Abstract WP179: Impact Of Different Cardiac Rhythm Monitoring Strategies On Secondary Stroke Prevention: A Systematic Review And Network Meta-analysis Of Randomized Controlled Clinical Trials

Background and Purpose: Prolonged cardiac rhythm monitoring can reveal a substantial proportion of ischemic stroke (IS) patients with atrial fibrillation (AF). We sought to evaluate the potential utility of available prolonged cardiac rhythm monitoring strategies with respect to secondary stroke prevention.

Methods: We searched Medline and Scopus databases to identify randomized controlled clinical trials (RCTs) comparing AF detection, anticoagulation initiation and stroke recurrence rates in patients with history of recent IS or transient ischemic attack (TIA) receiving cardiac rhythm monitoring with implantable loop recorders (ILRs), 30-days external loop recorders or Holter monitors. We performed a network meta-analysis to combine direct and indirect evidence for any given pair of monitoring devices that were evaluated within a trial and reported effect estimates with risk ratios (RRs) and corresponding 95% confidence intervals (95%CIs).

Results: We identified 5 RCTs including a total of 2202 patients (mean age 68 years, 40% women). In indirect analyses the likelihood of AF detection and anticoagulation initiation was higher for both ILR (RR=8.48, 95%CI: 3.41, 21.06; RR=3.29, 95%CI: 1.70-6.39) and external loop recorders (RR=3.06, 95%CI: 1.66, 5.61; RR=1.63, 95%CI: 1.03-2.58) compared to Holter devices. The probability of AF detection and anticoagulation initiation was lower for Holter and external loop recorders compared to ILR devices (RR=0.36, 95%CI: 0.15, 0.85 and RR=0.50, 95%CI: 0.25-0.98, respectively). No difference in the risk of stroke recurrence was found in the indirect comparisons of different cardiac rhythm monitoring strategies.

Conclusion: The likelihood of AF detection and anticoagulation initiation after an ischemic stroke or TIA is higher with ILRs compared to both external loop recorders and Holter devices.

Troponin Improves the Yield of Transthoracic Echocardiography in Ischemic Stroke Patients of Determined Stroke Subtype

Background and Purpose- Transthoracic echocardiography (TTE) is widely used in the ischemic stroke setting. In this study, we aim to investigate the yield of TTE in patients with ischemic stroke and known subtype and whether the admission troponin level improves the yield of TTE. Methods- Data were abstracted from a single-center prospective ischemic stroke database for 18 months and included all patients with ischemic stroke whose etiologic subtype could be obtained without the need of TTE. Unadjusted and adjusted regression models were built to determine whether positive cardiac troponin levels (≥0.1 ng/mL) improve the yield of TTE, adjusting for demographic and clinical characteristics. Results- We identified 578 patients who met the inclusion criteria. TTE changed clinical management in 64 patients (11.1%), but intracardiac thrombus was detected in only 4 patients (0.7%). In multivariable models, there was an association between TTE changing management and positive serum troponin level (adjusted odds ratio, 4.26; 95% CI, 2.17-8.34; P<0.001). Conclusions- In patients with ischemic stroke, TTE might lead to a change in clinical management in ≈1 of 10 patients with known stroke subtype before TTE but changed acute treatment decisions in <1 percent of patients. Serum troponin levels improved the yield of TTE in these patients.

Echocardiographic wall motion abnormalities in patients with stroke may warrant cardiac evaluation

Background

The aetiology of wall motion abnormalities (WMA) in patients with ischaemic stroke is unclear. We hypothesised that WMAs on transthoracic echocardiography (TTE) in the setting of ischaemic stroke mostly reflect pre-existing coronary heart disease rather than simply an isolated neurocardiogenic phenomenon.

Methods

Data were retrospectively abstracted from a prospective ischaemic stroke database over 18 months and included patients with ischaemic stroke who underwent a TTE. Coronary artery disease was defined as history of myocardial infarction (MI), coronary intervention or ECG evidence of prior MI. The presence (vs absence) of WMA was abstracted. Multivariable logistic regression was used to determine the association between coronary artery disease and WMA in models adjusting for potential confounders.

