Machine learning-based prediction of in-hospital death for patients with takotsubo syndrome: The InterTAK-ML model

AIMS

Takotsubo syndrome (TTS) is associated with a substantial rate of adverse events. We sought to design a machine learning (ML)-based model to predict the risk of in-hospital death and to perform a clustering of TTS patients to identify different risk profiles.

METHODS AND RESULTS

A ridge logistic regression-based ML model for predicting in-hospital death was developed on 3482 TTS patients from the International Takotsubo (InterTAK) Registry, randomly split in a train and an internal validation cohort (75% and 25% of the sample size, respectively) and evaluated in an external validation cohort (1037 patients). Thirty-one clinically relevant variables were included in the prediction model. Model performance represented the primary endpoint and was assessed according to area under the curve (AUC), sensitivity and specificity. As secondary endpoint, a K-medoids clustering algorithm was designed to stratify patients into phenotypic groups based on the 10 most relevant features emerging from the main model. The overall incidence of in-hospital death was 5.2%. The InterTAK-ML model showed an AUC of 0.89 (0.85-0.92), a sensitivity of 0.85 (0.78-0.95) and a specificity of 0.76 (0.74-0.79) in the internal validation cohort and an AUC of 0.82 (0.73-0.91), a sensitivity of 0.74 (0.61-0.87) and a specificity of 0.79 (0.77-0.81) in the external cohort for in-hospital death prediction. By exploiting the 10 variables showing the highest feature importance, TTS patients were clustered into six groups associated with different risks of in-hospital death (28.8% vs. 15.5% vs. 5.4% vs. 1.0.8% vs. 0.5%) which were consistent also in the external cohort.

CONCLUSION

A ML-based approach for the identification of TTS patients at risk of adverse short-term prognosis is feasible and effective. The InterTAK-ML model showed unprecedented discriminative capability for the prediction of in-hospital death.

Clinical characteristics and outcomes of patients with takotsubo syndrome versus spontaneous coronary artery dissection

BACKGROUND

Takotsubo syndrome (TTS) and spontaneous coronary artery dissection (SCAD) are now increasingly recognized. Both conditions predominantly affect females; however, the exact pathophysiology remains unclear. Large multi-center databases can help elucidate the underlying mechanism and optimize treatments to improve outcomes by allowing us to compare features and outcomes of patients with TTS and patients with SCAD.

METHODS

Takotsubo syndrome patients were enrolled from the International Takotsubo Registry and compared to SCAD patients from the Canadian Spontaneous Coronary Artery Dissection Cohort Study. In total 2098 TTS patients and 750 SCAD patients were included in the present study.

RESULTS

More than 85% of patients in both groups were females. TTS patients were older compared to SCAD patients. Physical triggers were more common in TTS patients, while emotional triggers and non-identifiable triggering events were more common in SCAD patients. Left ventricular ejection fraction was more impaired in TTS compared to SCAD. TTS patients had more major cardiovascular risk factors, while SCAD patients had a higher rate of migraines and anxiety disorders than TTS patients. Thirty-day mortality was significantly higher in TTS patients, while 30-day stroke rates were comparable between groups.

CONCLUSIONS

These findings suggest that women are at higher risk for TTS and SCAD compared to men, which should be considered in the differential diagnosis of those presenting with acute coronary syndrome. Additionally, emotional stressors play a significant role in triggering events particularly in younger women suffering from SCAD. The present findings may help clinicians better differentiate these two entities and aid in the appropriate risk stratification, diagnosis, and management.

TRIAL REGISTRATION

ClinicalTrials.gov no. NCT01947621.

Impact of Atrial Fibrillation on Outcome in Takotsubo Syndrome: Data From the International Takotsubo Registry

Background

Atrial fibrillation (AF) is a major risk factor for mortality. The prevalence, clinical correlates, and prognostic impact of AF in Takotsubo syndrome (TTS) have not yet been investigated in a large patient cohort. This study aimed to investigate the prevalence, clinical correlates, and prognostic impact of AF in patients with TTS.

