Risk prediction models for discrete ordinal outcomes: Calibration and the impact of the proportional odds assumption.

Calibration is a vital aspect of the performance of risk prediction models, but research in the context of ordinal outcomes is scarce. This study compared calibration measures for risk models predicting a discrete ordinal outcome, and investigated the impact of the proportional odds assumption on calibration and overfitting. We studied the multinomial, cumulative, adjacent category, continuation ratio, and stereotype logit/logistic models. To assess calibration, we investigated calibration intercepts and slopes, calibration plots, and the estimated calibration index. Using large sample simulations, we studied the performance of models for risk estimation under various conditions, assuming that the true model has either a multinomial logistic form or a cumulative logit proportional odds form. Small sample simulations were used to compare the tendency for overfitting between models. As a case study, we developed models to diagnose the degree of coronary artery disease (five categories) in symptomatic patients. When the true model was multinomial logistic, proportional odds models often yielded poor risk estimates, with calibration slopes deviating considerably from unity even on large model development datasets. The stereotype logistic model improved the calibration slope, but still provided biased risk estimates for individual patients. When the true model had a cumulative logit proportional odds form, multinomial logistic regression provided biased risk estimates, although these biases were modest. Nonproportional odds models require more parameters to be estimated from the data, and hence suffered more from overfitting. Despite larger sample size requirements, we generally recommend multinomial logistic regression for risk prediction modeling of discrete ordinal outcomes.

Improved in-hospital outcome for radial access in a large contemporary cohort of primary percutaneous coronary intervention.

BACKGROUND: Randomised controlled trials have shown diverse results for radial access in patients undergoing primary percutaneous coronary intervention (PPCI). Moreover, it is questionable whether radial access improves outcome in patients with cardiogenic shock undergoing PPCI. We aimed to investigate the outcome according to access site in patients with or without cardiogenic shock, in daily clinical practice. METHODS: For the present analysis we included 9,980 patients undergoing PPCI between 2012 and 2018, registered in the multi-centre, nationwide registry on PCI for myocardial infarction (MI). In-hospital mortality, major adverse cardiovascular events (MACE), and net adverse clinical events (NACE) until discharge were compared between 4,498 patients with radial (45%) and 5,482 patients with femoral (55%) access. RESULTS: Radial compared to femoral access was associated with lower in-hospital mortality (3.5% vs. 7.7%; P<0.01). Multivariable logistic regression analysis confirmed reduced in-hospital mortality [odds ratio (OR) 0.57, 95% confidence interval (CI): 0.43 to 0.75]. Furthermore, MACE (OR 0.60, 95% CI: 0.47 to 0.78) as well as NACE (OR 0.59, 95% CI: 0.46 to 0.75) occurred less frequently in patients with radial access. Interaction analysis with cardiogenic shock showed an effect modification, resulting in lower mortality in PCI via radial access in patients without, but no difference in those with cardiogenic shock (OR 1.78, 95% CI: 1.07 to 2.96). CONCLUSIONS: Radial access for patients with acute MI undergoing PPCI is associated with improved survival in a large contemporary cohort of daily practice. However, this beneficial effect is restricted to hemodynamically stable patients.

Changes and innovations of the 2017 ESC guidelines on dual antiplatelet therapy in coronary artery disease-a review.

Duration and compostion of dual antiplatelet therapy has been increasingly changed within the past few years as also indicated in the firmer ESC guidelines. The current manuscript summarizes the most important changes in dual antiplatelet therapy as shown by a recent ESC position paper and offers quick insight into these new developments.

Cohort profile: the Coronary Artery disease Risk Determination In Innsbruck by diaGnostic ANgiography (CARDIIGAN) cohort.

