Early Effects of Ticagrelor Versus Clopidogrel on Peripheral Endothelial Function After Non-ST-Elevation Acute Coronary Syndrome and Assessment of Its Relationship With Coronary Microvascular Function

Peripheral endothelial dysfunction is an independent predictor of adverse long-term prognosis after acute coronary syndrome. Data are lacking on the effects of oral P2Y12-inhibitors on peripheral endothelial function in non-ST-elevation acute coronary syndrome (NSTEACS). Furthermore, the relation between peripheral endothelial function and invasive indexes of coronary microvascular function in NSTEACS is unclear. Between March 2018 and July 2020, hospitalized patients with NSTEACS were randomized (1:1) to ticagrelor or clopidogrel. Peripheral endothelial function was assessed with brachial artery flow-mediated vasodilation (FMD). Invasive indexes of coronary microvascular function were obtained using an intracoronary pressure-temperature sensor-tipped wire. In 70 patients included, mean age was 58.6 years, 78.6% (n = 55) were male and 20% (n = 14) had diabetes mellitus. Compared with clopidogrel, ticagrelor significantly improved FMD (14.2 ± 5.4% vs 8.9 ± 5.3%, p <0.001) after a median treatment time of 41.2 hours. The FMD was significantly correlated with the index of microcirculatory resistance (IMR) measured in the infarct-related artery (r = -0.38, p = 0.001), with a stronger correlation found in those who did not have percutaneous coronary intervention (r = -0.52, p = 0.03). Using receiver operating characteristic curve analysis, an FMD of 8.2% identified an IMR of >34 as the threshold, with 77.6% sensitivity and 52.4% specificity. In patients who did not have a percutaneous coronary intervention, an FMD of 11.49% identified an IMR of >34 with 84.6% sensitivity and 80% specificity. In conclusion, ticagrelor significantly improved peripheral endothelial function compared with clopidogrel in patients with NSTEACS. There was a significant correlation between brachial artery FMD and IMR of the infarct-related artery.

Reperfusion strategy and late clinical outcomes of patients with ST-elevation myocardial infarction (STEMI) in the absence of standard modifiable risk factors (SMuRFs)

Introduction

There is growing evidence that patients presenting with STEMI in the absence of standard modifiable cardiovascular risk factors (SMuRFs; smoking, hypertension, hypercholesterolemia, diabetes) have poorer outcomes compared to those with atleast one SMuRF. It has been hypothesised that this may be in part due to decreased administration of pharmacotherapies in the post-infarct period due to perceived low risk. Long term outcomes of patients without SMuRFs based on reperfusion strategy received during the index admission have not been investigated.

Purpose

We sought to analyse late clinical outcomes of STEMI patients with and without SMuRFs based on reperfusion strategy received during the index admission.

Methods

All patients who underwent PCI between 2003 and 2014 were identified from a PCI centre STEMI database. Late clinical outcomes of patients with and without SMuRFs were analysed overall and based on reperfusion strategy [primary PCI (pPCI) vs pharmaco-invasive PCI (PI-PCI)]. Propensity matching was used to account for differences in baseline characteristics between the groups.

Results

Amongst 2,091 STEMI patients, 531 (25%) had no SMuRFs (51% pPCI, 49% PI-PCI) and 1560 (75%) had ≥1 SMuRF (52% pPCI, 48% PI-PCI). Unadjusted late mortality in SMuRF-less patients was 13.4% (18.8% pPCI, 7.7% PI-PCI) and for those with ≥1 SMuRF was 9.7% (11.0% pPCI, 8.4% PI-PCI). After propensity-matching clinical and angiographic characteristics, 5 year mortality rates were significantly higher for patients without SMuRFs compared to those with SMuRFs [HR 1.36, CI: 1.03–1.81, p=0.031]. This difference was attenuated for patients who underwent pPCI [HR 1.72, CI: 1.22–2.43, p=0.002]. Interestingly, this discrepancy was not observed amongst individuals who underwent pharmaco-invasive PCI [HR 1.13, CI: 0.53–1.48, p=0.638], as SMuRF-less patients had similar mortality rates to their counterparts. Long term rates of reinfarction, stent thrombosis and target vessel revascularisation were similar between the groups. Additionally, there was no significant difference in rates of stroke and major bleeding amongst all 4 subgroups.

Conclusion

Patients presenting with STEMI in the absence of SMuRFs have increased overall late mortality compared to those with at least one SMuRF. However, this difference was not observed in patients who underwent a pharmaco-invasive strategy, whereby patients without SMuRFs had similar outcomes to those with SMuRFs after adjusting for confounders. Our findings suggest the use of a pharmaco-invasive strategy in appropriate SMuRF-less patients presenting with STEMI.

Funding Acknowledgement

Type of funding sources: None.

Utility of prehospital electrocardiogram interpretation in ST-segment elevation myocardial infarction utilizing computer interpretation and transmission for interventional cardiologist consultation

Objectives

We examined the appropriateness of prehospital cardiac catheter laboratory activation (CCL‐A) in ST‐segment elevation myocardial infarction (STEMI) utilizing the University of Glasgow algorithm (UGA) and remote interventional cardiologist consultation.

Background

The incremental benefit of prehospital electrocardiogram (PH‐ECG) transmission on the diagnostic accuracy and appropriateness of CCL‐A has been examined in a small number of studies with conflicting results.

Methods

We identified consecutive PH‐ECG transmissions between June 2, 2010 and October 6, 2016. Blinded adjudication of ECGs, appropriateness of CCL‐A, and index diagnoses were performed using the fourth universal definition of MI. The primary outcome was the appropriate CCL‐A rate. Secondary outcomes included rates of false‐positive CCL‐A, inappropriate CCL‐A, and inappropriate CCL nonactivation.

Results

Among 1088 PH‐ECG transmissions, there were 565 (52%) CCL‐As and 523 (48%) CCL nonactivations. The appropriate CCL‐A rate was 97% (550 of 565 CCL‐As), of which 4.9% (n = 27) were false‐positive. The inappropriate CCL‐A rate was 2.7% (15 of 565 CCL‐As) and the inappropriate CCL nonactivation rate was 3.6% (19 of 523 CCL nonactivations). Reasons for appropriate CCL nonactivation (n = 504) included nondiagnostic ST‐segment elevation (n = 128, 25%), bundle branch block (n = 132, 26%), repolarization abnormality (n = 61, 12%), artefact (n = 72, 14%), no ischemic symptoms (n = 32, 6.3%), severe comorbidities (n = 26, 5.2%), transient ST‐segment elevation (n = 20, 4.0%), and others.

