Appropriate assessment using virtual reality simulation for a novel reshaped curve sheath during percutaneous left atrial appendage closure: a follow-up case report.

Background: We previously reported a case of successful percutaneous left atrial appendage closure (LAAC) for complex left atrial appendage (LAA) morphology using a handmade double-curve delivery sheath (DS) reshaped by a heat gun. However, whether the reshaped curve was appropriately adjusted as an optimal configuration for this patient's anatomy remained uncertain. Case summary: We established the LAAC procedural simulation model supported by virtual reality (VR) technology. With this VR simulator, the patient's whole heart model with venous access route and atrial septal puncture point of foramen ovale (FO) could be replicated based on the pre-procedural computed tomography image. Multiple views of the VR image provided a deep understanding of the patient-specific anatomy. Additionally, the operators were enabled to perform the virtual LAAC procedure using VR-derived LAAC devices, including various DS types. In the VR simulator, the manually reshaped DS showed better co-axiality from the FO to the LAA orifice than the conventional double-curve DS, resulting in the successful deployment inside the LAA of the VR simulator. However, the perpendicularity of the device towards the LAA orifice of the handmade reshaped DS remained insufficient. The VR simulator suggested that the ideal curve of the DS needed to change relatively posteriorly and have a more aggressive inferior slide than the previously reshaped DS. Discussion: The post-procedural review of the VR simulator confirmed that the sheath reshaping technique helped ensure successful LAAC. Pre-procedural VR simulation may be useful for procedural planning that includes DS reshaping for patients with challenging anatomy undergoing LAAC.

A case report of virtual reality-guided percutaneous coronary intervention for anomalous origin of right coronary artery chronic total occlusion.

Background: Engagement of the guiding catheter (GC) for the coronary artery is sometimes difficult, depending on the patient's anatomy. The most suitable GC before percutaneous coronary intervention (PCI) in individual cases has not been determined yet. Case summary: An 81-year-old woman who had a right coronary artery chronic total occlusion had difficulty to engage the catheter for the right coronary artery in the first examination. Virtual reality (VR)-guided GC simulation before PCI using cardiac computed tomography (CT) could overcome the difficulty of GC engagement for the coronary artery and achieve procedure success. Discussion: VR-guided GC simulation has the potential to solve the catheter approach difficulty for any cardiovascular intervention.

Fulminant myocarditis with complete atrioventricular block after mRNA COVID-19 vaccination: A case report.

A 71-year-old man was transferred urgently to our hospital after collapsing near his home post the first shot of the BNT162b2 coronavirus disease 2019 vaccine (Pfizer-BioNTech, Comirnaty®). Immediately after arrival at our hospital, cardiac arrest due to complete atrioventricular block with no ventricular escaped beats was observed on electrocardiogram. Echocardiography showed preserved left ventricular ejection fraction, however, diffuse severe hypokinesia was revealed after 3 weeks, and he died 3 months after admission because of worsening heart failure. An autopsy examination revealed eosinophilic myocarditis or hypersensitivity myocarditis with extensive fibrosis and widespread myocardial dropout throughout the heart. Learning objective: 1. Severe myocarditis occurs extremely rarely after mRNA coronavirus disease 2019 (COVID-19) vaccination. 2. Myocarditis after mRNA COVID-19 vaccination might cause complete atrioventricular block, followed by a course of decreased left ventricular ejection fraction. 3. Histologically, severe myocarditis after mRNA COVID-19 vaccination seems to present as fulminant necrotizing eosinophilic myocarditis or hypersensitivity myocarditis.

Clinical features and prognosis of patients with and without diabetes mellitus undergoing endovascular aortic aneurysm repair.

