Daylight saving time does not seem to be associated with number of percutaneous coronary interventions for acute myocardial infarction in the Netherlands.

BACKGROUND: In multiple studies, the potential relationship between daylight saving time (DST) and the occurrence of acute myocardial infarction (MI) has been investigated, with mixed results. Using the Dutch Percutaneous Coronary Intervention (PCI) registry facilitated by the Netherlands Heart Registration, we investigated whether the transitions to and from DST interact with the incidence rate of PCI for acute MI. METHODS: We assessed changes in hospital admissions for patients with ST-elevation myocardial infarction (STEMI) or non-STEMI (NSTEMI) undergoing PCI between 1 January 2015 and 31 December 2018. We compared the incidence rate of PCI procedures during the first 3 or 7 days after the transition with that during a control period (2 weeks before transition plus second week after transition). Incidence rate ratio (IRR) was calculated using Poisson regression. Potential gender differences were also investigated. RESULTS: A total of 80,970 PCI procedures for STEMI or NSTEMI were performed. No difference in incidence rate a week after the transition to DST in spring was observed for STEMI (IRR 0.95, 95% confidence interval (CI) 0.87-1.03) or NSTEMI (IRR 1.04, 95% CI 0.96-1.12). After the transition from DST in autumn, the IRR was also comparable with the control period (STEMI: 1.03, 95% CI 0.95-1.12, and NSTEMI: 0.98, 95% CI 0.91-1.06). Observing the first 3 days after each transition yielded similar results. Gender-specific results were comparable. CONCLUSION: Based on data from a large, nationwide registry, there was no correlation between the transition to or from DST and a change in the incidence rate of PCI for acute MI.

How often and to what extent do admitted COVID-19 patients have signs of cardiac injury?

BACKGROUND: COVID-19 can cause myocardial injury in a significant proportion of patients admitted to the hospital and seems to be associated with worse prognosis. The aim of this review was to study how often and to what extent COVID-19 causes myocardial injury and whether this is an important contributor to outcome with implications for management. METHODS: A literature search was performed in Medline and Embase. Myocardial injury was defined as elevated cardiac troponin (cTn) levels with at least one value > 99th percentile of the upper reference limit. The primary outcome measure was mortality, whereas secondary outcome measures were intensive care unit (ICU) admission and length of hospital stay. RESULTS: Four studies and one review were included. The presence of myocardial injury varied between 9.6 and 46.3%. Myocardial injury was associated with a higher mortality rate (risk ratio (RR) 5.54, 95% confidence interval (CI) 3.48-8.80) and more ICU admissions (RR 3.78, 95% CI 2.07-6.89). The results regarding length of hospital stay were inconclusive. CONCLUSION: Patients with myocardial injury might be classified as high-risk patients, with probably a higher mortality rate and a larger need for ICU admission. cTn levels can be used in risk stratification models and can indicate which patients potentially benefit from early medication administration. We recommend measuring cTn levels in all COVID-19 patients admitted to the hospital or who deteriorate during admission.

The 2010s in clinical drug-eluting stent and bioresorbable scaffold research: a Dutch perspective.

Dutch researchers were among the first to perform clinical studies in bare metal coronary stents, the use of which was initially limited by a high incidence of in-stent restenosis. This problem was greatly solved by the introduction of drug-eluting stents (DES). Nevertheless, enthusiasm about first-generation DES was subdued by discussions about a higher risk of very-late stent thrombosis and mortality, which stimulated the development, refinement, and rapid adoption of new DES with more biocompatible durable polymer coatings, biodegradable polymer coatings, or no coating at all. In terms of clinical DES research, the 2010s were characterised by numerous large-scale randomised trials in all-comers and patients with minimal exclusion criteria. Bioresorbable scaffolds (BRS) were developed and investigated. The Igaki-Tamai scaffold without drug elution was clinically tested in the Netherlands in 1999, followed by an everolimus-eluting BRS (Absorb) which showed favourable imaging and clinical results. Afterwards, multiple clinical trials comparing Absorb and its metallic counterpart were performed, revealing an increased rate of scaffold thrombosis during follow-up. Based on these studies, the commercialisation of the device was subsequently halted. Novel technologies are being developed to overcome shortcomings of first-generation BRS. In this narrative review, we look back on numerous devices and on the DES and BRS trials reported by Dutch researchers.