PURPOSE: The Coronary Artery disease Risk Determination In Innsbruck by diaGnostic ANgiography (CARDIIGAN) cohort is aimed to gain a better understanding of cardiovascular risk factors and their relation to the diagnosis and severity of coronary artery disease, as well as to the long-term prognosis in consecutive (including revascularised) patients referred for elective coronary angiography. PARTICIPANTS: The included patients visited the University Clinic of Cardiology at Innsbruck (Austria), which fulfils a secondary and tertiary hospital function. Inclusion took place in the period between February 2004 and April 2008 and resulted in a total of 8296 patients aged 18-91 years; 65% of them were men. FINDINGS TO DATE: There was one follow-up round on vital status through record linkage for 84% of the cohort (those with residence in Tyrol), resulting in a follow-up duration of over 5.5 to nearly 10.0 years among survivors. The data contain basic patient characteristics, cardiovascular risk factors, laboratory measurements, medications, detailed information on the extent and severity of coronary artery disease, revascularisation history, treatment strategy and mortality specifics. A few studies have already been published. FUTURE PLANS: Various diagnostic and prognostic studies are planned, also concerning complications, competing risks and cost-effectiveness. Collaboration with other research groups is welcomed.

[Secondary prevention with antiplatelet therapy in cardiac rehabilitation]. / Sekundärpräventive Antiplättchentherapie in der kardiologischen Rehabilitation.

The long-term increased cardiovascular risk of patients with an acute coronary syndrome (ACS) is a challenging and common clinical problem. Recent evidence demonstrated an ischemic benefit for a prolonged dual antiplatelet therapy beyond the initial 12 months at the cost of an increased bleeding risk. Individual, careful and repeated risk-benefit analyses are essential for an optimized patient management in which cardiovascular rehabilitation providers may play a central role.

External validation and extension of a diagnostic model for obstructive coronary artery disease: a cross-sectional predictive evaluation in 4888 patients of the Austrian Coronary Artery disease Risk Determination In Innsbruck by diaGnostic ANgiography (CARDIIGAN) cohort.

OBJECTIVE: To externally validate and extend a recently proposed prediction model to diagnose obstructive coronary artery disease (CAD), with the ultimate aim to better select patients for coronary angiography. DESIGN: Analysis of individual baseline data of a prospective cardiology cohort. SETTING: Single-centre secondary and tertiary cardiology clinic. PARTICIPANTS: 4888 patients with suspected CAD, without known previous CAD or other heart diseases, who underwent an elective coronary angiography between 2004 and 2008 as part of the prospective Coronary Artery disease Risk Determination In Innsbruck by diaGnostic ANgiography (CARDIIGAN) cohort. Relevant data were recorded as in routine clinical practice. MAIN OUTCOME MEASURES: The probability of obstructive CAD, defined as a stenosis of minimally 50% diameter in at least one of the main coronary arteries, estimated with the predictors age, sex, type of chest pain, diabetes status, hypertension, dyslipidaemia, smoking status and laboratory data. Missing predictor data were multiply imputed. Performance of the suggested models was evaluated according to discrimination (area under the receiver operating characteristic curve, depicted by the c statistic) and calibration. Logistic regression modelling was applied for model updating. RESULTS: Among the 4888 participants (38% women and 62% men), 2127 (44%) had an obstructive CAD. The previously proposed model had a c statistic of 0.69 (95% CI 0.67 to 0.70), which was lower than the expected c statistic while correcting for case mix (c=0.80). Regarding calibration, there was overprediction of risk for high-risk patients. All logistic regression coefficients were smaller than expected, especially for the predictor 'chest pain'. Extension of the model with high-density lipoprotein and low-density lipoprotein cholesterol, fibrinogen, and C reactive protein led to better discrimination (c=0.72, 95% CI 0.71 to 0.74, p<0.001 for improvement). CONCLUSIONS: The proposed prediction model has a moderate performance to diagnose obstructive CAD in an unselected patient group with suspected CAD referred for elective CA. A small, but significant improvement was attained by including easily available and measurable cardiovascular risk factors.

Expert position paper on prolonged dual antiplatelet therapy in secondary prevention following myocardial infarction.

The protective effect of dual antiplatelet therapy (DAPT) following acute coronary syndrome is undisputed, but its duration is subject of debate. Several studies show that prolonged therapy provides a clinical benefit in patients following acute coronary syndrome. The aim of this position paper authored by Austrian experts is to outline the current evidence and provide an overview of recent studies. It is also intended to serve as a practical guide to identify those patients who may benefit from prolonged DAPT.

