Initial conditions combine with sensory evidence to induce decision-related dynamics in premotor cortex

We used a dynamical systems perspective to understand decision-related neural activity, a fundamentally unresolved problem. This perspective posits that time-varying neural activity is described by a state equation with an initial condition and evolves in time by combining at each time step, recurrent activity and inputs. We hypothesized various dynamical mechanisms of decisions, simulated them in models to derive predictions, and evaluated these predictions by examining firing rates of neurons in the dorsal premotor cortex (PMd) of monkeys performing a perceptual decision-making task. Prestimulus neural activity (i.e., the initial condition) predicted poststimulus neural trajectories, covaried with RT and the outcome of the previous trial, but not with choice. Poststimulus dynamics depended on both the sensory evidence and initial condition, with easier stimuli and fast initial conditions leading to the fastest choice-related dynamics. Together, these results suggest that initial conditions combine with sensory evidence to induce decision-related dynamics in PMd.

How do cardiovascular risk factors and cardiac remodeling type affect left ventricular global longitudinal strain and right ventricular free wall strain in patients with obesity

Background

Obesity, defined by the World Health Organization (WHO) as a BMI greater than 30k g/m2, has reached epidemic proportions worldwide, related to approximately 2.8 million deaths/year as of June 2021. WHO sub-classifies obesity based on BMI in Class 1: 30–34.9 kg/m2, Class 2: 35–39.9 kg/m2, and Class 3: ≥40 kg/m2. This state of increased body weight is associated with an increased risk of cardiovascular disease. Cardiac remodeling can be affected by obesity and/or other cardiovascular risk factors (CVRF) as an adaptive physiological response. The remodeling patterns, Normal Geometry (NG), Concentric Remodeling (CR), Concentric Hypertrophy (CH), and Eccentric Hypertrophy, are classified by changes in Relative Wall Thickness (RWT), ≤ or >0.42, and/or Left Ventricular Mass Index (LVMI g/m2), ≤ or >88 for women and ≤ or >102 for men. Left Ventricular Ejection Fraction (LVEF) can remain within normal limits in patients with obesity with multiple CVRF and cardiac remodeling. Left Ventricular Global Longitudinal Strain (LV-GLS) and Right ventricular free wall strain (RV-FWS) can be useful to detect subclinical myocardial dysfunction. The aim of this study was to evaluate if these strain variables are affected in patients with obesity associated to other CVRF in relation to cardiac remodeling type when compared to controls.

Methods

2859 patients with BMI ≥30 kg/m2 and 2616 normal-weight controls (BMI between 18.5 and 24.9 kg/m2), with normal and abnormal cardiac geometry, and normal ejection fraction by echocardiography performed between 01/01/2008 and 12/31/2018, were compared. Obesity was classified based on the World Health Organization. CVRF included were Hypertension (HTN), Diabetes Mellitus (DM), Dyslipidemia, history of Vascular Event (myocardial infarction and/or stroke), and Obstructive sleep apnea (OSA).

Results

BMI, cardiac geometry, CVRF, and the number of comorbidities independently affected GLS and RV-FWS (Figure 1 and Figure 2). LV-GLS and RV-FWS values [mean (SD)] in obesity classes 1, 2, and 3 were −19 (2.9), −18.9 (2.9), −18.7 (2.9) & −24.2 (5.2), −23.8 (6.2), −24.5 (5.9), respectively. In the control group LV-GLS and RV-FWS values [mean (SD)] were −20.1 (3.0) & −27 (5.6), respectively. CH was associated with the greatest decrease in LV-GLS and RV-FWS in males and females, regardless of BMI (Figure 2). LV-GLS values [mean (SD)] associated to CH for obesity class 1, 2, and 3, and controls in females were −18.4 (3.4), −18 (3.1) −17.6 (3.6), and −17.8 (4), respectively, and for obesity class 1, 2, and 3, and controls in males were −16.1 (3.5), 16.5 (3.2), −14.4 (2.7), and −16.6 (4.7), respectively (Figure 1).

Conclusion

Obesity associated to CVRF and CH have the lowest values of GLS in patients with normal ejection fraction. These values were exceedingly below average compared to other groups. These parameters should be used as reference values for this population.

