigators randomised 1200 patients >75 years presenting with ACS or stable CAD to either Synergy DES or BMS. Patients with stable CAD receive 1 month DAPT while unstable patients were prescribed 6 months DAPT. Approximately 20% patients in both DES and BMS arm continued DAPT for 12 months with no difference between these arms. At 1 year, the composite endpoint (all-cause mortality, MI, and ischemia-driven TLR) was lower in the DES group (11.6% vs 16.4%, P=0.01). There was no significant difference in death, MI, stroke or bleeding between the two groups. TLR was more common with BMS (5.9% vs 1.7%, P=0.0002).9 Therefore, BMS should not be used as a strategy to reduce DAPT duration in elderly patients >75 years and instead should receive DES with a bioabsorbable polymer.
Shorter durations of DAPT were also utilised in the DAPT-STEMI trial where patients received either 6 or 12 months of DAPT following STEMI PCI. Following up the 870 patients who were randomised after 6 months revealed that DAPT for 6 months was non-inferior to 12 months with respect to death, MI, stent thrombosis, revascularisation, stroke and major bleeding.10 This challenges current guidelines which recommend 12 months DAPT following STEMI but does provide physicians with some assurance that their patients should not come to harm if it is necessary to discontinue DAPT prematurely.
PCI for stable CAD was scrutinised with the ORBITA trial which randomised patients with ischaemic symptoms to either PCI or optimal medical therapy. 200 patients with single vessel stenosis >70% were intensively medically optimised over 6 weeks and subsequently randomised to PCI or placebo procedure. Lesions had a mean stenosis of 84%, FFR 0.69 and iFR 0.76 indicating that they were flow limiting, although operators were blinded to the FFR/iFR data.11 Surprisingly, at 6 week follow up, there was no statistically significant difference in the primary endpoint of exercise time increment between the two groups, however PCI did significantly reduce the ischaemic burden assessed by dobutamine stress echocardiography.
Although dominated by coronary intervention, TCT also played host to some important structural heart disease trials. Evidence for TAVI in intermediate risk patients with symptomatic severe aortic stenosis has been established with the PARTNER 2A and SURTAVI trials.12,13 A cost-effectiveness analysis, based upon an American based healthcare system, presented at TCT has added further weight to the argument. TAVI patients experienced a shorter procedure time (102 minutes vs 236 minutes, P<0.001) and shorter length of stay in hospital (6.4 vs 10.9 days, P<0.001). Index procedural costs were higher with TAVI, however reduced length of stay and follow up made it the economically dominant strategy in this patient cohort.14 Although the United Kingdom has a different remuneration system, these findings are still likely to be applicable in a system which is financially constrained with a large number of patients to treat.
The clinical impact of LBBB post TAVI is debatable but some studies suggest that these patients are at an increased risk of sudden cardiac death. The MARE trial aimed to clarify this by utilising ambulatory ECG monitoring with an implantable loop recorder (ILR) in patients with new onset LBBB post TAVI. 103 patients with new onset persistent LBBB (>3 days) following TAVI with CoreValve/ Evolut R and SAPIEN XT / SAPIEN 3 valves received an ILR. Bradyarrthymias were noted in 22 patients, 16 of which had high grade AV block, 10 of which received a pacemaker. 13 patients developed new onset atrial fibrillation/ flutter.15 MARE has drawn attention to the high risk of arrthymia in patients who develop persistent LBBB post TAVI and there may be a case for more intensive rhythm monitoring in this cohort.
Percutaneous mitral valve repair solutions are becoming increasingly innovative and are translating to the clinical setting. The TRACER trial presented 6 month outcomes for chordal repair of severe primary mitral regurgitation using the Harpoon mitral valve repair system. This beating heart, transventricular device allows real time imaging guided adjustment of chordae length. This study recruited 30 patients with severe degenerative MR and technical success was achieved in 28/30 cases. Mitral regurgitation was reduced to none/trace in 24/28 (86%) and mild in 4/28 (14%). There was no stroke, device embolisation or death and results were sustained to 6 months with 85% patients having mild MR or less.16 The Harpoon mitral valve repair system appears to be a viable and safe minimally invasive approach to treating severe degenerative MR and further validation in larger numbers of patients will be eagerly awaited.
A novel percutaneous suture device for closing patent foramen ovale (PFO) was revealed, where the procedure had been performed in 76 patients. The NobelStitch device uses a percutaneous suture mounted on a catheter to close PFO. The suture then promotes endothelialisation without leaving a device behind. Early experience from this Italian and Swedish registry has demonstrated the NobelStitch device to be effective in closing PFO with similar or slightly better efficacy than Amplatzer occluder devices with a better safety profile.17
Conclusion
TCT has once again demonstrated itself to be one of the world’s leading cardiology conferences with some dramatic and potentially practice changing studies and even a visit from Hollywood royalty, Tom Hanks, discussing his first-hand experience of undergoing PCI. It remains to be seen how the interventional community adopts the latest evidence and technology but there is no doubt that these influential trials will challenge current guidelines and practice.
References
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