Effects of coronary sinus Reducer implantation on oxygen kinetics in patients with refractory angina

Aims: Refractory angina is still a major public health problem. The coronary sinus Reducer (CSR) has recently been introduced as an alternative treatment to reduce symptoms in these patients. The aim of this study was to investigate objective improvements in effort tolerance and oxygen kinetics as assessed by cardiopulmonary exercise testing (CPET) in patients suffering from refractory angina undergoing CSR implantation.

Methods and results: In this multicentre prospective study, patients with chronic refractory angina undergoing CSR implantation were scheduled for CPET before the index procedure and at six-month follow-up. The main endpoints of this analysis were improvements in VO₂ max and in VO2 at the anaerobic threshold (AT). Clinical events and improvements in symptoms were also recorded. A total of 37 patients formed the study population. The CSR implantation procedure was successful and without complications in all. At follow-up CPET, significant improvement in VO₂ max (+0.97 ml/kg/min [+11.3%]; 12.2±3.6 ml/kg/min at baseline vs 13.2±3.7 ml/kg/min, p=0.026), and workload (+12.9 [+34%]; 68±28 W vs 81±49 W, p=0.05) were observed, with non-significant differences in VO2 at the AT (9.84±3.4 ml/kg/min vs 10.74±3.05 ml/kg/min, p=0.06). Canadian Cardiovascular Society (CCS) grade improved from a mean of 3.2±0.5 to 1.6±0.8 (p<0.01), and significant benefits in all Seattle Angina Questionnaire variables were shown.

Conclusions: In patients with obstructive coronary artery disease suffering from refractory angina, the implantation of a CSR was associated with objective improvement in exercise capacity and oxygen kinetics at CPET, suggesting a possible reduction of myocardial ischaemia.