Cardiac thrombus in acute ischemic stroke: impact on endovascular thrombectomy utilization

Abstract

Cardiac embolism plays a very significant role in acute ischemic strokes (AIS), constituting approximately one-third of cases. The origin of these emboli often stems from intracardiac thrombi in the left atrium or left ventricle. Utilizing the National Readmission Database from 2016 to 2019, we investigate the prevalence of cardiac thrombi in AIS patients and explore their potential correlation with endovascular thrombectomy (EVT) utilization, and mortality rates. Among 1,272,456 AIS patients, 0.6% had concurrent cardiac thrombus, with an increasing trend observed over the study period (P value < 0.001). The cardiac thrombus cohort showed a higher prevalence of comorbidities such as congestive heart failure and atrial fibrillation. After propensity-score matching, groups were well-balanced in terms of baseline characteristics. Patients within the cardiac thrombus cohort experienced a longer hospital stay (median 5 days vs. 3 days), but no significant difference in mortality was noted. Importantly, the cardiac thrombus cohort demonstrated a higher frequency of EVT utilization, suggesting a link to larger vessel occlusions. Despite matching based on atrial fibrillation, the EVT utilization in the cardiac thrombus cohort remained high, highlighting a significant association. While 30-day readmission rates were comparable, cardiac thrombus patients faced a higher risk of gastrointestinal bleeding and hemorrhagic stroke, likely attributed to anticoagulation use. Limitations include potential miscoding in the administrative database and a lack of detailed imaging findings. In conclusion, this study highlights the increased likelihood of EVT in AIS patients with cardiac thrombus, possibly indicative of larger vessel occlusion associated with cardiac thrombus.

Introduction

Cardiac embolism plays a significant role in the occurrence of acute ischemic stroke (AIS), accounting for roughly one-third of cases [1]. These emboli can be from intracardiac thrombi, which may develop within the left atrium or left ventricle. Left atrial thrombi can originate from the primary left atrium or the atrial appendage, often associated with atrial fibrillation [2]. On the other hand, left ventricular thrombi typically occur following acute myocardial infarction or in patients with a reduced ejection fraction [3]. Atrial fibrillation has been shown to be associated with large strokes requiring endovascular thrombectomy (EVT) [4]. There is limited data regarding the prevalence of cardiac thrombi among AIS patients and its potential association with and the likelihood of requiring EVT. This study seeks to address this knowledge gap by investigating the prevalence of cardiac thrombi in AIS patients and determining whether their presence is indicative of increased utilization of EVT and elevated mortality rates.

Methods

We used the National Readmission Database (NRD) to identify patients who were hospitalized for AIS and had a concurrent cardiac thrombus between 2016 and 2019. The NRD, a publicly accessible database developed by the Agency for Healthcare Research and Quality (AHRQ) as part of the Healthcare Cost and Utilization Project (HCUP) [5]. We used the International Classification of Diseases Tenth Revisions ICD-10) codes for AIS (I63) and cardiac thrombus (I513 and I236). Patients were stratified according to the presence of concurrent cardiac thrombus into two groups: AIS with cardiac thrombus and without cardiac thrombus. An unadjusted analysis was performed to compare baseline characteristics between both groups. Our main objectives were to examine the prevalence of cardiac thrombus in patients hospitalized for AIS and utilization of EVT, as well as to assess mortality and the readmission rate within 30 days. To calculate the 30-day readmission, we excluded patients who died during index hospitalization and those admitted in the month of December.

To account for the non-random selection of patients with inherent differences in characteristics, we matched patients by creating a propensity score using the relevant variables as independent variables. A P-value of < 0.05 was considered statistically significant. We used R (4.3.2) to run the statistical analysis for this study.

Results

A total of 1,272,456 patients with acute ischemic stroke were identified during our study period, of whom 7545 (0.6%) had cardiac thrombus. The median age (IQR) was 64 years (54,74) for the cardiac thrombus group and 69 years (58,79) for patients without cardiac thrombus. Baseline comorbidities such as congestive heart failure (CHF) (57% vs. 16%, p < 0.001), coronary artery disease (54% vs. 27%, p < 0.001), non-ischemic cardiomyopathy (20% vs. 3.2%, p < 0.001), and atrial fibrillation/flutter (35 vs. 22%, p < 0.001) more prevalent in the cardiac thrombus group Table 1.

Table 1 Baseline characteristics of the study groups

After propensity-score matching, both groups were well-balanced in terms of baseline characteristics (Table 2).

