Transient ischemic attacks: a single institutional experience

Introduction

A transient ischemic attack is a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarction.[1] The incidence of TIA, for example, in the United States, has been estimated to be about 200 000-500 000 per year, with a population prevalence of 2.3% that translates into 5 million individuals.[2,3]Thus, the actual prevalence of this condition may be considerably larger.[4] There are an estimated 800,000 acute completed ischemic strokes per year in the United States, and it is estimated that 15-30% are preceded by a transient ischemic attack.[5,6] The Cardiovascular Health Study estimated a prevalence of TIA in men of 2.7% for 65-69 years of age and 3.6% for 75-79 years of age, while for women, TIA prevalence was 1.6% for 65-69 years of age and 4.1% for 75-79 years of age. In the younger Atherosclerosis Risk in Communities cohort study, the overall prevalence of TIAs was found to be 0.4% among adults 45-64 years of age.[1] TIA reduces survival by 4% in the first year and by 20% within 9 years.[6]

Patients and methods:

This cross-sectional observational study was conducted from December 1, 2018, to October 31, 2019. Eighty patients, who developed TIAs and who had attended the Rizgary Teaching Hospital’s emergency department and its neurology outpatients’ clinic at Erbil, Iraq, were enrolled consecutively. Sixty males and 20 females, aging from 27-83 years were the patients.

A detailed history was taken from the patients, their caregivers, or next of kin and thorough physical and neurological examinations were carried out by neurologists and neurology trainees. All patients underwent an extensive battery of investigations: complete blood counts, ESR, blood sugar, urea and electrolytes, serum lipids, liver functions, serum TSH, 12-lead ECG, transthoracic echocardiography, and carotid Doppler ultrasound. Investigations for connective tissue diseases and thrombophilia were done in young patients (

All patients were treated acutely with aspirin 300 mg (if the patient was not on aspirin or other antiplatelet). Patients who were already taking aspirin were treated with clopidogrel (300 mg followed 75 mg per day).  Patients with atrial fibrillation and those with antiplatelet failure were acutely anticoagulated with heparin followed by warfarin. Patients who were hypertensive or diabetic were treated accordingly. All patients received a statin before their hospital discharge. Patients who had demonstrated acute ischemic lesions on the DWI sequences underwent another brain MRI with DWI after 2 months.

The data were analyzed by an independent statistician using Statistical Package for Social Sciences version 19.0. The Chi-square test of association was used to compare proportions. Fisher’s exact test was used in the analysis of contingency tables. The Student’s t-test was used to compare the means values of the two groups. The Binary logistic regression analysis was used when values were dependent variables in both groups, and factors that were significantly associated (via Chi-square) with stroke were entered as independent variables into the model. A P-value of ≤ 0.05 was considered statistically significant.

Results:

Out of 80 patients, there was male predominance with a male to female ratio of 3:1 (60 males and 20 females), with an age ranging from 27-83 years, (mean age was 56.63 ±SD of 11.63years). Peak age in male patients was in sixth decade while in female patients was in fifth decade. Table 1 shows the age and gender distribution in TIA patients.

            Table 1: Age and gender of the TIA patients (n=80).

TIA symptoms were as follows: unilateral weakness in 31 patients, followed by unilateral sensory deficit in 25 patients, speech difficulty (dysphasia or dysarthria) in 11 patients, vertigo in 10 patients, and facial paresthesia in 2 patients. The least common symptom was amaurosis fugax (one patient, as shown in table 2). The mean duration of symptoms was 42.66 minutes (ranging from 3 minutes to 4 hours).

               Table 2: Frequency of symptoms in TIA patients (n=80).

During routine cardiovascular system examination, we found that out of 80 patients, 3 patients (3.75%) had carotid bruit (table3). At presentation, 64 patients had no neurological signs on examination, 10 patients had unilateral pyramidal weakness, 3 patients had speech problem (dysphasia or dysarthria), 2 patients had unilateral sensory impairment, and one patient had nystagmus.