Methods and Results

Patients with TTS were enrolled from the International Takotsubo Registry, which is a multinational network with 26 participating centers in Europe and the United States. Patients were dichotomized according to the presence or absence of AF at the time of admission. Of 1584 patients with TTS, 112 (7.1%) had AF. The mean age was higher (P<0.001), and there were fewer women (P=0.046) in the AF than in the non‐AF group. Left ventricular ejection fraction was significantly lower (P=0.001), and cardiogenic shock was more often observed (P<0.001) in the AF group. Both in‐hospital (P<0.001) and long‐term mortality (P<0.001) were higher in the AF group. Multivariable Cox regression analysis revealed that AF was independently associated with higher long‐term mortality (hazard ratio, 2.31; 95% CI, 1.50–3.55; P<0.001). Among patients with AF on admission, 42% had no known history of AF before the acute TTS event, and such patients had comparable in‐hospital and long‐term outcomes compared with those with a history of AF.

Conclusions

In patients presenting with TTS, AF on admission is significantly associated with increased in‐hospital and long‐term mortality rates. Whether antiarrhythmics and/or cardioversion are beneficial in TTS with AF should thus be tested in a future trial.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01947621.

Prognostic impact of acute pulmonary triggers in patients with takotsubo syndrome: new insights from the International Takotsubo Registry

AIMS

Acute pulmonary disorders are known physical triggers of takotsubo syndrome (TTS). This study aimed to investigate prevalence of acute pulmonary triggers in patients with TTS and their impact on outcomes.

METHODS AND RESULTS

Patients with TTS were enrolled from the International Takotsubo Registry and screened for triggering factors and comorbidities. Patients were categorized into three groups (acute pulmonary trigger, chronic lung disease, and no lung disease) to compare clinical characteristics and outcomes. Of the 1670 included patients with TTS, 123 (7%) were identified with an acute pulmonary trigger, and 194 (12%) had a known history of chronic lung disease. The incidence of cardiogenic shock was highest in patients with an acute pulmonary trigger compared with those with chronic lung disease or without lung disease (17% vs. 10% vs. 9%, P = 0.017). In-hospital mortality was also higher in patients with an acute pulmonary trigger than in the other two groups, although not significantly (5.7% vs. 1.5% vs. 4.2%, P = 0.13). Survival analysis demonstrated that patients with an acute pulmonary trigger had the worst long-term outcome (P = 0.002). The presence of an acute pulmonary trigger was independently associated with worse long-term mortality (hazard ratio 2.12, 95% confidence interval 1.33-3.38; P = 0.002).

CONCLUSIONS

The present study demonstrates that TTS is related to acute pulmonary triggers in 7% of all TTS patients, which accounts for 21% of patients with physical triggers. The presence of acute pulmonary trigger is associated with a severe in-hospital course and a worse long-term outcome.

Age-Related Variations in Takotsubo Syndrome

BACKGROUND

Takotsubo syndrome (TTS) occurs predominantly in post-menopausal women but is also found in younger patients.

OBJECTIVES

This study aimed to investigate age-related differences in TTS.

METHODS

Patients diagnosed with TTS and enrolled in the International Takotsubo Registry between January 2011 and February 2017 were included in this analysis and were stratified by age (younger: ≤50 years, middle-age: 51 to 74 years, elderly: ≥75 years). Baseline characteristics, hospital course, as well as short- and long-term mortality were compared among groups.

RESULTS

Of 2,098 TTS patients, 242 (11.5%) patients were ≤50 years of age, 1,194 (56.9%) were 51 to 74 years of age, and 662 (31.6%) were ≥75 years of age. Younger patients were more often men (12.4% vs. 10.9% vs. 6.3%; p = 0.002) and had an increased prevalence of acute neurological (16.3% vs. 8.4% vs. 8.8%; p = 0.001) or psychiatric disorders (14.1% vs. 10.3% vs. 5.6%; p < 0.001) compared with middle-aged and elderly TTS patients. Furthermore, younger patients had more often cardiogenic shock (15.3% vs. 9.1% vs. 8.1%; p = 0.004) and had a numerically higher in-hospital mortality (6.6% vs. 3.6% vs. 5.1%; p = 0.07). At multivariable analysis, younger (odds ratio: 1.60; 95% confidence interval: 0.86 to 3.01; p = 0.14) and older age (odds ratio: 1.09; 95% confidence interval: 0.66 to 1.80; p = 0.75) were not independently associated with in-hospital mortality using the middle-aged group as a reference. There were no differences in 60-day mortality rates among groups.

