N-of-1 Trial of Angina Verification Before Percutaneous Coronary Intervention.

BACKGROUND: In stable coronary artery disease, 30% to 60% of patients remain symptomatic despite successful revascularization. Perhaps not all symptoms reported by a patient with myocardial ischemia are, in fact, angina. OBJECTIVES: This study sought to determine whether independent symptom verification using a placebo-controlled ischemic stimulus could distinguish which patients achieve greatest symptom relief from percutaneous coronary intervention (PCI). METHODS: ORBITA-STAR was a multicenter, n-of-1, placebo-controlled study in patients undergoing single-vessel PCI for stable symptoms. Participants underwent 4 episodes (60 seconds each) of low-pressure balloon occlusion across their coronary stenosis, randomly paired with 4 episodes of placebo inflation. Following each episode, patients reported the similarity of the induced symptom in comparison with their usual symptom. The similarity score ranged from -10 (placebo replicated the symptom more than balloon occlusion) to +10 (balloon occlusion exactly replicated the symptom). The primary endpoint was the ability of the similarity score to predict symptom relief with PCI. RESULTS: Fifty-one patients were recruited, aged 62.9 ± 8.6 years. The median fractional flow reserve was 0.68 (Q1-Q3: 0.57-0.79), and the instantaneous wave-free ratio was 0.80 (Q1-Q3: 0.48-0.89). The median similarity score was 3 (Q1-Q3: 0.875-5.25). The similarity score was a strong predictor of symptom improvement following PCI: a patient with an upper quartile similarity score of 5.25 was significantly more likely to have lower angina frequency at follow-up (OR: 8.01; 95% credible interval: 2.39-15.86) than a patient with a lower quartile similarity score of 0.875 (OR: 1.31; 95% credible interval: 0.71-1.99), Pr(difference) >99.9%. CONCLUSIONS: Similarity score powerfully predicted symptom improvement from PCI. These data lay the foundation for independent symptom mapping to target PCI to those patients most likely to benefit. (Systematic Trial of Angina Assessment Before Revascularization [ORBITA-STAR]; NCT04280575).

Comparison of bolus versus continuous thermodilution derived indices of microvascular dysfunction in revascularized coronary syndromes.

Background: The assessment of coronary microvascular dysfunction (CMD) using invasive methods is a field of growing interest, however the preferred method remains debated. Bolus and continuous thermodilution are commonly used methods, but weak agreement has been observed in patients with angina with non-obstructive coronary arteries (ANOCA). This study examined their agreement in revascularized acute coronary syndromes (ACS) and chronic coronary syndromes (CCS) patients. Objective: To compare bolus thermodilution and continuous thermodilution indices of CMD in revascularized ACS and CCS patients and assess their diagnostic agreement at pre-defined cut-off points. Methods: Patients from two centers underwent paired bolus and continuous thermodilution assessments after revascularization. CMD indices were compared between the two methods and their agreements at binary cut-off points were assessed. Results: Ninety-six patients and 116 vessels were included. The mean age was 64 ± 11 years, and 20 (21 %) were female. Overall, weak correlations were observed between the Index of Microcirculatory Resistance (IMR) and continuous thermodilution microvascular resistance (Rµ) (rho = 0.30p = 0.001). The median coronary flow reserve (CFR) from continuous thermodilution (CFRcont) and bolus thermodilution (CFRbolus) were 2.19 (1.76-2.67) and 2.55 (1.50-3.58), respectively (p < 0.001). Weak correlation and agreement were observed between CFRcont and CFRbolus (rho = 0.37, p < 0.001, ICC 0.228 [0.055-0.389]). When assessed at CFR cut-off values of 2.0 and 2.5, the methods disagreed in 41 (35 %) and 45 (39 %) of cases, respectively. Conclusions: There is a significant difference and weak agreement between bolus and continuous thermodilution-derived indices, which must be considered when diagnosing CMD in ACS and CCS patients.

The Effect of Hydrostatic Pressure on Coronary Flow and Pressure-Based Indices of Coronary Stenosis Severity.

