Mortality and readmission in non-ischemic compared with ischemic cardiomyopathies after implantable cardioverter-defibrillator implantation

Background/Introduction

Uncertainty remains regarding the benefit of primary prevention ICDs overall in contemporary practice, and particularly in those with NICM compared with ICM.

Purpose

To evaluate the contemporary risk of death and readmission following following implantable cardioverter-defibrillator (ICD) implantation in patients with non-ischemic cardiomyopathies (NICM) compared with ischemic cardiomyopathies (ICM) in a large nationally representative cohort in the United States.

Methods

We used data from the American College of Cardiology (ACC) National Cardiovascular Data Registry (NCDR) ICD Registry linked with Medicare claims from April 1, 2010 to December 31, 2013 to establish a cohort of NICM and ICM patients with a left ventricular ejection fraction ≤35% who received a de novo, primary prevention ICD. We compared mortality, all-cause readmission, and heart failure readmission using Kaplan-Meier curves and Cox proportional hazard regressions models. We also evaluated temporal trends in mortality.

Results

Among 31,044 NICM and 68,458 ICM patients with a median follow up of 2.4 years, one-year mortality was significantly higher in ICM patients (12.3%) compared with NICM (7.9%, p<0.001). The higher mortality in ICM patients remained significant after adjustment for covariates (hazard ratio (HR) 1.40; 95% confidence interval (CI) 1.36 to 1.45), and was consistent in subgroup analyses. These findings were consistent across the duration of the study. ICM patients were also significantly more likely to be readmitted for all causes (adjusted HR 1.15, CI 1.12 to 1.18) and for heart failure (adjusted HR 1.25, CI 1.21 to 1.31).

Conclusions

The risks of mortality and hospital readmission after primary prevention ICD implantation were significantly higher in patients with ICM compared with NICM, and these findings were consistent across all patient subgroups tested and over the duration of the study.

Funding Acknowledgement

Type of funding source: None

P4779High facility preference for rivaroxaban in atrial fibrillation increases risk of major bleeding compared to facility preference for apixaban

Background

No randomized trial has compared efficacy and safety of non-vitamin K antagonist oral anticoagulants (NOACs) in atrial fibrillation (AF). Previous real-world comparisons could be biased by patient characteristics of importance for treatment selection, but instrumental variables could potentially account for measured and unmeasured confounders.

Purpose

To compare efficacy and safety of rivaroxaban and apixaban using facility preference for type of NOAC as instrumental variable.

Methods

AF patients started on apixaban or rivaroxaban were identified using nationwide registries. We categorized patients according to facility preference for type of NOAC, measured as percentage of the prior 20 AF patients started on rivaroxaban in the same facility. Occurrence of stroke/thromboembolism (TE), major bleeding, myocardial infarction and all-cause mortality during two years of follow-up were investigated using adjusted Cox regressions. To further examine general frailty according to facility preferences we also investigated occurrence of cancer, urogenital tract infection, dehydration and fracture.

Results

We analyzed 6264 AF patients initiated on rivaroxaban or apixaban. Compared with patients treated in facilities that used rivaroxaban in 0–20% of cases, the adjusted hazard ratio for bleeding was 1.05 when treated in a facility with 25–40% use; 1.40 with 45–60% use; 1.50 with 65–80% use; and 1.81 for 85–100% use (Ptrend=0.002). Higher facility level use of rivaroxaban was not associated with increased risk of stroke/TE (Ptrend=0.06), myocardial infarction (Ptrend=0.87) or all-cause mortality (Ptrend=0.91), and there was no association between facility preference for rivaroxaban and risk of cancer (Ptrend=0.83), urogenital tract infection (Ptrend=0.49), dehydration (Ptrend=0.91) or fracture (Ptrend=0.47).

Characteristics by facility preference Percent of previous AF patients from facility started on rivaroxaban P for trend 0–20% 25–40% 45–60% 65–80% 85–100% No. of patients 1406 1421 1551 930 956 Received rivaroxaban, (%) 279, (19.8) 499, (35.1) 711, (45.8) 632, (68.0) 774, (81.0) <0.001 Standard dose, (%) 1216, (86.5) 1232, (86.7%) 1366, (88.1%) 793, (85.3%) 824, (86.2%) 0.62 Median age, (interquartile range) 70, (63.3–74) 69, (63–74) 70, (64–74) 70, (64–75) 70, (63–75) 0.11 Below median income, (%) 740, (52.6) 699, (49.2) 764, (49.3) 458, (49.3) 471, (49.3) 0.31 Prior stroke, (%) 99, (7.0) 115, (8.1) 134, (8.6) 69, (7.4) 74, (7.7) 0.56 Prior bleeding, (%) 136, (9.7) 141, (9.9) 163, (10.5) 91, (9.8) 97, (10.1) 0.51 Antiplatelet therapy, (%) 445, (31.7) 465, (32.7) 491, (31.7) 303, (32.6) 317, (33.2) 0.49

Rate of events according to instrument

Conclusion

High facility preference for rivaroxaban increases risk of major bleeding compared to facility preference for apixaban.

