Echocardiography and Cardiac Embolic Stroke

Background: Cardiogenic embolism accounts for 15 to 40 % of all ischemic stroke. In general, cardiogenic embolic stroke is a severe case and usually recurrent, treatment and prognosis are different from other strokes. Cardiac embolic strokes need to be diagnosed by imaging tools with evidence of cardiac resources of embolism. Transthoracic Echocardiography and Transesophageal Echocardiography are useful tools for detection of the cardioembolic resources. Cardioembolic strokes may have symptoms and signs (atrial fibrillation, rheumatic heart disease, infective endocarditi) but may not have any symptom and sign even have normal result on transthoracic ehocardiography in some cardioembolic strokes (Patent Foramen Ovale, IAS aneurysm) Purpose: By echocardiography (transthoracic and transesophageal) detection of cardiacembolic resources in suspected cardioembolic stroke patients. Methods: Suspected cardiogenic embolic strokes were refered to our department to perfome echocardiography. All patients were determined cerebral infarction or TIA by neurologist with appropriate results of brain MRI or MSCT. Transthoracic Echocardiography was formerly performed, and Transesophageal Echocardiography followed latter in patients who had negative or unexplained findings on Transthoracic Echocardiography. Results: 63patients (59 strokes and 4 transient ischemic attacks) including 28 men and 35 women, mean age 49 ± 15. Transthoracic Echocardiography was done for all patients, Only 14 cases of Transesophageal Echocardiography were performed (2 cases of left atrial dilation due to intermittent atrial fibrillation, 12 cases of normal result on Transthoracic Echocardiography). In 2 cases with left atrial dilation we found spontaneous contrast in the LA and LAA. In 12 cases of normal result on Transthoracic Echocardiography, there were 9 cases of PFO, 1 case of PFO associated with IAS aneurysm and 2 normal results. Conclusion: Beside major risk cardiogenic sources, echocardiography can detect underlying cardiac lesions of cardioembolic stroke. TTE has been shown to be effective in detecting potential cardiac sources at ventricles. TTE associated with TEE obtain more effectiveness in detection of cardiogenic sources. *Correspondence to: Vu NT, Pham Ngoc Thach University of Medicine, MEDIC HCMC VN, E-mail: tuanvu2401@yahoo.com Received: June 14, 2020; Accepted: June 22, 2020; Published: June 25, 2020 Background Stroke is the second leading cause of death worldwide behind ischemic heart disease, with 5.5 million stroke deaths in 2016 [1]. About 85% case of strokes are due to acute ischemia [2]. In the United States approximately 795 000 peoples experience strokes each year. On average, every 40 seconds a stroke is diagnosed, and every 4 minutes a stroke death occurs [3]. Besides from 24% to 49% stroke survivals have some level of disability [4], the cost of their care is substantial. In south Vietnam, from a stroke data shows the incidence of 161/100.000 and the prevalence of 415/100.000 [5]. Cardioembolic stroke accounts for 15 to 40 % in ischemic stroke [6]. The incidences are different from reports from countries, for example 20% in United State,19% in Australia, 31% in France, 38% in Greece and 17% in Germany [7]. Usually recurrent, treatment and prognosis of cardiacembolic stroke are different from other strokes, it is important to determine whether strokes are due to cardiac source of embolism or not. There are many tools can be used for detecting cardioembolic resources but Echocardiography is the first choice technique that can show comprehensive informations of cardioembolic risk in stroke patients. Purpose Detection of cardiacembolic resources in patients with suspected cardioembolic stroke by echocardiographic techniques (TTE and TEE). Methods 63 patients including 59 strokes and 4 transient ischemic attacks ( TIA ) suspected cardiogenic embolism were refered to our department to perfome Echocardiography. Instrument: Philips X MATRIX iE33 machine with TTE and TEE probes. All patients were determined cerebral infarction or TIA by neurologist and MRI or MDCT imagings. TTE was performed first, TEE was indicated latter in cases of doubtful or negative result on TTE. Results Among 63 studied patients (59 strokes and 4 transient ischemic attacks) patients including 28 men and 35 women, mean age 49 ± 15. TTE was done all of these patients,TEE was indicated in 14 cases ( 2 cases of LA dilation due to intermittent atrial fibrillation, 12 cases with normal result on TTE ). In 2 cases with LA dilation we found spontaneous contrast in the LA and LAA. In 12 cases of normal results on Transthoracic Echocardiography, there were 9 cases of Patent Foramen Ovale, 1 case of PFO associated with IAS aneurysm and 2 cases with normal results (Table 1). Nguyen Tuan Vu (2020) Echocardiography and cardiac embolic stroke Vascul Dis Ther, 2020 doi: 10.15761/VDT.1000180 Volume 5: 2-7 Our study shows the combination of TTE and TEE