A 78-year-old male patient with a medical history of hypertension, hyperlipidemia, coronary artery disease (CAD), and smoking presents for the evaluation of chest pain. The patient reports episodic chest pain that is retrosternal with left arm radiation for the last 3 months. The pain is largely related to exertion; however, he notes at times it occurs at rest as well without clear triggers. Each episode of chest pain lasts roughly 20 minutes before resolution. He had an inferior ST-segment elevation myocardial infarction 5 years before, and the coronary angiogram then showed total right coronary artery (RCA) occlusion, which was revascularized with a drug-eluting stent. The remainder of the angiogram at that time demonstrated nonobstructive plaque in the other coronary vessels. His medications include aspirin 81 mg daily, metoprolol 25 mg daily, losartan 50 mg daily, isosorbide mononitrate 60 mg daily, and atorvastatin 80 mg daily.
On examination, his heart rate is 68 bpm and blood pressure is 128/72. Cardiovascular examination discloses normal first and second heart sounds with no murmurs. The remainder of the examination is unremarkable. An electrocardiogram shows normal sinus rhythm with Q waves in the inferior leads, unchanged when compared with prior. He is referred for cardiac catheterization that shows a moderately obstructive focal lesion in the proximal left circumflex artery (LCx) that is graded as 60% by visual approximation, mild-moderate nonobstructive lesion in the mid LCx, unchanged mild nonobstructive disease in the left anterior descending artery (LAD), and a patent RCA stent with minimal restenosis. A hemodynamic assessment with instantaneous wave-free ratio (iFR) is performed at the proximal LCx site, which demonstrates a ratio of 0.81, and a drug-eluting stent is successfully placed with Thrombolysis in Myocardial Infarction 3 post-percutaneous coronary intervention (PCI) angiographic flow.
The correct answer is: C. Post-PCI hemodynamic assessment with either fractional flow reserve (FFR) or iFR of the LCx artery
This patient has known CAD on medical therapy that has progressed, and he now presents with progressive anginal symptoms. His coronary angiogram demonstrated a moderately obstructive lesion in the LCx by visual approximation, which was then appropriately assessed for physiologic significance by measuring an iFR.1 The lesion was hemodynamically significant with a positive iFR value (<0.90); therefore, PCI was performed with an angiographically successful result. Studies have demonstrated that impaired FFR or iFR after angiographically adequate PCI occurs in 20-25% of cases, with pressure loss identified at the treated lesion site as well as across other untreated plaques or diffusely diseased segment. In the DEFINE PCI (Physiologic Assessment of Coronary Stenosis Following PCI) study in patients with angina and either multivessel or multi-lesion CAD with an abnormal baseline iFR, post-PCI physiological assessment with iFR detected residual ischemia (iFR <0.90) in nearly 1 in 4 patients after coronary stenting despite an operator-determined angiographically successful result.2
Several large observational studies and post hoc analyses of randomized trials have established that post-PCI FFR and iFR values in the intervened coronary artery are independently predictive of long-term outcomes (higher is better).3-5 Prospective randomized studies with appropriate sample size and statistical power to determine whether functional optimization with FFR or iFR will improve long-term outcomes are important to perform. The large-scale DEFINE GPS (Distal Evaluation of Functional Performance with Intravascular Sensors to Assess the Narrowing Effect: Guided Physiologic Stenting) randomized clinical trial will evaluate whether guidance from a pre- and post-PCI iFR pullback will improve target vessel failure at 2 years when compared with a conventional non-physiology-guided PCI strategy.2
Deferring assessment to a noninvasive method with myocardial perfusion imaging at a later date is not appropriate to determine if the current PCI was successful because direct coronary physiology is superior to noninvasive ischemia-driven strategies (answer A). There was only minimal to mild stenosis of the RCA and the LAD, so further hemodynamic assessment of these vessels is not indicated and will not provide additional prognostic information (answer B).
References
- Knuuti J, Wijns W, Saraste A, et al. 2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes. Eur Heart J 2020;41:407-77.
- Jeremias A, Stone GW. Assessing Post-Percutaneous Coronary Intervention Physiology: Is Hyperemia Necessary? JACC Cardiovasc Interv 2020;13:1934-6.
- Hakeem A, Uretsky BF. Role of Postintervention Fractional Flow Reserve to Improve Procedural and Clinical Outcomes. Circulation 2019;139:694-706.
- Piroth Z, Toth GG, Tonino PAL, et al. Prognostic Value of Fractional Flow Reserve Measured Immediately After Drug-Eluting Stent Implantation. Circ Cardiovasc Interv 2017;10:e005233.
- DEFINE Studies Presented at TCT 2020 Address FFR/CFR and Post-PCI iFR (ACC.org). October 16, 2020. Available at https://www.acc.org/latest-in-cardiology/articles/2020/10/15/02/34/fri-1140am-define-flow-tct-2020. Accessed January 20, 2021.
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