Sex differences in independent factors associated with coronary artery disease.

BACKGROUND: Women undergoing coronary angiography (CA) due to chest pain are more likely to present with less extensive coronary artery disease (CAD) than men, which might be attributed to different effects of cardiovascular risk factors on coronary atherogenesis between sexes. The aim of the present study was to evaluate sex differences in independent factors associated with obstructive and non-obstructive CAD in a large consecutive cohort of patients undergoing elective CA. METHODS: Data from 7819 patients (2653 women and 5184 men), including cardiovascular risk factors, clinical presentation, CAD severity and treatment decisions were analysed. RESULTS: Women were older than men (65 ± 11 vs. 63 ± 11 years, p < 0.001); low-density lipoprotein cholesterol (LDL; 125 ± 38 vs. 122 ± 37 mg/dL, p < 0.001) and high-density lipoprotein cholesterol (HDL) cholesterol levels (62 ± 18 vs. 51 ± 15 mg/dL, p < 0.001) were higher in women; and smokers were more frequently men (14.4 vs. 20.1%, p < 0.001). Men more frequently had an obstructive CAD (41.1 vs. 65.6%, p < 0.001). Multivariable analyses revealed age, HDL cholesterol, hypercholesterolaemia, diabetes mellitus, arterial hypertension and a positive family history being associated with obstructive CAD in both sexes, whereas smoking was independently associated with obstructive CAD only in women. The association of hypercholesterolaemia with obstructive CAD was stronger in men. For non-obstructive CAD, no sex-specific associated factors could be identified. CONCLUSION: The impact of smoking and hypercholesterolaemia on coronary atherosclerosis is different between women and men. This might be taken into account when planning individual interventions to reduce cardiovascular risk.

Comparison of brachial artery wall thickness versus endothelial function to predict late cardiovascular events in patients undergoing elective coronary angiography.

An increased brachial artery intima media thickness (BA-IMT) has been shown to be of prognostic value. Conflicting prognostic data have been reported for brachial artery flow-mediated vasodilation (BA-FMD), and the longest evaluated follow-up period to date is 5.5 years. We sought to investigate the very late prognostic value of BA-IMT and BA-FMD in 396 consecutive patients (age 54 ± 9 years) admitted for invasive evaluation of chest pain. BA-IMT and BA-FMD were measured using high-resolution ultrasonography. The patients were divided according to the median BA-IMT (0.37 mm) and median BA-FMD (7.6%). After a mean follow-up of 141 ± 12 months, cardiovascular events were documented. More cardiovascular events were found in patients with an increased BA-IMT (50 vs 78 events, p = 0.003). When the groups were compared according to the median BA-FMD, no differences in the number of events were documented (70 vs 75 events, p = 0.60). On multivariate Cox regression analysis, including age, number of risk factors, BA diameter, presence of coronary artery disease, BA-FMD, and BA-IMT, only the presence of coronary artery disease and BA-IMT remained significantly associated with outcome. In conclusion, BA-IMT, but not BA-FMD, predicted cardiovascular events and cardiovascular death with ≤12 years of follow-up in patients undergoing an invasive evaluation of chest pain. Our results represent, by far, the longest follow-up of BA-IMT and peripheral endothelial function testing compared with previously reported data.

Clopidogrel pre-treatment is associated with reduced in-hospital mortality in primary percutaneous coronary intervention for acute ST-elevation myocardial infarction.