Funding Acknowledgement

Type of funding sources: None.

Left ventricular diastolic dysfunction, including an impaired myocardial relaxation pattern, predicts long-term cardiovascular and non-cardiovascular mortality in the community

Funding Acknowledgements

Type of funding sources: None.

Background/Introduction

Prior studies have demonstrated abnormalities of diastolic function are independent predictors of heart failure and all-cause mortality. The optimal way to classify diastolic function has continued to evolve over time, particularly in those with preserved left ventricular ejection fraction. A notable change in the 2016 American Society of Echocardiography (ASE)/European Association of Cardiovascular Imaging (EACVI) guidelines is that individuals with impaired myocardial relaxation and normal filling pressure can be classified as normal diastolic function.

Purpose

To determine whether the association of diastolic dysfunction with increased risk of all-cause mortality is driven by cardiovascular or non-cardiovascular death. Second, to evaluate if the presence of an impaired myocardial relaxation inflow pattern without other diastolic abnormalities conveys a marker of increased risk.

Methods

This study utilized the Olmsted County Heart Function Study (OCHFS), a well characterized prospective adult community cohort with comprehensive echocardiography between 2001 and 2004 and long-term follow-up. Only individuals with measurable diastolic function were included (n = 1,104). Those with reduced left ventricular ejection fraction, more than moderate valve disease, or a clinical diagnosis of heart failure (n = 52); or indeterminate diastolic function (n = 47) were excluded. Diastolic function was assessed by the current Mayo Clinic diagnostic algorithm (Figure).

Results

A total of 695 individuals were classified as normal, 265 with impaired myocardial relaxation or grade 1 diastolic dysfunction, and 45 with grade 2-3 diastolic dysfunction. Those with diastolic dysfunction were older and had more comorbidities including diabetes, hypertension and coronary disease (Table). There were 264 deaths in the median follow up period of 15.2 years (IQR 14.4 – 18.0), including 173 non-cardiovascular and 81 cardiovascular deaths. Both cardiovascular and non-cardiovascular mortality were associated with the presence and grade of diastolic dysfunction (Table 1). Individuals classified as normal by 2016 ASE/EACVI criteria, but grade 1 by the Mayo algorithm had an increased risk of all-cause mortality after univariate analysis (HR 4.35, 95% CI (3.35, 5.65), p < 0.0001) compared to normal subjects and remained associated after adjustment for age (HR 1.55, 95% CI (1.15, 2.09), p < 0.0001. Subjects with a grade 1 pattern had a higher rate of cardiovascular mortality (ꭕ2 70.1, p < 0.0001).

Conclusions

Individuals with diastolic dysfunction, including those with an impaired relaxation mitral inflow, were at increased risk of mortality, particularly cardiovascular mortality. This study highlights the importance of separating grade 1 diastolic dysfunction from normal in the assessment of diastolic function as it represents a clinically significant risk marker of myocardial disease. Abstract Figure.  Abstract Figure.

Rate of transesophageal echocardiography related complications during 1229 TEE-guided structural heart disease procedures

Funding Acknowledgements

Type of funding sources: None.

Background/Introduction: Transesophageal echocardiography (TEE) has long provided excellent diagnostic imaging of left-sided valvular pathology with an excellent safety profile; however, recent data has suggested an increased risk of injury related to TEE guidance.

Purpose

This study aims to evaluate the incidence and nature of TEE-related oropharyngeal or esophageal complications in patients undergoing TEE-guided structural heart procedures and identify associated risk factors.

Methods

We reviewed consecutive patients undergoing TEE-guided structural heart procedures from 2005-2020. All procedures were performed under general anesthesia. TEE-related oropharyngeal or esophageal complications were defined as those occurring within 30 days of the procedure resulting in i) persistent dysphagia, odynophagia, or upper gastrointestinal bleeding requiring prolonged endotracheal intubation, therapeutic endoscopic or surgical intervention, or diagnostic imaging that demonstrated oropharyngeal or esophageal injury.  ii) upper gastrointestinal bleed requiring transfusion, hemodynamic compromise warranting mechanical or pharmacologic support; or iii) oropharyngeal or esophageal complications leading to death. For multivariate analysis, all variables with a p < 0.15 at univariate analysis were included in the model.

