Risk Prediction Models for Long-Term Survival after Cardiac Surgery: A Systematic Review

BACKGROUND

The reporting of alternative postoperative measures of quality after cardiac surgery is becoming increasingly important as in-hospital mortality rates continue to decline. This study aims to systematically review and assess risk models designed to predict long-term outcomes after cardiac surgery.

METHODS

The MEDLINE and Embase databases were searched for articles published between 1990 and 2020. Studies developing or validating risk prediction models for long-term outcomes after cardiac surgery were included. Data were extracted using checklists for critical appraisal and systematic review of prediction modeling studies.

RESULTS

Eleven studies were identified for inclusion in the review, of which nine studies described the development of long-term risk prediction models after cardiac surgery and two were external validation studies. A total of 70 predictors were included across the nine models. The most frequently used predictors were age (n = 9), peripheral vascular disease (n = 8), renal disease (n = 8), and pulmonary disease (n = 8). Despite all models demonstrating acceptable performance on internal validation, only two models underwent external validation, both of which performed poorly.

CONCLUSION

Nine risk prediction models predicting long-term mortality after cardiac surgery have been identified in this review. Statistical issues with model development, limited inclusion of outcomes beyond 5 years of follow-up, and a lack of external validation studies means that none of the models identified can be recommended for use in contemporary cardiac surgery. Further work is needed either to successfully externally validate existing models or to develop new models. Newly developed models should aim to use standardized long-term specific reproducible outcome measures.

In-hospital outcomes after percutaneous coronary interventions in cardiac allograft recipients

Introduction

The average age and survival of heart transplant recipients have improved significantly over the last 10 years. In these long-term survivors, coronary allograft vasculopathy is one of the most common causes of death. There is a paucity of large-data research highlighting the short-term outcomes of percutaneous coronary interventions in cardiac allograft recipients.

Methods

We compared the in-hospital outcomes of heart transplant recipient and non-transplant recipients following percutaneous coronary intervention using data from the National inpatient sample (NIS). All adult patients (age ⩾ 18 years) who had percutaneous coronary intervention in the index admissions from January of 2005 to December of 2014 were included in the analysis. They were then divided into two groups based on their heart transplant status. The primary outcome was in-hospital mortality. Secondary outcomes were stroke, cardiac arrest, duration of hospitalization, and total hospital charges. Logistic regression models were used to compare in-hospital outcomes between the two groups.

Results

Of 1,316,528 patients who had percutaneous coronary intervention, 618 (0.05%) were heart transplant recipients and 1,315,910 (99.95%) were not. The heart transplant recipient group was significantly younger with lower rates of obesity and peripheral vascular disease but higher rate of chronic kidney disease, iron deficiency anemia, and chronic liver disease. There was significantly higher in-hospital mortality in transplant recipients below 65 years of age (adjusted odds ration = 2.3, p value < 0.0001). Subjects in the heart transplant recipient group also had longer hospital stays (p value = 0.002).

Conclusion

Heart transplant recipients younger than 65 years had higher in-hospital mortality. Subjects in the heart transplant recipient group were also younger and had longer duration of hospitalization than the non-transplant cohorts.

A fitting machine learning prediction model for short-term mortality following percutaneous catheterization intervention: a nationwide population-based study

BACKGROUND

A suitable multivariate predictor for predicting mortality following percutaneous coronary intervention (PCI) remains undetermined. We used a nationwide database to construct mortality prediction models to find the appropriate model.

METHODS

Data were analyzed from the Taiwan National Health Insurance Research Database (NHIRD) covering the period from 2004 to 2013. The study cohort was composed of 3,421 patients with acute myocardial infarction (AMI) diagnosis undergoing PCI. The dataset of enrolled patients was used to construct multivariate prediction models. Of these, 3,079 and 342 patients were included in the training and test groups, respectively. Each patient had 22 input features and 2 output features that represented mortality. This study implemented an artificial neural network model (ANN), a decision tree (DT), a linear discriminant analysis classifier (LDA), a logistic regression model (LR), a naïve Bayes classifier (NB), and a support vector machine (SVM) to predict post-PCI patient mortality.

RESULTS

The DT model was found to be the most suitable in terms of performance and real-world applicability. The DT model achieved an area under receiving operating characteristic of 0.895 (95% confidence interval: 0.865-0.925), F1 of 0.969, precision of 0.971, and recall of 0.974.

CONCLUSIONS

The DT model constructed using data from the NHIRD exhibited effective 30-day mortality prediction for patients with AMI following PCI.