Conclusions

PH‐ECG interpretation utilizing UGA with interventional cardiologist consultation accurately identified STEMI with low rates of inappropriate and false‐positive CCL‐As, whereas using UGA alone would have almost doubled CCL‐As. The benefits of cardiologist consultation were identifying “masquerading” STEMI and avoiding unnecessary CCL‐As.

Late Outcomes of Patients With Prehospital ST-Segment Elevation and Appropriate Cardiac Catheterization Laboratory Nonactivation

Background Patients with suspected ST-segment-elevation myocardial infarction (STEMI) and cardiac catheterization laboratory nonactivation (CCL-NA) or cancellation have reportedly similar crude and higher adjusted risks of death compared with those with CCL activation, though reasons for these poor outcomes are not clear. We determined late clinical outcomes among patients with prehospital ECG STEMI criteria who had CCL-NA compared with those who had CCL activation. Methods and Results We identified consecutive prehospital ECG transmissions between June 2, 2010 to October 6, 2016. Diagnoses according to the Fourth Universal Definition of myocardial infarction (MI), particularly rates of myocardial injury, were adjudicated. The primary outcome was all-cause death. Secondary outcomes included cardiovascular death/MI/stroke and noncardiovascular death. To explore competing risks, cause-specific hazard ratios (HRs) were obtained. Among 1033 included ECG transmissions, there were 569 (55%) CCL activations and 464 (45%) CCL-NAs (1.8% were inappropriate CCL-NAs). In the CCL activation group, adjudicated index diagnoses included MI (n=534, 94%, of which 99.6% were STEMI and 0.4% non-STEMI), acute myocardial injury (n=15, 2.6%), and chronic myocardial injury (n=6, 1.1%). In the CCL-NA group, diagnoses included MI (n=173, 37%, of which 61% were non-STEMI and 39% STEMI), chronic myocardial injury (n=107, 23%), and acute myocardial injury (n=47, 10%). At 2 years, the risk of all-cause death was higher in patients who had CCL-NA compared with CCL activation (23% versus 7.9%, adjusted risk ratio, 1.58, 95% CI, 1.24-2.00), primarily because of an excess in noncardiovascular deaths (adjusted HR, 3.56, 95% CI, 2.07-6.13). There was no significant difference in the adjusted risk for cardiovascular death/MI/stroke between the 2 groups (HR, 1.23, 95% CI, 0.87-1.73). Conclusions CCL-NA was not primarily attributable to missed STEMI, but attributable to "masquerading" with high rates of non-STEMI and myocardial injury. These patients had worse late outcomes than patients who had CCL activation, mainly because of higher rates of noncardiovascular deaths.

Impact of Ticagrelor Versus Clopidogrel on Coronary Microvascular Function After Non-ST-Segment-Elevation Acute Coronary Syndrome

BACKGROUND

Coronary microvascular dysfunction after acute coronary syndrome is an important predictor of long-term prognosis. Data is lacking on the effects of oral P2Y₁₂-inhibitors on coronary microvascular function in non-ST-segment-elevation acute coronary syndrome. The aim of this study was to compare the acute effects of ticagrelor versus clopidogrel pretreatment on coronary microvascular function in non-ST-segment-elevation acute coronary syndrome patients.

METHODS

Hospitalized non-ST-segment-elevation acute coronary syndrome patients were randomized (1:1) to ticagrelor or clopidogrel. The index of microcirculatory resistance, coronary flow reserve, and resistive reserve ratio were obtained using an intracoronary pressure-temperature sensor-tipped wire.

RESULTS

In total, 128 patients were randomized between March 2018 and July 2020. Mean age 59.2±11.8 years, 84% were male, mean Global Registry of Acute Coronary Events score was 93.7±24.5. Intracoronary physiological measurements were obtained in 118 patients (60 ticagrelor, 58 clopidogrel). In the infarct-related artery, the ticagrelor group had lower baseline index of microcirculatory resistance (22.0 [13.0-34.9] versus 27.7 [19.3-29.8]; P=0.02) and higher baseline resistive reserve ratio (3.0 [2.3-4.4] versus 2.4 [1.7-3.4]; P=0.01) compared with the clopidogrel group. A total of 88 patients underwent percutaneous coronary intervention (PCI; 45 ticagrelor, 43 clopidogrel). The ticagrelor group had lower post-PCI index of microcirculatory resistance (22.0 [15.0-29.0] versus 27.0 [18.5-47.5]; P=0.02) and higher post-PCI resistive reserve ratio (3.0 [1.8-3.8] versus 1.8 [1.5-3.4]; P=0.006) compared with the clopidogrel group. The coronary flow reserve was not significantly different between the 2 groups at baseline or post-PCI. No between-group differences were seen in any of the indices in the non-infarct-related artery.

CONCLUSIONS

In non-ST-segment-elevation acute coronary syndrome patients, ticagrelor significantly improved coronary microvascular function before and after PCI compared with clopidogrel.

REGISTRATION

URL: https://www.anzctr.org.au; Unique identifier: ACTRN12618001610224.

P333Late mortality after pharmaco-invasive PCI for STEMI

Background

Worldwide, and in Australia, a large proportion of patients with ST-segment elevation myocardial infarction (STEMI) are unable to undergo timely primary percutaneous coronary intervention (PCI), and so are transferred for PCI after receiving fibrinolytic therapy (so-called pharmaco-invasive PCI).

Methods

Our Hospital, the primary PCI centre for Southwest Sydney, Australia receives patients for both primary PCI and transferred post- fibrinolytic therapy for rescue or prognostic PCI. Associations were determined between late outcomes (bleeding according to Bleeding Academic Research Consortium (BARC) criteria and mortality) and reperfusion strategy, either primary PCI, or pharmaco-invasive PCI, in patients undergoing PCI for STEMI during hospitalization.