Results

Among 1229 adult patients undergoing TEE-guided structural heart procedures between 2005-2020, 274 underwent a transcatheter aortic valve replacement (TAVR) with the remaining 955 undergoing either mitral valve transcatheter edge-to-edge repair (mTEER, n = 278), mitral paravalvular leak closure (PVLC, n = 354), mitral valve-in-valve replacement (VIV, n = 41), or left atrial appendage closure (LAAO, n = 282). Of these, 6 (0.5 %) had TEE-related complications; 0% TAVR, 0% VIV, 0.36% LAAO, 0.28% PVLC, 1.41% mTEER (p = 0.14). Of the six patients with complications 3 required at least one day of prolonged tracheal intubation and one a blood transfusion. None required surgical repair.  Factors associated with increased complication risk (Table) included a prior history of gastrointestinal bleed (Odds ratio 5.44 [0.98-30.04; p = 0.05]) and longer procedural time (OR per 30 min 1.15 [1.01-1.31, p = 0.03]). Patients undergoing mTEER had an increased risk of complication (OR 6.76 [1.23-37.1 p = 0.03]) and longer procedural time (OR per 30 mins 1.15[1.01-1.31, p = 0.04]) compared to other all other procedures.

Conclusion(s): In a large series of patients undergoing cardiac structural interventions under general anesthesia with TEE-guidance, rates of TEE-induced injury were low. Risk of oropharyngeal or esophageal complications was increased with longer procedure times, prior gastrointestinal bleeding history, increased age, increased pre-procedural creatinine, procedural type being mTEER and in male patients, lower height. Abstract Table

Tricuspid annulus dynamics in atrial fibrillation compared to sinus rhythm using 3-D echocardiography: relation with tricuspid regurgitation

Funding Acknowledgements

Type of funding sources: None.

Background

Atrial fibrillation (AF) is known to cause dilation in both the mitral (MA) and the tricuspid (TA) annuli. Few studies have investigated MA dynamics and function in AF compared to sinus rhythm (SR). However, no study addressed this issue in TA. Hence, we set forth to describe TA dynamics in AF and SR and its relationship with severity of tricuspid regurgitation (TR).

Methods

3D echocardiographic imaging data were acquired from adult patients in AF or SR with varying degrees of TR between 2018 and 2020. TA was automatically tracked throughout the cardiac cycle using a commercially available software (TomTec 4MV software; Figure 1) over 4-6 cardiac cycles per patient. Time to minimal area as percentage of the R-R interval was recorded in each of the cycles. Absolute change in TA area was calculated as the difference between maximal and minimal TA area in each cardiac cycle and was averaged over 4-6 cycles per patient. This measurement was used to reflect the dynamic range of TA deformation during the cardiac cycle. Right atrial (RA) and right ventricular (RV) volumes and longitudinal strain were also measured (speckle tracking, 4-ch view).

Results

A total of 70 patients were studied (35 AF; 35 SR; 54% males in each group). Patients with AF were older [median (IQR) of 81 (72-86) years vs. 69 (59-78) years in SR, p < 0.001], had larger maximal TA area and circumference (p < 0.001 for both), larger RA size (p < 0.001), lower RA reservoir strain  (p < 0.001) and RV free-wall strain (p < 0.001). Absolute change in TA area was significantly decreased in AF [2.3 (1.7-2.7) cm2] vs. 3.1 (2.3-3.5) cm2 in SR, p = 0.002. Patients with ≥ moderate TR (n = 41, 59%) had lower absolute change in TA area [2.4 (1.7-3.1) cm2 vs. 2.8 (2.2-3.5) cm2 in < moderate TR, p = 0.05]. Female sex was associated with lower absolute change in TA area [2.3 (1.7-3.2) cm2 vs. 2.7 (2.2-3.6) cm2 in males, p = 0.02] on univariate analysis. AF patients had more frequently ≥ moderate TR [28 AF vs. 13 SR, p < 0.001]. On multivariate analysis including sex, rhythm, TR severity, RA and RV strains, and averaged maximal TA area, independent factors associated with lower absolute change in TA area were AF, ≥ moderate TR, and larger maximal TA area (p < 0.05 for all).  Time to minimal TA size was achieved in (0-40%) of the R-R interval in 70% of patients in SR compared to only 41% of patients in AF (Figure 2) and in 73% in patients with < moderate TR compared to 43% in patients with ≥ moderate TR.