Background: To assess whether hydrostatic pressure gradients caused by coronary height differences in supine versus prone positioning during invasive physiological stenosis assessment affect resting and hyperaemic pressure-based indices or coronary flow. Methods: Twenty-three coronary stenoses were assessed in twenty-one patients with stable coronary artery disease. All patients had a stenosis of at least 50% visually defined on previous coronary angiography. Pd/Pa, iFR, FFR, and coronary flow velocity (APV) measured using a Doppler were recorded across the same stenosis, with the patient in the prone position, followed by repeat measurements in the standard supine position. Results: When comparing prone to supine measurements in the same stenosis, in the LAD, there was a significant change in mean Pd/Pa of 0.08 ± 0.04 (p = 0.0006), in the iFR of 0.06 ± 0.07 (p = 0.02), and in the FFR of 0.09 ± 0.07 (p = 0.003). In the Cx, there was a change in mean Pd/Pa of 0.05 ± 0.04 (p = 0.009), iFR of 0.07 ± 0.04 (p = 0.01), and FFR of 0.05 ± 0.03 (p = 0.006). In the RCA, there was a change in Pd/Pa of 0.05 ± 0.04 (p = 0.032), iFR of 0.04 ± 0.05 (p = 0.19), and FFR of 0.04+-0.03 (p = 0.004). Resting and hyperaemic coronary flow did not change significantly (resting delta APV = 1.6 cm/s, p = 0.31; hyperaemic delta APV = 0.9 cm/s, p = 0.85). Finally, 36% of iFR measurements and 26% of FFR measurements were re-classified across an ischaemic threshold when prone and supine measurements were compared across the same stenosis. Conclusions: Pd/Pa, iFR, and FFR were affected by hydrostatic pressure variations caused by coronary height differences in prone versus supine positioning. Coronary flow did not change signifying a purely pressure-based phenomenon.

The challenges of a randomised placebo-controlled trial of CTO PCI vs. placebo with optimal medical therapy: The ORBITA-CTO pilot study design and protocol.

Background: Percutaneous coronary intervention (PCI) for coronary chronic total occlusion (CTO) has been performed for the improvement of symptoms and quality of life in patients with stable angina. The ORBITA study demonstrated the role of the placebo effect in contemporary PCI in non-CTO chronic coronary syndromes. However, the benefit of CTO PCI beyond that of a placebo has not been demonstrated. Aims: The ORBITA-CTO pilot study will be a double-blind, placebo-controlled study of CTO PCI randomising patients who have: (1) been accepted by a CTO operator for PCI; (2) experienced symptoms due to a CTO; (3) evidence of ischaemia; (4) evidence of viability within the CTO territory; and (5) a J-CTO score ≤3. Methods: Patients will undergo medication optimisation that will ensure they are on at least a minimum amount of anti-anginals and complete questionnaires. Patients will record their symptoms on an app daily throughout the study. Patients will undergo randomisation procedures, including an overnight stay, and be discharged the following day. All anti-anginals will be stopped after randomisation and re-initiated on a patient-led basis during the 6-month follow-up period. At follow-up, patients will undergo repeat questionnaires and unblinding, with a further 2-week unblinded follow-up. Results: The co-primary outcomes are feasibility (blinding) in this cohort and angina symptom score using an ordinal clinical outcome scale for angina. Secondary outcomes include changes in quality-of-life measures, Seattle Angina Questionnaire (SAQ), peak VO2, and anaerobic threshold on the cardiopulmonary exercise test. Conclusion: The feasibility of a placebo-controlled CTO PCI study will lead to future studies assessing efficacy. The impact of CTO PCI on angina measured using a novel daily symptom app may provide improved fidelity in assessing symptoms in patients with CTO's.

Changes in absolute flow, myocardial resistance and FFR after chronic total occlusion percutaneous coronary intervention.