Results

Among 2083 consecutive patients (80% male) with STEMI who underwent PCI (1076 [52%] primary PCI and 1007 [48%] pharmaco-invasive PCI), mortality at 3 years was 8.7%,11.1% after primary PCI and 6.2% after pharmaco-invasive PCI (9.4% after rescue PCI and 4.6% after prognostic PCI); p<0.001 (Figure). Rates of type 2–5 BARC bleeding post-PCI were 35% after primary PCI and 24% after pharmaco-invasive PCI (42% after rescue PCI and 15% after prognostic PCI); p<0.001. while the rate of major bleeding type 3b-5 were 5% after primary PCI and 3% after pharmaco-invasive PCI (8% after rescue PCI and 1% after prognostic PCI); p=0.112.The independent predictors of 3 year mortality were, pre-PCI cardiogenic shock HR=0.25 [95% CI: 0.16–0.39], p<0.001), age (HR=1.05 [95% CI: 1.03–1.06], p<0.001), TIMI 3 flow post-PCI (HR=5.25 [95% CI: 2.51–11.00], p≤0.001), eGFR<60mL/min/1.73m2 (HR=2.90 [95% CI: 1.93–4.34], p≤0.001), post PCI bleeding (HR=2.17 [95% CI: 1.53–3.08], p≤0.001), anterior infarction (HR=1.76 [95% CI: 1.23–2.51], p=0.002), and female gender (HR=1.56 [95% CI: 1.07–2.27], p=0.022); and primary PCI (HR=1.6 [95% CI: 1.18–2.19; p=0.003]. On multi-variable analysis, age, cardiogenic shock presentation, rescue PCI, intra-aortic balloon pump, Pre-procedural anaemia, (all p<0.001) and eGFR<60mL/min/1.73m2 (p=0.006) were associated with bleeding.

Figure 1. Late survival after primary & PI PCI

Conclusion

Among patients with STEMI who underwent pharmaco-invasive PCI had lower mortality rates than to those who had primary PCI, though procedural selection criteria may have been different; bleeding rates were similar. Among suitable patients pharmaco-invasive PCI should be evaluated in large clinical trials.

Real-world use of ticagrelor versus clopidogrel in percutaneous coronary intervention-treated ST-elevation myocardial infarction patients: A single-center registry study

Objectives

The primary aim was to investigate the efficacy and safety of dual antiplatelet therapy (DAPT) using ticagrelor (T-DAPT) versus clopidogrel (C-DAPT) in a real-world ST-elevation myocardial infarction (STEMI) population.

Methods

We retrospectively analyzed 655 consecutive patients having primary percutaneous coronary intervention (PCI) for STEMI at Liverpool Hospital, Sydney, Australia (from January 2013 to April 2016). Medical and procedural therapies were at clinician discretion. Patient data were retrieved from hospital records and primary clinicians.

Results

T-DAPT (65%) was used more frequently, and in patients with lower mean CRUSADE (Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes with Early Implementation of the American College of Cardiology/American Heart Association Guidelines) score, than C-DAPT (24.6 vs. 32.2; p < 0.0001, respectively). All-cause mortality was 9.0% at 2.7 years follow-up, with fewer deaths for T-DAPT (4.5% vs. 17.2%; p < 0.0001). T-DAPT incurred less BARC (Bleeding Academic Research Consortium) 3-5 major bleeding (5.0% vs. 12.4%; p < 0.0001). Multivariate regression showed that C-DAPT, GRACE (Global Registry of Acute Cardiac Events) score, and renal insufficiency were independently associated with mortality. Intra-aortic balloon pump (IABP) and GRACE score independently predicted BARC 3-5 bleeding. Early DAPT discontinuation (1.7%) and ticagrelor intolerance (7.6%) was rare. Switching DAPT regimen was infrequent (21.7%) and mostly attributed to clinician preference (73.2%). Independent determinants of C-DAPT selection were older age, diabetes, prior PCI, IABP, and higher CRUSADE score.

Conclusion

Ticagrelor was preferred in low bleeding risk patients, which may have contributed to less BARC 3-5 bleeding and lower mortality for T-DAPT. Thus, bleeding mitigation is a clinical priority when selecting DAPT for PCI-treated STEMI patients. Continuation of initial DAPT regimen was typical, but early switching from clopidogrel to ticagrelor shows willingness to optimize DAPT. Patients with very low CRUSADE scores (<21.5) may be appropriate for switching to a potent P2Y12 inhibitor.

The Plague Doctor of Venice

There is a distinctive Venetian carnival mask with sinister overtones and historical significance to physicians because it belongs to the 'Doctor of the Plague'. The costume features a beaked white mask, black hat and waxed gown. This was worn by mediaeval Plague Doctors as protection according to the Miasma Theory of disease propagation. The plague (or Black Death), ravaged Europe over several centuries with each pandemic leaving millions of people dead. The cause of the contagion was not known, nor was there a cure, which added to the widespread desperation and fear. Venice was a major seaport, and each visitation of the plague (beginning in 1348) devastated the local population. In response, Venetians were among the first to establish the principles of quarantine and 'Lazarets' which we still use today. Plague outbreaks have occurred in Australia, notably in Sydney (1900-1925), and continue to flare up in poorer communities, most recently in Madagascar (2017). Antibiotics are the mainstay of treatment, but there are concerns regarding the emergence of resistant pathogenic strains of Yersinia pestis, and their potential use in bio-terrorism.

Clinical and Angiographic Predictors of Mortality in Sudden Cardiac Arrest Patients Having Cardiac Catheterisation: A Single Centre Registry

BACKGROUND

Immediate cardiac catheterisation (CC) is recommended in ST-elevation myocardial infarction (STEMI) following sudden cardiac arrest (SCA). Guidelines advise urgent CC for SCA patients without-STEMI, at clinician discretion. We examined the clinical and angiographic factors predicting mortality in SCA patients having CC.

METHODS

Consecutive SCA patients having CC at Liverpool Hospital, Sydney (January 2011-September 2015) were retrospectively analysed. Patient data were retrieved from hospital records, and angiographic SYNTAX scores (SS) were quantified online. Independent predictors of mortality were derived using multivariate logistic analysis.