One-year efficacy and safety of routine prasugrel in patients with acute coronary syndromes treated with percutaneous coronary intervention: results of the prospective rijnmond collective cardiology research study.

OBJECTIVE: To investigate 1­year outcomes with routine prasugrel treatment after acute coronary syndrome (ACS) in a large-scale registry. METHODS: The Rijnmond Collective Cardiology Research registry is a prospective, observational study that enrolled 4,258 consecutive ACS patients treated with percutaneous coronary intervention (PCI) with 1­year follow-up. Patients received prasugrel as first-choice antiplatelet agent, except for increased bleeding risk patients in which clopidogrel was recommended. Events were validated by an independent clinical endpoint committee. RESULTS: A total number of 2,677 patients received prasugrel at discharge after the index event. Eighty-one percent of the target population was on prasugrel treatment at hospital discharge. At 1 year, the primary endpoint, a composite of all-cause mortality and myocardial infarction, occurred in 2.4% of patients receiving prasugrel. All-cause mortality occurred in 1.0%, myocardial infarction in 1.5%, target-vessel revascularisation in 3.1%, stent thrombosis in 0.6%, and stroke in 0.5% of the patients treated with prasugrel. Thrombolysis in Myocardial Infarction defined major bleeding episodes not related to coronary artery bypass grafting were observed in 1.4% of patients receiving prasugrel. CONCLUSIONS: In routine practice, a tailored approach of prasugrel prescription in ACS patients undergoing PCI, resulted in low ischaemic and low bleeding rates up to 1 year post PCI.

Impact of percutaneous coronary intervention timing on 5-year outcome in patients with non-ST-segment elevation acute coronary syndromes. The 'wait a day' approach might be safer.

BACKGROUND: The OPTIMA trial was a randomised multicentre trial exploring the influence of the timing of percutaneous coronary intervention (PCI) on patient outcomes in an intermediate to high risk non-ST-elevation acute coronary syndrome (NSTE-ACS) population. In order to decide the best treatment strategy for patients presenting with NSTE-ACS, long-term outcomes are essential. METHODS: Five-year follow-up data from 133 of the 142 patients could be retrieved (94 %). The primary endpoint was a composite of death and spontaneous myocardial infarction (MI). Spontaneous MI was defined as MI occurring more than 30 days after randomisation. Secondary endpoints were the individual outcomes of death, spontaneous MI or re-PCI. RESULTS: No significant difference with respect to the primary endpoint was observed (17.8 vs. 10.1 %; HR 1.55, 95 % CI: 0.73-4.22, p = 0.21). There was no significant difference in mortality rate. However, spontaneous MI was significantly more common in the group receiving immediate PCI (11.0 vs. 1.4 %; HR 4.46, 95 % CI: 1.21-16.50, p = 0.02). We did not find a significant difference between the groups with respect to re-PCI rate. CONCLUSION: There was no difference in the composite of death and spontaneous MI. The trial suggests an increased long-term risk of spontaneous MI for patients treated with immediate PCI.

Adoption of prasugrel into routine practice: rationale and design of the Rijnmond Collective Cardiology Research (CCR) study in percutaneous coronary intervention for acute coronary syndromes.

BACKGROUND: Platelet inhibition is crucial in reducing both short- and long-term atherothrombotic risks in patients with acute coronary syndromes (ACS) managed with percutaneous coronary intervention (PCI). Based on randomised trials, recent recommendations in the current guidelines include the endorsement of prasugrel as a first-choice adenosine diphosphate receptor inhibitor. Yet, there is limited experience with the use of prasugrel in routine practice. METHODS: The Rijnmond Collective Cardiology Research (CCR) registry is a prospective, observational study that will follow-up 4000 PCI-treated ACS patients in the larger region of Rotterdam, the Netherlands. Based on recently implemented hospital protocols, all patients will receive prasugrel as first-choice antiplatelet agent, unless contraindicated, in accordance with European guidelines, and will be followed for up to 1 year post-discharge for longitudinal assessment of outcomes and bleeding events. This registry exemplifies a collaborative study design that employs a regional PCI registry platform and provides feedback to participating sites regarding their practice patterns, thereby supporting and promoting improvement of quality of care. CONCLUSION: The CCR registry will evaluate the adoption of prasugrel into routine clinical practice and thus, will provide important evidence with regard to the benefits and risks of real-world utilisation of prasugrel as antiplatelet therapy in PCI-treated ACS patients.

