**7. PCI versus CABG in acute coronary syndromes versus stable ischemic coronary artery disease**

### **7.1. Non-ST-elevation acute coronary syndromes (NSTEACS)**

Although there are limited studies designed to address this specific question, it is generally accepted that the same considerations that are used to decide between PCI and CABG in stable ischemic coronary artery disease would be applied when faced with an NSTEACS **(Class I recommendation, Level B evidence)**[14]. Comparisons between PCI and CABG have typically included a mixture of patients with stable and unstable symptoms [45]. The ERACI II study contained the highest proportion of patients with unstable symptoms constituting 92% of the randomized patients whereas MASS II included the least with 0% having unstable symptoms [60, 61]. However in a large meta-analysis including individual patient data from 10 large randomized studies (n=7812) did not reveal any significant interaction between the presence or absence of unstable symptoms and mode of revascularization (PCI vs CABG) with respect to mortality outcomes over a 5 year period [45].

The optimal approach to PCI in the setting of a NSTEACS and MVD is still somewhat uncertain. There are currently no randomized trials in the literature comparing the multivessel PCI to culprit only PCI in NSTEACS [62].

#### **7.2. ST -elevation acute coronary syndromes (STEACS)**

Primary PCI remains the main modality of revascularization in STEACS *(Class I recommenda‐ tion, Level A evidence)*. It is common to encounter MVD during the index angiogram for STEACS having an estimated incidence of up to 40-50 percent [62]. Current evidence supports primary PCI of the culprit vessel only, in the absence of hemodynamic instability, as the optimal approach [14, 62, 63]. *Multivessel PCI in this setting has been associated with a higher mortality and is not recommended (Class III recommendation, Level B evidence) [14, 62, 63].* The approach to residual coronary disease has been a subject of controversy and the decisions are likely made clinically on an individual basis.