A simple-to-use nomogram to predict long term survival of patients undergoing coronary artery bypass grafting (CABG) using bilateral internal thoracic artery grafting technique

BACKGROUND

Several risk scores have been created to predict long term mortality after coronary artery bypass grafting (CABG). Several studies demonstrated a reduction in long-term mortality following bilateral internal thoracic arteries (BITA) compared to single internal thoracic artery. However, these prediction models usually referred to long term survival as survival of up to 5 years. Moreover, none of these models were built specifically for operation incorporating BITA grafting.

METHODS

A historical cohort study of all patients who underwent isolated BITA grafting between 1996 and 2011 at Tel-Aviv Sourasky medical center, a tertiary referral university affiliated medical center with a 24-bed cardio-thoracic surgery department. Study population (N = 2,935) was randomly divided into 2 groups: learning group which was used to build the prediction model and validation group. Cox regression was used to predict death using pre-procedural risk factors (demographic data, patient comorbidities, cardiac characteristics and patient's status). The accuracy (discrimination and calibration) of the prediction model was evaluated.

METHODS AND FINDINGS

The learning (1,468 patients) and validation (1,467 patients) groups had similar preoperative characteristics and similar survival. Older age, diabetes mellitus, chronic obstructive lung disease, congestive heart failure, chronic renal failure, old MI, ejection fraction ≤30%, pre-operative use of intra-aortic balloon, and peripheral vascular disease, were significant predictors of mortality and were used to build the prediction model. The area under the ROC curves for 5, 10, and 15-year survival ranged between 0.742 and 0.762 for the learning group and between 0.766 and 0.770 for the validation group. The prediction model showed good calibration performance in both groups. A nomogram was built in order to introduce a simple-to-use tool for prediction of 5, 10, and 15-year survival.

CONCLUSIONS

A simple-to-use validated model can be used for a prediction of 5, 10, and 15-year mortality after CABG using the BITA grafting technique.

Cost-Effectiveness of Percutaneous Coronary Intervention Compared With Medical Therapy for Ischemic Heart Disease in Japan

BACKGROUND

The cost-effectiveness of percutaneous coronary intervention (PCI) for ischemic heart disease is undetermined in Japan. The aim of this study was to analyze the cost-effectiveness of PCI compared with medical therapy for ST-elevation myocardial infarction (STEMI) and angina pectoris (AP) in Japan.

METHODS AND RESULTS

We used Markov models for STEMI and AP to assess the costs and benefits associated with PCI or medical therapy from a health system perspective. We estimated the incremental cost-effectiveness ratio (ICER), expressed as quality-adjusted life-years (QALY), and ICER <¥5 m per QALY gained was judged to be cost-effective. The impact of PCI on cardiovascular events was based on previous publications. In STEMI patients, the ICER of PCI over medical treatment was ¥0.97 m per QALY gained. The cost-effectiveness probability of PCI was 99.9%. In AP patients, the ICER of fractional flow reserve (FFR)-guided PCI over medical treatment was ¥4.63 m per QALY gained. The cost-effectiveness probability of PCI was 50.4%. The ICER of FFR-guided PCI for asymptomatic patients was ¥23 m per QALY gained.

CONCLUSIONS

In STEMI patients, PCI was cost-effective compared with medical therapy. In AP patients, FFR-guided PCI for symptomatic patients could be cost-effective compared with medical therapy. FFR-guided PCI for asymptomatic patients with myocardial ischemia was not cost-effective.

Risk stratification model for in-hospital death in patients undergoing percutaneous coronary intervention: a nationwide retrospective cohort study in Japan

OBJECTIVES

To provide an accurate adjustment for mortality in a benchmark, developing a risk prediction model from its own dataset is mandatory. We aimed to develop and validate a risk model predicting in-hospital mortality in a broad spectrum of Japanese patients after percutaneous coronary intervention (PCI).

DESIGN

A retrospective cohort study was conducted.

SETTING

The Japanese-PCI (J-PCI) registry includes a nationally representative retrospective sample of patients who underwent PCI and covers approximately 88% of all PCIs in Japan.

PARTICIPANTS

Overall, 669 181 patients who underwent PCI between January 2014 and December 2016 in 1018 institutes.

MAIN OUTCOME MEASURES

In-hospital death.