BACKGROUND: Randomised studies of percutaneous coronary intervention (PCI) in patients with chronic total occlusion (CTO) have shown inconsistent outcomes, suggesting incomplete understanding of this cohort and their coronary physiology. To address this shortcoming, we designed a prospective observational study to measure the recovery of absolute coronary blood flow following successful CTO PCI Aims: We sought to identify patient and procedural characteristics associated with a favourable physiological outcome after CTO PCI. METHODS: Consecutive patients with a CTO subtending viable myocardium underwent PCI utilising contemporary techniques and the hybrid algorithm. Immediately after PCI, and at 3-month follow-up, physiological measurements were performed utilising continuous thermodilution. RESULTS: A total of 81 patients were included with a mean age of 63.6±8.9 years, and 66 (81.5%) were male. Physiological measurements of absolute coronary blood flow in the CTO vessel increased by 30% (p<0.001) and microvascular resistance reduced by 16% (p<0.001) from immediately post-CTO PCI to follow-up assessment. Fractional flow reserve increased by 0.02 (p=0.015) in the same period. Prior coronary artery bypass graft (CABG) and a higher estimated glomerular filtration rate (eGFR) were associated with a larger change in absolute flow. An extraplaque strategy was associated with a smaller change in absolute flow. CONCLUSIONS: Post-CTO PCI, there is a continued augmentation in absolute coronary blood flow and reduction in microvascular resistance from baseline to follow-up at 3 months. Prior CABG and a higher baseline eGFR were predictors of a larger change in absolute coronary flow, whilst an extraplaque final wire path strategy predicted a smaller change. Lastly, the patient characteristics and comorbidities had a larger influence than procedural factors on the observed change in absolute flow.

Changes in coronary collateral function after successful chronic total occlusion percutaneous coronary intervention.

BACKGROUND: Contemporary chronic total occlusion (CTO) percutaneous coronary intervention (PCI) incorporates wire escalation and dissection/re-entry recanalisation strategies. AIMS: The purpose of the study was to investigate changes in collateral function after CTO PCI and to identify whether the mode of successful recanalisation influences collateral function regression. METHODS: Patients scheduled for elective CTO PCI with evidence of viability in the CTO territory by noninvasive imaging were included in this study. After successful CTO PCI, the aortic pressure (Pa) and distal coronary artery wedge pressure (Pw) during balloon occlusion were measured, both in a resting state and during infusion of intravenous adenosine, allowing the calculation of the pressure-derived collateral pressure index at rest and hyperaemia (CPIrest and the collateral fractional flow reserve [FFRcoll], respectively). Measurements were repeated 3 months later during angiographic follow-up. RESULTS: Eighty-one patients had physiological measurements at baseline and follow-up. In the final cohort the mean age was 64 years and 82% were male. The mean maximal stent diameter and total stent length were 3.2±0.5 mm and 68±31 mm, respectively. Successful strategies were antegrade wiring (64.2%), antegrade dissection re-entry (8.6%), and retrograde dissection re-entry (27.1%). Between the index procedure and follow-up, wedge pressure decreased from 34±11 mmHg to 21±8.5 mmHg (p<0.01), respectively. FFRcoll changed from 0.34±0.11 to 0.19±0.09 (p<0.01) at follow-up and CPIrest from 0.40±0.14 to 0.17±0.09 (p<0.01). Absolute maximum collateral flow decreased from 55±32 ml/min directly after PCI to 38±24 ml/min (p<0.01). There was no relation between the recanalisation technique and changes in FFRcoll. CONCLUSIONS: There was a significant reduction in collateral flow over time, independent of the recanalisation technique.

Clinical effectiveness of thrombus aspiration during percutaneous coronary intervention for stent thrombosis in a contemporary setting.

OBJECTIVE: The impact of adjunctive manual thrombus aspiration (TA) in patients with stent thrombosis (ST) treated with percutaneous intervention has not been evaluated in the current era of potent P2Y12 agents and new-generation drug-eluting stents. We sought to assess the effect of TA using data from a large contemporary registry. METHODS: The study population was derived from the Essex ST Investigation Registry (ESTHIR), which contains all consecutive cases of angiographically determined definite ST undergoing interventional treatment in a tertiary cardiac centre between November 2015 and June 2018. Propensity score matching was performed to match patients who underwent TA (TA group) to those who did not (n-TA group). The study endpoints were final TIMI flow and survival free of cardiovascular death (CD) or target lesion revascularisation (TLR). RESULTS: A total of 128 ST patients were included in the present analysis. The mean age was 65 ± 11 years, and 84% were male. About 90% of the patients presented with STEMI, and 85% had very late ST. Seventy-two patients (56%) underwent TA. After propensity score matching, 30 patients were included in each study group. A higher rate of final TIMI III flow was observed in the TA group (TA vs n-TA group, 100% vs 83%), but this difference did not reach statistical significance (p = 0.052). At 1000 days of follow-up, survival free of CD or TLR was not different between the two groups (p = 0.8). CONCLUSION: In a propensity-matched population of ST patients undergoing PCI in a contemporary setting, TA was not associated with improved final TIMI flow or long-term cardiovascular outcomes.

