Coronary Occlusion

The ACh‐provocation test was performed as described previously in the indication and procedure of the VSA Guideline by the Japanese Circulation Society.^{22 (link)} Coronary spasm was defined as total or subtotal obstruction within the borders of 1 isolated coronary segment as defined by the American Heart Association^{23 (link)} (focal spasm) or severe diffuse vasoconstriction (90% stenosis defined by the American Heart Association^{23 (link)} [76% to 90% narrowing of the luminal diameter]) observed in ≥2 adjacent coronary segments (diffuse spasm) of epicardial coronary arteries associated with transient myocardial ischemia, as evidenced by ischemic ST‐segment changes on the ECG. In the present study, we divided the patients positive for ACh‐provocation test into 2 groups based on the pattern of coronary artery spasm on coronary angiography during ACh‐provocation test: those with focal and those with nonfocal (diffuse) spasm patterns. Figure 1 shows coronary angiographic findings of representative cases of focal and diffuse spasm patterns. Patients who developed ACh‐induced focal spasm with or without diffuse spasm in other coronary segments were included into the focal spasm group (Figure 1A through 1C), whereas patients who had only ACh‐induced diffuse spasm were included in the diffuse spasm group (Figure 1D through 1F). In this study, ischemic ST‐segment changes were defined as ST‐segment elevation (>0.1 mV), ST‐segment depression (>0.1 mV) from baseline level occurring at 60 to 80 ms after J point in at least 2 contiguous leads on the 12‐lead ECG, or appearance of a new negative U wave on the ECG. Multivessel spasm was defined as ACh‐induced spasm of ≥2 major epicardial arteries. Myocardial lactate production was evidenced by comparing serum lactate concentrations at the root of the aorta and coronary sinus, sampled during myocardial ischemia induced by ACh‐provocation.

It is a preliminary report with a quasi-experimental design, and with a pre-test and post-test approach to compare the effect of PCI in CTO patients. Forty subjects were recruited from January through June 2019. The inclusion criteria in this study were: 1) coronary heart disease (CHD) patients who showed CTO on coronary angiography that involved only one coronary artery branch occlusion; 2) patients who were willing to sign the informed consent of the study to undergo elective PCI; 3) patients who did not have heart failure abnormalities; 4) age between 40 and 70 years; 5) not in the acute phase of myocardial infarction; 6) not having abnormalities on the 12-lead electrocardiography (ECG) (signs of acute ischemia in the form of ST-elevation or ST depression); 7) left ventricular ejection fraction (LVEF) > 50%; 8) angiography with critical stenosis > 90%; and 9) normal valvular function. Based on the included samples, patients who were: 1) with multi-vessel disease; 2) with stage V renal failure requiring regular hemodialysis; 3) with malignancy; 4) with conditions that do not allow elective PCI intervention; and 5) with diastolic dysfunction (> grade 1) on echocardiography, should be excluded from the study sample.

We started a CTO program in our institution in May 2007 with a low case volume during its initial stages increasing trend in patient recruitment with at least 50 procedures a year since 2013. Five workshops over 5 consecutive years with experienced operators were organized in our center as part of training in CTO-PCI and in order to improve local operators’ experience. We had a dedicated operator in our institution for CTOs, although a few procedures were performed by a second operator in the first 100 block of cases. A CTO was defined as the presence of a coronary artery segment obstruction greater than 3 months standing with Thrombolysis in Myocardial Infarction (TIMI) grade 0 flow [10 (link)]. All data were prospectively introduced into a database including all potential angiographic variables previously related to the difficulty of the procedural success such as ostial location for example [11 (link)]. Since the publication of the J-CTO score by Morino et al. [7 (link)] in 2011 derived from Multicenter CTO Registry in Japan [12 (link)] those variables related to the wire crossing time through a CTO in this study were introduced in our database and reviewed and checked retrospectively. The J-CTO score was derived from the analysis of a cohort of 494 CTO-PCIs defining the complexity of the cases in accordance with the guidewire crossing through the CTO segment within 30 min [7 (link)]. Five independent predictors were found: in segment or CTO entry tortuosity more than 45°, calcification, the CTO length ≥ 20 mm, a blunt stump and any reattempted procedure. The score gives one point to each variable, if present, categorizing the level of difficulty of the procedure in easy (J-CTO = 0), intermediate (J-CTO = 1), difficult (J-CTO = 2) and very difficult (J-CTO ≥ 3), respectively. A thorough review of the above-mentioned variables was carried out by two observers working in our cath lab and, in case of any discrepancy the opinion of a third examiner was asked and a final consensus was established. After completing the review, J-CTO variables of 50 randomly selected cases were examined again and the level of concordance between two observers was estimated in order to assess and resolve any possible interobserver bias. Successful angiographic result was defined when recanalization of the occluded artery with final TIMI flow grade III (TIMI III) and residual lesion less than 30% was achieved. All complication such as in-hospital death, peri-procedural myocardial infarction (MI), coronary perforation requiring pericardiocentesis, major vascular complications needing percutaneous or surgical intervention were reported and its incidence was compared between failed and successful procedure groups. Attribution of peri-procedural MI was in accordance with the universal definition of PCI-related MI (type 4a) [13 (link)].