Current discharge management of acute coronary syndromes: data from the Rijnmond Collective Cardiology Research (CCR) study.

BACKGROUND: Medical discharge management of acute coronary syndromes (ACS) remains suboptimal outside randomised trials and constitutes an essential quality benchmark for ACS. We sought to evaluate the rates of key guideline-recommended pharmacological agents after ACS and characteristics associated with optimal treatment at discharge. METHODS: The Rijnmond Collective Cardiology Research (CCR) registry is an ongoing prospective, observational study in the Netherlands that aims to enrol 4000 patients with ACS. We examined discharge and 1-month follow-up medication use among the first 1000 patients enrolled in the CCR registry. Logistic regression was performed to identify patient and hospital characteristics associated with collective guideline-recommended pharmacotherapy at hospital discharge. RESULTS: At discharge, 94 % of patients received aspirin, 100 % thienopyridines, 80 % angiotensin-converting enzyme inhibitors/angiotensin-II receptor blockers, 87 % ß-blockers, 96 % statins, and 65 % the combination of all 5 agents. ST-segment elevation myocardial infarction, hypertension, hypercholesterolaemia, and enrolment in an interventional centre were positive independent predictors of 5-drug combination therapy at discharge. Negative independent predictors were unstable angina and advanced age. CONCLUSION: Current data from the CCR registry reflect a high quality of care for ACS discharge management in the Rotterdam-Rijnmond region. However, potential still remains for further optimisation.

Everolimus- and sirolimus-eluting stents in patients with and without ST-segment elevation myocardial infarction.

AIMS: Everolimus-eluting stents (EES) were superior to sirolimus-eluting stents (SES) in a dedicated myocardial infarction trial, a finding that was not observed in trials with low percentages of ST-elevation myocardial infarction (STEMI). Therefore, this study sought to investigate the influence of clinical presentation on outcome after EES and SES implantation. METHODS: A pooled population of 1602 randomised patients was formed from XAMI (acute MI trial) and APPENDIX-AMI (all-comer trial). Primary outcome was cardiac mortality, MI and target vessel revascularisation at 2 years. Secondary endpoints included definite/probable stent thrombosis (ST). Adjustment was done using Cox regression. RESULTS: In total, 902 EES and 700 SES patients were included, of which 44 % STEMI patients (EES 455; SES 257) and 56 % without STEMI (EES 447; SES 443). In the pooled population, EES and SES showed similar outcomes during follow-up. Moreover, no differences in the endpoints were observed after stratification according to presentation. Although a trend toward reduced early definite/probable ST was observed in EES compared with SES in STEMI patients, long-term ST rates were low and comparable. CONCLUSIONS: EES and SES showed a similar outcome during 2-year follow-up, regardless of clinical presentation. Long-term safety was excellent for both devices, despite wide inclusion criteria and a large sub-population of STEMI patients.

Angioscopic complex lesions are predominantly compensatory enlarged: an angioscopy and intracoronary ultrasound study.

OBJECTIVES: Atherosclerotic remodeling of the coronary artery may lead to compensatory enlargement or to shrinkage. Post-mortem data suggest a relation between compensatory enlargement and histopathological markers of plaque vulnerability. In patients that required a coronary intervention, we investigated retrospectively the relation between the angioscopic appearance and the remodeling mode of the culprit lesion. METHODS: In 34 patients, coronary angioscopy and intracoronary ultrasound (ICUS) imaging was performed across the culprit lesion before the intervention. Only single de novo lesions were included. With angioscopy, lesions with a smooth surface without thrombus were classified as smooth, whereas lesions with an irregular surface with or without thrombus were classified as complex. With ICUS, remodeling of the culprit lesions was determined by the relative cross-sectional vessel area (lesion vessel area/reference vessel area) x 100%. Lesions were divided into three groups: compensatory enlargement (relative vessel area > or = 105%), no-remodeling (relative vessel area between 95 and 105%) and shrinkage (relative vessel area < or = 95%). RESULTS: In 22 patients good images were obtained with both imaging modalities. More complex lesions were compensatory enlarged compared to shrunken lesions, whereas more smooth lesions were shrunken compared to compensatory enlarged lesions, 8/9 versus 2/7 and 5/7 versus 1/9, respectively (p = 0.035). CONCLUSIONS: In patients selected for coronary intervention, angioscopic complex atherosclerotic lesions were found predominantly in compensatory enlarged arterial segments, whereas smooth lesions were found predominantly in shrunken arterial segments.