Results

We identified 1044 patients who met inclusion criteria; 139 (13.3%, 95% CI 11.2% to 15.4%) had evidence of WMA of whom only 23 (16.6%, 95% CI 10.4% to 22.8%) had no history of heart disease or ECG evidence of prior MI. Among these 23 patients, 12 had a follow-up TTE after the stroke and WMA persisted in 92.7% (11/12) of patients. In fully adjusted models, factors associated with WMA were older age (OR per year increase 1.03, 95% 1.01 to 1.05, p=0.009), congestive heart failure (OR 4.44, 95% CI 2.39 to 8.33, p<0.001), history of coronary heart disease or ECG evidence prior MI (OR 27.03, 95% CI 14.93 to 50.0, p<0.001) and elevated serum troponin levels (OR 2.00, 95% CI 1.06 to 3.75, p=0.031).

Conclusion

In patients with ischaemic stroke, WMA on TTE may reflect underlying cardiac disease and further cardiac evaluation may be considered.

Prolonged Cardiac Rhythm Monitoring and Secondary Stroke Prevention in Patients With Cryptogenic Cerebral Ischemia

Background and Purpose- Although prolonged cardiac rhythm monitoring (PCM) can reveal a substantial proportion of ischemic stroke (IS) patients with atrial fibrillation not detected by conventional short-term monitoring, current guidelines indicate an uncertain clinical benefit for PCM. We evaluated the impact of PCM on secondary stroke prevention using data from available to date randomized clinical trials and observational studies. Methods- We performed a comprehensive literature search in MEDLINE, SCOPUS, CENTRAL (Cochrane Central Register of Controlled Trial), and conference proceedings to identify studies reporting stroke recurrence rates in patients with history of cryptogenic IS or transient ischemic attack (TIA) receiving PCM compared with patients receiving conventional (non-PCM) cardiac monitoring. Results- We included 4 studies (2 randomized clinical trials and 2 observational studies), including a total of 1102 patients (mean age: 68 years, 41% women). We documented an increased incidence of atrial fibrillation detection (risk ratio=2.46; 95% CI, 1.61-3.76) and anticoagulant initiation (risk ratio=2.07; 95% CI, 1.36-3.17) and decreased risk of recurrent stroke (risk ratio=0.45; 95% CI, 0.21-0.97) and recurrent stroke/TIA (risk ratio=0.49; 95% CI, 0.30-0.81) during follow-up for IS/TIA patients who underwent PCM compared with IS/TIA patients receiving conventional cardiac monitoring. In the subgroup analysis, according to study type, atrial fibrillation detection, anticoagulant initiation, and IS/TIA recurrence rates were comparable between PCM and non-PCM in randomized clinical trials and observational studies. No evidence of heterogeneity (I²<12%) was documented across all the aforementioned subgroups. Conclusions- We provide preliminary evidence for a potential impact of PCM on secondary stroke prevention, as patients with cryptogenic IS/TIA undergoing PCM had higher rates of atrial fibrillation detection, anticoagulant initiation, and lower stroke recurrence.

Abstract WP278: Underutilization of Outpatient Cardiac Monitoring in Patients With Embolic Stroke of Unknown Source

Background: Recent studies have shown that outpatient cardiac monitoring for 30 days or longer increases detection rate of paroxysmal atrial fibrillation (AF) after Embolic Stroke of Unknown Source (ESUS). For patients with AF detected on monitoring, anticoagulation can be initiated to reduce risk of recurrent stroke. In this study, we aim to compare characteristics between patients who received cardiac monitoring and those who did not to further elucidate trends in the use of prolonged outpatient cardiac monitoring following ESUS.

Methods: We analyzed a retrospective cohort of patients discharged with a diagnosis of ESUS over a period of 18 months in whom outpatient cardiac monitoring was ordered. Patients who were deceased or without follow-up at 90 days were excluded. Patients were divided into two groups based on whether or not they received outpatient cardiac monitoring. We compared demographic data, clinical risk factors, and NIHSS between the two groups.