    Table 3: Neurological signs in TIA patients (n=80).

No patient had an ABCD2 score of zero. Many patients (23 ones) had a score of 2. Figure 1 shows the ABCD2 score of TIA patients.

        Figure 2: ABCD2 score of TIA patients

Among 80 patients, 43 (53.75%) patients were hypertensive, 9 patients were on regular antihypertensive drugs, 4 patients were on diet control, others were irregularly taking treatment, 24 (30%) patients were diabetic, only 3 of them on regular treatment, 23 (28.75%) patients were smoker, ranging from 15-60 cigarettes/day. Fourteen (17.5%) patients had hyperlipidemia, 13 (16.25%) had history of TIA, 12 (15%) patients had history of ischemic heart disease, 5 (6.25%) had previous stroke, 3 (3.75%) patients had AF, family history of TIA was positive in 2 (2.5%) patients aging 27, 28 years respectively, and one (1.25%) patient had dilated cardiomyopathy whose age was 28 years (table 4).

                   Table 4: Risk factors of TIA.

The mean random blood sugar was 139.14mg/dl, ranging from 70-410 mg/dl. The mean total serum cholesterol level was 137.3 mg/dl, ranging from 70-420 mg/dl. The mean serum triglyceride level was 149 mg/dl, ranging from 30-610mg/dl. Resting ECG abnormalities were found in 16 patients in the form of left ventricular hypertrophy, ischemic heart disease, atrial fibrillation, and left bundle brunch block, as shown in table 5.

               Table 5: Resting 12-lead ECG findings in the TIA patients (n=80).

Echocardiographic abnormalities were seen in 34 (42.5%) patients in the form of hypertensive heart disease, ischemic heart disease (IHD), left ventricular hypertrophy, and dilated cardiomyopathy, as shown in table 2.6.

               Table 6: Transthoracic echocardiographic findings in the TIA patients (n=80).

Carotid Doppler studies showed right-sided internal carotid artery stenosis in 3 patients of 20%, 46%, 65% respectively, and left-side internal carotid artery stenosis in 2 patients (which were 50% and 70% respectively). In 3 patients, the carotid stenosis was symptomatic and in 2 patients it was asymptomatic. Table 7 shows the frequency of internal carotid artery stenosis in TIA patients.

Table 7: Frequency of internal carotid artery stenosis by Doppler ultrasonography (n=80).

The results of brain CT scan of 5 participants showed old infarction as they had previous history of stroke, otherwise all CT scans were normal, while DWI of the brain revealed ischemic lesions in 25 patients, in 5 patients the ischemic lesions were irrelevant to the clinical symptoms (old infarction), in the other 20 patients the ischemic lesions were relevant to the clinical symptoms, after two months, the follow up DWI was done for those patients, there were resolution of the ischemic lesions in 15 patients while in 5 patients the ischemic lesions persisted, they regarded as infarction and already excluded from the study. Conventional MRI showed ischemic lesions in 10 patients (5 patients with previous stroke and 5 patients were regarded as infarction).

Table 8: Brain imaging findings in the TIA patients (n=80).

Thirteen patients were already on aspirin, 6 patients with previous IHD (100 mg par day), 4 patients with previous TIA (300 mg per day) and 3 patients with previous stroke (300 mg per day), one of a previously stroke patient was on clopidogrel 75 mg per day, 3 patients (1 IHD and 2 TIAs) were on a daily dual antiplatelets of aspirin 100 mg and clopidogrel 75mg, and 2 patients were on warfarin 3 mg per day, one of them with a history of 5 strokes and the other was IHD. Those patients who were on aspirin, their treatment changed to clopidogrel 75mg per day , those patients who were on clopidogrel 75 mg, a combination of aspirin and clopidogrel and who had atrial fibrillation were anticoagulated with heparin and warfarin, and those received warfarin 3 per day mg the dose had been increased to 5 mg per day according to international normalized ratio (table 9).