RESULTS

The study cohort comprised 104 SCA patients; mean age 61±12years, and 79% male. Immediate CC (<2hours post-SCA) was performed in 35% overall. Compared to the without-STEMI subgroup, STEMI patients had more ventricular fibrillation (91 vs 50%; p<0.0001), and higher mean peak serum high-sensitivity troponin-T (8.25±14.7 vs 1.97±6.13 ug/L; p=0.006); in the context of higher median SS (18 vs 6.5; p=0.002) and target-lesion SS (tSS, 10 vs 0; p<0.001). Percutaneous coronary intervention (PCI; 75 vs 23%; p<0.0001) and target vessel revascularisation (11 vs 0%; p=0.005) were more frequent for STEMI. All-cause mortality was 39%, at 1.3±1.5years follow-up. Independent mortality predictors were: delayed CC (HR 4.08), serum lactate >7mmol/L (HR 3.47), and tSS (HR 1.05).

CONCLUSIONS

Elevated serum lactate, tSS, and delayed CC, were predictive of longer-term mortality in SCA patients having CC. Late CC in patients without-STEMI suggest scope for improvement in real-world systems of care. Closer scrutiny of target lesion complexity may aid prognostication in SCA survivors.

Late clinical outcomes for SeQuent please paclitaxel-coated balloons in PCI of instent restenosis and de novo lesions: A single-center, real world registry

OBJECTIVES

The aims of this study were to evaluate clinical outcomes following PCI using SeQuent Please paclitaxel-coated balloons (PCB) of ISR and denovo lesions (DNL), in all-comer patients at Liverpool Hospital, Sydney, Australia.

BACKGROUND

There have been promising results for PCI using drug-coated balloons; however, long-term data for clinical outcomes are lacking.

METHODS

Baseline patient demographics, PCI procedural details, and clinical outcomes were collected. The primary endpoint was the incidence of MACE, a composite of cardiac death, myocardial infarction (MI), and clinical-driven target lesion restenosis (TLR). The median follow-up for clinical events was 1.3 [0.6-1.9] years.

RESULTS

A total of 188 lesions (n = 147 patients) were treated with PCB, comprising 118 (63%) ISR lesions and 70 (38%) DNL. Patient mean age was 67 ± 11years, 79% were male, and 54% had type 2 diabetes mellitus (DM). MACE was recorded in 17 patients (12%), with cardiac death confirmed in 1 patient (0.7%). MACE was significantly lower for DNL than ISR (1% vs. 15%, P = 0.03), and PCB had favourable TLR for DNL. Cox regression demonstrated that DM (HR 7.17, 0.92-55.6, P = 0.05) and prior CABG (HR 3.22, 1.17-8.83, P = 0.02) were independent predictors of MACE for ISR lesions.

CONCLUSIONS

MACE rates were acceptable, with overall low incidence of cardiac death, MI, and TLR, for PCB treatment of ISR and DNL. Independent predictors of poor outcome in the ISR group were DM and prior CABG. The particularly low MACE for the DNL group supports direct PCB as a viable stent-sparing PCI strategy in challenging patients and lesion subsets. © 2016 Wiley Periodicals, Inc.

Prognostic value of high sensitivity troponin T after ST-segment elevation myocardial infarction in the era of cardiac magnetic resonance imaging

Aims

To determine if high sensitivity troponin T (hs-TnT) measurements performed during the 'plateau phase' of troponin release (≥48 h) following ST-segment elevation myocardial infarction (STEMI) can predict major adverse cardiovascular endpoints (MACE), and to evaluate its prognostic value compared with cardiac magnetic resonance imaging (CMRI) parameters.

Methods and results

We prospectively recruited 201 first presentation STEMI patients. Serial hs-TnT levels were measured at admission, peak (highest), 24, 48 and 72 h. CMRI and transthoracic echocardiography were performed (4 days median) post-STEMI, evaluating infarct scar characteristics and left ventricular ejection fraction (LVEF). Associations were determined between hs-TnT levels and CMRI parameters early after STEMI with MACE (comprising mortality, re-infarction, new or worsening of heart failure, cerebrovascular accident, and sustained ventricular arrhythmias) at medium-term follow-up. After 602 days (median), 33 (17%) patients had MACE. Upper tertile hs-TnT levels at 48 and 72 h were associated with MACE (Kaplan-Meier P = 0.002 and P = 0.012, respectively). Multivariate Cox analyses, incorporating diabetes, CMRI scar size, LVEF and hs-TnT levels (applied at a single hs-TnT time point) showed that 48 and 72 h hs-TnT levels were independent predictors for MACE (HR = 1.20, P = 0.002, and HR = 1.21, P = 0.035 respectively).

Conclusion

Measurement of hs-TnT in the plateau phase after STEMI is an inexpensive method of prognostic risk assessment.

Practical experience with ticagrelor: an Australian and New Zealand perspective

OBJECTIVE

Ticagrelor is recommended in local and international guidelines as first-line therapy in combination with aspirin in patients presenting with acute coronary syndromes (ACS). The purpose of this article is to provide practical guidance regarding the use of ticagrelor in this setting.

METHODS AND RESULTS

Ticagrelor, a direct-acting, reversible P2Y12 receptor antagonist, has a faster onset, and a more potent and predictable antiplatelet effect compared with clopidogrel. The authors recommend considering the use of ticagrelor in moderate-to-high risk ACS patients treated with an invasive approach and those managed non-invasively who have elevated troponin levels. Consistent with outcomes observed in the PLATO trial overall, ticagrelor was superior to clopidogrel treatment in patients with chronic kidney disease, a history of stroke or transient ischemic attack, the elderly, and patients requiring surgical revascularization.

CONCLUSIONS

When switching from clopidogrel to ticagrelor, patients established on clopidogrel therapy can be switched directly without loading; patients not loaded with clopidogrel and not taking maintenance dose clopidogrel for at least 5 days should first be loaded with ticagrelor. Guidelines recommend discontinuing ticagrelor 5 days before surgery if antiplatelet effects are not desired and recommencing therapy as soon as safe following surgery. Ticagrelor should be avoided in individuals with a history of intracranial hemorrhage, moderate-to-severe hepatic impairment, high bleeding risk, within 24 hours of thrombolytic therapy, and in those treated with oral anticoagulants. Local, real-world experience suggests low bleeding rates with ticagrelor therapy. Dyspnoea is a common symptom in patients with ACS and is also a side-effect of ticagrelor therapy. Discontinuation of ticagrelor due to dyspnoea has been uncommon in clinical trials. However, local registry data suggest higher discontinuation rates (2-9%) related to dyspnoea in the real-world setting, indicating that clinicians may need to consider other potential causes of dyspnoea before discontinuing ticagrelor.

