Syncope and collapse in acute pulmonary embolism

Sex disparities of clinical manifestations in acute pulmonary embolism and predictive value for in-hospital mortality: Insights from CURES

BACKGROUND

Pulmonary embolism (PE) is a common and potentially fatal disease, with differences in mortality rates among PE patients of different sexes. This study aims to investigate the disparities in clinical manifestations and in-hospital mortality rates between sexes in PE patients, as well as the association of clinical symptoms with in-hospital mortality.

METHODS

We analyzed data from the China pUlmonary thromboembolism REgistry Study (CURES), a nationwide, multicenter, prospective registry focusing on patients with acute PE. Using propensity score matching (PSM) to pair male and female patients with PE, we explored the correlation between clinical symptoms and in-hospital mortality through multivariable regression analysis.

RESULTS

A total of 15,203 patients with acute PE were enrolled, and 380 died during hospitalization. The incidence of chest pain, hemoptysis, and palpitations was significantly higher in males compared to females. The incidence of dyspnea, fever, and syncope was higher in females. Hemoptysis and dyspnea were associated with increased in-hospital mortality in males, whereas dyspnea, fever, and palpitations were linked to higher mortality in females. Overall, males exhibited a higher in-hospital mortality than females (2.9 % vs. 2.1 %, p = 0.002). After matching 13,130 patients using the PSM method, the mortality rate of males remained higher than that of females (2.7 % vs. 2.1 %, p = 0.020).

CONCLUSIONS

Our study demonstrates that male patients with PE have a higher risk of in-hospital mortality than females. Significant differences in clinical symptoms between sexes are associated with increased mortality risk, emphasizing the need for clinical awareness.

Heart Rate Variability Impairment Is Associated with Right Ventricular Overload and Early Mortality Risk in Patients with Acute Pulmonary Embolism

The association between heart rate variability (HRV) and mortality risk of acute pulmonary embolism (APE), as well as its association with right ventricular (RV) overload is not well established. We performed an observational study on consecutive patients with confirmed APE. In the first 48 h after admission, 24 h Holter monitoring with assessment of time-domain HRV, echocardiography and NT-proBNP (N-terminal pro-B-type natriuretic peptide) measurement were performed in all participants. We pre-examined 166 patients: 32 (20%) with low risk of early mortality, 65 (40%) with intermediate-low, 65 (40%) with intermediate-high, and 4 (0.02%) in the high risk category. The last group was excluded from further analysis due to sample size, and finally, 162 patients aged 56.3 ± 18.5 years were examined. We observed significant correlations between HRV parameters and echocardiographic signs of RV overload. SDNN (standard deviation of intervals of all normal beats) correlated with echocardiography-derived RVSP (right ventricular systolic pressure; r = -0.31, p = 0.001), TAPSE (tricuspid annulus plane systolic excursion; r = 0.21, p = 0.033), IVC (inferior vena cava diameter; r = -0.27, p = 0.002) and also with NT-proBNP concentration (r = -0.30, p = 0.004). HRV indices were also associated with APE risk stratification, especially in the low-risk category (r = 0.30, p = 0.004 for SDNN). Univariate and multivariate analyses confirmed that SDNN values were associated with signs of RV overload. In conclusion, we observed a significant association between time-domain HRV parameters and echocardiographic and biochemical signs of RV overload. Impaired HRV parameters were also associated with worse a clinical risk status of APE.

Detection of pulmonary embolism severity using clinical characteristics, hematological indices, and machine learning techniques

INTRODUCTION

Pulmonary embolism (PE) is a cardiopulmonary condition that can be fatal. PE can lead to sudden cardiovascular collapse and is potentially life-threatening, necessitating risk classification to modify therapy following the diagnosis of PE. We collected clinical characteristics, routine blood data, and arterial blood gas analysis data from all 139 patients.

METHODS

Combining these data, this paper proposes a PE risk stratified prediction framework based on machine learning technology. An improved algorithm is proposed by adding sobol sequence and black hole mechanism to the cuckoo search algorithm (CS), called SBCS. Based on the coupling of the enhanced algorithm and the kernel extreme learning machine (KELM), a prediction framework is also proposed.