1-Year Outcomes of Blinded Physiological Assessment of Residual Ischemia After Successful PCI: DEFINE PCI Trial.

OBJECTIVES: The aim of this study was to identify the post-percutaneous coronary intervention (PCI) target value of instantaneous wave-free ratio (iFR) that would best discriminate clinical events at 1 year in the DEFINE PCI (Physiologic Assessment of Coronary Stenosis Following PCI) study. BACKGROUND: The impact of residual ischemia detected by iFR post-PCI on clinical and symptom-related outcomes is unknown. METHODS: Blinded iFR pull back was performed after successful stent implantation in 500 patients. The primary endpoint was the rate of residual ischemia, defined as iFR ≤0.89, after operator-assessed angiographically successful PCI. Secondary endpoints included clinical events at 1 year and change in Seattle Angina Questionnaire angina frequency (SAQ-AF) score during follow-up. RESULTS: As reported, 24.0% of patients had residual ischemia (iFR ≤0.89) after successful PCI, with 81.6% of cases attributable to angiographically inapparent focal lesions. Post-PCI iFR ≥0.95 (present in 182 cases [39%]) was associated with a significant reduction in the composite of cardiac death, spontaneous myocardial infarction, or clinically driven target vessel revascularization compared with post-PCI iFR <0.95 (1.8% vs 5.7%; P = 0.04). Baseline SAQ-AF score was 73.3 ± 22.8. For highly symptomatic patients (baseline SAQ-AF score ≤60), SAQ-AF score increased by ≥10 points more frequently in patients with versus without post-PCI iFR ≥0.95 (100.0% vs 88.5%; P = 0.01). CONCLUSIONS: In DEFINE PCI, despite angiographically successful PCI, highly symptomatic patients at baseline without residual ischemia by post-PCI iFR had greater reductions in anginal symptoms at 1 year compared with patients with residual ischemia. Achieving post-PCI iFR ≥0.95 was also associated with improved 1-year event-free survival. (Physiologic Assessment of Coronary Stenosis Following PCI [DEFINE PCI]; NCT03084367).

Feasibility of early waking cardiac arrest patients whilst receiving therapeutic hypothermia: The therapeutic hypothermia and early waking (THAW) trial.

AIM: To determine the safety and feasibility of an early (12 h) waking and extubation protocol for out-of-hospital cardiac arrest (OHCA) patients receiving targeted temperature management (TTM). METHODS: This was a single-centre, prospective, non-randomised, observational, safety and feasibility pilot study which included successfully resuscitated OHCA patients, of presumed cardiac cause. Inclusion criteria were: OHCA patients aged over 18 years with a return of spontaneous circulation, who were going to receive TTM33 (TTM at 33 °C for 24 h and prevention of hyperthermia for 72 h) as part of their post cardiac arrest care. Clinical stability was measured against physiological and neurological parameters as well as clinical assessment. RESULTS: 50 consecutive patients were included (median age 65.5 years, 82% male) in the study. Four (8%) patients died within the first twelve hours and were excluded from the final cohort (n = 46). Twenty-three patients (46%) were considered clinically stable and suitable for early waking based on the intention to treat analysis; 12 patients were extubated early based on a variety of clinical factors (21.4 ± 8.6 h) whilst continuing to receive TTM33 with a mean core temperature of 34.2 °C when extubated. Of these, five patients were discharged from the intensive care unit (ICU) <48 h after admission with a mean ICU length of stay 1.8 ± 0.4 days. Twenty-eight patients (56%) were discharged from the ICU with a modified Rankin Score of 0-2. The overall intra-hospital mortality was 50% (n = 25). CONCLUSIONS: It is safe and feasible to wake selected comatose OHCA patients at 12 h, allowing for earlier positive neuro-prognostication and reduced ICU stay.