Conclusion

AF is associated with blunted TA dynamics resulting in lower decrease in TA size and with a heterogenous timing of minimal TA size throughout the cardiac cycle. The blunted and discoordinated annular contraction may reduce systolic tricuspid valve competence and be involved in the pathophysiology of functional TR. Future studies are needed to confirm this hypothesis and evaluate the effect of restoration of SR on TA dynamics and time to minimal TA size. Abstract Figure 1Abstract Figure 2

Defining echocardiographic reference values of LV volume indices and biventricular strain in obese patients with normal ejection fraction in different cardiac remodeling patterns – a single center study

Background

The left ventricle (LV) in obese patients undergoes different patterns of remodeling in order to normalize wall stress. However, little is known about how LV volume indices, LV global longitudinal strain and right ventricular free wall strain (GLS) vary according to the pattern of LV remodeling.

Aim

To define the echocardiographic reference values of LV volumes and biventricular GLS across the different LV remodeling patterns in obese patients with a preserved ejection fraction.

Methods

2393 adult obese patients (1428 females, 965 males) with a normal ejection fraction who underwent echocardiography from January 2008 to December 2018 were selected. They were categorized according to 4 cardiac remodeling groups defined by LV mass index (102g/m2 in males, 88g/m2 in females) and relative ventricular wall thickness (0.42): normal geometry (NG), eccentric hypertrophy (EH), concentric remodeling (CR) and concentric hypertrophy (CH). Obese subjects were further categorized by BMI class (30–35, 35–40, >40 kg/m2). Obese subjects were gender matched to controls with a normal BMI (18.5–25 kg/m2) and normal cardiac geometry. Mean ± SD, One-way Anova and Tukey- Kramer HSD were applied. P<0.05 is considered significant.

Results

The mean age of controls and obese patients' were 50±16 and 57±13.6 years respectively (P<0.0001). LV GLS for controls compared to obese subjects with NG, EH, CR and CH was −21.1±2 vs. −20.2±1.9, −19.6±2.8, −18.5±2.9, −17.5±3.4 respectively (p<0.0001 for all), and for RV GLS it was −27.9±4 vs −26.7±3.9, −25.1±5, −23.5±5.5, −24.1±5.2 respectively (p<0.01 for all, except for NG where p=0.2). The distribution of LV indices according to cardiac remodeling subtypes is shown in the figure. Indexed end diastolic and end systolic volumes were smaller in NG, CH and CR compared to controls (p<0.001 for each respectively). LV GLS and ejection fraction were higher in females, while indexed LV volumes were higher in males within each remodeling category (P<0.0001). No significant difference in LV GLS or indexed LV volume was seen across BMI categories within each remodeling pattern (P>0.05). Obese subjects with CH had the highest incidence of the cardiovascular risk factors hyperlipidemia, hypertension and history of myocardial infarction or stroke, compared to those with other remodeling patterns (p<0.0001 for each, vs. NG, EH and CR).

Conclusion

To our knowledge, this is the largest study to define LV volumes and left and right ventricular GLS according to LV remodeling pattern and BMI category. The Lowest GLS was noted in CH. Ejection fraction was similar across the LV remodeling patterns. There were no differences in GLS and LV indexed volumes across BMI categories within each remodeling group. These results can be applied as a reference values for the obese population with a normal LV ejection fraction.

Funding Acknowledgement

Type of funding source: None

1678 Impact of anemia in exercise stress echocardiography: effects on exercise capacity and stress testing safety

Funding Acknowledgements

None

Background/Purpose:

Anemia is a common condition in patients with cardiovascular disease. The effect of anemia in exercise stress testing has not been evaluated in a large cohort of patients.