RESULTS

To confirm the overall performance of SBCS, we run benchmark function experiments in this work. The results demonstrate that SBCS has great convergence accuracy and speed. Then, tests based on seven open data sets are carried out in this study to verify the performance of SBCS on the feature selection problem. To further demonstrate the usefulness and applicability of the SBCS-KELM framework, this paper conducts aided diagnosis experiments on PE data collected from the hospital.

DISCUSSION

The experiment findings show that the indicators chosen, such as syncope, systolic blood pressure (SBP), oxygen saturation (SaO2%), white blood cell (WBC), neutrophil percentage (NEUT%), and others, are crucial for the feature selection approach presented in this study to assess the severity of PE. The classification results reveal that the prediction model's accuracy is 99.26% and its sensitivity is 98.57%. It is expected to become a new and accurate method to distinguish the severity of PE.

Major bleeding in patients with pulmonary embolism presenting with syncope

INTRODUCTION

Syncope has been shown to be a risk factor of bleeding in patients receiving thrombolytic therapy for acute pulmonary embolism (PE). Whether syncope predicts bleeding in a broader population of patients with PE remains unknown.

METHODS

We used the RIETE registry data to assess whether initial presentation with syncope could predict bleeding in PE patients receiving anticoagulant therapy, and to explore the association between presence of syncope and timing and site of major bleeding events.

RESULTS

Among 45,765 patients with acute PE from March 2001 to January 2021, 6760 (14.8%) had syncope. Patients with syncope were older and more likely to have hypotension, tachycardia, hypoxaemia or elevated troponin levels than those without syncope. They also were more likely to receive thrombolytics. During the first 90 days, 1097 patients (2.4%) suffered major bleeding (gastrointestinal 335, hematoma 271 and intracranial 163) and 3611 died (158 had fatal bleeding). Patients with syncope had a higher rate of major bleeding (odds ratio [OR]: 1.63; 95% CI: 1.41-1.89) and a nonsignificantly higher rate of fatal bleeding (OR: 1.47; 95% CI: 0.99-2.17) than those without syncope. Multivariable analysis confirmed that patients with syncope were at increased risk for major bleeding (adjusted hazard ratio [aHR]: 1.34; 95% CI: 1.15-1.55). On sensitivity analysis, the increased risk for major bleeding was confirmed in patients initially receiving anticoagulant therapy without thrombolytics at 7 days (aHR: 1.47; 95% CI: 1.13-1.91) and 90 days (aHR: 1.33; 95%CI: 1.13-1.56).

DISCUSSION

Syncope is a predictor of major bleeding events in patients with PE, even among those receiving anticoagulation monotherapy.

Clinical Phenotypes With Prognostic Implications in Pulmonary Embolism Patients With Syncope

Objectives

There are conflicting data concerning the prognostic significance of syncope in acute pulmonary embolism (PE). This study aimed to investigate the impact of syncope on clinical outcomes of acute PE, and determine the clinical phenotypes of PE patients with syncope and their correlation with prognosis.

Methods

In the ongoing, national, multicenter, registry study, the China pUlmonary thromboembolism REgistry Study (CURES) enrolling consecutive patients with acute PE, patients with and without syncope were investigated. Principal component analysis (PCA) was performed using nine variables relevant to syncope and PE, including age, sex, body mass index, history of cardiovascular disease, recent surgery or trauma, malignancy, pulse, systolic blood pressure, and respiratory rate. Patient classification was performed using cluster analysis based on the PCA-transformed data. The clinical presentation, disease severity and outcomes were compared among the phenotypes.

Results

In 7,438 patients with acute PE, 777 (10.4%) had syncope, with younger age, more females and higher body mass index. Patients with syncope had higher frequency of precordial pain, palpitation, and elevated cardiac biomarkers, as well as higher D-Dimer level. In the syncope group, more patients had right ventricular/left ventricular ratio > 0.9 in ultrasonic cardiogram and these patients had higher estimated pulmonary arterial systolic pressure compared with patients without syncope. As the initial antithrombotic treatment, more patients with syncope received systemic thrombolysis. Despite a higher prevalence of hemodynamic instability (OR 7.626, 95% CI 2.960–19.644, P < 0.001), syncope did not increase in-hospital death. Principal component analysis revealed that four independent components accounted for 60.3% of variance. PE patients with syncope were classified into four phenotypes, in which patients with high pulse and respiratory rate had markedly higher all-cause mortality during admission.