RESULTS

The study population (n=669 181; mean (SD) age, 70.1(11.0) years; women, 24.0%) was divided into two groups: 50% of the sample was used for model derivation (n=334 591), while the remaining 50% was used for model validation (n=334 590). Using the derivation cohort, both 'full' and 'preprocedure' risk models were developed using logistic regression analysis. Using the validation cohort, the developed risk models were internally validated. The in-hospital mortality rate was 0.7%. The preprocedure model included age, sex, clinical presentation, previous PCI, previous coronary artery bypass grafting, hypertension, dyslipidaemia, smoking, renal dysfunction, dialysis, peripheral vascular disease, previous heart failure and cardiogenic shock. Angiographic information, such as the number of diseased vessel and location of the target lesion, was also included in the full model. Both models performed well in the entire validation cohort (C-indexes: 0.929 and 0.926 for full and preprocedure models, respectively) and among prespecified subgroups with good calibration, although both models underestimated the risk of mortality in high-risk patients with the elective procedure.

CONCLUSIONS

These simple models from a nationwide J-PCI registry, which is easily applicable in clinical practice and readily available directly at the patients' presentation, are valid tools for preprocedural risk stratification of patients undergoing PCI in contemporary Japanese practice.

The influence of Elixhauser comorbidity index on percutaneous coronary intervention outcomes

BACKGROUND

Clinical outcomes with respect to the evolution of comorbidity burden in national cohorts of patients undergoing PCI have not been reported.

OBJECTIVES

We sought to explore the association between comorbidity burden and periprocedural outcomes in patients treated with PCI in the National Inpatient Sample.

METHODS

6,601,526 PCI procedures were identified between 2004 and 2014 and comorbidities were defined by the Elixhauser classification system (ECS) consisting of 30 comorbidity measures. Endpoints included in-hospital mortality, periprocedural complications, length of stay and cost. Patients were classified based on their ECS in five categories (ECS I < 0, ECS II = 0, ECS III = 1-5, ECS IV = 6-13, and ECS V ≥ 14).

RESULTS

Patients with a score over 13 had a fivefold increase in the odds of mortality (OR: 5.13, 95% CI: 4.76-5.54), major bleeding (OR: 11.46, 95% CI: 10.66-12.33) and doubled the hospitalization costs ($31,452 vs $17.566).

CONCLUSIONS

Our study of over six million PCI procedures demonstrates that patients with the greatest comorbid burden (as defined by an ECS of >13) have a fivefold increase risk of in-hospital mortality, a fourfold increase in in-hospital periprocedural complications and an 11-fold increase in major bleeding events once differences in baseline patient characteristics are adjusted for. In addition, ECS significantly impacts the length of stay and doubles the healthcare costs. Comorbid burden is an important predictor of poor outcomes after PCI and should be considered as part of the decision-making processes in patients undergoing PCI.

Impact of co-morbid burden on mortality in patients with coronary heart disease, heart failure, and cerebrovascular accident: a systematic review and meta-analysis

Aims

We sought to investigate the prognostic impact of co-morbid burden as defined by the Charlson Co-morbidity Index (CCI) in patients with a range of prevalent cardiovascular diseases.

Methods and results

We searched MEDLINE and EMBASE to identify studies that evaluated the impact of CCI on mortality in patients with cardiovascular disease. A random-effects meta-analysis was undertaken to evaluate the impact of CCI on mortality in patients with coronary heart disease (CHD), heart failure (HF), and cerebrovascular accident (CVA). A total of 11 studies of acute coronary syndrome (ACS), 2 stable coronary disease, 5 percutaneous coronary intervention (PCI), 13 HF, and 4 CVA met the inclusion criteria. An increase in CCI score per point was significantly associated with a greater risk of mortality in patients with ACS [pooled relative risk ratio (RR) 1.33; 95% CI 1.15-1.54], PCI (RR 1.21; 95% CI 1.12-1.31), stable coronary artery disease (RR 1.38; 95% CI 1.29-1.48), and HF (RR 1.21; 95% CI 1.13-1.29), but not CVA. A CCI score of >2 significantly increased the risk of mortality in ACS (RR 2.52; 95% CI 1.58-4.04), PCI (RR 3.36; 95% CI 2.14-5.29), HF (RR 1.76; 95% CI 1.65-1.87), and CVA (RR 3.80; 95% CI 1.20-12.01).

Conclusion

Increasing co-morbid burden as defined by CCI is associated with a significant increase in risk of mortality in patients with underlying CHD, HF, and CVA. CCI provides a simple way of predicting adverse outcomes in patients with cardiovascular disease and should be incorporated into decision-making processes when counselling patients.