Table 9: Treatments of TIA patients

After 2 days of follow up we found that 2 cases of TIA developed stroke who were male patients aged 50, 63 years respectively, one with rapid AF who refused to be admitted to the hospital and he didn’t receive treatment, the other was with ABCD2 score of 7. Within 1-3 months, only 22 patients came back for follow up and there were no stroke or recurrent TIA in those patients.

Discussion:

In this study we found that, mean age of TIA patients in our locality was 56.63±11.63years which is less than the mean age of other localities, possibly due to low mean age of people in our population, or may be due low health education regarding diet, lack of exercise, and noncompliance to the drugs that are given for controlling of risk factors. Kleindorfer et al 2005 and Inoue et al 2004 found that aging is a risk factor for TIA (>60years).^[7,8]

Men had a significant higher incidence of TIA when compared with women; this is consistent with previously published studies by Kleindorfer et al 2005 and Calvet et al 2007.^[7,9] Hemiparesis was the most common presenting symptom, this is comparable with previous study by Inoue et al 2004,^[39]the mean duration of symptoms was 42.66 minutes, in 66 patients the duration of symptoms was less than one hour this is consistent with previously published study by Calvet et al 2007.^[9]

The most common risk factor was hypertension, this agrees with other studies by Inoue et al 2004, Sheehan et al 2010, Hill et al 2004 and Lisabeth et al 2004,^[8,10-12] other risk factors like smoking (28.8%), IHD (15%), were near to the results of previously published studies by Inoue et al 2004 and Tsivgoulis et al 2006.^[8,13]  Twenty four (30%) patients were diabetic, which is similar to that of Purroy et al 2007,^[14] hyperlipidemia was found in 14 (17.5%) patients, this is near to 19.2% by Kimura et al 2004 and Cucchiara et al 2006.^[15,16]

There was previous TIA in 16.25% patients, in a study by Hankey 2003^[17] he found that the risk of recurrent TIA within one year is about 12%, in our patients the rate is more than that which could be due to ignorance of the treatments, lack of exercise or unhealthy dietary program. In this study the frequency of patients with AF was 3.75%, in a previous publication by Lavallee et al 2007^[18] had found that 5% of TIA is due to AF. In this study we found that 6.25% TIA due to carotid stenosis.^[19] In a previously published study by Poisson et al 2010 found that 10% of TIA is due to carotid stenosis. There were ischemic lesions in DWI of 18.75% patients; this was nearly within the range (13.5%-25%) of previously published studies.^[19-26]

Two patients (2.5%) developed stroke after 2 days of TIA, one patient was AF and doesn’t receive treatment, the other was with ABCD2 score=7, this is expected because patients with higher ABCD2 score caries higher risk of stroke, in previous studies by Giles et al, Purroy et al, Sheehan et al,  and Verro mentioned that 2 days stroke risk after TIA was 3%-4.9% and with ABDC2 score  of 7 was 4.4%.^[21,27-29]

Thirteen (16.25%) patients who were on aspirin they developed TIA, this may be due ignorance of the drug and aspirin by itself prevent recurrent vascular events by 13-22% as in previously published study by Halkes et al, Ovbiagele, Diener et al, and Dengler et al.^[30-33] Among our patients; 33 patients were with ABCD2 score between 4-7, which is high score and carry high risk of stroke, better to be hospitalized for 24hours,^[34,35] but our patients neglect their symptoms as TIA is transient and most of the patients (80%) when arrive to the hospital their symptoms and signs already resolve.

In conclusion, transient ischemic attack is a common neurological emergency in Erbil. In our city, TIA occurred in younger patients than other areas. Hypertension was the most important risk factor for TIA followed by diabetes mellitus and smoking. Unilateral weakness was the most common symptom of TIA followed by unilateral sensory deficit. Diffusion weighted MRI of the brain is more sensitive than conventional MRI in the detection of ischemic changes in patients who present with TIA.

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DOI: 10.33899/mjn.2020.167520