Conclusion

Syncope was associated with hemodynamic instability and more application of thrombolysis, without increasing in-hospital deaths. Different clinical phenotypes existed in PE patients with syncope, which might be caused by various mechanisms and thus correlated with clinical outcomes.

D-Dimer Tests in the Emergency Department: Current Insights

In the Emergency Medicine setting, D-dimer is currently employed in the diagnostic assessment of suspected venous thromboembolism and aortic syndrome. The nonspecific symptoms reported by patients, like chest pain, dyspnea or syncope, uncover a wide range of differential diagnosis, spanning from mild to life-threatening conditions. Therefore, we assumed the perspective of the Emergency Physician and, in this narrative review, we reported a brief presentation of the epidemiology of these symptoms and the characteristics of patients, in whom we could suspect the aforementioned pathologies. We also reported in which patients D-dimer gives useful information. In fact, when the probability of the disease is high, the D-dimer level is futile. On the contrary, given the low specificity of the test, when the probability of the disease is very low, a false-positive value of the D-dimer only increases the risk of overtesting. Patients with low to moderate probability really benefit from the D-dimer testing, in order to prevent the execution of expensive and potentially dangerous imaging tests. In the second part of the review, we focused on the prognostic value of the test in septic patients. The early prognostic stratification of septic patients remains a challenge for the Emergency Physician, in the absence of a definite biomarker or score to rely on. Therefore, we need several parameters for the early identification of patients at risk of an adverse prognosis and the D-dimer may play a role in this demanding task. SARS COVID-19 patients represent an emerging reality, where the role of the D-dimer for prognostic stratification could be relevant. In fact, in patients with severe forms of this disease, the D-dimer reaches very high values, which appear to parallel the course of respiratory failure. Whether the test may add useful information for the management of these patients remains to be determined.

The Prognostic Value of Syncope on Mortality in Patients With Pulmonary Embolism: A Systematic Review and Meta-analysis

STUDY OBJECTIVE

Syncope is a presenting symptom in 10% to 20% of patients with pulmonary embolism. We perform a meta-analysis to clarify the prognostic value of syncope on short-term mortality in pulmonary embolism patients and its association with hemodynamic instability.

METHODS

PubMed, EMBASE, and the Cochrane Library were searched up until January 7, 2020. Studies reporting inhospital or 30-day mortality of adults with pulmonary embolism with and without syncope were included. Quality of included studies was evaluated with the Quality in Prognosis Studies tool. Meta-analysis was conducted to derive pooled odds ratios (ORs) and risk differences for the relation of syncope with mortality and hemodynamic instability. To study the influence of hemodynamic instability on the association between syncope and mortality, meta-regression was performed.

RESULTS

Search and selection resulted in 26 studies, of which 20 were pooled, involving 9,419 of 335,120 patients (3%) with syncope. Syncope was associated with higher mortality (OR 1.82; 95% confidence interval [CI] 1.14 to 2.90; I2 88%; risk difference 4% [95% CI 1% to 8%]) and higher prevalence of hemodynamic instability (OR 4.36; 95% CI 2.27 to 8.37; I2 93%; risk difference 12% [95% CI 7% to 18%]). OR for mortality in patients with pulmonary embolism with syncope versus without it was higher in the presence of a larger difference in hemodynamic instability between groups (coefficient 0.05; 95% CI 0.01 to 0.09).

CONCLUSION

The association between syncope and short-term mortality in patients with pulmonary embolism is explained by a difference in hemodynamic instability. This emphasizes the importance of risk stratification by hemodynamic status in pulmonary embolism patients with and without syncope.

Presyncope Is Associated with Intensive Care Unit Admission in Emergency Department Patients with Acute Pulmonary Embolism

INTRODUCTION

Syncope is common among emergency department (ED) patients with acute pulmonary embolism (PE) and indicates a higher acuity and worse prognosis than in patients without syncope. Whether presyncope carries the same prognostic implications has not been established. We compared incidence of intensive care unit (ICU) admission in three groups of ED PE patients: those with presyncope; syncope; and neither.