Bare-metal stenting of large coronary arteries in ST-elevation myocardial infarction is associated with low rates of target vessel revascularization

BACKGROUND

During percutaneous coronary intervention (PCI) performed in the emergent setting of ST-segment elevation myocardial infarction (STEMI), uncertainty about patients' ability to comply with 12 months dual antiplatelet therapy after drug-eluting stenting is common, and thus, selective bare-metal stent (BMS) deployment could be an attractive strategy if this achieved low target vessel revascularization (TVR) rates in large infarct-related arteries (IRAs) (≥3.5 mm).

METHODS AND RESULTS

To evaluate this hypothesis, among 1,282 patients with STEMI who underwent PCI during their initial hospitalization, we studied 1,059 patients (83%) who received BMS, of whom 512 (48%) had large IRAs ≥3.5 mm in diameter, 333 (31%) had IRAs 3 to 3.49 mm, and 214 (20%) had IRAs <3 mm. At 1 year, TVR rate in patients with BMS was 5.8% (2.2% with large BMS [≥3.5 mm], 9.2% with BMS 3-3.49 mm [intermediate], and 9.0% with BMS <3.0 mm [small], P < .001). The rates of death/reinfarction among patients with large BMS compared with intermediate BMS or small BMS were lower (6.6% vs 11.7% vs 9.0%, P = .042). Among patients who received BMS, the independent predictors of TVR at 1 year were the following: vessel diameter <3.5 mm (odds ratio [OR] 4.39 [95% CI 2.24-8.60], P < .001), proximal left anterior descending coronary artery lesions (OR 1.89 [95% CI 1.08-3.31], P = .027), hypertension (OR 2.01 [95% CI 1.17-3.438], P = .011), and prior PCI (OR 3.46 [95% CI 1.21-9.85], P = .02). The predictors of death/myocardial infarction at 1 year were pre-PCI cardiogenic shock (OR 8.16 [95% CI 4.16-16.01], P < .001), age ≥65 years (OR 2.63 [95% CI 1.58-4.39], P < .001), left anterior descending coronary artery culprit lesions (OR 1.95 [95% CI 1.19-3.21], P = .008), female gender (OR 1.93 [95% CI 1.12-3.32], P = .019), and American College of Cardiology/American Heart Association lesion classes B2 and C (OR 2.17 [95% CI 1.10-4.27], P = .026).

CONCLUSION

Bare-metal stent deployment in STEMI patients with IRAs ≥3.5 mm was associated with low rates of TVR. Their use in this setting warrants comparison with second-generation drug-eluting stenting deployment in future randomized clinical trials.

Outcomes of coronary revascularization (percutaneous or bypass) in patients with diabetes mellitus and multivessel coronary disease

Clinical outcomes in patients with diabetes mellitus and multivessel disease (MVD) undergoing coronary revascularization have not been extensively evaluated, we sought to examine outcomes in a diabetic cohort of 195 consecutive patients with MVD characterized by SYNTAX scores (SSs) undergoing nonrandomized revascularization, 102 (52%) by percutaneous intervention (PCI) and 93 (48%) by coronary artery bypass grafting (CABG) at Liverpool Hospital (Sydney, Australia) from June 2006 to March 2010. Clinical outcomes were assessed at a median term of 14 months. The overall median SS was 44, with significantly higher SSs in CABG- than PCI-treated patients (48 vs 39, p <0.0001). There was a similar incidence of all-cause death, nonfatal myocardial infarction and stroke in PCI- and CABG-treated patients (6.1% vs 8.3%, p = 0.383; 12% vs 4.9%, p = 0.152; 3.1% vs 3.5%, p = 0.680 respectively). However, the rates of target vessel revascularization and major adverse coronary and cerebral event were significantly higher in PCI-treated patients than in those undergoing CABG (20% vs 1.2%, p <0.0001; 29% vs 15%, p = 0.034). Despite a much higher SS, patients who underwent PCI achieved comparable outcomes at 1 year to those with diabetes mellitus and a SS ≥ 33 as reported in the SYNTAX trial. In conclusion, in this single-center nonrandomized observational study, coronary revascularization by PCI is associated with increased major adverse coronary and cerebral events at 1-year follow-up, predominantly driven by a high rate of target vessel revascularization. Thus, CABG should remain the revascularization procedure of choice for diabetic patients with MVD and high SSs.

Risk factor modification in diabetic patients following angiographic identification of multi-vessel disease

There is little information on whether identification of multi-vessel disease (MVD) in patients with diabetic mellitus (DM) affects risk factor management. From 1125 consecutively screened patients between June 2006 and March 2010, we examined 227 diabetic patients with MVD on coronary angiography. Diabetic control and cholesterol levels were assessed by glycated haemoglobin (HbA1c) and total cholesterol (TC) respectively which were evaluated at baseline and at 1-year follow-up. Patients were grouped by age into <55(n=33), 55-65(n=75), 66-75(n=75) and >75(n=44). Target levels were defined as HbA1c<7% and TC<4.0 mmol/L. Patients <55 years had the highest HbA1c at 9.1[7.6-11.2]% with the lowest proportion of patients (n=3; 11.1%) within target at baseline, while 66-75 years had the best HbA1c at 7.1[6.4-7.8]% with the highest proportion (n=28, 45.2%) reaching target (p<0.0001). At 1-year, the poorest HbA1c control was again observed in the age <55 with fewer patients achieving target compared to the 66-75 age group (HbA1c: 8.5% vs 6.9%; % of patients at target: 20.7% vs 54.5%; p<0.0001). Furthermore, the group <55 years demonstrated the worst TC control at 1-year with a significant increase compared to the baseline TC (p=0.01). Patients with a lower body mass index (BMI) were likely to have an improvement in HbA1c and reach target (p=0.01). Paradoxically, patients who were current smokers demonstrated a beneficial effect on optimal TC control (29.2% vs 15.4%, p=0.027). In younger diabetic patients, risk factor modification at 1-year was poor despite identification of MVD. Developing an effective education and monitoring programme to improve glycaemic control in this high risk group should be a priority.