Results: Out of 282 patients with ESUS, 189 (67.0%) patients had 90 day follow-up data available; 118 (62.4%) underwent cardiac monitoring and 71 (37.6%) did not undergo cardiac monitoring. Of the patients who were monitored, 81.4% (96/118) received a 30 day non-invasive monitor and 43.2% (51/118) patients had an ICM implanted. There were no significant differences in baseline characteristics among patients who underwent cardiac monitoring versus those who did not.

Conclusion: More than one-third of patients with ESUS for whom outpatient cardiac monitoring was recommended and ordered did not actually receive it. This finding supports the need for more convenient, effective processes by which patients can follow through with outpatient cardiac monitoring which could perhaps be initiated at discharge.

Abstract WP202: A Simple Score That Predicts Paroxysmal Atrial Fibrillation on Outpatient Cardiac Monitoring After Embolic Stroke of Unknown Source

Background: Occult paroxysmal atrial fibrillation (AF) is detected in up to 30% of patients with Embolic Stroke of Unknown Source (ESUS). We aim to identify predictors of AF on outpatient cardiac monitoring in patients with ESUS.

Methods: We included ischemic stroke patients with ESUS subtype between January 1 st , 2013 and December 31 1st, 2016 who underwent an inpatient diagnostic evaluation, including 24 hour telemetry, followed by outpatient cardiac monitoring with 30-day cardiac monitors and/or implantable cardiac monitor (ICM). Patients were divided into two groups based on detection of AF or atrial flutter during monitoring. We compared demographic data, clinical risk factors, NIHSS, and cardiac biomarkers (left atrial enlargement on echocardiography, PR interval on ECG) between the two groups. Multivariable models were used to identify independent predictors of AF and to develop an AF prediction-risk scoring system.

Results: We identified 296 consecutive patients during the study period; 38 (12.8%) demonstrated previously undetected AF on outpatient cardiac monitoring. Compared to non-AF patients, AF patients were older (72.0 ± 11.0 vs. 62.7 ± 14.9; p <0.001), less likely to be current smokers (10.5% vs. 27.2%, p = 0.027), had lower NIHSS (3, IQR 1-7 vs. 3, IQR 1-5; p=0.002), and larger left atrial diameter in mm (39.3 ± 6.0 vs. 35.2 ± 6.4; p=0.001). In multivariable regression analysis, advanced age (ages 65-74: odds ratio 2.36, 95% confidence interval 0.85-6.52; ages ≥75: odds ratio 4.08, 95% confidence interval 1.58-10.52) and moderate-to-severe LAE (odds ratio 4.66, 95% confidence interval 1.79-12.12) were predictive of AF detection on outpatient monitoring. NIHSS, current smoking status, and mild LAE did not contribute significantly to AF prediction. We developed the Brown ESUS-AF score: age (65-74 years: 1 point, ≥ 75 years: 2 points) and left atrial enlargement (moderate/severe: 2 points) with good prediction of AF (AUC 0.725). The percentage of patients in each score category were: 0: 4.2%, 1: 14.8%, 2: 20.8%, 3: 22.2%, 4: 55.6%.

Conclusion: In this large sample of patients with ESUS, the Brown ESUS-AF score predicts AF detection on prolonged outpatient monitoring. More studies are needed to externally validate our findings.

Abstract 155: What Predicts Symptomatic Intracranial Hemorrhage in Ischemic Stroke Patients Undergoing Emergent Brain Imaging for Neurological Deterioration After IV tPA?

Background: Early neurological deterioration (END) prompting urgent brain imaging occurs in up to 15% of ischemic stroke patients receiving intravenous tissue plasminogen activator (tPA). Most of these are not related to symptomatic intracranial hemorrhage (sICH) but lead to unnecessary interruption of the tPA infusion. We aim to determine predictors of sICH in ischemic stroke patients undergoing emergent brain imaging after tPA.

Methods: We queried our prospective stroke database and included all patients who received tPA for ischemic stroke from March 1 st , 2015 until March 1 st , 2017. We then identified patients who underwent emergent brain imaging before the planned 24-hour brain imaging and divided these patients into: sICH+ and sICH- defined by NINDS criteria. We compared baseline clinical factors, pre-admission medications, admission blood pressure, symptoms prompting repeat scan [change in level of consciousness (LOC); worsening or new (W/N) neurological symptoms without change in LOC; headache/nausea/vomiting), thrombectomy, 24-hour NIHSS and 90 day outcome.