METHODS

This retrospective cohort study included all adults with acute, objectively confirmed PE in 21 community EDs from January 2013-April 2015. We combined electronic health record extraction with manual chart abstraction. We used chi-square test for univariate comparisons and performed multivariate analysis to evaluate associations between presyncope or syncope and ICU admission from the ED, reported as adjusted odds ratios (aOR) with 95% confidence intervals (CI).

RESULTS

Among 2996 PE patients, 82 (2.7%) had presyncope and 109 (3.6%) had syncope. ICU admission was similar between groups (presyncope 18.3% vs syncope 25.7%) and different than their non-syncope counterparts (either 22.5% vs neither 4.7%; p<0.0001). On multivariate analysis, both presyncope and syncope were independently associated with ICU admission, controlling for demographics, higher-risk PE Severity Index (PESI) class, ventilatory support, proximal clot location, and submassive and massive PE classification: presyncope, aOR 2.79 (95% CI, 1.40, 5.56); syncope, aOR 4.44 (95% CI 2.52, 7.80). These associations were only minimally affected when excluding massive PE from the model. There was no significant interaction between either syncope or presyncope and PESI, submassive or massive classification in predicting ICU admission.

CONCLUSION

Presyncope appears to carry similar strength of association with ICU admission as syncope in ED patients with acute PE. If this is confirmed, clinicians evaluating patients with acute PE may benefit from including presyncope in their calculus of risk assessment and site-of-care decision-making.

Differential impact of syncope on the prognosis of patients with acute pulmonary embolism: a systematic review and meta-analysis

Aims

Controversial reports exist in the literature regarding the prognostic role and therapeutic implications of syncope in patients with acute pulmonary embolism (PE). We conducted a systematic review and meta-analysis to investigate the association between syncope and short-term adverse outcomes, taking into account the presence or absence of haemodynamic compromise at acute PE presentation.

Methods and results

The literature search identified 1664 studies, 29 of which were included for a total of 21 956 patients with PE (n = 3706 with syncope). Syncope was associated with higher prevalence of haemodynamic instability [odds ratio (OR) 3.50; 95% confidence interval (CI) 2.67-4.58], as well as with echocardiographic signs of right ventricular (RV) dysfunction (OR 2.10; CI 1.60-2.77) at presentation. Patients with syncope had a higher risks of all-cause early (either in-hospital or within 30 days) death (OR 1.73; CI 1.22-2.47) and PE-related 30-day adverse outcomes (OR 2.00; CI 1.11-3.60). The absolute risk difference (95% CI) for all-cause death was +6% (+1% to +10%) in studies including unselected patients, but it was -1% (-2% to +1%) in studies restricted to normotensive patients. We observed no prognostic impact of syncope in studies with a lower score at formal quality assessment and in those conducted retrospectively.

Conclusion

Syncope as a manifestation of acute PE was associated with a higher prevalence of haemodynamic instability and RV dysfunction at presentation, and an elevated risk for early PE-related adverse outcomes. The association with an increased risk of early death appeared more prominent in studies including unselected patients, when compared with those focusing on normotensive patients only.

Prevalence and Predictors of Pulmonary Embolism in Hospitalized Patients with Syncope

OBJECTIVES

Approximately one in six patients hospitalized with syncope have pulmonary embolism (PE), according to the PE in Syncope Italian Trial study. Subsequent studies using administrative data have reported a PE prevalence of <3%. The aim of the study was to determine the prevalence and predictors of PE in hospitalized patients with syncope.

METHODS

We retrospectively reviewed the records of patients who were hospitalized in the MedStar Washington Hospital Center between May 1, 2015 and June 30, 2017 with deep venous thrombosis, PE, and syncope. Only patients who presented to the emergency department with syncope were included in the final analysis. PE was diagnosed by either positive computed tomographic angiography or a high-probability ventilation-perfusion scan. Univariate and multivariate logistic regressions were used to assess the associations between clinical variables and the diagnosis of PE in patients with syncope.

