Discussion
Both Revivent TC™ approaches are essentially less invasive than conventional SVR. Therapeutic volume reduction was achieved regardless of delivery method. Interestingly, there was no additional benefit of adding coronary revascularization to the procedure. This data compares favourably with the STICH sub-analysis, which established a survival benefit in patients realizing >30% reduction in LVESVI and/or post-operative LVESVI <60ml/m2 (4).
Surgical ventricular reconstruction or SVR, has been applied clinically in a large number of patients during the past two decades (5-9).In the STS database, for a 10 year period ending 2017, 2273 SVR procedures were undertaken. Mortality ranged between 8 and 15%. During the same period, 7205 LV aneurysm repairs were carried out.
SVR improves heart failure symptoms and long-term survival for patients with ischemic cardiomyopathy (10). The majority of cases in these studies underwent standard open-heart surgery via sternotomy with cardiopulmonary bypass, cardioplegic myocardial arrest, and ventriculotomy. Concomitant coronary revascularization was performed in most cases, sometimes also in combination with an intervention to the mitral valve for functional or secondary mitral valve regurgitation. Implantation of the Revivent TC™ System device does not require cardiopulmonary bypass, cardioplegic arrest, or a ventriculotomy. Implantation was initially performed with sternotomy, followed by the hybrid approach. Both approaches are less-invasive compared to standard SVR procedures.
The outcomes and the rate of adverse events during and after implantation of the Revivent TC™ System appear to be in an acceptable range when compared with SVR. The 30 day mortality of 5% in this group of patients is within the range of STS mortality. Hospital stay could be significantly reduced by using the hybrid approach rather than the initial surgical approach. The observed 1- and 2-year survival of 91% and 89%, respectively, are also comparable to SVR outcomes (11,12,13,14).
By comparison, the reported survival from the international Reconstructive Endoventricular Surgery returning Torsion Original Radius Elliptical shape to the left ventricle (RESTORE) registry of 1,198 post-anterior infarction SVR cases at 2-years was ~85%. Improvement in outcomes after implantation of the Revivent TC™ System should be possible through application of experience gained in selecting candidates and in the technique of implantation. This might also offer an alternative in patients at high risk of perioperative complications or with a frail preoperative condition.
An important element of the Revivent TC™ System implantation technique is that the anchor pairs are set to a configuration parallel to the long axis of the heart. Each tether and the excluded portion of the scar is taken from the short axis of the heart. With this configuration, virtually all volume reduction decreases the radius of the LV and is not just the result of amputation of an apical aneurysm. Aligning good functioning myocardium edge to edge optimizes myocardial function. This is not the case with a Dacron patch which only reduces size of the LV cavity but offers an akinetic neo LV wall. Reduction in wall tension, reorientation of myofibers, and improvement in torsional dynamics is, therefore, the most likely explanation for the functional improvement observed in the patients.