Acknowledgement/Funding

This study was funded by an unrestricted grant from the Capital Region of Denmark, Foundation for Health Research.

P4765Men who live alone have poor anticoagulation control: results from Danish registries

Background

Efficacy and safety of vitamin K antagonists (VKAs) depend on quality of anticoagulation control, usually measured as time in therapeutic range (TTR). Factors that predict low TTR on VKAs could be used to identify patients who might benefit from interventions, or who would be better treated with a non-VKA oral anticoagulant (NOAC). Patients living alone may have difficulties in taking their medications, managing their diets, or coming to clinic for monitoring.

Purpose

To assess influence of cohabitation status on TTR with VKA among men and women.

Methods

We identified all Danish patients with atrial fibrillation (AF) who initiated VKA between 1997 and 2012, and studied patients who had 6 months of continuous VKA use and international normalized ratio (INR) monitoring. Patients were divided according to sex and whether they lived alone or with others. We calculated TTR using the Rosendaal method, and INR variability using Fihns method. We used a linear regression model to test for associations between TTR and covariates, and adjusted for age, income, medications and comorbidities.

Results

We identified 4,772 AF patients with 6 months of continuous VKA use and INR monitoring. 713 (15%) were men living alone, 1,073 (23%) were women living alone, 2,164 (45%) were men not living alone and 822 (17%) were women not living alone. INR was measured a median of 11 (interquartile range 8–15) times during the 180 days of VKA use, but men who lived alone had 0.6 (95% confidence interval (CI): 0.2 to 1.2) fewer INR measurements during the period. Median TTR was lowest among men living alone (57.2%), followed by women living alone (58.8%), women not living alone (61.0%) and men not living alone (62.5%). After multivariable adjustment, men who lived alone had a 3.6% (CI −5.6 to −1.6) lower TTR compared with men not living alone, but women who lived alone did not have significantly lower TTR (P=0.80) compared with women not living alone. Living alone had significantly greater effect on TTR among men than among women (interaction P=0.02). Men living alone also had higher adjusted INR variability (0.2, CI 0.0 to 0.4) compared with men not living alone.

Conclusion

Living alone was significantly related to low quality of anticoagulation control among men, but not among women.

Acknowledgement/Funding

this study was funded by an unrestricted grant from the Capital Region of Denmark, Foundation for Health Research

Canadian-American differences in the management of acute coronary syndromes in the GUSTO IIb trial: one-year follow-up of patients without ST-segment elevation. Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) II Investigators

BACKGROUND

Little information exists concerning practice patterns between Canada and the United States in the management of myocardial infarction (MI) patients without ST-segment elevation and unstable angina.

METHODS AND RESULTS

We examined the practice patterns and 1-year outcomes of 2250 US and 922 Canadian patients without ST-elevation acute coronary syndromes in the Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) IIb trial. The US hospitals more commonly had on-site facilities for angiography and revascularization. These procedures were performed more often and sooner in the United States than Canada, whereas Canadian patients were more likely to undergo noninvasive stress testing. The length of initial hospital stay was 1 day longer for Canadian than US patients. Recurrent and refractory ischemia was more common in Canada. One-year mortality was comparable between the 2 countries. However, at 6 months, even after baseline differences were accounted for, the (re)MI rate was significantly higher in Canadian than US patients with unstable angina (8.8% versus 5.8%, P:=0.039), as was the composite rate of death or (re)MI (13.1% versus 9.1%, P:=0.016).

CONCLUSIONS

One-year mortality was comparable between Canada and the United States in both MI and unstable angina cohorts despite higher intervention rates in the United States. However, outcomes at 6 months among patients with unstable angina differed. Whereas more frequent coronary interventions were not associated with reduced recurrent MI or death among MI patients without ST elevation, they may favorably affect outcomes in patients with unstable angina.

A comparison of thrombolytic therapy with primary coronary angioplasty for acute myocardial infarction. Myocardial Infarction Triage and Intervention Investigators

BACKGROUND

Several relatively small randomized trials have shown that primary angioplasty results in a better short-term outcome than thrombolytic therapy in patients with acute myocardial infarction. These results, however, have not been duplicated other than in investigational trials.