RESULTS

Of the 408 patients hospitalized with syncope (mean age, 67.5 years; 51% men [N = 208]), 25 (6%) had a diagnosis of PE. Elevated troponin levels (odds ratio 6.6, 95% confidence interval 1.9-22.9) and a dilated right ventricle on echocardiogram (odds ratio 6.9, 95% confidence interval 2.0-23.6) were independently associated with the diagnosis of PE. Age, active cancer, and history of deep venous thrombosis were not associated with the diagnosis of PE.

CONCLUSIONS

The prevalence of PE in this study is approximately one-third of the reported prevalence in the PE in Syncope Italian Trial study and almost three times the value reported in administrative data-based studies. PE should be suspected in patients with syncope and elevated troponin levels or a dilated right ventricle on echocardiogram.

Pearls and Myths in the Evaluation of Patients with Suspected Acute Pulmonary Embolism

Significant improvement has been achieved in diagnostic accuracy, validation of probability scores, and standardized treatment algorithms for patients with suspected acute pulmonary embolism. These developments have provided the tools for a safe and cost-effective management for most of these patients. In our experience, however, the presence of medical myths and ongoing controversies seem to hinder the implementation of these tools in everyday clinical practice. This review provides a selection of such dilemmas and controversies and discusses the published evidence beyond them. By doing so, we try to overcome these dilemmas and suggest pragmatic approaches guided by the available evidence and current guidelines.

Acute Pulmonary Embolism Presenting with Symptomatic Bradycardia: A Case Report and Review of the Literature

BACKGROUND Acute pulmonary embolism (PE) is a common life-threatening cardiovascular emergency. The diagnosis of PE may be challenging, as there can be a wide range of atypical presentations. CASE REPORT A 92-year-old man with asymptomatic first-degree atrioventricular (AV) block, hypertension that was controlled on medication, and a past medical history of deep venous thrombosis (DVT), presented with dizziness, weakness, and collapse while getting dressed. On examination by the attending paramedics, he was noted to have sinus bradycardia at a rate of 18 bpm, which improved to 80 bpm after intravenous injection of atropine. An echocardiogram obtained in the emergency room (ER) showed a markedly dilated right ventricle (RV) with a hypokinetic RV free wall, preserved RV apical contractility, and septal wall motion abnormalities consistent with RV pressure overload. A ventilation/perfusion (V/Q) scan showed a massive PE involving more than 50% of the pulmonary vasculature. Urgent catheter-directed thrombolysis was performed, but the patient's condition deteriorated, and he died shortly afterward. CONCLUSIONS Sinus bradycardia is an unusual initial presentation of PE, but the diagnosis should be considered in patients with multiple risk factors for thromboembolism.

Syncope in the German Nationwide inpatient sample - Syncope in atrial fibrillation/flutter is related to pulmonary embolism and is accompanied by higher in-hospital mortality

AIMS

Syncope is a common phenomenon in the general population. Although most of the causes are of benign origin, some comorbidities are accompanied by high mortality. We aimed to compare the in-hospital mortality of patients with syncope related to different comorbities and investigate the impact of syncope in patients with atrial fibrillation/flutter (AF).

METHODS

The nationwide inpatient sample of Germany of the years 2011-2014 was used for this analysis. Patients with syncope (ICD-code R55) were stratified by presence of selected comorbidities. Additionally, AF patients with and without syncope were compared. Incidence of syncope and in-hospital mortality were calculated. Syncope as a predictor of adverse outcome in AF patients was investigated.

RESULTS

In total, 1,628,859 hospitalizations of patients with syncope were identified; incidence was 504.6/100,000 citizens/year with case-fatality rate of 1.6%. Patients with syncope revealed frequently comorbidities as AF, heart failure and pneumonia. In-hospital mortality was high in syncope patients with pulmonary embolism (PE, 13.0%), pneumonia (12.8%), myocardial infarction (MI, 9.7%) and stroke (8.5%). We analysed 1,106,019 hospitalizations (52.9% females, 54.9% aged > 70 years) of patients with AF (2011-2014). Among these, 23,694 (2.1%) were coded with syncope and 0.7% died. Syncope had no significant impact on in-hospital mortality (OR 1.04, 95%CI 0.92-1.17, P = .503) independently of age, sex and comorbidities, but was associated with PE (OR 1.83, 95%CI 1.42-2.36, P < .001), MI (OR 1.68, 95%CI 1.48-1.90, P < .001), stroke (OR 1.66, 95%CI 1.42-1.94, P < .001) and pneumonia (OR 1.26, 95%CI 1.16-1.37, P < .001).

