Left ventricular volume reduction and reshape – ‘Re‐<scp>STICHING</scp>’ the field. Reply
Authors: Patrick Klein, Stefan D. Anker, Andrew Wechsler, Sebastian Kelle
Journal: European Journal of Heart Failure (2020)

We thank Bonios et al. for their interesting and relevant remarks to our study of the Revivent TC System as an additional personalized therapy for a specific type of patients with heart failure after myocardial infarction with scar tissue in the antero-septal or apical wall of the left ventricle.1 Multiple publications described the clinical and functional improvement after (open) surgical ventricular reconstruction in patients with ischaemic cardiomyopathy. In line with these findings, we demonstrated at least equivalent functional and echocardiographic improvements by hybrid left ventricular (LV) reconstruction using the Revivent TC system. The basis for the rationale of LV reconstruction is, as Bonios et al. rightfully refer to, formed by the LaPlace law: decrease of LV volume reduces LV wall stress and both this and the (anatomic/physiologic) reconstruction improve LV contractile properties. Pressure–volume analysis provides the most comprehensive means of assessing ventricular contractile properties and the most rigorous means of measuring these relations in the clinical setting is with the conductance catheter as used by Tulner and colleagues from the Leiden University Medical Center.2, 3 They provided the scientific and pathophysiologic proof for LV reconstruction by demonstrating improvement in systolic and diastolic function, wall stress, dyssynchrony and mechanical efficiency by pressure–volume loop measurements. After surgical ventricular reconstruction, end-diastolic and end-systolic volumes were reduced from 211 ± 54 to 169 ± 34 mL (P = 0.03) and from 147 ± 41 to 110 ± 59 mL (P = 0.04), respectively. LV ejection fraction (from 27 ± 7% to 37 ± 13%, P = 0.04) and end-systolic elastance (from 1.12 ± 0.71 to 1.57 ± 0.63 mmHg/mL, P = 0.03) improved. Peak wall stress (from 358 ± 108 to 244 ± 79 mmHg, P < 0.01) and mechanical dyssynchrony (from 26 ± 4% to 19 ± 6%, P < 0.01) were reduced, whereas mechanical efficiency improved (from 0.34 ± 13 to 0.49 ± 0.14, P = 0.03). With regard to pressure–volume relations, there were leftward shifts of both end-diastolic and end-systolic pressure–volume relationships towards more normal volumes. Decreased ventricular compliance has also been demonstrated by them and also in other studies on LV reconstruction and moreover also in settings of prolonged myocardial ischaemia. Hybrid LV reconstruction or the Revivent procedure is performed on the beating heart, without cardioplegic arrest and without the use of an akinetic/stiff Dacron patch. Therefore, the impact on diastolic functional properties should be less than in its open-surgical predecessor. Essentially, it all comes down to determine the balance between the relatively beneficial effects of decreasing wall stress and the detrimental effects of increasing diastolic filling pressures as a consequence of reducing chamber volume. Michler et al.4 found that an LV end-systolic volume of 60 mL/m2 body surface area after reconstruction to be a threshold at or under which a mortality benefit was observed. As such, it does not represent a target, but rather the upper limit of the target volume. The fact that in the Revivent procedure, the heart is beating and anchors can be removed or adjusted, under-sizing would be recognized in real-time intraoperatively, and corrected. We fully agree with Bonios et al. that the exact/ideal volume that should be achieved after LV reconstruction in remodelled ventricles is still unclear and it could very well be that it should be personalized in every single patient. Concerning the changes in LV shape, we agree that additional data on pre- and postoperative shape would be very interesting. However, DiDonato and the RESTORE Group published already in 2006 that the adverse effects of ischaemic cardiomyopathy are statistically evident in every parameter except global sphericity, which remained unchanged between normal patients and those with dilated hearts after anterior infarction. Both ventricular length and width increased following anterior infarction, and hence the dimensionless ratio between length and width did not change, so that the sphericity index was unaltered.5 Classical parameters of LV shape such as the sphericity index therefore seem insufficient to assess improvements in LV shape post-reconstruction and therefore there is a need for new (perhaps three-dimensional or fusion) imaging parameters on shape (and function) in LV reconstruction procedures.