Results: We identified 511 patients who received tPA (sICH rate 4.1%). Emergent repeat brain CT was performed on 108 (21.1%); 17.5% (19/108) had sICH and 21.3% (23/108) occurred during the tPA infusion with only one being related to sICH. The mean time from tPA infusion to symptoms prompting brain imaging in sICH was 7.3 ± 5.3 hours. In patients who underwent emergent brain imaging, sICH+ patients were older (80.2 ± 15.8 vs. 70.8 ± 15.4, p = 0.026), with higher admission NIHSS (14 vs. 7, p = 0.0016) and 90-day mortality (87.5% vs. 22.4%, p<0.001), more likely to have a change in LOC (78.9% vs. 21.3%, p<0.001) and less likely to have W/N symptoms without LOC change (5.3% vs. 42.7%, p=0.002). On multivariable analyses, the only predictor of sICH was LOC change (OR 6.62 95% CI 1.64-26.70, p=0.008).

Conclusion: Nearly 95% of patients with ischemic stroke had unnecessary interruption of the tPA infusion for new symptoms shortly after the tPA infusion. A change in LOC was the only predictor of sICH among tPA patients undergoing emergent brain imaging. In this group of patients, the preparation of tPA reversal agents awaiting brain imaging may help reduce tPA reversal times and improve outcomes

Abstract WP208: Elevated Troponin Levels in Ischemic Stroke is Independently Associated With Cardioembolism

Background: Elevated cardiac troponin is a marker of cardiac disease and has been recently shown to be associated with embolic stroke risk in the general population. In the acute stroke setting, we hypothesize that elevated troponin levels are more prevalent in patients with embolic stroke subtypes [cardioembolic (CE) and embolic stroke of unknown source (ESUS)] as opposed to known non cardioembolic subtypes (NE) (large vessel disease, small vessel disease, and other).

Methods: We abstracted data from our prospective stroke database and included all patients with ischemic stroke over a 22 month period. We defined positive troponin as ≥ 0.1 ng/mL. Patients diagnosed with acute myocardial infarction were excluded (n = 3).We compared clinical, laboratory and echocardiographic findings, and stroke subtypes using ESUS criteria between the two groups: Troponin+ and Troponin-.

Results: We identified 1231 patients; 1129 had troponin levels available and 10.0% (113/1129) were trop+. On univariate analyses, Troponin+ patients were more likely to be older (77.4 ± 12.6 vs. 70.8 ± 15.0, p<0.001), have hypertension (85.8% vs. 74.2%, p=0.003), coronary heart disease (31.3% vs. 20.1%, p=0.003), congestive heart failure (20.9% vs. 9.5%,p<0.001), smoking (42.5% vs. 26.4%, p<0.001), and atrial fibrillation (42.5% vs. 26.4%, p<0.001), higher admission NIHSS (14 vs. 6, p<0.001), eGFR < 60 (53.7% vs. 33.4%), larger left atrial diameter (40.9 ± 8.8 vs.37.1 ± 7.6, P<0.001), lower ejection fraction (60 vs. 65, p<0.001), and wall motion abnormalities (26.1% vs. 11.5%, p<0.001) compared troponin- patients. When compared to NE subtype, troponin+ patients were more likely to have CE (79.0% vs. 52.4%, p<0.001) and ESUS (75.0% vs. 58.9%, p=0.001) subtypes. In multivariable models, factors associated with troponin+ are NIHSS (adjusted OR per 1 unit increase1.05, 95% 1.02-1.08; p<0.001), eGFR < 60 (adjusted OR 2.41 95% CI 1.40-4.13; p=0.001), CE subtype (adjusted OR 3.37 95% CI 1.35-8.43,p=0.009), and ESUS subtype (adjusted OR 2.77 95% CI 1.15-6.66,p=0.023).

Conclusion: Elevated troponin levels in ischemic stroke is independently associated with a cardiac embolic source. Studies are needed to test anticoagulation vs. antiplatelet in patients with ESUS and elevated troponin.