Stent sizing by coronary computed tomographic angiography: comparison with conventional coronary angiography in an experienced setting

OBJECTIVES

The goal was to compare stent sizing by coronary computed tomographic angiography (CCTA) with that deployed in an experienced setting based upon conventional coronary angiography (CA).

BACKGROUND

Stent sizing is currently performed by visual estimation, with infrequent guidance by intravascular ultrasound. CCTA permits quantitative determination of stent length (Stent L) and diameter (Stent D).

METHODS

Projected L (CTA-Stent L) and D (CTA-Stent D) were determined from CCTA obtained in 248 patients with 352 lesions undergoing percutaneous coronary intervention within 4 months of the CCTA, and were compared to the Stent-L and Stent-D of the actually deployed stents. The effects of lesion modification and calcified plaque were also evaluated.

RESULTS

There were significant correlations between CTA-Stent L and Stent L (r = 0.656, P < 0.0001) and between CTA-Stent D and Stent D (r = 0.40, P < 0.001). Median predicted CTA-Stent L was slightly longer (20 mm vs. 18 mm, P < 0.0001) and predicted CTA-Stent D was slightly smaller (3.0 mm vs. 3.2 mm, P < 0.0001) than Stent-L and Stent-D, respectively. The differences were unchanged in stents with lesion modification by pre-dilation or intracoronary nitroglycerin. CTA Stent-L and CTA Stent-D increased significantly with increasing calcium (P < 0.0001 and P = 0.019, respectively).

CONCLUSIONS

(1) There are significant correlations between CCTA and CA based stent sizing in an experienced setting. (2) CCTA projects slightly longer and slightly smaller diameter stents than those deployed during PCI irrespective of lesion modification; the small differences are unlikely to have clinical significance. (3) CCTA may offer a noninvasive alternative to intravascular ultrasound for stent planning.

Carotid stenting and bivalirudin with and without vascular closure: 3-year analysis of procedural outcomes

OBJECTIVES

The purpose of this study was to examine the outcome of carotid stenting using bivalirudin and the influence of vascular closure devices (VCD) on the incidence and severity of peri-procedural hypotension.

BACKGROUND

Bivalirudin, a short-acting direct thrombin inhibitor, has been shown to be an effective anticoagulant in coronary interventions, with less risk of bleeding compared with heparin. Routine use of VCD has become the standard of care, facilitating patient ambulation after percutaneous carotid and coronary interventions. The combined use of these two therapies (bivalirudin and VCD) may improve outcomes in carotid interventions where prolonged patient immobilization may exacerbate hypotension following stenting.

METHODS

A total of 514 patients underwent 536 carotid stenting procedures in the 3-year period from September 2004 to September 2007. All patients received adjunctive bivalirudin, with and without VCD. This cohort was analyzed for peri-procedural and 30-day clinical outcomes and length of hospitalization.

RESULTS

Thirty-day stroke and death rate was 1.7%. A total of 83 patients (15.4%) experienced intra- or post-procedural hypotension (systolic BP < 80 mm Hg). There were four (0.7%) major bleeding complications requiring transfusion, and length of stay was delayed more than 24 hr in five patients (0.93%), all of whom were in the manual compression group.

CONCLUSIONS

This was a negative study, with no significant difference on prolonged hypotensive events in patients with vascular closure device and bivalirudin, compared with those with manual compression and bivalirudin. Vascular closure devices were safe and effective with a low incidence of complications. In carotid artery stenting, bivalirudin is safe with low incidence of major bleeding and acceptable 30-day adverse event rates (stroke and death).

Radioligand binding, autoradiographic and functional studies demonstrate tachykinin NK-2 receptors in dog urinary bladder

Tachykinin receptors in the dog bladder were characterized using radioligand binding, functional and autoradiographic techniques. In detrusor muscle homogenates, specific binding of [125l]iodohistidyl neurokinin A (INKA) and [125l]Bolton Hunter eledoisin was reversible, saturable and, to a single class of sites of Kd, 3,6 and 27 nM, respectively. No specific binding of [125l]Bolton Hunter[Sar9, Met (O2)11] substance P occurred. INKA binding was reduced by the peptidase inhibitor bacitracin. The rank potency order of agonists competing for binding of both radioligands indicated interaction at NK-2 sites. NK-2-selective antagonists also competed for INKA binding, with SR 48968, GR 94800, MDL 29913 and the selective agonist [Lys5, MeLeu9, Nle10]-NKA(4-10) showing biphasic binding profiles. Autoradiographic studies revealed specific binding of INKA and [125l]Bolton Hunter eledoisin over detrusor muscle and small arteries. [125l]Bolton Hunter [Sar9, Met (O2)11] SP labeled the intima of arteries and arterioles, but not the detrusor muscle. Tachykinins contracted detrusor muscle strips, with potency order at the carbachol EC15 NKA = kassinin > [Lys5, MeLeu9, Nle10]-NKA(4-10) = neuropeptide gamma = neuropeptide K = NKB > > MDL 28564, with [Sar9, Met(O2)11]-SP ineffective. Shallow concentration-response curves, variable efficacies and inhibition by atropine and mepyramine suggest that other mechanisms may influence contractile responses. Responses to [Lys5, MeLeu9, Nle10]-NKA(4-10) were inhibited competitively by MDL 29913 and MEN 10207 (pA2 values: 6.4 and 5.3, respectively). Antagonism by SR 48968 and GR 94800 was noncompetitive (both pK8 values 8.9). In summary, NK-2-preferring ligands showed superior potency as both binding competitors and contractile agonists, demonstrating that NK-2 receptors mediate detrusor muscle contraction, similar to the human detrusor. Tachykinins may play important roles in the micturition reflex and in regulating detrusor muscle blood flow in the dog.