Stress perfusion cardiovascular magnetic resonance and serial fractional flow reserve assessment of the left anterior descending artery in patients undergoing right coronary artery chronic total occlusion revascularization.

BACKGROUND: Fractional flow reserve (FFR) assessment of remote arteries, in the context of a bystander chronic total occlusion (CTO), can lead to false positive results. Adenosine stress cardiovascular magnetic resonance (CMR) evaluates perfusion defects across the entire myocardium and may therefore be a reliable tool in the work-up of remote lesions in CTO patients. The IMPACT-CTO study investigated donor artery invasive physiology before, immediately post, and at 4 months following right coronary artery (RCA) CTO percutaneous coronary intervention (PCI). The aim of this subanalysis was to assess the concordance between baseline perfusion CMR and serial FFR evaluation of left anterior descending artery (LAD) ischemia in patients from the IMPACT-CTO study. METHODS: Baseline adenosine stress CMR examinations from 26 patients were analyzed for qualitative evidence of LAD ischemia. The results were correlated with the serial LAD FFR measurements. RESULTS: The present findings demonstrated that before RCA CTO PCI, there was 62% agreement between perfusion CMR and FFR (ischemic threshold £ 0.8) in the assessment of LAD ischemia (k = 0.29; fair concordance). At 4 months after revascularization, there was 77% agreement (k = 0.52; moderate concordance) between the index CMR assessment of LAD ischemia and the follow-up LAD FFR. Concordance was improved at a LAD FFR ischemic threshold of £ 0.75. CONCLUSIONS: In this hypothesis generating study, baseline CMR assessment of LAD ischemia correlated better with the 4 months LAD FFR data (threshold £ 0.8) as compared to the FFR measurements taken prior to RCA CTO revascularization.

Comparing invasive hemodynamic responses in adenosine hyperemia versus physical exercise stress in chronic coronary syndromes.

OBJECTIVES: Adenosine hyperemia is an integral component of the physiological assessment of obstructive coronary artery disease in patients with chronic coronary syndrome (CCS). The aim of this study was to compare systemic, coronary and microcirculatory hemodynamics between intravenous (IV) adenosine hyperemia versus physical exercise stress in patients with CCS and coronary stenosis. METHODS: Twenty-three patients (mean age, 60.6 ± 8.1 years) with CCS and single-vessel coronary stenosis underwent cardiac catheterization. Continuous trans-stenotic coronary pressure-flow measurements were performed during: i) IV adenosine hyperemia, and ii) physical exercise using a catheter-table-mounted supine ergometer. Systemic, coronary and microcirculatory hemodynamic responses were compared between IV adenosine and exercise stimuli. RESULTS: Mean stenosis diameter was 74.6% ± 10.4. Median (interquartile range) FFR was 0.54 (0.44-0.72). At adenosine hyperemia versus exercise stress, mean aortic pressure (Pa, 91 ± 16 mmHg vs 99 ± 15 mmHg, p < 0.0001), distal coronary pressure (Pd, 58 ± 21 mmHg vs 69 ± 24 mmHg, p < 0.0001), trans-stenotic pressure ratio (Pd/Pa, 0.63 ± 0.18 vs 0.69 ± 0.19, p < 0.0001), microvascular resistance (MR, 2.9 ± 2.2 mmHg.cm-1.sec-1 vs 4.2 ± 1.7 mmHg.cm-1.sec-1, p = 0.001), heart rate (HR, 80 ± 15 bpm vs 85 ± 21 bpm, p = 0.02) and rate-pressure product (RPP, 7522 ± 2335 vs 9077 ± 3200, p = 0.0001) were all lower. Conversely, coronary flow velocity (APV, 23.7 ± 9.5 cm/s vs 18.5 ± 6.8 cm/s, p = 0.02) was higher. Additionally, temporal changes in Pa, Pd, Pd/Pa, MR, HR, RPP and APV during IV adenosine hyperemia versus exercise were all significantly different (p < 0.05 for all). CONCLUSIONS: In patients with CCS and coronary stenosis, invasive hemodynamic responses differed markedly between IV adenosine hyperemia versus physical exercise stress. These differences were observed across systemic, coronary and microcirculatory hemodynamics.