BACKGROUND: This study aimed to compare the clinical features and prognoses of patients with and without diabetes mellitus (DM) who underwent endovascular repair for aortic aneurysm (AA). METHODS: We analyzed the clinical database of a prospective multicenter study, registering 929 patients who underwent their first endovascular AA repair in Japan between January 2016 and June 2018. The baseline characteristics and prognoses (including all-cause mortality and cardiovascular events) after repair were compared between the DM and non-DM groups. Prognoses were also compared between the groups after propensity score matching. RESULTS: In total, 226 patients (24.3%) had DM. Compared with non-DM patients, DM patients had higher pack-years of smoking (P = 0.011), higher body mass index (P = 0.009), lower high-density lipoprotein cholesterol levels (P = 0.038), higher triglyceride levels (P = 0.025), and lower left ventricular ejection fraction (P = 0.005). Meanwhile, the low-density lipoprotein cholesterol and blood pressure levels showed no significant intergroup difference (all P > 0.05). DM patients had a higher prevalence of myocardial infarction (P = 0.016), history of coronary revascularization (P = 0.015), and lower extremity artery disease (P = 0.019). Lesion characteristics and procedures were similar between the groups (all P > 0.05). DM patients had a higher risk of all-cause mortality and cardiovascular events than non-DM patients (both P < 0.001). Subsequent propensity score matching also demonstrated that DM patients had a significantly lower rate of overall survival (P = 0.001) and freedom from cardiovascular events (P = 0.010). The Kaplan-Meier estimates at 1 year for the overall survival were 85.6% (95% confidence interval [CI], 80.9% to 90.5%) and 94.3% (95% CI, 91.7% to 97.0%) for patients with and without DM, respectively. The corresponding estimates for freedom from cardiovascular events were 79.8% (95% CI, 74.5% to 85.5%) and 87.7% (95% CI, 84.2% to 91.3%), respectively. CONCLUSIONS: Among patients undergoing endovascular AA repair, those with DM had more cardiovascular risk factors. DM patients had a higher incidence rate of all-cause mortality and cardiovascular events. Matching analysis indicated that DM per se would be a risk factor for poor prognoses after AA repair.

Effect of Crack Patterns in Calcified Plaque on Lumen Area after Stenting for a Severe Calcified Coronary Artery (from the Optical Frequency Domain Imaging-Guided Percutaneous Coronary Artery Intervention for Calcified Lesion Registry).

Background: Severely calcified coronary artery stenting remains a challenge due to stent thrombosis, target vessel failure, and higher mortality. Moreover, optimal vessel preparation for calcified plaque with a crack formation pattern has not been established yet. We aimed to identify the effect of crack formation in calcified plaque in the coronary artery on the lumen area after stenting. Materials and Methods: We evaluated 50 consecutive patients undergoing drug-eluting stent implantation for severely calcified lesions by using optical frequency domain imaging (OFDI) (54 lesions); we analyzed OFDI image slices every 3 mm and evaluated the segments of 242 images in those who had the arc of calcium more than 180°. Crack formation in calcified plaque was classified into three types: type 0, no cracks; type 1, no dissection between calcified plaque and vessel wall; and type 2, any dissection between calcified plaque and vessel wall. Results: Type 2 had a significantly higher area expansion ratio between preballooning and poststenting (type 0, 196% (interquartile range (IQR), 163-244); type 1, 210% (IQR, 174-244); type 2, 237% (IQR, 203-294)). Conclusions: The dissection between calcified plaque and vessel wall was a significant factor affecting lumen area expansion after stenting.

Reinforcement of the anchor balloon system in percutaneous coronary intervention: an in vitro assessment.

We evaluated the factors that increase the maximum static friction force between the anchoring balloon and the vessel wall. The anchor technique in percutaneous coronary intervention (PCI) may be better supported by a guiding catheter. However, in some cases, the anchor balloon does not perform optimally due to slippage within the anchoring vessel. Furthermore, the optimal procedure for balloon anchoring remains unknown. We evaluated the maximum static friction force of the anchor balloon via in vitro assessments using a simulated vessel model and coronary balloons. The simulated vessel model was composed of polytetrafluoroethylene, and its inner diameter was 1.5 mm. The various-sized balloons (diameter: 1.5 mm, 1.75 mm, and 2.0 mm; length: 10 mm and 15 mm) were inflated within the simulated vessel at various atmospheres. The maximum static friction force was measured by pulling on the balloon catheter shaft using 10-g weights. We performed the same experiment with a jailing 0.014″ wire under the anchoring balloon. Evaluated wires included a silicon coating coil wire, hydrophilic coating coil wire, polymer-coated non-tapering wire, and polymer-coated tapered wire. The maximum static friction force between the anchoring balloon and the simulated vessel increased with an increase in inflation pressure and balloon length. However, increasing the balloon diameter was not effective. The jailing 0.014″ wire, particularly coil wire, was effective in increasing the maximum static friction force of the anchor balloon. A longer balloon, higher inflation pressure, and jailing coil wire could reinforce the anchor balloon system.