Early Elevated Troponin Levels After Ischemic Stroke Suggests a Cardioembolic Source

Background and Purpose—

Elevated cardiac troponin is a marker of cardiac disease and has been recently shown to be associated with embolic stroke risk. We hypothesize that early elevated troponin levels in the acute stroke setting are more prevalent in patients with embolic stroke subtypes (cardioembolic and embolic stroke of unknown source) as opposed to noncardioembolic subtypes (large-vessel disease, small-vessel disease, and other).

Methods—

We abstracted data from our prospective ischemic stroke database and included all patients with ischemic stroke during an 18-month period. Per our laboratory, we defined positive troponin as ≥0.1 ng/mL and intermediate as ≥0.06 ng/mL and <0.1 ng/mL. Unadjusted and adjusted regression models were built to determine the association between stroke subtype (embolic stroke of unknown source and cardioembolic subtypes) and positive and intermediate troponin levels, adjusting for key confounders, including demographics (age and sex), clinical characteristics (hypertension, hyperlipidemia, diabetes mellitus, renal function, coronary heart disease, congestive heart failure, current smoking, and National Institutes of Health Stroke Scale score), cardiac variables (left atrial diameter, wall-motion abnormalities, ejection fraction, and PR interval on ECG), and insular involvement of infarct.

Results—

We identified 1234 patients, of whom 1129 had admission troponin levels available; 10.0% (113/1129) of these had a positive troponin. In fully adjusted models, there was an association between troponin positivity and embolic stroke of unknown source subtype (adjusted odds ratio, 4.46; 95% confidence interval, 1.03–7.97; P =0.003) and cardioembolic stroke subtype (odds ratio, 5.00; 95% confidence interval, 1.83–13.63; P =0.002).

Conclusions—

We found that early positive troponin after ischemic stroke may be independently associated with a cardiac embolic source. Future studies are needed to confirm our findings using high-sensitivity troponin assays and to test optimal secondary prevention strategies in patients with embolic stroke of unknown source and positive troponin.

Defense of breast cancer malpractice claims

The goal of this study was to determine whether factors associated with the successful defense and cost of malpractice cases involving the failure to diagnose breast cancer could be identified in medical and legal records. Secondary goals were to develop a multidisciplinary clinical algorithm utilizing National Comprehensive Cancer Network (NCCN) practice guidelines with practitioner risk management strategies. Physician deviations from these guidelines were tracked to identify high-risk areas in the diagnosis of breast cancer. A multidisciplinary clinical algorithm was introduced and practitioner risk management issues were addressed. In this study specific medical, legal, and cost factors were retrospectively abstracted and analyzed to identify associations between medical and legal factors and medicolegal outcome. ProMutual handled 156 malpractice cases involving breast cancer between January 22, 1986, and November 20, 1997. Of the total, 124 cases involving 212 defendants were closed. The closed cases were analyzed, using multivariable stepwise logistic and linear regression, to identify associations between clinical factors and case outcome. Women's health practitioners (WHPs), including obstetrician-gynecologists (OB-GYNs), family medicine, and internal medicine clinicians, were the largest group of defendants (97). Others included radiologists (43), surgeons (33), and pathologists (3). OB-GYNs accounted for 31% of these defendants, with a cost of more than $16 million. The greatest number of specialists represented in the open cases were radiologists, with 38% of the total. The defense model predicts that the probability of successful defense is lessened with inadequate record keeping, a patient that has metastasis and is alive, and a delay in diagnosis of 12 months or more. The overall indemnity model predicts a higher indemnity with the spread of disease at the time of evaluation, a patient who has metastasis and is alive, and a date of occurrence closer to the present. Indemnity is less in patients who have had a lymph node dissection, who have died, or who are alive without metastasis. The WHP model predicts an increased overall indemnity with the spread of disease at the time of evaluation and the presence of a mass without pain. Indemnity decreases with a history of pregnancy, absence of presenting symptoms, or presentation with pain with or without a mass, and the performance of a lymph node dissection.