CONCLUSIONS

A substantial proportion of TTS patients are younger than 50 years of age. TTS is associated with severe complications requiring intensive care, particularly in younger patients.

Acute dilated cardiomyopathy in the setting of catastrophic antiphospholipid syndrome and thrombotic microangiopathy: A case series and review

Catastrophic antiphospholipid antibody syndrome (CAPS) is a rare form of antiphospholipid syndrome, an autoimmune condition characterized by vascular thromboses, pregnancy loss, and antiphospholipid (aPL) antibodies. Diagnosis of CAPS relies on thrombosis of at least three different organs systems over 1 week, histopathological evidence of small vessel occlusion, and high aPL antibody titers. In a subset of precipitating circumstances, activation or disruption of endothelial cells in the microvasculature may occur along with cardiomyopathy. We present two cases of CAPS‐associated dilated cardiomyopathy at our institution, focusing on disease management, pathophysiology, and treatment. These patients were of Southeastern Asian descent, raising the possibility of genetic polymorphisms contributing to the development of cardiomyopathy. Both met CAPS criteria and both demonstrated clinicopathologic thrombotic microangiopathy (TMA) and complement activation and developed severe dilated cardiomyopathy with shock. Complement activation plays an important role in the development of CAPS and may be important in the pathogenesis of CAPS‐associated cardiomyopathy. Clinical suspicion for TMA as a pathophysiologic mechanism of unexplained heart failure in CAPS is important and increased awareness of cardiac side effects is necessary so that early treatment can be initiated to halt further cardiac and systemic complications.

Ventricular asystole in a CRT-D device. What is the mechanism?

We present a case of an 89-year-old man with a left ventricular assist device and cardiac resynchronization therapy device (CRT-D) who presented with multiple presyncopal events. On the night of admission, telemetry revealed a 13-s pause with appropriately timed pacing spikes but with failure to capture, followed by intermittent ventricular contraction with different QRS morphology. What was the mechanism for his ventricular asystole?

Clinical Features and Outcomes of Patients With Malignancy and Takotsubo Syndrome: Observations From the International Takotsubo Registry

Background Clinical characteristics and outcomes of takotsubo syndrome (TTS) patients with malignancy have not been fully elucidated. This study sought to explore differences in clinical characteristics and to investigate short- and long-term outcomes in TTS patients with or without malignancy. Methods and Results TTS patients were enrolled from the International Takotsubo Registry. The TTS cohort was divided into patients with and without malignancy to investigate differences in clinical characteristics and to assess short- and long-term mortality. A subanalysis was performed comparing long-term mortality between a subset of TTS patients with or without malignancy and acute coronary syndrome (ACS) patients with or without malignancy. Malignancy was observed in 16.6% of 1604 TTS patients. Patients with malignancy were older and more likely to have physical triggers, but less likely to have emotional triggers compared with those without malignancy. Long-term mortality was higher in patients with malignancy (P<0.001), while short-term outcome was comparable (P=0.17). In a subanalysis, long-term mortality was comparable between TTS patients with malignancies and ACS patients with malignancies (P=0.13). Malignancy emerged as an independent predictor of long-term mortality. Conclusions A substantial number of TTS patients show an association with malignancy. History of malignancy might increase the risk for TTS, and therefore, appropriate screening for malignancy should be considered in these patients. Clinical Trial Registration URL: http://www.clinicaltrial.gov. Unique identifier: NCT01947621.

Late onset cardiac cirrhosis and portal hypertensive ascites after atrial fibrillation ablation

Pulmonary vein stenosis is a potential complication following catheter ablation of atrial fibrillation (AF). We report the case of a patient with refractory ascites late after multiple catheter ablation procedures for AF. This is the first case report of portal hypertensive ascites due to acquired multiple pulmonary vein stenoses resulting in pulmonary hypertension (PH) and cardiac cirrhosis late after AF ablation. Despite extensive surgical reconstruction of the affected pulmonary veins, the patient has PH and right heart failure with persistent ascites and lower extremity edema.