Methods

We performed a retrospective review of patients undergoing exercise stress echocardiography over a 10 year period who had blood hemoglobin assessed within 48 hours of stress testing. World Health Organization cutoffs were used in defining the degree of anemia. The effect of anemia on exercise capacity and stress testing safety outcomes was assessed.

Results

In 15,652 patients, 90.3% were non-anemic, 7.6% mildly anemic, 2.1% moderately anemic, and 0.1% severely anemic. The incidence of serious supraventricular or ventricular arrhythmias and need to transfer to the hospital was low (0.1%) and did not correlate to anemia severity (p = 0.25). There was an increased incidence of non-sustained SVT or atrial fibrillation with moderate anemia and increased incidence of hypotension with stress testing with mild and moderate anemia. There was a significant reduction in duration of exercise (p < 0.001) and METS (p < 0.001) achieved with worsening anemia.

Conclusion

Our study demonstrates that exercise stress testing is safe in patients with mild and moderate anemia, albeit with reduced exercise capacity. Low numbers of severely anemic patients despite a large study population limit generalizability of these results in this group.

Exercise Capacity Severe Anemia (N = 9) Moderate Anemia (N = 332) Mild Anemia (N = 1183) Non-anemic (N = 14128) P value Resting heart rate 81 ± 13 # 79 ± 14 # 72 ± 14 74 ± 13 <0.001* Peak heart rate 148 ± 22 139 ± 24 # 138 ± 23 # 147 ±22 <0.001* Exercise duration 5.3 ± 2.5 # 6.3 ± 2.1 # 7.2 ± 2.5 # 8.6 ± 2.7 <0.001* METS 6.3 ± 2.5 # 7.1 ± 2.2 # 8.0 ± 2.5 # 9.5 ± 2.7 <0.001* Safety Hypotension with stress 0 (0%) 31 (9.4%) # 94 (8.0%) # 437 (3.1%) <0.001* Mild supraventricular arrhythmia 1 (11.1%) 15 (4.5%) # 20 (1.7%) # 237 (2.3%) 0.04* Severe supraventricular arrhythmia 0 (0%) 0 (0%) 0 (0%) 7 (0.1%) 0.99 Mild ventricular arrhythmia 0 (0%) 20 (6.0%) 74 (6.3%) 756 (5.4%) 0.94 Moderate ventricular arrhythmia 0 (0%) 3 (0.9%) 13 (1.1%) 182 (1.3%) 0.78 Severe ventricular arrhythmia 0 (0%) 1 (0.3%) 2 (0.2%) 1 (0.0%) 0.02 Transfer to hospital 0 (0%) 2 (0.6%) 1 (0.1%) 9 (0.1%) 0.29 Any severe arrhythmia or hospitalization 0 (0%) 2 (0.6%) 3 (0.3%) 17 (0.1%) 0.25 # Multi-comparison adjusted P-value <0.05 compared to non-anemic when group P < 0.05

3260Prognostic value of cardiac power reserve in patients with normal left ventricular ejection fraction undergoing exercise stress echocardiography

Background

Cardiac power output-to-mass (CPOM) ratio is a measure of myocardial performance that incorporates both pressure and flow output, normalized to left ventricular (LV) mass generating that cardiac work. Prior small studies have shown that CPOM predicts outcomes in patients with ischemic cardiomyopathy and reduced LV ejection fraction (EF). We sought to evaluate the prognostic significance of peak exercise CPOM and power reserve (increase from rest to peak exercise) in patients with normal EF.

Methods and results

Retrospective study in 24,783 patients (age 59±13 years, 45% females) with EF≥50% and no significant valve disease or right ventricular (RV) dysfunction, undergoing exercise stress echocardiography between 2004–2018. CPOM was calculated as previously described (0.222 x cardiac output x mean blood pressure / LV mass) and expressed in Watts/100g myocardium. Power reserve was calculated as difference in CPOM between peak stress and rest. All-cause mortality was the primary endpoint. Patients were divided into quartiles of power reserve. Patients with higher power reserve were younger, had higher blood pressure and heart rate, lower LV mass, and lower prevalence of prior myocardial infarction. (Table). During follow-up (median (IQR) 3.9 (0.6–8.3) years), 931 (3.8%) patients died. Progressively lower power reserve was associated with increasing mortality (Figure A). Compared to patients with abnormal stress test, patients with the lowest power reserve but otherwise normal stress test had the same survival as those with infarction/cardiomyopathy or ischemia on stress test (Figure B). Resting CPOM had lower predictive value. After adjusting for age, sex, METs achieved, ischemia/infarction on stress test results, and diastolic function grade, both peak exercise CPOM and power reserve were independent predictors of mortality (p<0.0001), incremental to conventional measures.

