Neuromodulation in patients with refractory angina pectoris: a review.

The number of patients with coronary artery disease (CAD) who have persisting angina pectoris despite optimal medical treatment known as refractory angina pectoris (RAP) is growing. Current estimates indicate that 5-10% of patients with stable CAD have RAP. In absolute numbers, there are 50 000-100 000 new cases of RAP each year in the USA and 30 000-50 000 new cases each year in Europe. The term RAP was formulated in 2002. RAP is defined as a chronic disease (more than 3 months) characterized by diffuse CAD in the presence of proven ischaemia which is not amendable to a combination of medical therapy, angioplasty, or coronary bypass surgery. There are currently few treatment options for patients with RAP. One such last-resort treatment option is spinal cord stimulation (SCS) with a Class of recommendation IIB, level of evidence B in the 2019 European Society of Cardiology guidelines for the diagnosis and management of chronic coronary syndromes. The aim of this review is to give an overview of neuromodulation as treatment modality for patients with RAP. A comprehensive overview is given on the history, proposed mechanism of action, safety, efficacy, and current use of SCS.

Changes in coronary collateral function after successful chronic total occlusion percutaneous coronary intervention.

BACKGROUND: Contemporary chronic total occlusion (CTO) percutaneous coronary intervention (PCI) incorporates wire escalation and dissection/re-entry recanalisation strategies. AIMS: The purpose of the study was to investigate changes in collateral function after CTO PCI and to identify whether the mode of successful recanalisation influences collateral function regression. METHODS: Patients scheduled for elective CTO PCI with evidence of viability in the CTO territory by noninvasive imaging were included in this study. After successful CTO PCI, the aortic pressure (Pa) and distal coronary artery wedge pressure (Pw) during balloon occlusion were measured, both in a resting state and during infusion of intravenous adenosine, allowing the calculation of the pressure-derived collateral pressure index at rest and hyperaemia (CPIrest and the collateral fractional flow reserve [FFRcoll], respectively). Measurements were repeated 3 months later during angiographic follow-up. RESULTS: Eighty-one patients had physiological measurements at baseline and follow-up. In the final cohort the mean age was 64 years and 82% were male. The mean maximal stent diameter and total stent length were 3.2±0.5 mm and 68±31 mm, respectively. Successful strategies were antegrade wiring (64.2%), antegrade dissection re-entry (8.6%), and retrograde dissection re-entry (27.1%). Between the index procedure and follow-up, wedge pressure decreased from 34±11 mmHg to 21±8.5 mmHg (p<0.01), respectively. FFRcoll changed from 0.34±0.11 to 0.19±0.09 (p<0.01) at follow-up and CPIrest from 0.40±0.14 to 0.17±0.09 (p<0.01). Absolute maximum collateral flow decreased from 55±32 ml/min directly after PCI to 38±24 ml/min (p<0.01). There was no relation between the recanalisation technique and changes in FFRcoll. CONCLUSIONS: There was a significant reduction in collateral flow over time, independent of the recanalisation technique.

Thermodilution-Based Invasive Assessment of Absolute Coronary Blood Flow and Microvascular Resistance: Quantification of Microvascular (Dys)Function?

During the last two decades, there has been a sharp increase in both interest and knowledge about the coronary microcirculation. Since these small vessels are not visible by the human eye, physiologic measurements should be used to characterize their function. The invasive methods presently used (coronary flow reserve (CFR) and index of microvascular resistance (IMR)) are operator-dependent and mandate the use of adenosine to induce hyperemia. In recent years, a new thermodilution-based method for measurement of absolute coronary blood flow and microvascular resistance has been proposed and initial procedural problems have been overcome. Presently, the technique is easy to perform using the Rayflow infusion catheter and the Coroventis software. The method is accurate, reproducible, and completely operator-independent. This method has been validated noninvasively against the current golden standard for flow assessment: Positron Emission Tomography-Computed Tomography (PET-CT). In addition, absolute flow and resistance measurements have proved to be safe, both periprocedurally and at long-term follow-up. With an increasing number of studies being performed, this method has great potential for better understanding and quantification of microvascular disease.

Recovery of Absolute Coronary Blood Flow and Microvascular Resistance After Chronic Total Occlusion Percutaneous Coronary Intervention: An Exploratory Study.

Background This study aimed to investigate longitudinal physiological changes in the recanalized coronary chronic total occlusion (CTO) vessel and its dependent myocardium after successful percutaneous coronary intervention (PCI). Methods and Results In this pilot study, 25 patients scheduled for elective CTO PCI with viable myocardium and angiographically visible collaterals were included. Absolute coronary blood flow and absolute microvascular resistance were measured invasively using continuous thermodilution. Measurements were performed immediately after successful CTO PCI and at short-term follow-up. In a subgroup of patients, physiological measurements were performed at the predominant donor vessel before CTO PCI, immediately afterwards, and at follow-up. Absolute coronary blood flow in the recanalized CTO artery increased from 148±53 mL/min immediately after PCI to 221±77 mL/min at follow-up (P<0.001). In agreement, absolute resistance in the myocardial territory perfused by the CTO artery, decreased from 545±255 Wood units immediately after the procedure to 387±128 Wood units at follow-up (P=0.014). There were no significant changes in the absolute coronary blood flow and resistance in the predominant donor between baseline and follow-up. Positive remodeling of the distal CTO vessel with an increase in lumen diameter was observed. Conclusions After successful CTO PCI, blood flow in the recanalized artery and microvascular function of the dependent myocardium are not immediately normal but recover over time.

Three-year clinical outcome in the Primary Stenting of Totally Occluded Native Coronary Arteries III (PRISON III) trial: a randomised comparison between sirolimus-eluting stent implantation and zotarolimus-eluting stent implantation for the treatment of total coronary occlusions.

AIMS: Sirolimus-eluting stents (SES) have been shown to be superior to Endeavor zotarolimus-eluting stents (ZES) and comparable to Resolute ZES at eight-month angiography in patients treated for total coronary occlusions (TCO). This study investigated clinical outcome at three-year follow-up. METHODS AND RESULTS: The PRISON III trial investigated the efficacy and safety of SES against ZES (Endeavor and Resolute) in two study phases. In the first phase, 51 patients were randomised to receive SES and 46 to Endeavor ZES. In the second phase, 103 and 104 patients were randomised to SES or Resolute ZES, respectively. Between one and three years there were only a few additional clinical events in all groups. As a result, the rates of target lesion revascularisation 12.2% vs. 19.6%, p=0.49, target vessel failure 14.3% vs. 19.6%, p=0.68, and definite or probable stent thrombosis 4.1% vs. 2.2% were comparable between SES and Endeavor ZES at three years. In the second study phase, the rates of target lesion revascularisation 10% vs. 5.9%, p=0.42, target vessel failure 10% vs. 7.9%, p=0.79 and definite or probable stent thrombosis 1.0% vs. 0% were similar between SES and Resolute ZES. CONCLUSIONS: The present study demonstrated a low incidence of clinical events between one- and three-year follow-up with either SES compared to Endeavor ZES or SES versus Resolute ZES in patients treated for total coronary occlusions.