Statistical models of outcome in malpractice lawsuits involving death or neurologically impaired infants

The objective was to determine whether factors could be identified in medical and legal records that are associated with the successful defense of obstetrical malpractice cases involving the death or neurological impairment of infants. Obstetrical claims (169) closed by PROMUTUAL between January 1, 1990, and December 31, 1994, were retrospectively abstracted and analyzed to identify associations between medical and legal factors, and the medicolegal outcome. Multivariable analysis identifies that the use of pitocin, diagnosis of asphyxia, a delay in delivery, and the use of multiple defense expert witnesses decreased the chances of a successful defense. Two statistical models explaining indemnity payment were developed. The first, based on medical outcome, showed an increased indemnity payment when a case involved major neurological deficits, diagnosis of asphyxia, newborn seizures, later year of delivery, and participation of a particular defense firm. Perinatal or childhood death and the use of pitocin were indicators of a decrease in payment. The second model was based on long-term care requirements. In this model, indicators of increased indemnity payment were: nonreassuring intrapartum fetal heart rate tracing, later year of delivery, intensity of long-term care required, and participation of a particular defense law firm. Perinatal or childhood death, the use of pitocin, and settlement date increasingly removed from the occurrence date were the determinants of decreased payments in this model. Finally, the presence of major neurological deficits, the prolongation of a case, and the involvement of multiple law firms and defense witnesses increased the expense charged to and paid by the insurance company. Using the medical, legal, and financial data relevant to 169 obstetrical cases closed by one malpractice insurance carrier between 1990 and 1994, statistical models with potential predictive values for future malpractice claims involving neurologically impaired infants were constructed. These models may help determine in advance the chance a future case has for successful defense and the likely amount of expense and indemnity dollars that will be paid out to settle and defend it.

Enhancement of the pressor response to norepinephrine by angiotensin in the conscious rabbit

The pressor interactions between angiotensin II and norepinephrine were investigated in conscious New Zealand white rabbits receiving a low sodium diet. Angiotensin II was administered continuously by intraperitoneal osmotic pumps in a subpressor dose so as to avoid the potentially confounding effects of experimentally-induced hypertension. Norepinephrine challenges were given as a series of graded intravenous boluses. During the 3 days of study the baseline blood pressure in the angiotensin-treated rabbits (n=10) did not differ from that in controls (n=10) whose intraperitoneal pumps contained only diluent. After 24 hours the systolic and diastolic blood pressure responses to norepinephrine in the angiotensin-treated group were, on average, 45% and 30% higher than in the controls; after 72 hours, they were 46% and 34% higher. Although the pressor amplitudes were increased by angiotensin II, they were not prolonged. Thus, facilitation by the subpressor angiotensin II of the blood pressure responses to norepinephrine did not seem dependent upon alterations in endogenous sympathetic mechanisms or the uptake of norepinephrine; nor could it be explained by sodium retention. It is possible that angiotensin II exhibits its effect by enhancing contractile responsiveness to norepinephrine at the postreceptor level.

A vasodilator that avoids renin stimulation and fluid retention: antihypertensive treatment with trimazosin

Trimazosin was given for periods of at least 6 mo to 25 patients with mild to moderate essential hypertension. In doses of 300 to 900 mg dialy trimazosin alone led to blood pressure control (supine diastolic blood pressure less than 90 mm Hg with a fall of at least 10 mm Hg) in 16 patients (64%). Despite the decrements in blood pressure there were no changes in body weight or creatinine clearance. There was also no changes in plasma renin activity or urinary aldosterone excretion rate. Although patients with high control renin values appeared to have greater blood pressure decreases than those with low renin values, responsiveness to treatment was not associated with consistent effects of trimazosin on the renin-angiotensin system. Trimazosin induced a small decrease in plasma total cholesterol concentration. In seven patients whose blood pressures were not controlled by trimazosin alone, the addition of polythiazide led to decreased blood pressure and in five control of pressure was achieved. Thus, trimazosin is an effective antihypertensive when given by itself or in combination with a diuretic. Its mechanism of action has not been established, but its ability to induce vasodilation without concomitant sodium retention or stimulation of the renin axis may be an important factor in its effectiveness.