Combined effect of left ventricular ejection fraction and post-cardiac depressive symptoms on major adverse cardiac events after successful primary percutaneous coronary intervention: a 12-month follow-up

BACKGROUND

Despite the technical advancement of percutaneous coronary intervention, major adverse cardiac events after percutaneous coronary intervention are still a critical issue in Korea as well as in western society. Recently, low left ventricular ejection fraction and depressive symptoms have been regarded as independent predictors of adverse outcomes after successful primary percutaneous coronary intervention. However, there are few studies on the combined effect of left ventricular ejection fraction at baseline and post-cardiac depressive symptoms on major adverse cardiac events after percutaneous coronary intervention.

AIM

The aim of the current study is to examine the combined effect of low left ventricular ejection fraction and post-cardiac depressive symptoms on major adverse cardiac events after successful primary percutaneous coronary intervention.

METHODS

A total of 221 patients who underwent successful percutaneous coronary intervention were assessed for left ventricular ejection fraction and depressive symptoms at baseline and 1 month after discharge, using the patient health questionnaire 9. Major adverse cardiac event-free survival rates during the 12-month follow-up period were analysed by Kaplan-Meier survival curves and Cox proportional hazard regression methods.

RESULTS

We found that the combined effect of baseline left ventricular ejection fraction less than 60% and depressive symptoms at 1 month after discharge were significantly correlated with increased incidence of major adverse cardiac events after successful primary percutaneous coronary intervention (hazard ratio 4.049; 95% confidence interval 1.365-12.011) after adjusting for sex, high sensitivity C-reactive protein, depressive symptoms at baseline and comorbidity.

CONCLUSIONS

Our results suggest that healthcare professionals should be aware of the necessity of early screening for post-cardiac depressive symptoms after discharge in percutaneous coronary intervention patients with a low left ventricular ejection fraction.

Prevalence and Impact of Co-morbidity Burden as Defined by the Charlson Co-morbidity Index on 30-Day and 1- and 5-Year Outcomes After Coronary Stent Implantation (from the Nobori-2 Study)

Co-morbidities have typically been considered as prevalent cardiovascular risk factors and cardiovascular diseases rather than systematic measures of general co-morbidity burden in patients who underwent percutaneous coronary intervention (PCI). Charlson co-morbidity index (CCI) is a measure of co-morbidity burden providing a means of quantifying the prognostic impact of 22 co-morbid conditions on the basis of their number and prognostic impact. The study evaluated the impact of the CCI on cardiac mortality and major adverse cardiovascular events (MACE) after PCI through analysis of the Nobori-2 study. The prognostic impact of CCI was studied in 3,067 patients who underwent PCI in 4,479 lesions across 125 centers worldwide on 30-day and 1- and 5-year cardiac mortality and MACE. Data were adjusted for potential confounders using stepwise logistic regression; 2,280 of 3,067 patients (74.4%) had ≥1 co-morbid conditions. CCI (per unit increase) was independently associated with an increase in both cardiac death (odds ratio [OR] 1.47 95% confidence interval [CI] 1.20 to 1.80, p = 0.0002) and MACE (OR 1.29 95% CI 1.14 to 1.47, p ≤0.0011) at 30 days, with similar observations recorded at 1 and 5 years. CCI score ≥2 was independently associated with increased 30-day cardiac death (OR 4.25, 95% CI 1.24 to 14.56, p = 0.02) at 1 month, and this increased risk was also observed at 1 and 5 years. In conclusion, co-morbid burden, as measured using CCI, is an independent predictor of adverse outcomes in the short, medium, and long term. Co-morbidity should be considered in the decision-making process when counseling patients regarding the periprocedural risks associated with PCI, in conjunction with traditional risk factors.

Outcome after coronary artery bypass surgery and percutaneous coronary intervention in patients with atrial fibrillation and oral anticoagulation

AIM

This study was planned to compare the clinical characteristics and outcome of patients on warfarin treatment for atrial fibrillation (AF) undergoing coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI).

METHODS

This is a retrospective analysis of 121 patients who underwent isolated CABG and 301 patients who underwent PCI.