is useful for finding cardioembolic resources. We avoid performing unnecessary TEE (such as clear apical LV thrombus). The anterior and near structures of the heart may be appropriate for TTE in detecting thromboembolic sources but TEE is the advantage technique of choice in cases of deep thromboembolic origin in the posterior cardiac structures and in the thoracic Aorta (Table 2). Cardioembolic sources also may be detected by TTE in some cases, TEE is performed in patients with unclear results on TTE or get more informations for guiding therapeutic decision. Discussion Because recurrence of strokes, treatment and prognosis of cardiaoembolic strokes are different from other strokes, early diagnosis of stroke from cardiac embolic sources is very important for treatment as well as secondary prevention. In symptomatic patients, ECG and TTE can diagnose cardioembolic stroke. TEE provide usefull informations for treatment like detecting thrombi in LAA prior to cardioversion of AF or percutaneous balloon mitral valvuloplasty in mitral stenosis. In case of asymptomatic patients, TEE is helpful for diagnosis as well as treatment High risk of cardioembolic strokes Atrial Fibrillation: Atrial fibrillation (AF) is the most common cardiac arrhythmia, with prevalence of 1 % in the general population and increasing with age [8]. The incidence of stroke in atrial fibrillation patients is about from 2 to 10.5% per year depending on risk factors [9,10] including LA enlargement [11]. This arrhythmia is the most important resource responsible for 45% of cardioembolic stroke in Western countries [12] but in our data the rate is 25%. TTE evaluates size and function of cardiac chambers, associated cardiac lesions such as valvular heart diseases, pericardial abnormalities. TEE evaluates size and morphology of LAA, velocity of LAA blood flow, identifies and excludes spontaneous contrast and thrombus of LAA and LA. TTE can detect LA thrombus but the sensitivity is low. TEE is the credible technique to detect LA and LAA thrombi, with values of sensitivity and specificity about 99% [13]. In stroke patients due to atrial fibrillation may be no evidence of thrombus in LA or LAA but there is a decrease contractility and function of LAA, manifests as a low velocity of LAA blood flow and dilation of the LAA. In 4 types morphology of LAA (cactus, chicken wing, windsock and cauliflower), patients with non-chicken wing morphology of LAA are significant more likely to have embolic events after adjustment with other risk factors [14]. Rheumatic valvular diseases: Mitral stenosis is majority, stroke often occurs in mitral stenosis patients with atrial fibrillation, LA enlargement, spontaneous contrast, absence or presence of thrombus. Rheumatic heart disease has the highest rate of cardioembolic stroke in our data 37% but only 12.4% in develop countries [15]. Vietnam as well as other developing countries lack of good socioeconomic and environmental conditions in previous decades leading to persistence this disease [16], while almost eradicated in developed countries [17]. TTE identifies the disease. TEE detects spontaneous contrast and thrombi in LA, LAA of patients with mitral stenosis. It is important to decide using anticoagulation before percutaneous balloon mitral valvuloplasty or surgery (Figures 1-8). Left ventricular thrombus: In the context of old myocardial infarction, LV aneurysm, ischemic cardiomyopathy and dilated cardiomyopathy. In our data of 2 cases of LV thrombus including 1 case of old MI and 1 case of ischemic cardiomyopathy. Features of LV thrombus on echocardiography: a mass with dense echogen, defined margin located adjacent endocardium but distinct from endocardium, existing at least in 2 views (Figure 9). Cardiac mass: The two common cardiac tumors causing cardiac embolic stroke are myxoma and papillary fibroelastoma. Myxoma is the most common, located 75% in LA, 20% in RA and 5% in 2 ventricles with equal distribution [18]. Causes of cardioembolic strokes Patients (%) Rheumatic mitral stenosis 23 (37%), in which: 18 cases (78%) with AF and 5 cases (22%) without AF Atrial fibrillation without mitral valvulopathy 16 (25%) Patent Foramen Ovale (PFO) 10 (16%) (9 cases PFO and 1 case PFO with atrial septal aneurysm) Endocarditis 3 (5%) Mitral Valve Prolapse 3 (5%) LV thrombus 2 (3%) LA myxoma 1 (1.5%) Sick sinus sydrome 3 (5%) Normal finding on ultrasound 2 (3%) Table 1. Causes of cardioembolic strokes Thromboembolic sources Detected by TTE Detected by TEE Spontaneous contrast 12 18 LA thrombus 12 15 LAA thrombus 0 20 PFO 3 10 Vegetation 1 3 Myxoma 1 1 LV thrombus 2 Mitral stenosis 22 22 Mitral valve prolapse 3 3 Table 2. TEE in comparison with TTE in detecting cardioembolic sources Figure 1. Mitral stenosis with thrombus of LA; “TTE image from Nguyen Tuan Vu” Nguyen Tuan Vu (2020) Echocardiography and cardiac embolic stroke Vascul Dis Ther, 2020 doi: 10.15761/VDT.1000180 Volume 5: 3-7 Figure 2. LA thrombus on 3 D TEE; “TEE image from Nguyen Tua