Conclusion

Cardiac power output and reserve measured during exercise stress echo provides independent prognostic information in patients with normal resting EF and no significant valve disease or RV dysfunction. The survival of patients with low power reserve but normal stress test was similar to patients with prior infarction/ cardiomyopathy or ischemia on stress test.

A Survey Exploring the Experiences & Attitudes of Dental Implant Clinicians in the Management of Peri-implantitis within the United Kingdom

Peri-implantitis remains one of the most challenging complications that could threaten the long-term survival of implants. The aim of this survey is to explore the experiences, attitudes and challenges that face clinicians in the management of peri-implantitis. A validated online questionnaire was emailed to implant clinicians in the United Kingdom. 72 clinicians responded to the questionnaire, all of whom face many challenges during the treatment of peri-implantitis, with 79% finding difficulties due to lack of treatment consensus and 78% finding treatment outcomes unpredictable. This survey highlights the marked differences in opinion and attitudes of clinicians in the management of peri-implantitis.

Has the practice of radiation oncology for locally advanced and metastatic non-small-cell lung cancer changed in Canada?

Aim

Previous surveys have revealed wide variations in the management by radiation oncologists of non-small-cell lung cancer (nsclc) in Canada. The aim of the present study was to determine the current patterns of practice for locally advanced and metastatic nsclc among Canadian radiation oncologists.

Materials and Methods

An online survey was distributed electronically to all members of the Canadian Association of Radiation Oncologists. Those who treat lung cancer were invited to participate. The survey consisted of three scenarios focusing on areas of nsclc treatment in which the radiotherapy (rt) regimen that provides the best therapeutic ratio is unclear.

Results

Replies from 41 respondents were analyzed. For an asymptomatic patient with stage iiib nsclc unsuitable for radical treatment, 22% recommended immediate rt, and 78% recommended rt only if the patient were to become symptomatic. Those who believed that immediate rt prolongs survival were more likely to recommend it (p = 0.028). For a patient with a bulky stage iiib tumour and good performance status, 39% recommended palliative treatment, and 61% recommended radical treatment (84% concurrent vs. 16% sequential chemoradiation at 60–66 Gy in 30–33 fractions). Those who believed that chemoradiation has a greater impact on survival were more likely to recommend it (p < 0.001). For a symptomatic patient with stage iv nsclc, 54% recommended external-beam rt (ebrt) alone, 41% recommended other modalities (brachytherapy, endobronchial therapy, or chemotherapy) with or without ebrt, and 5% recommended best supportive care. A majority (76%) prescribed 20 Gy in 5 fractions for ebrt.

Conclusions

Compared with previous surveys, more radiation oncologists now offer radical treatment for locally advanced nsclc. Management of nsclc in Canada may be evidence-based, but perception by radiation oncologists of the treatment’s impact on survival also influences treatment decisions.

Physiologically guided angioplasty in support to a provisional stenting strategy: immediate and six-month outcome

