Optimization of Absolute Coronary Blood Flow Measurements to Assess Microvascular Function: In Vivo Validation of Hyperemia and Higher Infusion Speeds.

BACKGROUND: Reliable assessment of coronary microvascular function is essential. Techniques to measure absolute coronary blood flow are promising but need validation. The objectives of this study were: first, to validate the potential of saline infusion to generate maximum hyperemia in vivo. Second, to validate absolute coronary blood flow measured with continuous coronary thermodilution at high (40-50 mL/min) infusion speeds and asses its safety. METHODS: Fourteen closed-chest sheep underwent absolute coronary blood flow measurements with increasing saline infusion speeds at different dosages under general anesthesia. An additional 7 open-chest sheep underwent these measurements with epicardial Doppler flow probes. Coronary flows were compared with reactive hyperemia after 45 s of coronary occlusion. RESULTS: Twenty milliliters per minute of saline infusion induced a significantly lower hyperemic coronary flow (140 versus 191 mL/min; P=0.0165), lower coronary flow reserve (1.82 versus 3.21; P≤0.0001), and higher coronary resistance (655 versus 422 woods units; P=0.0053) than coronary occlusion. On the other hand, 30 mL/min of saline infusion resulted in hyperemic coronary flow (196 versus 192 mL/min; P=0.8292), coronary flow reserve (2.77 versus 3.21; P=0.1107), and coronary resistance (415 versus 422 woods units; P=0.9181) that were not different from coronary occlusion. Hyperemic coronary flow was 40.7% with 5 mL/min, 40.8% with 10 mL/min, 73.1% with 20 mL/min, 102.3% with 30 mL/min, 99.0% with 40 mL/min, and 98.0% with 50 mL/min of saline infusion when compared with postocclusive hyperemic flow. There was a significant bias toward flow overestimation (Bland-Altman: bias±SD, -73.09±30.52; 95% limits of agreement, -132.9 to -13.27) with 40 to 50 mL/min of saline. Occasionally, ischemic changes resulted in ventricular fibrillation (9.5% with 50 mL/min) at higher infusion rates. CONCLUSIONS: Continuous saline infusion of 30 mL/min but not 20 mL/min induced maximal hyperemia. Absolute coronary blood flow measured with saline infusion speeds of 40 to 50 mL/min was not accurate and not safe.

Fractional Flow Reserve-Guided PCI or Coronary Bypass Surgery for 3-Vessel Coronary Artery Disease: 3-Year Follow-Up of the FAME 3 Trial.

BACKGROUND: Previous studies comparing percutaneous coronary intervention (PCI) with coronary artery bypass grafting (CABG) in patients with multivessel coronary disease not involving the left main have shown significantly lower rates of death, myocardial infarction (MI), or stroke after CABG. These studies did not routinely use current-generation drug-eluting stents or fractional flow reserve (FFR) to guide PCI. METHODS: FAME 3 (Fractional Flow Reserve versus Angiography for Multivessel Evaluation) is an investigator-initiated, multicenter, international, randomized trial involving patients with 3-vessel coronary artery disease (not involving the left main coronary artery) in 48 centers worldwide. Patients were randomly assigned to receive FFR-guided PCI using zotarolimus drug-eluting stents or CABG. The prespecified key secondary end point of the trial reported here is the 3-year incidence of the composite of death, MI, or stroke. RESULTS: A total of 1500 patients were randomized to FFR-guided PCI or CABG. Follow-up was achieved in >96% of patients in both groups. There was no difference in the incidence of the composite of death, MI, or stroke after FFR-guided PCI compared with CABG (12.0% versus 9.2%; hazard ratio [HR], 1.3 [95% CI, 0.98-1.83]; P=0.07). The rates of death (4.1% versus 3.9%; HR, 1.0 [95% CI, 0.6-1.7]; P=0.88) and stroke (1.6% versus 2.0%; HR, 0.8 [95% CI, 0.4-1.7]; P=0.56) were not different. MI occurred more frequently after PCI (7.0% versus 4.2%; HR, 1.7 [95% CI, 1.1-2.7]; P=0.02). CONCLUSIONS: At 3-year follow-up, there was no difference in the incidence of the composite of death, MI, or stroke after FFR-guided PCI with current-generation drug-eluting stents compared with CABG. There was a higher incidence of MI after PCI compared with CABG, with no difference in death or stroke. These results provide contemporary data to allow improved shared decision-making between physicians and patients with 3-vessel coronary artery disease. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02100722.