AIMS Pre-treatment with clopidogrel results in a reduction of ischaemic events in non-ST-elevation acute coronary syndromes. Data on upstream clopidogrel in the setting of primary percutaneous coronary intervention (PCI) are limited. The aim of this study was to investigate whether clopidogrel loading before arrival at the PCI centre may result in an improved outcome of primary PCI for ST-elevation myocardial infarction (STEMI). METHODS AND RESULTS In a multicentre registry of acute PCI, 5955 patients undergoing primary PCI in Austria between January 2005 and December 2009 were prospectively enrolled. The patients consisted of two groups, a clopidogrel pre-treatment group (n = 1635 patients) receiving clopidogrel before arrival at the PCI centre and a peri-interventional clopidogrel group (n = 4320 patients) receiving clopidogrel at a later stage. Multiple logistic regression analysis including major confounding factors stratified by the participating centres was applied to investigate the effect of pre-treatment with clopidogrel on the in-hospital mortality. Additionally, two subgroups, with or without the use of GP IIb/IIIa antagonist therapy in the catheterization laboratory, were analysed. On univariate analysis, clopidogrel pre-treatment was associated with a reduced in-hospital mortality (3.4 vs. 6.1%, P< 0.01) after primary PCI. On multivariate analysis, clopidogrel pre-treatment remained an independent predictor of in-hospital mortality [odds ratio (OR) = 0.60, 95% confidence interval (CI) 0.35-0.99; P =0.048], especially in patients receiving additional GP IIb/IIIa antagonist therapy in the catheterization laboratory (OR = 0.40, 95% CI 0.19-0.83; P =0.01). CONCLUSION Clopidogrel pre-treatment before arrival at the PCI centre is associated with reduced mortality in a real world setting of primary PCI. These results strongly support the recommendation of clopidogrel treatment 'as soon as possible' in patients with STEMI undergoing pimary PCI.

Prasugrel vs. ticagrelor in acute coronary syndromes: which one to choose?

Acute coronary syndromes (ACS) are still associated with significant morbidity and mortality. Dual antiplatelet therapy with clopidogrel and acetyl-salicylic acid has become the standard of care for patients with ACS in the last 2 decades. However, clopidogrel has drawbacks including delayed therapeutic effect, significant interindividual variability of platelet aggregation inhibition or reduced action on thrombocytes due to interaction with other drugs or genetic polymorphisms. Consequently, new antiplatelet drugs have been developed. Two of these drugs, namely prasugrel and ticagrelor, have been approved by the European Medicines Agency (EMA) and are already available in many European countries. For each substance a "mega-trial" has been published. Both agents were clearly superior compared to clopidogrel and should be therefore preferred in patients with ACS. However, no study has directly compared efficacy as well as safety of prasugrel and ticagrelor so far. Hence, clinicians will be claimed to decide which one to choose in everyday practice. The aim of this manuscript is to summarize the current literature and to provide a guide for individual decision-making between prasugrel and ticagrelor in ACS in daily routine.

Comparison of peripheral endothelial function in shift versus nonshift workers.

Shift working is related to increased cardiovascular morbidity. Peripheral endothelial dysfunction, an inherent feature of early atherosclerosis, has been suggested as a surrogate marker of cardiovascular risk. Whether shift working is associated with peripheral endothelial dysfunction has not been investigated to date. A total of 48 male shift workers (SWs) and 47 male nonshift workers (NSWs) (mean age 43 ± 5 years) were recruited from a glass manufactory. The SWs and NSWs were matched according to age, body mass index, smoking habits, family history of premature coronary artery disease, prevalence of hypercholesterolemia and hypertension, and work place. Their sport habits were also documented. Peripheral endothelial function was assessed using the EndoPAT technique to determine the peripheral arterial tone (PAT) index. According to the study design, no difference was found in the risk factor profiles between the SWs and NSWs. Despite a greater percentage of regular physical activity among the SWs (16.7 vs 4.3%, p = 0.05), shift working was associated with a reduced PAT index compared to working only on the day shift (PAT index 1.73 ± 0.4 vs 1.94 ± 0.5, p = 0.03). In the NSW group, the participants with regular physical training (n = 16) had a greater PAT index than those without regular physical activity (n = 12; PAT index 2.28 ± 0.45 vs 1.86 ± 0.51, p = 0.03). No such difference was found in the SWs. In conclusion, SWs had a reduced PAT index compared with NSWs, suggesting endothelial dysfunction. Therefore, the known increased cardiovascular risk in those shift working might be related to endothelial dysfunction.