The results of an observational multicenter angioplasty study suggested that stenting decisions may be facilitated by physiologic data. The purpose of this study was to evaluate the early and long-term clinical and angiographic outcome of prospective physiologically guided provisional stenting. Coronary angioplasty using a Doppler-tipped angioplasty guidewire was performed in 68 patients. The provisional stent strategy dictated that balloon angioplasty was to be continued until a coronary flow reserve was >/= 2.2 with a residual diameter stenosis by quantitative coronary angiography < 35%. Repeat coronary angiography was obtained at 6 months. Based on the study criteria, 32/68 patients (47%) received a stent. Compared to the stent group, the angioplasty alone group had higher postprocedural stenosis (23% +/- 13% vs. 13% +/- 10%; P < 0. 05) and lower coronary vasodilatory reserve (2.3 +/- 0.4 vs. 2.6 +/- 0.7; P < 0.05). At follow-up (6.0 +/- 1.5 months), the angiographic restenosis rate was 39% in the angioplasty group and 35% in the stent groups (P = NS). Adverse cardiac events (unstable angina, target lesion revascularization, myocardial infarction, death) occurred in 19% and 18% (P = NS) of the angioplasty and stent patients, respectively. A prospective application of a physiologically guided provisional stent strategy for coronary angioplasty indicated that stent implantation may be required in approximately 50% of patients, an approach that produces similar clinical and angiographic long-term outcomes for stenting and guided angioplasty. These data support a role of coronary physiology as an adjunct in conducting an angioplasty procedure without obligatory stenting.

Detection of coronary artery disease using dobutamine stress echocardiography in patients with an abnormal resting electrocardiograph

PURPOSE

We assessed the value of dobutamine stress echocardiography for the detection of coronary artery disease in patients with chest pain and an abnormal resting electrocardiograph (ECG).

METHODS

Dobutamine stress echocardiography was performed in a standard fashion. Significant coronary artery disease was defined as a >50% luminal diameter stenosis on coronary angiography.

RESULTS

The sensitivity, specificity, positive and negative predictive value of dobutamine stress echocardiography for the detection of coronary artery disease in 218 patients were 89, 50, 95 and 32%, respectively. The sensitivity for detection of multi-, double- and single vessel disease were 97, 82 and 81%, respectively. The sensitivity for the detection of coronary artery disease in a subgroup of 69 patients by treadmill exercise testing was 37%.

CONCLUSION

Dobutamine stress echocardiography is better than exercise ECG for the detection of significant coronary artery disease. The negative predictive value of dobutamine stress echocardiography in this patient group is low.

Design and implementation of the United States National Animal Health Monitoring System 1995 National Swine Study

The United States Department of Agriculture's National Animal Health Monitoring System 1995 National Swine Study was designed to estimate management, health and productivity parameters on pig operations in the United States. Sixteen major swine-producing states that accounted for nearly 91% of June 1, 1995 swine inventory and nearly three-fourths of United States swine producers were included in the study. In the initial phase of the study, National Agricultural Statistics Service enumerators collected information from 1477 producers involved in all phases of swine production (farrowing, nursery, and grower/finisher). Of these, 405 operations with > or = 300 finisher pigs (with at least one finisher pig > or = 54 kg) participated in the subsequent component of the study, which involved on-farm visits by state and federal veterinary medical officers and animal health technicians, and which concentrated on the grower/finisher phase of production. Of those eligible to take part in the second phase of the study, participation was higher among independent producers (48.3%) than among contract producers (15.3%). Participation was also higher among operations that used advanced record-keeping systems (such as record cards for individual breeding hogs or a computer-based record-keeping system). Thus, study results could have been influenced by response biases. As a biosecurity measure, 40.5 +/- 2.1% of operations restricted entry to employees only. For operations that permitted non-employees to enter the premises, relatively few enforced other biosecurity measures on visitors (0.4 +/- 0.1% required feed-delivery personnel and livestock handlers to shower before entering the premises; 3.3+/- 0.9% required a footbath; and 7.0 +/- 1.5% required feed-delivery personnel and livestock handlers not to have visited another operation with pigs on that day). The most common method of waste storage (used by 49.9 +/- 3.8% of operations with > or = 300 finisher pigs) was below-floor slurry or deep pit.

Comparison of dobutamine stress echocardiography and treadmill exercise electrocardiography for detection of coronary artery disease

BACKGROUND

Critical analysis of treadmill exercise testing (TMET) for the detection of coronary artery disease has revealed many shortcomings. Excellent diagnostic accuracy has been reported for dobutamine stress echocardiography (DSE).

METHODS

A prospective comparison of DSE and TMET for the detection of coronary artery disease in routine clinical practice was performed using contrast cineangiography (significant stenosis > or = 50%) as a gold standard.

