# Long-acting nitrate use before and after revascularization to evaluate angina in chronic coronary syndrome: a case-crossover study from SCAAR

## TL;DR

This study found that revascularization procedures reduce angina symptoms in chronic coronary syndrome patients, as indicated by decreased use of long-acting nitrates.

## Contribution

The study introduces a novel case-crossover design using long-acting nitrate prescriptions as a proxy for angina to evaluate revascularization efficacy in real-world populations.

## Key findings

- CABG surgery significantly reduced long-acting nitrate prescriptions compared to before treatment.
- Complete PCI was more effective than incomplete PCI in reducing nitrate use.
- No revascularization showed no change in nitrate prescriptions over time.

## Abstract

The ORBITA and ORBITA-2 trials have provided valuable insights into the effects of coronary revascularization in chronic coronary syndrome (CCS). However, uncertainties remain regarding the efficacy of revascularization on symptoms in large real-world populations. To evaluate the efficacy of revascularization, we used dispensed long-acting nitrates as a proxy for the presence of angina.

The Swedish Coronary Angiography and Angioplasty Registry (SCAAR) was used to identify all patients with CCS and at least one stenosis ≥50% undergoing angiography between the 1st of January 2014 and the 16th of January 2020. Four groups were defined based on treatment strategy: coronary artery bypass graft (CABG) surgery, complete revascularization with percutaneous coronary intervention (PCI), incomplete revascularization with PCI, and no revascularization. As patients in these treatment arms are inherently different, we employed a case-crossover design where each patient served as their own control with data collected during two periods: 1 year before up until angiography and 1–2 years after. This study design inherently controls for time-invariant confounding. The primary outcome was the use of long-acting nitrates defined as a dispensed prescription during the studied periods. Conditional Poisson regression was used to analyse the data.

For this study, 15,955 patients were eligible. CABG, complete revascularization with PCI, and incomplete revascularization with PCI were associated with a decrease in dispensed prescriptions of long-acting nitrates (from 989/2218 [30.8%] to 156/3207 [4.9%]; risk-ratio (RR): 0.16 [95% confidence interval (CI): 0.13–0.19]), (from 1676/7525 [22.3%] to 966/7525 [12.8%]; RR: 0.58 [95% CI: 0.53–0.62]), and (from 601/2180 [27.6%] to 495/2180 [22.7%]; RR: 0.82 [95% CI: 0.73–0.93]), respectively. No difference was observed for no revascularization (from 864/3043 [28.4%] to 856/3043 [28.1%]; RR: 0.99 [95% CI: 0.90–1.09]).

Revascularization reduces the use of long-acting nitrates in patients with CCS, suggesting angina symptom improvement. CABG appears to provide a more significant effect than PCI, with complete PCI demonstrating greater effectiveness than incomplete revascularization.

This work was supported by The Swedish Heart and Lung Foundation, ALF, Skane University Hospital funds, the Crafoord Foundation and the 10.13039/501100007308Swedish Medical Association.