[STEMI guidelines 2008--Do they influence today's myocardial infarction treatment strategies in rural areas?]. / STEMI-Guidelines 2008--Konsequenzen für die heutige Infarktversorgung im ländlichen Raum?

2008 new guidelines for the management of patients with ST-elevation myocardial infarction were published by the European Society of Cardiology. For daily clinical practice, changes in recommendations concerning the preferred revascularization therapy according to different time delays are of great interest. This review focuses on possible implications of these new guidelines on the choice of reperfusion strategies in rural areas.

Neopterin, CD4+CD28- lymphocytes and the extent and severity of coronary artery disease.

OBJECTIVES: Macrophages and pro-inflammatory CD3+CD4+CD28- T lymphocytes are involved in atherosclerotic plaque destabilization. Whether neopterin, a macrophage-specific activation-marker, and circulating CD3+CD4+CD28- cells are also related to the severity and extent of coronary artery disease (CAD) in stable patients is still unclear. METHODS: Coronary angiograms of 30 patients with stable angina pectoris were graded using the Gensini severity and an extent score. Patients were grouped according to the median of each score. Lymphocyte subsets were determined by FACS analysis and neopterin by radioimmunoassay. Peripheral endothelial function of the brachial artery (FMD) shown to correlate with cardiovascular risk factors was evaluated using high-resolution ultrasound. RESULTS: More extensive CAD was associated with increased neopterin levels (8.3 +/- 3.3 vs. 5.5 +/- 1.2 nmol/L, p < 0.001) and increased CD3+CD4+CD28- cells (3.1 +/- 1.6 vs. 2.0 +/- 1.2%, p < 0.05). A high Gensini severity score was associated with increased neopterin levels (7.8 +/- 2.7 vs. 6.3 +/- 1.7 nmol/L, p < 0.05), but not with CD3+CD4+CD28- cells. Neopterin correlated with both the extent (r = 0.59, p < 0.001) and the Gensini score (r = 0.57, p < 0.003). FMD was not correlated with both scores. CONCLUSIONS: Neopterin and CD3+CD4+CD28- lymphocytes are associated with CAD extent in stable patients, thereby emphasizing the inherent role of inflammation in atherogenesis itself beyond plaque destabilization. Neopterin's correlation with CAD severity might be additionally useful in identifying patients eligible for revascularization procedures.

Aortic valve calcification as quantified with multislice computed tomography predicts short-term clinical outcome in patients with asymptomatic aortic stenosis.

BACKGROUND AND AIM OF THE STUDY: Aortic valve calcification may be an independent risk factor for adverse clinical outcome. The study aim was to assess the predictive value of possible risk factors, including the severity of aortic valve calcification as quantified with 16-multislice computed tomography (MSCT) for adverse short-term clinical outcome in patients with asymptomatic, degenerative aortic stenosis (AS). METHODS: Possible risk factors for adverse short-term clinical outcome were prospectively tested in 34 consecutive patients with asymptomatic AS as follows: (i) aortic valve calcium (AVC) score as quantified with MSCT; (ii) echocardiographic parameters--aortic valve area (AVA) calculated with continuity equation, mean and maximal transvalvular pressure gradients, end-diastolic septal wall diameter; and (iii) laboratory tests (brain natriuretic peptide (BNP), C-reactive protein (CRP)). RESULTS: Within 18-24 months of follow up, 11 of 34 patients developed a major adverse clinical outcome. Ten patients suffered from onset of symptoms accompanied by hemodynamic progression, and one patient died from sudden cardiac death. Six of these 10 patients underwent aortic valve replacement, one patient declined surgery, and three patients were not accepted for surgery (one of these died suddenly shortly afterwards). The aortic valve calcium score was the strongest predictor of a major adverse clinical event (p < 0.001) among all parameters assessed (1,928 +/- 789 versus 5,111 +/- 2,409 Agatston units). The plasma level of BNP (p = 0.003), mean transvalvular pressure gradient (p = 0.002) and AVA (p = 0.003) were also risk factors for adverse clinical outcome. CONCLUSION: The AVC score as quantified with MSCT predicted adverse short-term clinical outcome in patients with asymptomatic AS. In patients with severe aortic valve calcification, close follow up examinations are mandatory, and early elective surgery may be considered even in the absence of symptoms. MSCT provides a comprehensive non-invasive imaging approach for risk stratification in patients with asymptomatic AS.