Evaluation of left ventricular volumes and ejection fraction with a nonfluoroscopic endoventricular three-dimensional mapping technique.

BACKGROUND: Recently, a novel nonfluoroscopic 3-dimensional electromechanical mapping technique was introduced in the clinical arena. Although initial in vitro and in vivo studies suggested the reliability of the system in volumetric and hemodynamic evaluation of the left ventricle, no validation in human beings has been performed. METHODS: A nonfluoroscopic electromechanical mapping (NOGA, Biosense-Webster) procedure was performed in 44 patients. All patients received a contrast left ventriculogram during the same session. Volumetric (end-diastolic [EDV] and end-systolic volumes [ESV]) and hemodynamic (left ventricular ejection fraction [LVEF] and stroke volume) parameters of both systems were compared. RESULTS: Two uncomplicated pericardial effusions occurred with the first-generation mapping catheters. No procedural complications were noted with the new-generation mapping catheters. Significant correlations were found between mapping-derived and ventriculography-based measurements for both ESV (r = 0.67, P <.001) and LVEF (r = 0.78, P <.001). Absolute volumes, however, were only comparable for ESV (46.6 +/- 25.3 mL vs 48.8 +/- 37.0 mL, respectively; P =.13) but differed greatly for LVEF (35% +/- 13% vs 65% +/- 19%, respectively; P <.001), EDV (69.1 +/- 28.6 mL vs 125.9 +/- 53.4 mL, respectively; P <.001) and stroke volume (22.4 +/- 9.9 mL vs 77.1 +/- 33.7 respirations; P <.001). Moreover, Bland-Altman analysis showed the clinical noninterchangeability between these techniques for the measurement of hemodynamic parameters. CONCLUSION: Measurement of hemodynamic parameters with nonfluoroscopic mapping of the left ventricle is feasible and safe. The system provides data that strongly correlate but that are in clinical disagreement with angiographic data. Therefore the interchangeability of these techniques may be questioned.

Comparison of mechanical properties of the left ventricle in patients with severe coronary artery disease by nonfluoroscopic mapping versus two-dimensional echocardiograms.

In 40 patients, we compared linear local shortening assessed with nonfluoroscopic electromechanical mapping as a function of regional wall motion with echocardiographic data in a subset of patients with severe coronary artery disease and subsequently decreased left ventricular function. Our study showed that nonfluoroscopic electromechanical mapping can accurately assess regional wall motion. In addition, this study showed a significant decrease in unipolar voltages among segments with declining regional function.

Shrinkage of human coronary arteries is an important determinant of de novo atherosclerotic luminal stenosis: an in vivo intravascular ultrasound study.

OBJECTIVE: To assess the occurrence of arterial remodelling types and its relation with the severity of luminal stenosis in atherosclerotic coronary arteries. PATIENTS AND METHODS: Twenty one de novo coronary lesions of 20 patients, who were scheduled for percutaneous transluminal coronary angioplasty (PTCA), were investigated with intravascular ultrasound before PTCA. Local arterial remodelling at the lesion site was studied by measuring the cross sectional area circumscribed by the external elastic lamina (EEL) relative to the reference site: (EEL area lesion/reference EEL area) x 100%. Three groups were defined. Group A: relative EEL area of less than 95% (shrinkage), group B: relative EEL area between 95% and 105% (no remodelling), group C: relative increase in EEL area of more than 105% (compensatory enlargement). RESULTS: All three types of remodelling were observed at the lesion site: group A (shrinkage) n = 8, group B (no remodelling) n = 5, group C (compensatory enlargement) n = 8. The mean (SD) relative EEL area at the lesion site in group A and C was 83(9)% and 132(30)%, respectively. In group A, 33% of the luminal area stenosis at the lesion site was caused by shrinkage of the artery. In contrast, group C showed that 87% of the plaque area did not contribute to luminal area stenosis because of compensatory arterial enlargement. CONCLUSIONS: These results show that both compensatory enlargement and paradoxical shrinkage occurs in the atherosclerotic coronary artery. Next to plaque accumulation, the type of atherosclerotic remodelling is an important determinant of luminal narrowing.