METHODS

We compared mortality during hospitalization and long-term mortality, as well as the use of resources, among 1050 patients in a primary-angioplasty group and 2095 patients in a thrombolytic-therapy group. Patients were selected from the Myocardial Infarction Triage and Intervention Project Registry cohort of 12,331 consecutive patients admitted with acute myocardial infarction to 19 Seattle hospitals between 1988 and 1994. Because of the potential for selection bias, several subgroup analyses were performed that included patients eligible for thrombolysis, high-risk patients, and patients in the primary-angioplasty group who were treated at hospitals with high volumes of angioplasty.

RESULTS

There was no significant difference in mortality during hospitalization or long-term follow-up between patients in the thrombolytic-therapy group and those in the primary-angioplasty group (mortality during hospitalization, 5.6 percent and 5.5 percent, respectively; P=0.93; adjusted hazard ratio for the risk of death within three years after primary angioplasty, 0.95; 95 percent confidence interval, 0.8 to 1.2). There was also no significant difference in mortality between high-risk subgroups of patients in the two treatment groups. The rates of procedures and costs were lower among patients in the thrombolytic-therapy group both at the time of hospital discharge and after three years of follow-up (30 percent fewer coronary angiograms, 15 percent fewer coronary angioplasties, and 13 percent lower costs after three years of follow-up).

CONCLUSIONS

In a community setting, we observed no benefit in terms of either mortality or the use of resources with a strategy of primary angioplasty rather than thrombolytic therapy in a large cohort of patients with acute myocardial infarction.

Length of hospital stay after acute myocardial infarction in the Myocardial Infarction Triage and Intervention (MITI) Project registry

OBJECTIVES

This study sought to identify current trends in length of stay in patients with an acute myocardial infarction and to evaluate which demographic, clinical, procedural and hospital-related factors explain the variation and reduction in length of stay observed during the study period.

BACKGROUND

Hospital length of stay is an important contribution to cost of care. Previous studies of length of stay after acute myocardial infarction have been performed largely on administrative data bases and do not reflect current practice patterns.

METHODS

We used univariate and multivariate models to evaluate which demographic, clinical and administrative factors influenced length of stay in 11,932 patients with acute myocardial infarction admitted to 19 Seattle-area hospitals between 1988 and 1994.

RESULTS

Length of hospital stay decreased from (mean +/- SD) 8.5 +/- 8.2 to 6.0 +/- 5.8 days during the study period. Demographic and clinical characteristics known at the time of admission explained only 6% of variation in length of stay, whereas hospital complications, procedure use and type of admitting hospital explained an additional 27% of variation. The use of primary angioplasty and early diagnostic coronary angiography predicted a shorter length of stay; however, none of the measured variables explained the 29% reduction in length of stay that occurred between 1988 and 1994.

CONCLUSIONS

Although hospital complications, procedure use and hospital characteristics are important predictors of length of hospital stay, none of these factors explains the 29% reduction in length of stay observed in postmyocardial infarction patients between 1988 and 1994. It is likely that unmeasured economic and administrative factors play important roles in influencing hospital length of stay.

Comparison of analytic models for estimating the effect of clinical factors on the cost of coronary artery bypass graft surgery

The cost of treating disease depends on patient characteristics, but standard tools for analyzing the clinical predictors of cost have deficiencies. To explore whether survival analysis techniques might overcome some of these deficiencies in the analysis of cost data, we compared ordinary least square (OLS) linear regression (with and without transformation of the data) and binary logistic regression with two survival models: the Cox proportional hazards model and a parametric model assuming a Weibull distribution. Each model was applied to data from 155 patients undergoing coronary artery bypass grafting. We examined the effects of age, sex, ejection fraction, unstable angina, and number of diseased vessels on univariable and multivariable predictions of costs. The significant univariable predictors of cost were consistent in all models: ejection fraction was significant in all five models, and age and number of diseased vessels were each significant in all but the OLS model, while sex and angina type were significant in none of the models. The significant multivariable predictors of cost, however, differed according to model: ejection fraction was a significant multivariable predictor of cost in all five models, age was significant in three models, and number of diseased vessels was significant in one model. All five models were also used to predict the costs for an average patient undergoing surgery. The Cox model provided the most accurate predictions of mean cost, median cost, and the proportion of patients with high cost. This study shows: (1) lower ejection fraction and older age are independent clinical predictors of increased cost of CABG, and (2) the Cox proportional hazards model shows considerable promise for the analysis of the impact of clinical factors upon cost.