Short-term improvement in submaximal exercise capacity by optimized therapy with ACE inhibitors and beta blockers in heart failure patients is associated with restoration of peripheral endothelial function.

BACKGROUND: Improved exercise capacity in chronic heart failure (CHF) has been attributed to restoration of endothelial function. ACE inhibitors as well as beta blockers have previously been shown to enhance endothelial function and exercise capacity. The aim of this study was to determine whether short-term improvement in submaximal exercise capacity induced by optimized therapy with ACE inhibitors in combination with beta blockers is associated with restoration of endothelial function in CHF patients. METHODS: Thirty-three patients with CHF were evaluated: six-minute walk test, NYHA class, brain natriuretic peptide (BNP), big Endothelin-1 (bigET-1) and flow-mediated vasodilation (FMD) of the brachial artery were assessed at baseline and after a 3-month period of optimized neurohormonal therapy. Two groups were formed retrospectively based on the changes in submaximal exercise capacity (responders and non-responders). RESULTS: Optimization of neurohormonal therapy was comparable between groups. Responders (n=17) revealed a significant increase in walking distance (304+/-109 to 441+/-75 m; p<0.01), which was paralleled by a decrease in NYHA class (2.7+/-0.6 to 2.0+/-0.4; p<0.01), BNP (484+/-454 to 243+/-197 pg/ml; p<0.01), and bigET-1 (2.0+/-0.9 vs. 1.5+/-0.6 fmol/ml; p=0.04). By contrast, the latter variables did not change in non-responders. Improvement in functional capacity in responders was associated with an increase in FMD (8.2+/-3.9% to 11.0+/-5.6%; p<0.05). Increments in FMD were directly correlated with increases in walking distance (r=0.34; p<0.05). CONCLUSION: Short-term improvement of submaximal exercise capacity in CHF patients following optimized therapy with ACE inhibitors and beta blockers is associated with restoration of endothelial function in conduit arteries.

Transient impairment of flow-mediated vasodilation in patients with metabolic syndrome at moderate altitude (1,700 m).

BACKGROUND: The influence of moderate altitude on the cardiovascular system in patients with metabolic syndrome has not been investigated sufficiently, yet. The aim of this study was to assess the effect of acute and mid-term exposure to moderate altitude (1,700 m) on endothelial function in patients with metabolic syndrome. METHODS: Flow-mediated (FMD) and nitroglycerin-mediated vasodilation (NMD) were assessed in 18 patients with coronary risk factors on 5 occasions: (1) at location A (576 m), (2) on the first day at moderate altitude (location B, 1,700 m), (3) after 3 weeks at moderate altitude, (4) and (5) again at location A (6 and 16 weeks after the stay at moderate altitude, respectively). In addition, markers of lipid metabolism, serum erythropoietin and endothelin were measured. RESULTS: FMD on the first day at moderate altitude was similar compared to baseline FMD at location A (7.0 +/- 3.3 vs. 7.4 +/- 4.6%; NS). A 3-week stay at moderate altitude was associated with a significant reduction in FMD (7.4 +/- 4.6 vs. 3.8 +/- 2.5%; p < 0.05) despite a decrease in baseline diameter (4.5 +/- 0.3 vs. 4.3 +/- 0.4 mm; p < 0.05). Six weeks after returning to location A, FMD was still reduced compared to baseline (4.3 +/- 2.8%; p < 0.05) and after further 16 weeks, FMD returned to baseline values (5.5 +/- 3.5%). However, metabolic parameters improved significantly. In contrast, NMD and endothelin levels remained unchanged. CONCLUSION: In patients with metabolic syndrome, a sojourn of 3 weeks at moderate altitude leads to a prolonged, but reversible impairment of FMD. The discrepancy to improvement of other cardiovascular and metabolic parameters requires further investigation.