Rate-dependent and unidirectional conduction block between the left pulmonary vein and left atrium after catheter ablation for atrial fibrillation.

A 77-year-old woman with symptomatic paroxysmal atrial fibrillation (PAF) underwent pulmonary vein isolation (PVI), but subsequently experienced recurrence. In the second session, unidirectional left atrium (LA)-left superior pulmonary vein (LSPV) conduction was revealed to exist at the carina of the LSPV. Left pulmonary vein (LPV) pacing performed in a cycle between 300 and 260 ms revealed rate-dependent pulmonary vein (PV)-LA conduction, and the location was estimated to be in the roof of the LSPV. PV isolation was achieved after ablation of two gaps. Consideration of the presence of rate-dependent gaps may be useful to confirm bidirectional block lines after ablation.

Long-Term Outcomes of Drug-Eluting Stent Implantation After Rotational Atherectomy for Left Main Coronary Artery Bifurcation Lesions.

The clinical outcomes of drug-eluting stent (DES) implantation after rotational atherectomy (RA) for complex left main coronary artery (LMCA) bifurcation lesions remain unclear. Among 1,809 patients retrospectively enrolled in the Assessing Optimal percutaneous coronary Intervention for LMCA Registry, we identified 1,199 patients with LMCA bifurcation lesions treated by crossover stenting with DES for the main vessel. The study population was divided according to the use of RA. The patients in the RA group were further subdivided into the 2 subgroups on the basis of the stenting approach. The rates of periprocedural myocardial infarction and in-hospital death in the RA group were comparable to those in the non-RA group. The cumulative 5-year incidences of all-cause death and target lesion revascularization (TLR) were significantly higher in the RA group than those in the non-RA group. However, after adjusting confounders, the excess risks of the RA group relative to the non-RA group for all-cause death and TLR were no longer significant (hazard ratio 0.95, 95% confidence intervals 0.59 to 1.52, p = 0.83, and hazard ratio 1.46, 95% confidence intervals 0.82 to 2.60, p = 0.20, respectively). In the RA group, the cumulative 5-year incidences of all-cause death and TLR were markedly higher in the 2-stent subgroup than in the 1-stent subgroup (58.1% vs 26.0%, p = 0.001, and 43.0% vs 16.3%, p = 0.001, respectively). In conclusion, DES implantation after RA was a safe and feasible strategy in treating those patients with complex LMCA bifurcation lesions. In this strategy, the 2-stent approach was associated with markedly worse 5-year clinical outcomes than the 1-stent approach.

Prognostic impact of final kissing balloon technique after crossover stenting for the left main coronary artery: from the AOI-LMCA registry.