CONCLUSIONS

Syncope is a frequent cause for referrals in hospitals. While the overall in-hospital mortality rate is low (<2%), syncope in coprevalence with PE, pneumonia, MI and stroke showed a mortality rate > 8%. Syncope in AF patients had no independent impact on in-hospital mortality.

Syncope in haemodynamically stable and unstable patients with acute pulmonary embolism - Results of the German nationwide inpatient sample

Syncope in pulmonary embolism (PE) could be the first sign of haemodynamic compromise. We aimed to investigate pathomechanisms of syncope and its impact on mortality. For this study, patients (aged ≥ 18years) were selected by screening the German nationwide inpatient sample for PE and stratified included patients by syncope (2011–2014). We analysed predictors of syncope in haemodynamically stable PE. Impact of syncope on in-hospital mortality in haemodynamically stable and unstable PE and benefit of systemic thrombolysis in haemodynamically stable PE with syncope (PE + Syncope) were analyzed. The German nationwide inpatient sample comprised 293,640 (84.9%) haemodynamically stable and 52,249 (15.1%) unstable PE patients; among them 2.3% had syncope. Right ventricular dysfunction (RVD) was a key predictor for syncope. In-hospital mortality-rate was lower in haemodynamically stable (6.4% vs. 7.6%, P < 0.001) and unstable PE + Syncope than in PE−Syncope (48.4% vs. 55.5%, P < 0.001) with reduced risk for in-hospital death in stable (OR 0.68 (95%CI 0.61–0.75), P < 0.001) and unstable (OR 0.69 (95% CI 0.62–0.78), P < 0.001) inpatients independent of age and sex. Haemodynamically stable PE + Syncope patients were more often treated with systemic thrombolysis (3.1% vs. 2.1%, P < 0.001). Systemic thrombolysis was associated with reduced in-hospital mortality in haemodynamically stable PE + Syncope (1.9% vs. 6.6%, P = 0.004) independently of age, RVD and tachycardia (OR 0.30 (95%CI 0.11–0.82), P = 0.019). In conclusion, in-hospital mortality was 6.4% in haemodynamically stable PE + Syncope. Haemodynamically stable PE + Syncope patients were more often treated with systemic thrombolysis and showed a trend to improved survial.

Impact of syncope and pre-syncope on short-term mortality in patients with acute pulmonary embolism

BACKGROUND

Syncope and pre-syncope are well-known symptoms of acute pulmonary embolism (PE). However, data about their impact on short-term mortality are scant. We assess the short-term mortality (30-day) for all-causes in PE patients admitted with syncope or with pre-syncope, according their hemodynamic status at admission.

METHODS

Patients from the prospective Italian Pulmonary Embolism Registry (IPER) were included in the study. At admission, subjects were stratified according to 2008 ESC guidelines (as high- and non-high-risk patients).

RESULTS

Among the 1716 patients with confirmed acute PE, syncope or pre-syncope was the initial manifestation of the disease in 458 (26.6%) patients. Short-term mortality (30-day) for all causes were significantly higher in patients with syncope/presyncope (42.5% vs 6.2%, p < 0.0001) while PE patients with presyncope demonstrated a worst short-term outcome, in terms of mortality for all-causes, when compared to those subjects with syncope at admission (47.2% vs 37.4%, p = 0.03). A statistically significant difference in survival between pre-syncope and syncope was observed only in hemodynamically unstable patients [log rank p = 0.036]. Cox regression analysis confirmed that pre-syncope resulted an independent predictor of 30-day mortality in hemodynamically unstable patients at admission (HR 2.13, 95% CI 1.08-4.22, p = 0.029), independently from right ventricular dysfunction (RVD) (HR 6.23, 95% CI 3.05-12.71, p < 0.0001), age (HR 1.03, 95% CI 1.00-1.06, p = 0.023) and thrombolysis (HR 2.27, 95% CI 1.11-4.66, p = 0.025).