Placebo-Controlled Efficacy of Percutaneous Coronary Intervention for Focal and Diffuse Patterns of Stable Coronary Artery Disease.

[Figure: see text].

Achieving Optimal Medical Therapy: Insights From the ORBITA Trial.

Background In stable coronary artery disease, medications are used for 2 purposes: cardiovascular risk reduction and symptom improvement. In clinical trials and clinical practice, medication use is often not optimal. The ORBITA (Objective Randomised Blinded Investigation With Optimal Medical Therapy of Angioplasty in Stable Angina) trial was the first placebo-controlled trial of percutaneous coronary intervention. A key component of the ORBITA trial design was the inclusion of a medical optimization phase, aimed at ensuring that all patients were treated with guideline-directed truly optimal medical therapy. In this study, we report the medical therapy that was achieved. Methods and Results After enrollment into the ORBITA trial, all 200 patients entered a 6-week period of intensive medical therapy optimization, with initiation and uptitration of risk reduction and antianginal therapy. At the prerandomization stage, the median number of antianginals established was 3 (interquartile range, 2-4). A total of 195 patients (97.5%) reached the prespecified target of ≥2 antianginals; 136 (68.0%) did not stop any antianginals because of adverse effects, and the median number of antianginals stopped for adverse effects per patient was 0 (interquartile range, 0-1). Amlodipine and bisoprolol were well tolerated (stopped for adverse effects in 4/175 [2.3%] and 9/167 [5.4%], respectively). Ranolazine and ivabradine were also well tolerated (stopped for adverse effects in 1/20 [5.0%] and 1/18 [5.6%], respectively). Isosorbide mononitrate and nicorandil were stopped for adverse effects in 36 of 172 (20.9%) and 32 of 141 (22.7%) of patients, respectively. Statins were well tolerated and taken by 191 of 200 (95.5%) patients. Conclusions In the 12-week ORBITA trial period, medical therapy was successfully optimized and well tolerated, with few drug adverse effects leading to therapy cessation. Truly optimal medical therapy can be achieved in clinical trials, and translating this into longer-term clinical practice should be a focus of future study. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02062593.

Impact of Intravascular Ultrasound on Chronic Total Occlusion Percutaneous Revascularization.

AIM: We sought to investigate the impact of IVUS use on chronic total occlusion (CTO) PCI using data from a contemporary registry of consecutive patients and applying a propensity score matching analysis. METHODS AND RESULTS: We evaluated 514 successful CTO-PCIs, median age: 67 years (IQR: 58-73), 83.5% males. IVUS-guided PCI was performed in 184 (35.8%) of cases. After using 1:1 propensity matching score analysis, two groups of 182 patients each (IVUS-guided vs. angiography-guided CTO-PCI group) were produced to form the study population. In the IVUS-guided group the median maximum stent diameter was larger and the median total stented segment was longer compared to the angiography-guided group [(3.5 mm, IQR: 3.0-4.0 vs. 3.2 mm, IQR: 3.0-3.5, p < 0.001) and (60.0 mm, IQR: 38.0-91.3 vs. 38.0 mm, IQR: 32.0-70.5, p < 0.001), respectively]. In the IVUS-guided group, retrograde recanalization was more frequently encountered compared to the angiography-guided PCI group (30.2% vs. 20.9%, p = 0.04). Procedural time was significantly longer in the IVUS-guided group, without any difference in fluoroscopy time, radiation dose and contrast volume. Multivariate linear regression analysis showed that IVUS use was the strongest independent factor associated with larger maximum diameter stents (p < 0.001) and a strong independent predictor for total stented segment length during CTO-PCI (p < 0.001). Up to 8 years follow-up, there was no difference in the incidence of the composite endpoint of all-cause death, cardiac death, myocardial infarction and target vessel revascularization between the IVUS-guided PCI and the angiography-guided PCI groups (hazard ratio: 13.7% vs. 15.9%, respectively, log-rank: p = 0.67, median follow-up time: 49.0 months, IQR: 33.0-67.0). CONCLUSIONS: Use of IVUS in CTO-PCI was associated with larger stent diameter and longer stented segments. Despite more frequent use of IVUS in retrograde CTO-PCI, there was no difference in long-term adverse events between IVUS and angiography CTO-PCI groups; nevertheless, the study was not powered to assess clinical outcomes.

