Case Commentary

This fascinating case by Dr. Jon George brings to mind some of the biggest controversies in interventional cardiology. First, does revascularization improve outcomes in stable angina patients? The COURAGE trial suggested similar outcomes between revascularization and maximal medical therapy, but the FAME-2 trial demonstrated that PCI in stable patients with an FFR ≤0.80 reduces the composite of urgent revascularization and myocardial infarction.

Second, should CTOs be revascularized? To date, we have no randomized evidence that opening CTOs is of benefit, though clinical trials are underway. Conventionally, the presence of a well-collateralized vessel was felt to be evidence of sufficient perfusion to prevent necrosis and possibly ischemia. But as demonstrated by Sachdeva et al, the vessel distal to a CTO almost invariably has an FFR ≤0.80. This implies that collaterals are often insufficient to prevent ischemia, which brings up yet more unanswered questions. Does treating ischemia improve outcomes? Does FFR accurately reflect ischemia and/or viability in a CTO vessel/territory? We believe so, but FFR has not been specifically compared with noninvasive testing in this population, so an FFR ≤0.80 in a CTO vessel may not have the same implications as it does for a patent artery.

Is FFR measurement useful for CTOs, or is it more of an academic exercise? If the FFR turns out to be >0.80, should an operator stop a PCI after finally getting a balloon and wire across? Although a normal FFR might indicate a lack of myocardial viability, the temptation to finish off the intervention would be hard to resist after hours of effort have already expended.

Those of us who work in the cath lab generally subscribe to the intuitive notion that having an open artery is preferable to having a closed one. A CTO represents the extreme case of coronary artery disease, where this open-artery hypothesis should most apply. FFR could help identify patients who might benefit from CTO-PCI, but as it can only be measured once the wire is across, FFR is unlikely to become a practical tool for CTO operators.