Validation of the local shortening function as assessed by nonfluoroscopic electromechanical mapping: a comparison with computerized left ventricular angiography.

BACKGROUND: Nonfluoroscopic electromechanical mapping (NEM) has been proposed as a new technique for the evaluation of electrical and mechanical functioning of the myocardium. In this system, linear local shortening (LLS) is the parameter used for assessment of local mechanical properties. To validate this parameter, we compared LLS with regional wall motion (RWM) data derived from contrast left ventriculograms acquired in the same patients. METHODS AND RESULTS: Angiographic left ventricular RWM was analyzed using the area-length method. The right anterior oblique view was divided in five segments, the left anterior oblique view in two. Through a comparison of enddiastolic and endsystolic areas drawn from a computer-defined central point to the respective wall delineation, RWM was calculated as change in area. In the first approach, we compared area changes to comparable NEM segments. In the second part of the study, LLS values for normokinetic, hypokinetic, akinetic and dyskinetic segments were correlated to the change in angiographic RWM. In the first approach, the overall comparison of segments yielded a correlation coefficient of 0.67 (P<0.0005). In the second part of the study, differences in LLS values between dyskinetic (LLS=-3.68+/-8.86%), akinetic (2.84+/-3.96%), hypokinetic (9.35+/-4.27%) and normokinetic (13.66+/-7.98%) segments were highly significant (overall ANOVA: P<0.0005). CONCLUSION: NEM is a powerful tool for invasive electromechanical assessment of myocardial function.

Clinical implications of online and off-line interobserver variability in intracoronary ultrasound-guided interventions.

UNLABELLED: Intracoronary ultrasound (ICUS)-guided interventions imply online decision making. We investigated the on- and off-line interobserver variability in ICUS measurements and evaluated the clinical implication of the interobserver variability for ICUS-guided interventions in 40 lesions (38 patients). On the same recorded ICUS images, an online and an off-line observer independently selected and analyzed the proximal and distal reference images, the most severe stenosis image before intervention and the minimal lumen area (MLA) image after intervention. In addition, the off-line observer analyzed the online selected images. The interobserver variability (percentage difference between the two observers) of ICUS measurements was determined on images independently selected by both observers (Analysis A) and on images selected by the online observer (Analysis B). The balloon size was determined from ICUS measurements according to the CLOUT trial. After intervention, the CLOUT and MUSIC criteria for MLA by ICUS had to be fulfilled for PTCA and stent procedures, respectively. In Analysis A, the on- and off-line interobserver variability in diameter and area measurements was maximally 9% and 18%, respectively. In Analysis B, the on- and off-line interobserver variability was maximally 6% and 11%, respectively. The off-line observer would have chosen a balloon size differing by more than 0.25 mm in 25 % (10 of 40) and 12.5% (5 of 40) of the procedures in Analysis A and B, respectively. After PTCA or stenting, the off-line observer would have taken different procedural decisions in 19% or 15% and in 13% or 7% of the procedures in Analysis A and B, respectively. IN CONCLUSION: when the same location was selected, the on- and off-line interobserver variability was low. When different locations were selected, however, the interobserver variability resulted in different balloon sizing in 25 % of the cases. Interobserver variability may be a confounding factor in the analysis of ICUS-guided interventions.

Myocardial repair with autologous skeletal myoblasts: a review of the clinical studies and problems.

Stem cell therapy for myocardial repair after myocardial infarction is a new and promising treatment modality. Currently, bone marrow derived stem cells are used in clinical studies to evaluate its beneficial effect on repair of infarcted/hibernating myocardium in the subacute phase after myocardial infarction. Whereas skeletal myoblasts are nowadays under investigation in the setting of scar repair in chronic congestive heart failure patients. The mechanism of bone marrow derived stem cells is probably mainly related to induction and stimulation of angiogenesis, whereas skeletal myoblasts are more likely to contribute to recovery of left ventricular function by the direct engraftment of contractile cells and hypothetically indirect by stimulation of native and circulation stem cells to home into the scarred tissue. This review will focus on the use of skeletal myoblasts in all clinical studies presented sofar and will discuss several issues like: different transplantation methods, potential mechanism of effect, potential risks like arrhythmia and future concepts. As the target population of skeletal myoblast transplantation is chronic post myocardial infarction heart failure patients, ventricular arrhythmias are very likely to occur. This review will specially address the presence of ventricular arrhythmias observed in some clinical studies and the pre-clinical data on the electrophysiology of skeletal myotubes and its relationship to the surrounding myocardium.