2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines.

AIM: The "2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease" provides an update to and consolidates new evidence since the "2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease" and the corresponding "2014 ACC/AHA/AATS/PCNA/SCAI/STS Focused Update of the Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease." METHODS: A comprehensive literature search was conducted from September 2021 to May 2022. Clinical studies, systematic reviews and meta-analyses, and other evidence conducted on human participants were identified that were published in English from MEDLINE (through PubMed), EMBASE, the Cochrane Library, Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. STRUCTURE: This guideline provides an evidenced-based and patient-centered approach to management of patients with chronic coronary disease, considering social determinants of health and incorporating the principles of shared decision-making and team-based care. Relevant topics include general approaches to treatment decisions, guideline-directed management and therapy to reduce symptoms and future cardiovascular events, decision-making pertaining to revascularization in patients with chronic coronary disease, recommendations for management in special populations, patient follow-up and monitoring, evidence gaps, and areas in need of future research. Where applicable, and based on availability of cost-effectiveness data, cost-value recommendations are also provided for clinicians. Many recommendations from previously published guidelines have been updated with new evidence, and new recommendations have been created when supported by published data.

2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines.

AIM: The "2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease" provides an update to and consolidates new evidence since the "2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease" and the corresponding "2014 ACC/AHA/AATS/PCNA/SCAI/STS Focused Update of the Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease." METHODS: A comprehensive literature search was conducted from September 2021 to May 2022. Clinical studies, systematic reviews and meta-analyses, and other evidence conducted on human participants were identified that were published in English from MEDLINE (through PubMed), EMBASE, the Cochrane Library, Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. STRUCTURE: This guideline provides an evidenced-based and patient-centered approach to management of patients with chronic coronary disease, considering social determinants of health and incorporating the principles of shared decision-making and team-based care. Relevant topics include general approaches to treatment decisions, guideline-directed management and therapy to reduce symptoms and future cardiovascular events, decision-making pertaining to revascularization in patients with chronic coronary disease, recommendations for management in special populations, patient follow-up and monitoring, evidence gaps, and areas in need of future research. Where applicable, and based on availability of cost-effectiveness data, cost-value recommendations are also provided for clinicians. Many recommendations from previously published guidelines have been updated with new evidence, and new recommendations have been created when supported by published data.

Quality of Life After Fractional Flow Reserve-Guided PCI Compared With Coronary Bypass Surgery.