It is still uncertain whether the final kissing balloon technique (FKBT) is mandatory after crossover stenting for the left main coronary artery (LMCA). Assessing Optimal Percutaneous Coronary Intervention for LMCA (AOI-LMCA) registry, a 6-center retrospective registry, enrolled 1809 consecutive patients for LMCA stenting in Japan. In the present analysis, 5-year clinical outcomes were compared between non-FKBT (n = 160) and FKBT (n = 578) groups in patients treated with crossover stenting with drug-eluting stents from the LMCA to the left anterior descending artery. Propensity score-matched analysis was also performed in 160 patient pairs. In the entire study population as well as in the propensity-matched population, the cumulative 5-year incidence of the primary outcome measure (target lesion revascularization: TLR) was not significantly different between the FKBT and non-FKBT groups (10.7 versus 14.3%, P = 0.49, and 11.8 versus 14.3%, P = 0.53, respectively). In the sensitivity analysis by the multivariable Cox proportional hazard model, the effect of FKBT relative to non-FKBT for TLR remained insignificant (adjusted HR 0.89, 95% CI 0.47-1.69, P = 0.72). Regarding the TLR location, there were no significant differences in the cumulative incidences of TLR for LMCA-only, for the main branch, and for the side branch between the 2 groups (2.2 versus 1.3%, P = 0.93, 11.8 versus 9.1%, P = 0.71, and 8.2 versus 7.6%, P = 0.82, respectively). FKBT after a 1-stent strategy for LMCA crossover stenting did not affect TLR and other clinical outcomes during 5-year follow-up.Clinical Trial Registration: Assessing Optimal Percutaneous Coronary Intervention for Left Main Coronary Artery Stenting Registry (AOI LMCA Stenting Registry). http://www.umin.ac.jp/ctr/index/htm/ . Unique Identifier: UMIN000014706.

Acute Coronary Syndrome With Unprotected Left Main Coronary Artery Culprit　- An Observation From the AOI-LMCA Registry.

BACKGROUND: Data on the clinical outcomes of percutaneous coronary intervention (PCI) for unprotected left main coronary artery (LMCA) in patients with acute coronary syndrome (ACS) are limited. Therefore, this study aimed to assess the clinical outcome of patients with ACS who underwent PCI for LMCA culprit lesion.Methods and Results:Of 1,809 patients enrolled in the Assessing Optimal Percutaneous Coronary Intervention for the LMCA (AOI-LMCA) registry (a retrospective 6-center registry of consecutive patients undergoing LMCA stenting in Japan), the current study population consisited of 1,500 patients with unprotected LMCA stenting for LMCA ACS (ACS with shock: 115 patients, ACS without shock: 281 patients) and stable CAD (1,104 patients). The cumulative 180-day incidence of death was markedly higher in the ACS with shock group than in the other groups (49.5%, 8.6%, and 3.3%, respectively; P<0.0001), but mortality beyond 180-day was not significantly different among the 3 groups (30.2%, 20.4%, and 19.5%, respectively; P=0.65). In the ACS with shock group, the initial TIMI flow grade did not affect 5-year mortality (57.1% and 62.2%, P=0.99), but in the ACS without shock group, 5-year mortality was significantly higher in patients with initial TIMI flow grade ≤1 than in patients with TIMI flow grade ≥2 (44.4% and 23.7%, respectively; P=0.008). CONCLUSIONS: In patients with LMCA ACS, survival correlates with baseline hemodynamic and coronary flow status.

Impact of previous drug-eluting stent restenosis in non-left main coronary artery lesions on long-term outcomes after left main coronary artery stenting: an observation from the AOI-LMCA registry.

We hypothesized that patients who had previous target-lesion revascularization (TLR) for DES restenosis in non-left main coronary artery (LMCA) lesions might have a higher risk for restenosis after subsequent DES implantation for a de novo unprotected LMCA lesion. Among 1809 patients enrolled in the Assessing Optimal Percutaneous Coronary Intervention for LMCA (AOI-LMCA) registry, which is a retrospective 6-centre registry of consecutive patients undergoing LMCA stenting in Japan, 251 patients with previous DES implantation for non-LMCA lesions were subdivided into the 2 groups with (N = 56) or without (N = 195) previous TLR in non-LMCA lesions. The risk for TLR for LMCA was neutral between the prior TLR for DES restenosis group and the no prior TLR for DES restenosis group [hazard ratio (HR) 0.99, 95% confidence interval (CI) 0.44-2.02, P = 0.98]. The risks for both TLR caused by restenosis of the LMCA main branch, and second TLR for restenosis after first TLR for LMCA were also neutral between the 2 groups (HR 0.42, 95% CI 0.10-1.25, P = 0.13, and HR 0.59, 95% CI 0.03-3.63, P = 0.60, respectively). In conclusion, prior TLR for DES restenosis in non-LMCA lesions was not associated with worse long-term clinical outcomes after DES implantation for de novo unprotected LMCA lesions. CLINICAL TRIAL REGISTRATION: Assessing Optimal Percutaneous Coronary Intervention for Left Main Coronary Artery Stenting Registry (AOI LMCA Stenting Registry). http://www.umin.ac.jp/ctr/index/htm/ . Unique Identifier: UMIN000014706.