Coronary artery height differences and their effect on fractional flow reserve.

BACKGROUND: Fractional flow reserve (FFR) uses pressure-based measurements to assess the severity of a coronary stenosis. Distal pressure (Pd) is often at a different vertical height to that of the proximal aortic pressure (Pa). The difference in pressure between Pd and Pa due to hydrostatic pressure, may impact FFR calculation. METHODS: One hundred computed tomography coronary angiographies were used to measure height differences between the coronary ostia and points in the coronary tree. Mean heights were used to calculate the hydrostatic pressure effect in each artery, using a correction factor of 0.8 mmHg/cm. This was tested in a simulation of intermediate coronary stenosis to give the "corrected FFR" (cFFR) and percentage of values, which crossed a threshold of 0.8. RESULTS: The mean height from coronary ostium to distal left anterior descending (LAD) was +5.26 cm, distal circumflex (Cx) -3.35 cm, distal right coronary artery-posterior left ventricular artery (RCA-PLV) -5.74 cm and distal RCA-posterior descending artery (PDA) +1.83 cm. For LAD, correction resulted in a mean change in FFR of +0.042, -0.027 in the Cx, -0.046 in the PLV and +0.015 in the PDA. Using 200 random FFR values between 0.75 and 0.85, the resulting cFFR crossed the clinical treatment threshold of 0.8 in 43% of LAD, 27% of Cx, 47% of PLV and 15% of PDA cases. CONCLUSIONS: There are significant vertical height differences between the distal artery (Pd) and its point of normalization (Pa). This is likely to have a modest effect on FFR, and correcting for this results in a proportion of values crossing treatment thresholds. Operators should be mindful of this phenomenon when interpreting FFR values.

Effects of stent postdilatation during primary PCI for STEMI: Insights from coronary physiology and optical coherence tomography.

OBJECTIVES: This study aimed to assess the impact of stent optimization by NC-balloon postdilatation (PD) during primary-PCI for STEMI with the use of coronary physiology and intracoronary imaging. METHODS: This was a prospective observational study (ClinicalTrials.gov:NCT02788396). Optical coherence tomography (OCT) and physiological measurements were performed immediately before and after PD with the operators blinded to all measurements. The index of microcirculatory resistance (IMR), coronary flow reserve (CFR) and fractional flow reserve (FFR) were measured. OCT analysis was performed for assessment of stent expansion, malapposition, in-stent plaque-thrombus prolapse (PTP) and stent-edge dissections (SED). The change in IMR before and after PD as a measure of microvascular injury was the primary objective of the study. RESULTS: Thirty-two STEMI patients undergoing primary-PCI had physiological measurements before and after PD. All patients received second-generation DES (diameter 3.1 ± 0.5 mm, length 29.9 ± 10.7 mm) and postdilatation with NC-balloons (diameter 3.6 ± 0.6 mm, inflation pressure 19.3 ± 2.0 atm). IMR (44.9 ± 25.6 vs. 48.8 ± 34.2, p = 0.26) and CFR (1.60 ± 0.89 vs. 1.58 ± 0.71, p = 0.87) did not change, while FFR increased after PD (0.91 ± 0.08 vs. 0.93 ± 0.06, p = 0.037). At an individual patient level, IMR increased in half of the cases. PD improved significantly absolute and relative stent expansion, reduced malapposition, and increased PTP. There was no difference in clinically relevant SED. CONCLUSION: In this exploratory, hypothesis-generating study, postdilatation during primary-PCI for STEMI improved stent expansion, apposition and post-PCI FFR, without a significant effect on coronary microcirculation overall. Nevertheless, IMR increased in a group of patients and larger studies are warranted to explore predictors of microcirculatory response to postdilatation.