BACKGROUND: Previous studies have shown that quality of life improves after coronary revascularization more so after coronary artery bypass grafting (CABG) than after percutaneous coronary intervention (PCI). This study aimed to evaluate the effect of fractional flow reserve guidance and current generation, zotarolimus drug-eluting stents on quality of life after PCI compared with CABG. METHODS: The FAME 3 trial (Fractional Flow Reserve Versus Angiography for Multivessel Evaluation) is a multicenter, international trial including 1500 patients with 3-vessel coronary artery disease who were randomly assigned to either CABG or fractional flow reserve-guided PCI. Quality of life was measured using the European Quality of Life-5 Dimensions (EQ-5D) questionnaire at baseline and 1 and 12 months. The Canadian Cardiovascular Class angina grade and working status were assessed at the same time points and at 6 months. The primary objective was to compare EQ-5D summary index at 12 months. Secondary end points included angina grade and work status. RESULTS: The EQ-5D summary index at 12 months did not differ between the PCI and CABG groups (difference, 0.001 [95% CI, -0.016 to 0.017]; P=0.946). The trajectory of EQ-5D during the 12 months differed (P<0.001) between PCI and CABG: at 1 month, EQ-5D was 0.063 (95% CI, 0.047 to 0.079) higher in the PCI group. A similar trajectory was found for the EQ (EuroQol) visual analogue scale. The proportion of patients with Canadian Cardiovascular Class 2 or greater angina at 12 months was 6.2% versus 3.1% (odds ratio, 2.5 [95% CI, 0.96-6.8]), respectively, in the PCI group compared with the CABG group. A greater percentage of younger patients (<65 years old) were working at 12 months in the PCI group compared with the CABG group (68% versus 57%; odds ratio, 3.9 [95% CI, 1.7-8.8]). CONCLUSIONS: In the FAME 3 trial, quality of life after fractional flow reserve-guided PCI with current generation drug-eluting stents compared with CABG was similar at 1 year. The rate of significant angina was low in both groups and not significantly different. The trajectory of improvement in quality of life was significantly better after PCI, as was working status in those <65 years old. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02100722.

Diagnostic performance and prognostic impact of coronary angiography-based Index of Microcirculatory Resistance assessment: A systematic review and meta-analysis.

BACKGROUND: The Index of Microcirculatory Resistance (IMR), measured with a pressure-thermistor tipped coronary guidewire has been established as a gold standard for coronary microvascular assessment. Angiography-based IMR (angio-IMR) is a novel method to derive IMR without intracoronary instrumentation or the need for adenosine. METHODS: PubMed and Embase databases were systemically searched in November 2021 for studies that measured angio-IMR. The primary outcomes were pooled sensitivity and specificity as well as the area under the curve (AUC) of the summary receiver operating characteristic curve using IMR as a reference standard. RESULTS: A total of 129 records were initially identified and 8 studies were included in the final analysis. Overall, 1653 lesions were included in this study, of which 733 were in patients presenting with ST-segment elevation myocardial infarction. Angio-IMR yielded high diagnostic performance predicting wire-based IMR with pooled sensitivity = 0.81 (95% confidence interval: 0.76, 0.85), specificity = 0.80 (0.72, 0.86), and AUC = 0.86 (0.82, 0.88), which was similar irrespective of patient presentation. When the clinical outcome was compared between high versus low angio-IMR in patients presenting with myocardial infarction, high angio-IMR predicted an increased risk of major adverse cardiac events (MACE). CONCLUSION: Our study found that coronary angio-IMR has relatively high diagnostic performance as well as prognostic values predicting MACE, supporting its use in clinical practice.

Fractional Flow Reserve-Guided PCI as Compared with Coronary Bypass Surgery.