Cardiovascular and renal toxicity of a nonionic radiographic contrast agent after cardiac catheterization. A prospective trial

STUDY OBJECTIVE

To determine the incidence of cardiovascular and renal toxicity of a nonionic contrast agent when used for cardiac catheterization, and to assess the value of electrolytes and urinalysis results as predictors of nephropathy induced by a contrast agent.

STUDY DESIGN

Nonrandomized trial using a criterion standard and a cohort analytic study with a 48-hour follow-up.

SETTING

Referral-based university hospital.

PATIENTS

Convenience sample of patients having diagnostic cardiac catheterization. Renal function and clinical status were evaluated at baseline in 1,144 patients; at 24 hours in 1,077 (94%); and at 48 hours in 663 (57%).

INTERVENTIONS

After patients received saline for hydration, coronary angiography and left ventriculography were done with iopamidol (average dose, 203 +/- 56 cc).

MEASUREMENTS AND MAIN RESULTS

The definite and possible incidence of major acute cardiovascular complications from nonionic contrast media was 0.2% and 0.7%, respectively. The mean serum creatinine level increased 11.5 mumol/L from baseline at 24 hours (P less than 0.0001) and 16.8 mumol/L from baseline at 48 hours (P less than 0.0001). Results in a randomly selected training sample were studied to determine predictors of a rise in serum creatinine of 44.2 mumol/L or more. The baseline serum creatinine level and age were significant predictors of renal injury, but hypertension, diabetes mellitus, congestive heart failure, vascular disease, the volume of contrast agent injected or baseline values of urinary variables did not predict nephrotoxicity. In an independent validation sample, only the baseline serum creatinine level was confirmed as a predictor of nephrotoxicity, whereas age was not. A model that predicted contrast-induced nephropathy by the serum creatinine level showed an exponential increase in the risk for nephrotoxicity if the baseline level was 106.1 mumol/L or higher.

CONCLUSIONS

Patients have a small but significant rise in serum creatinine after cardiac catheterization with a nonionic contrast agent. Baseline renal insufficiency is the only confirmed predictor of nonionic contrast-induced nephrotoxicity.

The independent value of exercise thallium scintigraphy to physicians

To determine the effect of exercise myocardial scintigraphy with thallium-201 on diagnostic accuracy and the need for coronary angiography, consecutive patients with a variety of clinical presentations were identified. Clinical summaries, including a detailed history, physical examination, and complete data from a standard treadmill exercise test, were presented to 91 cardiologists. The cardiologists assessed the probability of coronary disease and the need for coronary angiography. They were then presented the results of thallium scintigraphy and revised their assessments if warranted. Scintigraphy significantly increased the cardiologists' diagnostic accuracy beyond that attained with other clinical information (p less than 0.0001). The change in accuracy varied from + 4% to + 20% in different patient groups, and was greatest in patients with atypical angina and a positive exercise ECG. Ratings of the need for coronary angiography changed from -13% to +21% in different patient groups. We conclude that exercise thallium scintigraphy can provide independent diagnostic information and influence the need for coronary angiography.

Diagnostic accuracy of cardiologists compared with probability calculations using Bayes' rule

Probability analysis has provided insights into the use of diagnostic tests in coronary artery disease, and recent developments may permit clinical application of individual patients. To validate independently two available methods of probability calculation, their diagnostic accuracy was compared with that of cardiologists. Ninety-one cardiologists participated in the study; each evaluated the clinical summaries of eight randomly selected patients. For each patient, the cardiologist assessed the probability of coronary artery disease after reviewing the clinical history, physical examination and laboratory data, including complete results from a treadmill exercise test. The probability of coronary artery disease was also obtained for each patient, using the identical information, from two methods employing Bayes' rule: (1) from a published table of data based on the patient's age, sex, symptoms and degree of S-T segment change during exercise; and (2) from a computer program using the age, sex, risk factors, resting electrocardiogram and multiple exercise measurements. Diagnostic accuracy was assessed on a scale from 0 to 100 with the coronary angiogram as the diagnostic standard. The average diagnostic accuracy on this scale was: 80.2 for the cardiologists' estimates, 78.0 for the estimates based on tables (difference from cardiologists' estimates p less than 0.05) and 83.1 for the estimates based on computer calculations (p less than 0.01). Thus probability analysis incorporating sufficient detail can achieve a diagnostic accuracy comparable with that of cardiologists. Studies of the efficacy of probability analysis in patient care are warranted.