RESULTS

PCI patients were older (mean age, 72.9 versus 69.8 years) and more often had prior cardiac surgery (15.9% versus 1.7%) and acute coronary syndrome (53.8% versus 21.5%). CABG patients more often had two- and three-vessel disease (95.0% versus 60.2%) and left main stenosis (32.2% versus 7.0%). The 30-day outcome was similar after PCI and CABG. At 3 years, PCI was associated with lower overall survival (72.0% versus 86.4%, P = 0.006), freedom from repeat revascularization (85.3% versus 98.2%, P < 0.001), freedom from myocardial infarction (83.4% versus 93.8%, P = 0.008), and freedom from major cardiovascular events (57.4% versus 78.9%, P < 0.001). Propensity score adjusted analysis showed that PCI was associated with increased risk of all-cause mortality (P = 0.016, RR 2.166, CI 1.155-4.060), myocardial infarction (P = 0.017, RR 3.161, 95% CI 1.227-8.144), repeat revascularization (P = 0.001, RR 13.152, 95% CI 2.799-61.793), and major cardiac and cerebrovascular complications (P = 0.001, RR 2.347, 95% CI 1.408-3.914). There was no difference in terms of stroke and bleeding episodes at any time point.

CONCLUSION

In clinical practice, PCI is the preferred revascularization strategy in these frail patients. Patients selected for CABG have a relatively low operative risk and better mid-term outcome in spite of warfarin treatment. The poor prognosis after PCI may mainly reflect frequent co-morbidities in this patient group.

Severe left ventricular systolic dysfunction is independently associated with high on-clopidogrel platelet reactivity

OBJECTIVE

The purpose of the present study was to investigate the association between left ventricular systolic function and the response to clopidogrel.

METHODS

The efficacy of clopidogrel was measured by the vasodilator-stimulated phosphoprotein phosphorylation 20 ± 4 h after 600 mg of clopidogrel. High on-clopidogrel platelet reactivity (HCPR) was defined as a platelet reactivity index (PRI) ≥50%. The 30-day combined incidence of death, non-fatal acute coronary syndrome, re-percutaneous coronary intervention (PCI), stent thrombosis, and stroke was also investigated.

RESULTS

The study group consisted of 519 patients undergoing PCI. The values (mean and 95% confidence interval) of the PRI were as follows: 40.4% (37.8-43.0) in patients with left ventricular ejection fraction (LVEF) >50%, 42.4% (39.3-45.6) in patients with LVEF 35-50%, and 46.7% (40.6-52.9) in patients with LVEF <35% (p = 0.013). The proportions of patients with HCPR were 35.9% in patients with LVEF ≥35 and 51.9% in patients with LVEF <35% (p = 0.022). After adjustment for variables that significantly influenced clopidogrel efficacy, LVEF <35% was found to be independently associated with HCPR (p = 0.039). The 30-day combined clinical endpoint occurred in 18% of patients with LVEF <35% and in 7.3% of patients with LVEF ≥35% (p = 0.026). The 30-day incidence of all-cause mortality was 14% in patients with LVEF <35 and 1.0% in patients with LVEF ≥35% (p < 0.001).

CONCLUSION

An LVEF <35% was found to be independently associated with HCPR.

Body mass index is inversely associated with mortality in patients with peripheral vascular disease

BACKGROUND

Current guidelines contain no advice on how to manage obesity and underweight in patients with peripheral vascular disease (PVD).

OBJECTIVES

The aim of this study was to assess the association of underweight, overweight and obesity with mortality in patients with PVD.

PATIENTS AND METHODS

We recruited 1472 patients with a broad range of presentations of PVD. Underweight, overweight and obesity were defined by body mass index (BMI) and associated with mortality using Kaplan Meier and Cox proportional hazard analyses.

RESULTS

Survival at 3 years was 37.5, 78.1, 86.8 and 87.0% for patients that were underweight, normal weight, overweight and obese at recruitment, respectively, p<0.001. Patients that were underweight had approximately twice the risk of dying (RR 2.15, 95% CI 1.31-3.55, p=0.003), while patients that were overweight (RR 0.67, 95% CI 0.49-0.91, p=0.011) or obese (RR 0.59, 95% CI 0.41-0.85, p=0.005) had approximately half the risk of dying, after adjustment for other risk factors and using normal weight subjects as the reference group. 823 patients had waist circumference measured at recruitment. Patients with waist circumference in the top quartile had half the risk of dying (RR 0.50, 95% CI 0.26-0.98, p=0.045). In 267 patients we assessed the relationship between BMI and abdominal fat volumes using computed tomography. BMI was highly correlated with both intra-abdominal and subcutaneous fat volumes.

CONCLUSIONS

Obesity whether assessed by BMI or central fat deposition is associated with reduced risk of dying in patients with established PVD. Underweight is highly predictive of early mortality in patients with PVD.