BACKGROUND: Patients with three-vessel coronary artery disease have been found to have better outcomes with coronary-artery bypass grafting (CABG) than with percutaneous coronary intervention (PCI), but studies in which PCI is guided by measurement of fractional flow reserve (FFR) have been lacking. METHODS: In this multicenter, international, noninferiority trial, patients with three-vessel coronary artery disease were randomly assigned to undergo CABG or FFR-guided PCI with current-generation zotarolimus-eluting stents. The primary end point was the occurrence within 1 year of a major adverse cardiac or cerebrovascular event, defined as death from any cause, myocardial infarction, stroke, or repeat revascularization. Noninferiority of FFR-guided PCI to CABG was prespecified as an upper boundary of less than 1.65 for the 95% confidence interval of the hazard ratio. Secondary end points included a composite of death, myocardial infarction, or stroke; safety was also assessed. RESULTS: A total of 1500 patients underwent randomization at 48 centers. Patients assigned to undergo PCI received a mean (±SD) of 3.7±1.9 stents, and those assigned to undergo CABG received 3.4±1.0 distal anastomoses. The 1-year incidence of the composite primary end point was 10.6% among patients randomly assigned to undergo FFR-guided PCI and 6.9% among those assigned to undergo CABG (hazard ratio, 1.5; 95% confidence interval [CI], 1.1 to 2.2), findings that were not consistent with noninferiority of FFR-guided PCI (P = 0.35 for noninferiority). The incidence of death, myocardial infarction, or stroke was 7.3% in the FFR-guided PCI group and 5.2% in the CABG group (hazard ratio, 1.4; 95% CI, 0.9 to 2.1). The incidences of major bleeding, arrhythmia, and acute kidney injury were higher in the CABG group than in the FFR-guided PCI group. CONCLUSIONS: In patients with three-vessel coronary artery disease, FFR-guided PCI was not found to be noninferior to CABG with respect to the incidence of a composite of death, myocardial infarction, stroke, or repeat revascularization at 1 year. (Funded by Medtronic and Abbott Vascular; FAME 3 ClinicalTrials.gov number, NCT02100722.).

Microvascular Resistance Reserve for Assessment of Coronary Microvascular Function: JACC Technology Corner.

The need for a quantitative and operator-independent assessment of coronary microvascular function is increasingly recognized. We propose the theoretical framework of microvascular resistance reserve (MRR) as an index specific for the microvasculature, independent of autoregulation and myocardial mass, and based on operator-independent measurements of absolute values of coronary flow and pressure. In its general form, MRR equals coronary flow reserve (CFR) divided by fractional flow reserve (FFR) corrected for driving pressures. In 30 arteries, pressure, temperature, and flow velocity measurements were obtained simultaneously at baseline (BL), during infusion of saline at 10 mL/min (rest) and 20 mL/min (hyperemia). A strong correlation was found between continuous thermodilution-derived MRR and Doppler MRR (r = 0.88; 95% confidence interval: 0.72-0.93; P < 0.001). MRR was independent from the epicardial resistance, the lower the FFR value, the greater the difference between MRR and CFR. Therefore, MRR is proposed as a specific, quantitative, and operator-independent metric to quantify coronary microvascular dysfunction.

Performance versus Risk Factor-Based Approaches to Coronary Artery Disease Screening in Waitlisted Kidney Transplant Candidates.

INTRODUCTION: Current screening algorithms for coronary artery disease (CAD) before kidney transplantation result in many tests but few interventions. OBJECTIVE: The aim of this study was to study the utility of 6-minute walk test (6MWT), an office-based test of cardiorespiratory fitness, for risk stratification in this setting. METHODS: We enrolled 360 patients who are near the top of the kidney transplant waitlist at our institution. All patients underwent CAD evaluation irrespective of 6MWT results. We examined the association between 6MWT and time to CAD-related events (defined as cardiac death, revascularization, nonfatal myocardial infarction, and removal from the waitlist for CAD), treating noncardiac death and waitlist removal for non-CAD reasons as competing events. RESULTS: The 6MWT-based approach designated approximately 45% of patients as "low risk," whereas a risk factor- or symptom-based approach designated 14 and 81% of patients as "low risk," respectively. The 6MWT-based approach was not significantly associated with CAD-related events within 1 year (subproportional hazard ratio [sHR] 1.00 [0.90-1.11] per 50 m) but was significantly associated with competing events (sHR 0.70 [0.66-0.75] per 50 m). In a companion analysis, removing waitlist status from consideration, 6MWT result was associated with the development of CAD-related events (sHR 0.92 [0.84-1.00] per 50 m). CONCLUSIONS: The 6MWT designates fewer patients as high risk and in need of further testing (compared to risk factor-based approaches), but its utility as a pure CAD risk stratification tool is modulated by the background waitlist removal rate. CAD screening before kidney transplant should be tailored according to a patient's actual chance of receiving a transplant.