Table 2 Baseline characteristics of matched cohort

There was an uptrend of cardiac thrombus prevalence from 0.4% in 2016 (1,093 cases) to 0.7% (2,566 cases) during the study period (P value < 0.001) (Fig. 1).

Fig. 1

Trends in the prevalence of concurrent cardiac thrombus and acute ischemic

The median length of hospital stay (LOS) for patients with cardiac thrombus was 5 days, whereas it was 3 days for patients without cardiac thrombus (p < 0.001 as shown in the table. There was no significant difference in inpatient mortality for index hospitalization between patients with or without cardiac thrombus.

In the matched cohort, there was a higher frequency of advanced interventions, such as EVT (5.6% vs. 3.9%, p = 0.004), in the group with cardiac thrombus, while there was no difference in the utilization of tissue plasminogen activator (TPA) or both TPA and EVT between the two groups. The rate of 30-day readmission did not differ between patients with and without cardiac thrombus. However, patients with cardiac thrombus exhibited a higher risk of gastrointestinal bleeding and hemorrhagic stroke, likely attributable to the use of anticoagulation in this group (Table 3).

Table 3 In-hospital outcome in patients with AIS and intracardiac thrombus (Matched-Cohort)

Discussion

To the best of our knowledge, this study represents the first population-based investigation into the relationship between cardiac thrombus and EVT in AIS patients. Our findings reveal that AIS patients with concurrent cardiac thrombus are more likely to undergo EVT. Interestingly, we observed no significant difference in inpatient mortality rates between patients with and without cardiac thrombus. While 30-day readmission rates were comparable between the two groups, patients with cardiac thrombus showed a higher propensity for readmission due to hemorrhagic stroke and gastrointestinal bleeding.

Our findings indicate a higher rate of EVT usage among patients with cardiac thrombus, suggesting this group may be more prone to large vessel occlusions that require advanced interventional techniques. While previous research has linked atrial fibrillation to large vessel occlusions and increased EVT use [4], our study’s results are particularly noteworthy. Even after propensity matching for atrial fibrillation, we observed higher EVT utilization in the cardiac thrombus group. This implies that cardiac thrombus itself may be independently associated with large vessel occlusions, thus necessitating EVT. Our study showed a growing prevalence of cardiac thrombus in AIS patients from 2016 to 2019. This uptrend can be attributed to advancements in diagnostic imaging, particularly the increased utilization of cardiac magnetic resonance imaging (CMR) which enhances the detection of intracardiac thrombi [6]. Another study has showed that one in every 12 patients with AIS had cardiac thrombus detected on cardiac tomography (CT) and that had worse functional outcome [7]. This is likely a call for further investigation if more advanced imagine like CT or CMR will be beneficial for patient with AIS to detect cardiac thrombus and potentially affect management.

Our analysis revealed no significant disparity in in-hospital mortality between AIS patients with and without cardiac thrombus. However, we observed a notably higher 30-day readmission rate for hemorrhagic stroke and gastrointestinal bleeding in the cardiac thrombus group. These complications are likely attributable to anticoagulation therapy. Moreover, these patients may have been on dual antiplatelet therapy or even triple antithrombotic regimens if they had undergone percutaneous coronary intervention, which has been shown in previous studies to further elevate the risk of major bleeding events [8].

Limitations

The results of this study should be interpreted in the context of several limitations. NRD is an administrative database that has the potential for miscoding. However, it is pertinent to mention here that NRD has a robust quality control program that minimizes such miscoding. The available data lacks imaging findings (echocardiography, CMR, CT) and details on cardiac thrombus size, all of which could impact clinical outcomes. The NRD also doesn’t capture out-of-hospital mortality rates.

Conclusion

This study reveals that AIS patients with concurrent cardiac thrombus were more likely to undergo endovascular thrombectomy, possibly due to larger stroke size. An increased prevalence of cardiac thrombus in AIS hospitalizations was observed, potentially attributable to improved coding and increased cardiac CMR usage. While overall 30-day readmission rates were similar, patients with cardiac thrombus showed higher readmission rates for gastrointestinal bleeding and hemorrhagic stroke. Future research should focus on prospective studies to assess the impact of early cardiac thrombus detection on stroke management and outcomes. Investigation into optimal anticoagulation strategies and the mechanisms underlying increased bleeding risks in this population is also warranted. These efforts could inform targeted prevention strategies and improve clinical practice.