CONCLUSIONS

PE patients with syncope/presyncope had a higher 30-day mortality for all-causes as well as patients with presyncope had a worst short-term outcome when compared to PE patients with syncope. Moreover, hemodynamically unstable patients with presyncope had a worst prognosis independently from the presence of RVD, age, positive cTn and thrombolytic treatment.

Adenosine 5'-triphosphate's role in bradycardia and syncope associated with pulmonary embolism

Adenosine 5′-triphiosphate (ATP) is released from cells under physiologic and pathophysiologic conditions. Extracellular ATP acts as an autocrine and paracrine agent affecting various cell types by activating cell surface P2 receptors (P2R), which include trans-cell membrane cationic channels, P2XR, and G protein coupled receptors, P2YR. We have previously shown that ATP stimulates vagal afferent nerve terminals in the lungs by activating P2X2/3R. This action could lead to bronchoconstriction, cough and the local release of pro-inflammatory neuropeptides. In addition, ATP markedly enhances the IgE-dependent histamine release from human lung mast cells. Thus, we have proposed for the first time that extracellular ATP plays a mechanistic role in pulmonary pathophysiology in general and chronic obstructive pulmonary disease (COPD), and acute bronchoconstriction in asthma in particular. The present review examines whether ATP could also play a role in bradycardia and syncope in a subset of patients with pulmonary embolism.

Clinical Presentation and Risk Factors of Venous Thromboembolic Disease

Venous thromboembolism (VTE) has a wide range of clinical presentations. Deep venous thrombosis may occur in upper or lower extremities or in visceral veins. Extremity deep venous thrombosis usually manifests with unilateral painful swelling in the limb, while visceral deep venous thrombosis manifestations vary on the basis of the involved organ. Pulmonary embolism classically manifests with sudden pleuritic chest pain and unexplained dyspnea. Superficial thrombophlebitis usually presents with acute inflammation around a palpable thrombosed superficial vein. Risk factors of VTE are either inherited or acquired. The inherited causes of VTE tend to be familial and more common in younger patients. The common acquired risk factors of VTE include previous history of venous thrombosis, immobilization, recent surgery or trauma, malignancy, and pregnancy. Identifying high-risk patients for VTE based on these risk factors is the cornerstone to provide the prophylactic treatment to prevent thrombotic events.

Prevalence of Pulmonary Embolism among Patients Hospitalized for Syncope

BACKGROUND

The prevalence of pulmonary embolism among patients hospitalized for syncope is not well documented, and current guidelines pay little attention to a diagnostic workup for pulmonary embolism in these patients.

METHODS

We performed a systematic workup for pulmonary embolism in patients admitted to 11 hospitals in Italy for a first episode of syncope, regardless of whether there were alternative explanations for the syncope. The diagnosis of pulmonary embolism was ruled out in patients who had a low pretest clinical probability, which was defined according to the Wells score, in combination with a negative d-dimer assay. In all other patients, computed tomographic pulmonary angiography or ventilation-perfusion lung scanning was performed.

RESULTS

A total of 560 patients (mean age, 76 years) were included in the study. A diagnosis of pulmonary embolism was ruled out in 330 of the 560 patients (58.9%) on the basis of the combination of a low pretest clinical probability of pulmonary embolism and negative d-dimer assay. Among the remaining 230 patients, pulmonary embolism was identified in 97 (42.2%). In the entire cohort, the prevalence of pulmonary embolism was 17.3% (95% confidence interval, 14.2 to 20.5). Evidence of an embolus in a main pulmonary or lobar artery or evidence of perfusion defects larger than 25% of the total area of both lungs was found in 61 patients. Pulmonary embolism was identified in 45 of the 355 patients (12.7%) who had an alternative explanation for syncope and in 52 of the 205 patients (25.4%) who did not.

CONCLUSIONS

Pulmonary embolism was identified in nearly one of every six patients hospitalized for a first episode of syncope. (Funded by the University of Padua; PESIT ClinicalTrials.gov number, NCT01797289 .).