Elective Percutaneous Coronary Intervention in Ambulatory Surgery Centers.

OBJECTIVES: The aim of this study was to explore characteristics and outcomes of patients undergoing elective percutaneous coronary intervention (PCI) in ambulatory surgery centers (ASCs). BACKGROUND: Little is known about patients who underwent ASC PCI before Medicare reimbursement was instituted in 2020. METHODS: Using commercial insurance claims from MarketScan, adults who underwent hospital outpatient department (HOPD) or ASC PCI for stable ischemic heart disease from 2007 to 2016 were studied. Propensity score analysis was used to measure the association between treatment setting and the primary composite outcome of 30-day myocardial infarction, bleeding complications, and hospital admission. RESULTS: The unmatched sample consisted of 95,492 HOPD and 849 ASC PCIs. Patients who underwent ASC PCI were more likely to be younger than 65 years, to live in the southern United States, and to have managed or consumer-driven health insurance. ASC PCI was also associated with decreased fractional flow reserve utilization (odds ratio [OR]: 0.31; 95% confidence interval [CI]: 0.20 to 0.48; p < 0.001). In unmatched, multivariate analysis, ASC PCI was associated with increased odds of the primary outcome (OR: 1.25; 95% CI: 1.01 to 1.56; p = 0.039) and bleeding complications (OR: 1.80; 95% CI: 1.11 to 2.90; p = 0.016). In propensity-matched analysis, ASC PCI was not associated with the primary outcome (OR: 1.23; 95% CI: 0.94 to 1.60; p = 0.124) but was significantly associated with increased bleeding complications (OR: 2.49; 95% CI: 1.25 to 4.95; p = 0.009). CONCLUSIONS: Commercially insured patients undergoing ASC PCI were less likely to undergo fractional flow reserve testing and had higher odds of bleeding complications than HOPD-treated patients. Further study is warranted as Medicare ASC PCI volume increases.

Impact of cognitive behavioral therapy on depression symptoms after transcatheter aortic valve replacement: A randomized controlled trial.

BACKGROUND: Depression is a significant concern after cardiac surgery and has not been studied in patients undergoing transcatheter aortic valve replacement (TAVR). We sought to examine the prevalence of pre-procedure depression and anxiety symptoms and explore whether brief bedside cognitive behavioral therapy (CBT) could prevent post-TAVR psychological distress. METHODS: We prospectively recruited consecutive TAVR patients and randomized them to receive brief CBT or treatment as usual (TAU) during their hospitalization. Multi-level regression techniques were used to evaluate changes by treatment arm in depression, anxiety, and quality of life from baseline to 1 month post-TAVR adjusted for sex, race, DM, CHF, MMSE, and STS score. RESULTS: One hundred and forty six participants were randomized. The mean age was 82 years, and 43% were female. Self-reported depression and anxiety scores meeting cutoffs for clinical level distress were 24.6% and 23.2% respectively. Both TAU and CBT groups had comparable improvements in depressive symptoms at 1-month (31% reduction for TAU and 35% reduction for CBT, p = .83). Similarly, both TAU and CBT groups had comparable improvements in anxiety symptoms at 1-month (8% reduction for TAU and 11% reduction for CBT, p = .1). Quality of life scores also improved and were not significantly different between the two groups. CONCLUSIONS: Pre-procedure depression and anxiety may be common among patients undergoing TAVR. However, TAVR patients show spontaneous improvement in depression and anxiety scores at 1-month follow up, regardless of brief CBT. Further research is needed to determine whether more tailored CBT interventions may improve psychological and medical outcomes.

Quantitative flow ratio-guided strategy versus angiography-guided strategy for percutaneous coronary intervention: Rationale and design of the FAVOR III China trial.