A Case of Myocarditis and Near-Lethal Arrhythmia Associated With Interleukin-2 Therapy

We present a case of a 48-year-old female who developed myocarditis and near fatal arrhythmias during high dose Il-2 therapy for metastatic renal cancer. On day 5 of therapy, the patient developed sudden onset chest pain, elevated cardiac enzymes and ST segment changes on EKG. Coronary angiogram was normal, however echocardiogram showed reduced ejection fraction and hemodynamic measurements showed elevated bilateral elevated filling pressures. The patient then developed episodes of recurrent ventricular arrhythmia, precipitated by bradycardia and PVC, requiring defibrillation and temporary pacemaker placement. Endomycardial biopsy was nonspecific showing fibrosis with subsequent cardiac MRI showed evidence of myocardial edema, consistent with Il-2 induced myocarditis in the setting of no prior cardiac history. After the discontinuation of Il-2 therapy, the patient displayed clinical improvement as well as improved ejection fraction. This case brings attention to the cardiac toxicities associated with high dose Il-2 therapy including potentially lethal arrhythmias and highlights the importance of careful cardiac screening prior to initiation of treatment.

Calcific constrictive pericarditis demonstrated on 99mTc-MDP bone scintigraphy

The authors present a case of calcific constrictive pericarditis, imaged with bone scintigraphy. The patient presented with three months of shortness of breath, chest pain, and chest tightness during exercise, among other nonspecific symptoms. Although the diagnosis was made based on chest radiography and cardiac MRI, bone scintigraphy was used to corroborate the diagnosis of calcific constrictive pericarditis. Bone scintigraphy showed a pattern of tracer accumulation consistent with pericardial uptake. Calcific constrictive pericarditis was also confirmed at the time of surgery.

Triage practice guideline for patients hospitalized with congestive heart failure: improving the effectiveness of the coronary care unit

BACKGROUND

Decisions regarding the appropriate timing for transfer of patients hospitalized with congestive heart failure from the coronary care unit (CCU) to the medical ward are often not based on well-founded medical data. We investigated the potential safety and effectiveness of a practice guideline recommending early "step-down" transfer of low-risk patients with congestive heart failure.

PATIENTS AND METHODS

We studied the use of a practice guideline for 384 patients hospitalized with congestive heart failure in a hypothetic experiment. The guideline stated that patients without any of the following conditions may be suitable for transfer to a nonmonitored bed 24 hours after admission: acute myocardial infarction or ischemia, complications, active or planned cardiac interventions, unstable comorbidity, worsening clinical status, or lack of response to diuretic therapy. Patients with any of the above conditions were classified as higher risk and potentially not suitable for early transfer.

RESULTS

Life-threatening complications were 15.2 times more likely (95% confidence interval [CI] 2.2, 70, p = 0.001) and death 14.6 times more likely (95% CI 2.1, 68, p = 0.001) if the patient was classified as "high risk" rather than "low risk" by the guideline. The negative predictive value and sensitivity of the practice guideline for detecting patients who had life-threatening complications were 99.2% and 96.4%, respectively. Thirty-one percent of patients with congestive heart failure hospitalized in either the CCU or intermediate care unit were at low risk and potentially suitable for transfer to a nonmonitored bed 24 hours after admission. Use of the guideline would have reduced intermediate care unit lengths of stay from 2.91 days to 2.22 days and CCU length of stay from 2.06 to 2.04 days had it been used to triage patients with congestive heart failure. This reduction in length of stay would have resulted in 172 more intermediate care unit bed-days available per year to accommodate additional patients. On initial review, at least one cardiologist reviewer judged that use of the guideline may have adversely affected quality of care for 4% (95% CI 1%, 7%) of patients. After a consensus among the cardiologist reviewers, it was judged that the guideline may have adversely affected care for only 0.8% of patients (95% CI, 0%, 2.3%), and that no patient (95% CI 0%, 2.3%) would have had an unexpected life-threatening complication because of the guideline.

CONCLUSIONS

Use of a practice guideline has the potential to reduce the intermediate care unit lengths of stay for selected low-risk patients with congestive heart failure.