Eosinophil Deficiency Promotes Aberrant Repair and Adverse Remodeling Following Acute Myocardial Infarction.

In ST-segment elevation myocardial infarction of both patients and mice, there was a decline in blood eosinophil count, with activated eosinophils recruited to the infarct zone. Eosinophil deficiency resulted in attenuated anti-inflammatory macrophage polarization, enhanced myocardial inflammation, increased scar size, and deterioration of myocardial structure and function. Adverse cardiac remodeling in the setting of eosinophil deficiency was prevented by interleukin-4 therapy.

Absolute microvascular resistance by continuous thermodilution predicts microvascular dysfunction after ST-elevation myocardial infarction.

AIMS: Continuous thermodilution using intracoronary saline infusion is a novel technique able to provide accurate measurements of absolute coronary blood flow and microvascular resistance (Rmicro). The aim of this study was to assess the ability of Rmicro, measured by continuous thermodilution, to predict microvascular dysfunction in patients with ST-elevation myocardial infarction. METHODS AND RESULTS: In this prospective observational study, continuous thermodilution was used to measure Rmicro in the culprit coronary artery of 32 patients with STEMI (mean age ± SD, 66 ± 10 years; 78% male) immediately post-primary percutaneous coronary intervention (PCI). Concomitant measurements of the index of microvascular resistance (IMR) and coronary flow reserve (CFR) were obtained by bolus thermodilution. Microvascular dysfunction was defined as an IMR > 40 or a CFR < 2. Rmicro was higher in patients with microvascular dysfunction based on the predefined thresholds; for IMR: 863 (IQR, 521-1079) vs 474 (IQR, 337-616) Wood units, p = .004 and for CFR: 633 (IQR, 455-1039) vs 474 (IQR, 271-579) Wood units, p = .02. Receiver-operator characteristic analysis demonstrated that Rmicro was predictive of microvascular dysfunction; area under curve (AUC) 0.800 (95% CI: 0.637-0.963, p = .005) for IMR-defined microvascular dysfunction and AUC 0.758 (95% CI: 0.593-0.924, p = .02) for CFR-defined microvascular dysfunction. An Rmicro threshold of greater than 552 Wood units was optimal for predicting microvascular dysfunction defined by IMR > 40. CONCLUSIONS: Rmicro is able to identify STEMI patients in whom IMR and CFR measurements suggest significant microvascular dysfunction at the end of primary PCI.

Recovery of Absolute Coronary Blood Flow and Microvascular Resistance After Chronic Total Occlusion Percutaneous Coronary Intervention: An Exploratory Study.

Background This study aimed to investigate longitudinal physiological changes in the recanalized coronary chronic total occlusion (CTO) vessel and its dependent myocardium after successful percutaneous coronary intervention (PCI). Methods and Results In this pilot study, 25 patients scheduled for elective CTO PCI with viable myocardium and angiographically visible collaterals were included. Absolute coronary blood flow and absolute microvascular resistance were measured invasively using continuous thermodilution. Measurements were performed immediately after successful CTO PCI and at short-term follow-up. In a subgroup of patients, physiological measurements were performed at the predominant donor vessel before CTO PCI, immediately afterwards, and at follow-up. Absolute coronary blood flow in the recanalized CTO artery increased from 148±53 mL/min immediately after PCI to 221±77 mL/min at follow-up (P<0.001). In agreement, absolute resistance in the myocardial territory perfused by the CTO artery, decreased from 545±255 Wood units immediately after the procedure to 387±128 Wood units at follow-up (P=0.014). There were no significant changes in the absolute coronary blood flow and resistance in the predominant donor between baseline and follow-up. Positive remodeling of the distal CTO vessel with an increase in lumen diameter was observed. Conclusions After successful CTO PCI, blood flow in the recanalized artery and microvascular function of the dependent myocardium are not immediately normal but recover over time.