Binding sites for [125I]-Bolton-Hunter scyliorhinin II in guinea-pig ileum: a radioligand binding, functional and autoradiographic study

Binding of the tachykinin NK-3 receptor-preferring radioligand [125I]-Bolton-Hunter scyliorhinin II (BHSCYII) was investigated in membranes from guinea-pig ileum muscularis externa with myenteric plexus (MMP). Specific binding for BHSCYII was saturable and reversible. Curvilinear Scatchard plots and biphasic competition data indicate binding to two classes of sites (0.8 nM, 8% of sites; 340 nM, 92% of sites). Competition-binding data was ambiguous with the rank order of potency neuropeptide K (NPK) > substance P (SP) congruent to [Sar9,Met(O2)11]-SP congruent to [pGlu6,Pro9]SP(6-11) (septide) > neuropeptide gamma (NP gamma) > kassinin congruent to physalaemin > neurokinin A (NKA) > SCYII > neurokinin B (NKB). Senktide, eledoisin, [Lys5,MeLeu9,Nle10]-NKA(4-10), CP 96345, RP 67580, MDL 29913, SR 48968 and Gpp[NH]p were ineffective competitors, suggesting a lack of binding to conventional NK-1, NK-2 or NK-3 receptors. Competition curves for 5 agonists could be resolved into two sites, with no competitor showing outstanding affinity. Autoradiographic studies revealed moderate BHSCYII binding to myenteric plexus ganglia, unaffected by co-incubation with CP 96345 or with senktide. These data suggest a component of BHSCYII binding at unusual NPK/SP-preferring sites on ganglia. [Sar9,Met(O2)11]-SP was the most potent contractile agonist of the isolated ileum, followed by SCYII, NP gamma, senktide and NPK, with [Lys5,MeLeu9,Nle10]-NKA(4-10) least potent. Contractions elicited by senktide were entirely neurogenic. Responses to SCYII were partly sensitive to tetrodotoxin, atropine and CP 96345, indicative of action at both neuronal receptors and smooth muscle NK-1 receptors. The NK-2 antagonist SR 48968 did not alter responses to SCYII, [Sar9,Met(O2)11]-SP or senktide.

Characterization and autoradiographic localization of tachykinin receptors in rat gastric fundus

Tachykinin receptors in rat gastric fundus were characterized using radioligand binding, functional and autoradiographic techniques. In crude homogenates of fundus, the specific binding of 125I-iodohistidyl-neurokinin A (INKA), 125I-Bolton-Hunter eledoisin (BHELE) and 125I-Bolton-Hunter [Sar9,Met(O2)11]-SP (BHSar-SP) was reversible and saturable. INKA and, in particular, BHSar-SP showed high affinity binding (Kds, 2.2 and 0.6 nM, respectively), with lower affinity for BHELE (Kd, 17 nM). The binding capacity was higher for INKA and BHELE than for BHSar-SP. The superior potency of neurokinin (NK)-2-preferring agonists (neuropeptide gamma > or = [Lys5,MeLeu9,Nle10]-NKA(4-10) > or = neuropeptide K > neurokinin A [NKA] > [Sar9,Met(O2)11]-SP >> senktide) and antagonists (SR 48,968 > GR 94,800 > MDL 29,913 > L-659,877 > MEN 10,207) as competitors for INKA and BHELE binding suggests interaction at mainly NK-2 sites. Additional competition studies showed that BHSar-SP was binding to NK-1 sites. Autoradiographic studies revealed very dense INKA and BHELE specific binding over the circular muscle and muscularis mucosae, while BHSar-SP binding was observed only to the circular muscle. The weak specific binding for 125I-Bolton-Hunter scyliorhinin II localized to the muscularis mucosae may indicate NK-3 sites. This was consistent with functional studies showing concentration-dependent contractions of fundus strips by NK-2-preferring tachykinin agonists (potency, pD2s, 7.1 to 8.1) and [Sar9, Met(O2)11]-SP (pD2, 7.1). The NK-2 selective antagonist MDL 29,913 inhibited INKA binding (Kd, 14 nM) with more than tenfold greater affinity than did MEN 10,207. The antagonism by MDL 29,913 was noncompetitive, with a nonparallel rightward shift of the concentration-response curves to the agonists neuropeptide gamma, neuropeptide K, NKA and [Lys5,MeLeu9,Nle10]-NKA(4-10) (dose ratios at 400 nM MDL 29,913 were 230, 62, 40 and 23, respectively). These data indicate that classic NK-2 receptors predominate in the rat fundus and that NK-1 and perhaps NK-3 receptors also exist.

Tachykinin receptors: a radioligand binding perspective

The last decade has witnessed major breakthroughs in the study of tachykinin receptors. The currently described NK-1, NK-2, and NK-3 receptors have been sequenced and cloned from various mammalian sources. A far greater variety of tachykinin analogues are now available for use as selective agonists and antagonists. Importantly, potent nonpeptide antagonists highly selective for the NK-1 and NK-2 receptors have been developed recently. These improved tools for tachykinin receptor characterization have enabled us to describe at least three distinct receptor types. Furthermore, novel antagonists have yielded radioligand binding and functional data strongly favoring the existence of putative subtypes of NK-1 and especially NK-2 receptors. Whether these subtypes are species variants or true within-species subtypes awaits further evidence. As yet undiscovered mammalian tachykinins, or bioactive fragments, may have superior potency at a specific receptor class. The common C terminus of tachykinins permits varying degrees of interaction at essentially all tachykinin receptors. Although the exact physiological significance of this inherent capacity for receptor "cross talk" remains unknown, one implication is for multiple endogenous ligands at a single receptor. For example, NP gamma and NPK appear to be the preferred agonists and binding competitors at some NK-2 receptors, previously thought of as exclusively "NKA-preferring." Current evidence suggests that tachykinin coexistence and expression of multiple receptors may also occur with postulated NK-2 and NK-1 receptor subtypes. Other "tachykinin" receptors may recognize preprotachykinins and the N terminus of SP. In light of these recent developments, the convenient working hypothesis of three endogenous ligands (SP, NKA, and NKB) for three basic receptor types (NK-1, NK-2, and NK-3) may be too simplistic and in need of amendment as future developments occur (Burcher et al., 1991b). In retrospect, the 1980s contributed greatly to our understanding of the structure, function, and regulation of tachykinins and their various receptors. The development of improved, receptor subtype-selective antagonists and radioligands, in addition to recent advances in molecular biological techniques, may lead to a more conclusive pharmacological and biochemical characterization of tachykinin receptors. The 1990s may prove to be the decade of application, where a better understanding of the roles played by endogenous tachykinins (at various receptor subtypes) under pathophysiological conditions will no doubt hasten the realization of clinically useful therapeutic agents.