BACKGROUND: Quantitative flow ratio (QFR) is a novel angiography-based approach enabling fast computation of fractional flow reserve without use of pressure wire or adenosine. The objective of this investigator-initiated, multicenter, patient- and clinical assessor-blinded randomized trial is to evaluate the efficacy and cost-effectiveness of a QFR-augmented angiography-guided (QFR-guided) strategy versus an angiography-only guided (angiography-guided) strategy for percutaneous coronary intervention (PCI) in patients with coronary artery disease. METHODS: Approximately 3,830 patients will be randomized in a 1:1 ratio to a QFR-guided or an angiography-guided strategy. Included subjects scheduled for coronary angiography have at least 1 lesion eligible for PCI with 50%-90% stenosis in an artery with ≥2.5 mm reference diameter. Subjects assigned to the QFR-guided strategy will have QFR measured in each interrogated vessel and undergo PCI when QFR ≤0.80, with deferral for lesions with QFR >0.80. Those assigned to the angiography-guided strategy will undergo PCI based on angiography. Optimal medical therapy will be administered to all treated and deferred patients. The primary end point is the 1-year rate of major adverse cardiac events (MACE), a composite of all-cause mortality, any myocardial infarction, or any ischemia-driven revascularization. The major secondary end point is 1-year MACE excluding periprocedural myocardial infarction. Other secondary end points include the individual components of MACE and cost-effectiveness end points. The sample size affords 85% power to demonstrate superiority of QFR guidance compared with angiography guidance. CONCLUSIONS: The FAVOR III China study will be the first randomized trial to examine the effectiveness and cost-effectiveness of a QFR-guided versus an angiography-guided PCI strategy in coronary artery disease patients.

Five-Year Outcomes of Transcatheter or Surgical Aortic-Valve Replacement.

BACKGROUND: There are scant data on long-term clinical outcomes and bioprosthetic-valve function after transcatheter aortic-valve replacement (TAVR) as compared with surgical aortic-valve replacement in patients with severe aortic stenosis and intermediate surgical risk. METHODS: We enrolled 2032 intermediate-risk patients with severe, symptomatic aortic stenosis at 57 centers. Patients were stratified according to intended transfemoral or transthoracic access (76.3% and 23.7%, respectively) and were randomly assigned to undergo either TAVR or surgical replacement. Clinical, echocardiographic, and health-status outcomes were followed for 5 years. The primary end point was death from any cause or disabling stroke. RESULTS: At 5 years, there was no significant difference in the incidence of death from any cause or disabling stroke between the TAVR group and the surgery group (47.9% and 43.4%, respectively; hazard ratio, 1.09; 95% confidence interval [CI], 0.95 to 1.25; P = 0.21). Results were similar for the transfemoral-access cohort (44.5% and 42.0%, respectively; hazard ratio, 1.02; 95% CI, 0.87 to 1.20), but the incidence of death or disabling stroke was higher after TAVR than after surgery in the transthoracic-access cohort (59.3% vs. 48.3%; hazard ratio, 1.32; 95% CI, 1.02 to 1.71). At 5 years, more patients in the TAVR group than in the surgery group had at least mild paravalvular aortic regurgitation (33.3% vs. 6.3%). Repeat hospitalizations were more frequent after TAVR than after surgery (33.3% vs. 25.2%), as were aortic-valve reinterventions (3.2% vs. 0.8%). Improvement in health status at 5 years was similar for TAVR and surgery. CONCLUSIONS: Among patients with aortic stenosis who were at intermediate surgical risk, there was no significant difference in the incidence of death or disabling stroke at 5 years after TAVR as compared with surgical aortic-valve replacement. (Funded by Edwards Lifesciences; PARTNER 2 ClinicalTrials.gov number, NCT01314313.).

Individual Lesion-Level Meta-Analysis Comparing Various Doses of Intracoronary Bolus Injection of Adenosine With Intravenous Administration of Adenosine for Fractional Flow Reserve Assessment.