Thoracic endovascular aortic repair with branched Inoue Stent Graft for arch aortic aneurysms.

BACKGROUND: Thoracic endovascular aortic repair (TEVAR) for thoracic aortic aneurysms (TAAs) is in rapid expansion due to its minimal invasiveness. However, TEVAR for an arch aneurysm with a straight stent graft needs surgical reconstruction for supra-aortic vessels. A branched stent graft pioneered by Inoue (branched Inoue Stent Graft [ISG]) has been expected to resolve this problem, but its utility remains to be established in the real clinical setting. This study evaluated the long-term clinical outcome of branched ISGs for TAAs. METHODS: Among 217 consecutive patients who underwent TEVAR with ISGs between March 2003 and September 2013, 89 patients with TAAs were treated with implantation of the branched ISG (single branch: n = 64; double branch: n = 18; triple branch: n = 7). The primary end point was freedom from aneurysm-related death. Secondary end points included periprocedural adverse events, freedom from all-cause death and major adverse events (composite of aneurysm-related death, surgical conversion, aneurysm rapture, persistent type I or III endoleak, graft infection, graft occlusion, graft migration, and aneurysm expansion), changes of aneurysm diameter, stroke, and any endovascular reintervention during follow-up. RESULTS: All deployments of branched ISGs were successful. The 30-day mortality was 4.5% (single branch, 3.1%; double branch, 0%; triple branch, 29%), and periprocedural stroke was 16% (single branch, 7.8%; double branch, 33%; triple branch, 42%). At 1 and 5 years, freedom from aneurysm-related death was 93% and 93%, respectively, and freedom from all-cause death was 85% and 59%, respectively. Survival free of major adverse events was 76% at 5 years. The cumulative incidence of stroke was 11% at 5 years. Three patients underwent surgical conversion because of persistent type I endoleak. One branch graft occlusion was observed at the left subclavian artery in a patient who received a double-branched graft. CONCLUSIONS: Periprocedural outcome of the single-branched ISG was acceptable, and long-term safety and efficacy were demonstrated. However, the procedural complications of the multibranched ISG leave room for improvement.

Comparison of endovascular repair with branched stent graft and open repair for aortic arch aneurysm.

OBJECTIVES: Although conventional open repair is our preference for patients with aortic arch aneurysms, we have often chosen thoracic endovascular aneurysm repair (TEVAR) with a handmade branched stent graft (bTEVAR) in high-risk patients. The aim of this study was to compare the midterm clinical outcomes of our bTEVAR technique to those of the open repair. METHODS: Between January 2007 and December 2014, we treated 129 patients with aortic arch aneurysm by means of either conventional open repair (OPEN, n = 61) or bTEVAR (n = 68) at our institution. RESULTS: The mean ages were 70.5 ± 12.7 years in the OPEN group and 72.7 ± 12.5 years in the bTEVAR group (P = 0.32). The aetiologies included true aneurysm in 101 patients (78.3%) and chronic dissection in 26 (20.1%). There were 2 (3.3%) in-hospital deaths in the OPEN group and 3 (4.4%) in the bTEVAR group. The mean follow-up duration was 3.0 ± 2.1 years (2.4 ± 1.9 years in the OPEN group and 3.6 ± 2.3 years in the bTEVAR group). There was no difference in 5-year aneurysm-related mortality between groups (10.7% in OPEN vs 12.8% in bTEVAR, P = 0.50). In terms of late additional procedures, however, none were required in the OPEN group, whereas 10 (15.4%) additional endovascular repairs and 4 (6.2%) open repairs were required in the bTEVAR group. CONCLUSIONS: Our bTEVAR could be performed with low early mortality, and it yielded similar midterm aneurysm-related mortality to that of conventional open repair. However, these patients undergoing this technique required more late additional procedures than those undergoing conventional open repair.

