**4.1 Current status of the patient-specific cardiac reshaping net and future direction**

PS-CRN is the device that compresses the primary LV surface, the annulus of the mitral, and tricuspid valves. The amount of compression is designed by the patient's LV end-diastolic pressure-volume relationship. These two key features allow the PS-CRN to apply sufficient constraining pressure on the LV surface without compromising RV diastolic function. This direct mechanical action immediately reduces LV diastolic volume (LV reverse remodeling) and the mitral and tricuspid annulus, ultimately reducing functional mitral and tricuspid regurgitation. A first-in-human study supported these hypotheses.

With the use of the insertion tool, device implantation does not require lifting of the heart, which can cause hypotension or ventricular arrhythmias. None of the four patients in the first-in-human study required IABP or cardiopulmonary support. Insertion time in the last case was only 1 minute. The minimally invasive nature of PS-CRN implantation ensures rapid recovery from surgery.

Another advantage of this device is the ease of postoperative care. No anticoagulation or immunosuppressive medications are required, as is the case with LVADs or heart transplantation.

#### **4.2 Limitations**

The lack of randomization and the small number of patients with its possibility of bias are clear limitations in drawing definitive conclusions from our first-in-human study and need to be addressed in further studies. Another limitation is the lack of long-term results.

Future randomized trials will determine whether the observed beneficial effect is significant and sustained in patients who are maintained on evidence-based heart failure therapies over the long term.

For this reason, we believe that this device should be used preferentially in older patients until long-term results demonstrate sustained beneficial effects, such as quality of life and survival. The younger patients, who are eligible for heart transplantation, should be informed that the use of PS-CRN may increase the risk of heart transplantation. Although successful heart transplantation after CorCap implantation has been reported, the procedure required longer time for dissection of the dense adhesion of CorCap and epicardium and pericardium [13, 14].