BACKGROUND: Intravenous infusion of adenosine is considered standard practice for fractional flow reserve (FFR) assessment but is associated with adverse side-effects and is time-consuming. Intracoronary bolus injection of adenosine is better tolerated by patients, cheaper, and less time-consuming. However, current literature remains fragmented and modestly sized regarding the equivalence of intracoronary versus intravenous adenosine. We aim to investigate the relationship between intracoronary adenosine and intravenous adenosine to determine FFR. METHODS: We performed a lesion-level meta-analysis to compare intracoronary adenosine with intravenous adenosine (140 µg/kg per minute) for FFR assessment. The search was conducted in accordance to the Preferred Reporting for Systematic Reviews and Meta-Analysis statement. Lesion-level data were obtained by contacting the respective authors or by digitization of scatterplots using custom-made software. Intracoronary adenosine dose was defined as; low: <40 µg, intermediate: 40 to 99 µg, and high: ≥100 µg. RESULTS: We collected 1972 FFR measurements (1413 lesions) comparing intracoronary with intravenous adenosine from 16 studies. There was a strong correlation (correlation coefficient =0.915; P<0.001) between intracoronary-FFR and intravenous-FFR. Mean FFR was 0.81±0.11 for intracoronary adenosine and 0.81±0.11 for intravenous adenosine (P<0.001). We documented a nonclinically relevant mean difference of 0.006 (limits of agreement: -0.066 to 0.078) between the methods. When stratified by the intracoronary adenosine dose, mean differences between intracoronary and intravenous-FFR amounted to 0.004, 0.011, or 0.000 FFR units for low-dose, intermediate-dose, and high-dose intracoronary adenosine, respectively. CONCLUSIONS: The present study documents clinically irrelevant differences in FFR values obtained with intracoronary versus intravenous adenosine. Intracoronary adenosine hence confers a practical and patient-friendly alternative for intravenous adenosine for FFR assessment.

Remote Ischemic Preconditioning Acutely Improves Coronary Microcirculatory Function.

Background Remote ischemic preconditioning (RIPC) attenuates myocardial damage during elective and primary percutaneous coronary intervention. Recent studies suggest that coronary microcirculatory function is an important determinant of clinical outcome. The aim of this study was to assess the effect of RIPC on markers of microcirculatory function. Methods and Results Patients referred for cardiac catheterization and fractional flow reserve measurement were randomized to RIPC or sham. Operators and patients were blinded to treatment allocation. Comprehensive physiological assessments were performed before and after RIPC/sham including the index of microcirculatory resistance and coronary flow reserve after intracoronary glyceryl trinitrate and during the infusion of intravenous adenosine. Thirty patients were included (87% male; mean age: 63.1±10.0 years). RIPC and sham groups were similar with respect to baseline characteristics. RIPC decreased the calculated index of microcirculatory resistance (median, before RIPC: 22.6 [interquartile range [IQR]: 17.9-25.6]; after RIPC: 17.5 [IQR: 14.5-21.3]; P=0.007) and increased coronary flow reserve (2.6±0.9 versus 3.8±1.7, P=0.001). These RIPC-mediated changes were associated with a reduction in hyperemic transit time (median: 0.33 [IQR: 0.26-0.40] versus 0.25 [IQR: 0.20-0.30]; P=0.010). RIPC resulted in a significant decrease in the calculated index of microcirculatory resistance compared with sham (relative change with treatment [mean±SD] was -18.1±24.8% versus +6.1±37.5; P=0.047) and a significant increase in coronary flow reserve (+41.2% [IQR: 20.0-61.7] versus -7.8% [IQR: -19.1 to 10.3]; P<0.001). Conclusions The index of microcirculatory resistance and coronary flow reserve are acutely improved by remote ischemic preconditioning. This raises the possibility that RIPC confers cardioprotection during percutaneous coronary intervention as a result of an improvement in coronary microcirculatory function. Clinical Trial Registration URL: www.anzctr.org.au/ . Unique identifier: CTRN12616000486426.