Would SYNTAX have been a positive trial if XIENCE V had been used instead of TAXUS?: A meta-analysis of a first-generation vs. a second-generation drug-eluting stent system.

Treatment options for coronary revascularisation include percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). In the 'synergy between PCI with TAXUS and cardiac surgery (SYNTAX)' trial, PCI and CABG using state-of-the-art techniques (using paclitaxel-eluting stents and arterial grafts, respectively) were compared in the treatment of complex coronary artery disease. In Syntax, PCI was inferior to CABG at one year, entirely due to an increased repeat intervention rate. We hypothesised that the use of a superior drug-eluting stent system could reduce the need for repeat intervention. (Neth Heart J 2010;18:451-3.).

Immediate versus deferred coronary angioplasty in non-ST-segment elevation acute coronary syndromes.

BACKGROUND: The field of acute coronary syndromes is characterised by an increasing tendency towards early invasive catheter-based diagnostics and therapeutics-a practice based on observational and retrospective data. OBJECTIVE: To compare immediate versus deferred angioplasty in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS) METHODS: A randomised, prospective multicentre trial was performed in patients admitted with NSTE-ACS, eligible for percutaneous coronary intervention (PCI). Interim analysis was performed after enrolment of 251 patients; PCI was appropriate in 142 patients. These patients were randomised to immediate PCI (n = 73) or deferred PCI (24-48 h) (n = 69). Patients received protocol-driven glycoprotein IIb/IIIa blockers, aspirin and clopidogrel. The primary end point was a composite of death, non-fatal myocardial infarction (MI) or unplanned revascularisation, at 30 days. After hospital discharge outpatient follow-up was performed at 30 days and 6 months. RESULTS: The incidence at 30 days of the primary end point was 60% in the group receiving immediate PCI and 39% in the group receiving deferred PCI (relative risk (RR) = 1.5, 95% CI 1.09 to 2.15; p = 0.004). No deaths occurred in either group. MI was significantly more common in the group receiving immediate PCI (60% vs 38%, RR = 1.6, 95% CI 1.12 to 2.28, p = 0.005). Unplanned revascularisation was similar in both groups. The observed difference was preserved over 6-months' follow-up. CONCLUSIONS: Immediate PCI was associated with an increased rate of MI in comparison with a 24-48 h deferred strategy, despite aggressive antithrombotic treatment. The results suggest that PCI for high-risk patients with non-refractory NSTE-ACS should be delayed for at least 24 h after hospital admission. TRIAL REGISTRATION NUMBER: ISRCTN80874637.

Percutaneous coronary and peripheral angioscopy with saline solution and carbon dioxide gas in porcine and canine arteries.

To obtain a clear view with angioscopy, blood must be displaced. Carbon dioxide (CO2) gas has proved to be a safe intraarterial contrast agent, and it may have advantages over saline solution as an infusion medium for angioscopy. This study compared the use of CO2 gas and saline solution in the femoral artery, in the presence and absence of a proximal occlusion, in nine pigs and six dogs. The applicability of CO2 gas in the coronary arteries was also evaluated. In total 185 angioscopy procedures were evaluated. With proximal occlusion, angioscopy with CO2 gas was successful in all 28 peripheral procedures, whereas with saline solution only 65% of the procedures resulted in a clear view (p less than 0.005). Without proximal occlusion, angioscopy was successful with CO2 gas and saline solution in 61% and 3% of procedures, respectively (p less than 0.0001). Cardiovascular parameters and blood gases showed minor changes after administration of CO2 gas. During coronary angioscopy with CO2 gas, mechanical heart failure occurred in all instances, which was lethal in 12 animals. None of the animals died as a result of saline angioscopy. In conclusion, CO2 gas is a safe medium for angioscopy in the peripheral arteries and in general offers a better view than saline solution. In contrast to saline solution, without proximal balloon occlusion CO2 gas provided a clear view in 61% of the peripheral procedures. In the coronary arteries, however, CO2 angioscopy was generally fatal in both animal models.