Characterization of the tachykinin NK2 receptor subtype in the rabbit pulmonary artery

Contractile responses to neurokinin A (NKA), neuropeptide gamma(NP gamma), and the NK2 receptor-selective analogs [Lys5,MeLeu9,Nle10]NKA(4-10) and MDL 28,564 were determined in the endothelium-denuded rabbit pulmonary artery. Responses to NKA, NP gamma, and [Lys5,MeLeu9,Nle10]NKA(4-10) were antagonized by the NK2 receptor antagonist MDL 29,913, with pA2 values of 6.67, 6.46, and 7.32, respectively. Autoradiographic studies failed to demonstrate any specific binding sites for [125I]-iodohistidyl NKA (INKA) over the pulmonary artery. These data suggest the presence in rabbit pulmonary artery of an unusual "nonclassical" NK2 receptor subtype, which appears to lack affinity for INKA.

Radioiodinated substance P, neurokinin A, and eledoisin bind predominantly in NK1 receptors in guinea pig lung

In homogenates of guinea pig lung, binding of 125I-Bolton-Hunter-labeled substance P (BHSP), Bolton-Hunter-labeled eledoisin (BHELE), and [125I]iodohistidyl neurokinin A (INKA) was investigated. Equilibrium dissociation constants (derived from "cold" saturation experiments) for BHSP, INKA, and BHELE were 0.96 +/- 0.15, 1.61 +/- 0.26, and 1.98 +/- 0.12 nM, respectively. Specific binding of all three radioligands was increased 2-3-fold by 10 microM phosphoramidon. The rank order of potency of unlabeled tachykinins in competing against BHSP was substance P (SP) greater than [Sar9,Met(O2)11]-SP greater than SP methyl ester greater than neuropeptide gamma greater than neurokinin A greater than or equal to neurokinin B = kassinin greater than or equal to eledoisin greater than or equal to scyliorhinin II much greater than neuropeptide K, indicating binding to sites with the general characteristics of NK1 receptors. Similar rank potency orders were observed for INKA and BHELE, showing binding to NK1 sites, rather than to NK2 or NK3 sites, which are labeled with high affinity by these radioligands in other tissues. For all radioligands, competition curves for SP and the NK1-selective agonist [Sar9,Met(O2)11]-SP could be resolved into two components, representing high and low affinity binding sites. These were present in the approximate ratios 2:3 (for BHSP), 1:1 (for INKA), and 8:1 (for BHELE). Other agonist competition curves also yielded high and low affinity components. The data suggest that BHSP and INKA bind partly and BHELE predominantly to high affinity NK1 receptors. The nature of the low affinity site(s) could be another tachykinin receptor or a low affinity state of the NK1 receptor. Binding to a "classical" NK2 receptor is unlikely, because selective NK2 receptor antagonists and analogs were very weak competitors. Our data suggest that, in addition to the NK1 receptor, another type of tachykinin receptor may exist in this tissue. The inability to detect NK2 binding sites is strikingly at variance with functional studies.

[125I]-Bolton-Hunter scyliorhinin II: a novel, selective radioligand for the tachykinin NK3 receptor in rat brain

The cyclic tachykinin scyliorhinin II (SCYII) has high affinity for the [neurokinin B (NKB)-preferring] NK3 receptor. SCYII was iodinated using [125I]-Bolton-Hunter reagent and the product BHSCYII purified using reverse phase HPLC. In rat brain membranes, binding of BHSCYII and of the relatively unselective radioligand [125I]-Bolton-Hunter eledoisin (BHELE) was saturable, reversible and to an NK3 site. In competition studies, the rank order of potency in inhibiting binding of BHSCYII and BHELE was: SCYII greater than or equal to [MePhe7]-NKB approximately senktide greater than NKB greater than or equal to kassinin greater than or equal to eledoisin greater than [Pro7]-NKB greater than neurokinin A greater than neuropeptide K greater than or equal to substance P greater than [Sar9, Met(O2)11]-substance P. In "cold" saturation experiments, binding of BHELE occurred to a single class of high affinity sites (KD, 18.6 +/- 0.91 nM). Binding of BHSCYII was of greater affinity than for BHELE and could be resolved into a high (KD, 1.33 +/- 0.98 nM; 27% of sites) and low affinity (KD, 9.84 +/- 2.75; 73% of sites) component. The total number of binding sites was similar for both radioligands (BHSCYII, 8.27 +/- 0.98; BHELE, 7.94 +/- 0.32 fmol/mg wet weight). In vitro autoradiography in slide-mounted sections of rat brain showed identical binding patterns for both radioligands (100 pM), with dense binding localized predominantly to the cortex, Ammon's horn field 1, premammillary nuclei and interpeduncular nucleus.(ABSTRACT TRUNCATED AT 250 WORDS)

The autoradiographic distribution of substance P binding sites in guinea-pig vas deferens is altered by capsaicin pretreatment

The distribution of binding sites for [125I]Bolton-Hunter substance P (BHSP) was investigated in vasa deferentia from normal, capsaicin-pretreated and vehicle-pretreated guinea-pigs, using qualitative and quantitative autoradiography. Dense binding of BHSP was seen over the outer longitudinal muscle with less over the inner longitudinal muscle. Very low specific binding occurred to the circular muscle and was absent in the mucosa. Characterization in slide-mounted sections showed that binding was saturable and of high affinity, with equilibrium dissociation constant (KD) 91 +/- 15 pM. BHSP was displaced by substance P greater than neurokinin A greater than neurokinin B, suggesting binding to NK-1 receptors. Capsaicin pretreatment had no effect on the lengthwise distribution of binding sites but significantly altered their relative distribution between the different smooth muscle layers. There was a very marked increase in BHSP binding over the inner longitudinal muscle and the inner part of the circular muscle layer, whereas binding was virtually abolished over the outer longitudinal muscle, compared with vehicle control. Capsaicin-sensitive binding sites over the outer longitudinal muscle may be located presynaptically on capsaicin-susceptible primary afferent sensory neurons. In contrast, the increase in number of binding sites associated with the inner longitudinal muscle may be due to receptor upregulation resulting from loss of sensory innervation, and suggests that these binding sites are postsynaptic.