Long-Term Outcomes After Stent Implantation for Left Main Coronary Artery (from the Multicenter Assessing Optimal Percutaneous Coronary Intervention for Left Main Coronary Artery Stenting Registry).

We assessed long-term outcomes after left main coronary artery (LMCA) stenting based on lesion types and stenting strategies. In the Assessing Optimal percutaneous coronary Intervention for Left Main Coronary Artery stenting registry, we evaluated 1,607 consecutive patients undergoing stent implantation for unprotected LMCA lesions (bifurcation lesions: n = 1318 and nonbifurcation lesions: n = 289). Among the bifurcation lesions, 1,281 lesions were treated with stenting across the bifurcation (bifurcation 1-stent strategy: n = 999 or bifurcation 2-stent strategy: n = 282). Among the nonbifurcation lesions, 219 lesions were treated with nonbifurcation stenting. The median follow-up duration was 4.6 (95% CI 4.5 to 4.8) years. The 5-year risk of bifurcation lesions relative to nonbifurcation lesions was neutral for target lesion revascularization (TLR) (adjusted hazard ratio [HR] 0.82, 95% CI 0.55 to 1.23, p = 0.34) and all-cause death (adjusted HR 1.22, 95% CI 0.87 to 1.71, p = 0.26). The risk of the bifurcation 1-stent strategy relative to nonbifurcation stenting in nonbifurcation lesions was also neutral for TLR (adjusted HR 1.19, 95% CI 0.74 to 1.90, p = 0.47) and all-cause death (adjusted HR 0.81, 95% CI 0.56 to 1.18, p = 0.27). However, the bifurcation 2-stent strategy was associated with worse clinical outcomes than the bifurcation 1-stent strategy in TLR (adjusted HR 1.76, 95% CI 1.23 to 2.52, p = 0.002) and definite or probable stent thrombosis (crude HR 3.50, 95% CI 1.32 to 9.33, p = 0.01), despite neutral risk for all-cause death (adjusted HR 1.00, 95% CI 0.74 to 1.36, p = 0.99). There was no definite or probable very late stent thrombosis up to 5 years. In conclusion, long-term outcomes after stent implantation for unprotected LMCA lesions were not dependent on the bifurcation lesion types but related to the bifurcation stenting strategies with worse outcomes for the bifurcation 2-stent strategy.

Very Long-Term (10 to 14 Year) Outcomes After Percutaneous Coronary Intervention Versus Coronary Artery Bypass Grafting for Multivessel Coronary Artery Disease in the Bare-Metal Stent Era.

BACKGROUND: Many of the previous randomized trials comparing percutaneous coronary intervention (PCI) with coronary artery bypass grafting (CABG) in patients with multivessel coronary artery disease reported equivalent or better survival with CABG as compared with PCI at 5-year follow-up. However, 5-year follow-up might be too short to evaluate the true differences in long-term clinical outcomes between PCI and CABG. METHODS AND RESULTS: Among 8934 patients enrolled in the extended 10- to 14-year follow-up study of the CREDO-Kyoto registry cohort-1 (Coronary Revascularization Demonstrating Outcome study in Kyoto) conducted in the bare-metal stent era, 5152 (PCI: n=3490 and CABG: n=1662) patients had multivessel coronary artery disease without left main disease. Median follow-up duration was 11.2 (interquartile range: 10.2-12.2) years. The cumulative 10-year incidence of all-cause death was not significantly different between PCI and CABG (32.2% versus 31.7%; log-rank P=0.93). After adjusting for confounders, however, the mortality risk of PCI was significantly higher than that of CABG (hazard ratio, 1.19 [95% confidence interval, 1.02-1.39]; P=0.03). Within 5 years after the index procedure, the risk for all-cause death was significantly higher after PCI than after CABG (hazard ratio, 1.41; 95% CI, 1.12-1.79; P=0.004). By a landmark analysis at 5 years, however, the cumulative 10-year incidence of and adjusted risk for all-cause death beyond 5 years were not significantly different between PCI and CABG (19.3% versus 20.0%; log-rank P=0.22 and hazard ratio, 1.02, 95% confidence interval, 0.83-1.26; P=0.82). CONCLUSIONS: CABG as compared with PCI was associated with better 10-year survival in patients with multivessel coronary artery disease. However, the benefit of CABG compared with PCI on late mortality beyond 5 years was not observed in this study.

Prediction of the true fractional flow reserve of left main coronary artery stenosis with concomitant downstream stenoses: in vitro and in vivo experiments.

AIMS: The functional impact of downstream coronary stenoses on left main coronary artery (LMCA) stenosis has not been fully elucidated. This study therefore aimed to use in vitro and in vivo experiments to assess two novel equations that predict the true fractional flow reserve (FFR) of a left main coronary artery (LMCA) stenosis with concomitant downstream stenoses. METHODS AND RESULTS: Two novel equations were derived. One equation predicts the true fractional flow reserve (FFR) of an LMCA stenosis with a downstream stenosis (Equation A), and the other predicts the true FFR of an LMCA stenosis with downstream stenoses in both the left anterior descending and left circumflex arteries (Equation B). The equations were validated in both in vitro and in vivo models of the coronary circulation. The agreements between the apparent FFR (FFRapp), the predicted FFR (FFRpred) and the true FFR (FFRtrue) were assessed by Passing-Bablok regression analysis. Passing-Bablok regression analysis revealed that there were fixed proportional errors between FFRapp-m and FFRtrue-m, though a very small fixed error and no proportional errors between FFRpred-m and FFRtrue-m. The absolute differences between FFRpred and FFRtrue were significantly lower as compared to those between FFRapp and FFRtrue in all experiments. CONCLUSIONS: Two novel equations which predict the true FFR of LMCA stenosis were demonstrated to be correct. The study also revealed that the functional impact of downstream stenoses on the LMCA stenosis became stronger when the downstream stenoses became more severe.

In vitro assessment of physiological impact of recipient artery intervention on the contralateral donor artery.

BACKGROUND: Donor artery fractional flow reserve (FFR) often improves after treatment of recipient artery stenosis, but the physiological mechanism underlying this phenomenon has not been elucidated. This study aimed to assess two novel equations that explain the donor-recipient artery interaction. METHOD: Eq. (A) predicts the donor artery FFR after complete release of recipient artery stenosis, while Eq. (B) predicts the donor artery FFR after partial release of recipient artery stenosis. Eq. (B) is a general form of Eq. (A). FFR'1−pred = ((FFR1−CFI1)(FFR2−CFI2)−CFI1CFI2(1−FFR1)(1−FFR2)+CFI1(1−FFR1)(1−CFI2))/((1−C FI1)(FFR2−CFI2)) (A) FFR''1−pred = ((FFR1−CFI1)(FFR2−CFI2)−CFI1CFI2(1−FFR1)(1−FFR2)+CFI1(1−FFR1)(1−CFI2))FFR'2/((1−C FI1)(FFR2−CFI2)) (B) Eqs. (A) and (B) were assessed using an in vitro model of coronary circulation with a collateral channel connecting the donor and recipient arteries. RESULTS: The donor artery FFR always improved after releasing the recipient artery stenosis. A good linear correlation was found between the predicted FFR of Eq. (A) and the actual FFR (n=40, r=0.95, p<0.0001) and between the predicted FFR of Eq. (B) and the actual FFR (n=40, r=0.94, p<0.0001). CONCLUSIONS: Eqs. (A) and (B) accurately predicted the true FFR value of the donor artery in a coronary circulation model and explain the donor-recipient artery interaction observed in clinical practice.