RESULTS

A total of 116 patients (82 men, 34 women) were studied. Significant stenosis was detected by coronary angiography in 92 patients (79%). Single vessel disease occurred in 28, double-vessel disease in 32, and multivessel disease in 32 patients. Although sensitivity of DSE was better than that of TMET (82 versus 40%), specificity was worse (63 versus 79%). Positive predictive values for both DSE and TMET were good at 89 and 87%, respectively, whereas negative predictive values were poor for both (47% for DSE, 26% for TMET).

CONCLUSIONS

Overall, DSE performs better than TMET in terms of sensitivity and positive and negative predictive value. Its lower specificity than that of TMET may lead to more patients being referred for diagnostic coronary angiography. The poor negative predictive value of DSE and TMET means that one should not be falsely reassured by normal results.

Dobutamine stress echocardiography in the detection of coronary artery disease in a clinical practice setting

In this prospective study, patients referred for coronary angiography for detection of disease underwent dobutamine stress echocardiography to define its value in a clinical practice setting.

RESULTS

Of 219 patients studied, 170 (78%) had significant coronary artery disease. The overall sensitivity and specificity of dobutamine stress echocardiography for coronary artery disease were 82 and 65%, respectively. The sensitivity was 88% for detection of triple-vessel disease, 83% for double-vessel disease, and 74% for single-vessel disease. Positive and negative predictive values for coronary artery disease were 89 and 51%, respectively. Dobutamine stress echocardiography correctly identified only 72 of 138 patients with significant stenosis of the left anterior descending coronary artery. In 219 patients, 345 of 657 major epicardial vessels had significant disease. Dobutamine stress echocardiography could only correctly identify the vessel involved in 188. Triple-vessel disease was present in 65 patients. Dobutamine stress echocardiography correctly categorised 18% (n = 12) of these. The remainder were incorrectly classified as having double-vessel disease or single-vessel disease (n = 45), or no disease at all (n = 8).

CONCLUSION

Dobutamine stress echocardiography performs well. However, lower specificity may lead to unwarranted referrals for coronary angiography, and the low NPV give false reassurance as to the absence of disease.

Dobutamine stress echocardiography in the detection of coronary artery disease: importance of the pretest likelihood of disease

Although the accuracy of dobutamine stress echocardiography for the detection of coronary artery disease in a high-risk population is known, it has not been well defined for lower risk groups. Two probability groups, high (>75%; n = 199) and intermediate (>10% but < or =75%; n = 118), were studied. Dobutamine stress echocardiography was performed in a standard fashion. Significant coronary artery disease was defined as a >50% luminal diameter stenosis on coronary angiography. The positive predictive accuracy of dobutamine stress echocardiography for the detection of coronary artery disease was greater in the high-probability group (96% vs 86%), as was the sensitivity (89% vs 78%), whereas the negative predictive value was greater in the intermediate-probability group (50% vs 23%), as was the specificity (63% vs 50%). Dobutamine stress echocardiography does have a diagnostic role in the evaluation of patients with an intermediate probability of coronary artery disease.

Role of coronary artery lumen enlargement in improving coronary blood flow after balloon angioplasty and stenting: a combined intravascular ultrasound Doppler flow and imaging study

OBJECTIVES

This study sought to examine the mechanism of increasing coronary flow reserve after balloon angioplasty and stenting.

BACKGROUND

Coronary vasodilatory reserve (CVR) does not improve after percutaneous transluminal coronary angioplasty in > or = 50% of patients, postulated to be due to impaired microvascular circulation or inadequate lumen expansion despite adequate angiographic results.

METHODS

To demonstrate the role of coronary lumen expansion, serial coronary flow velocity (0.014-in. Doppler guide wire) was measured in 42 patients before and after balloon angioplasty and again after stent placement. A subset (n = 17) also underwent intravascular ultrasound (IVUS) imaging of the target sites after angioplasty and stenting. CVR (velocity) was computed as the ratio of adenosine-induced maximal hyperemic to basal average peak velocity.

RESULTS

The percent diameter stenosis decreased from (mean +/- SD) 84 +/- 13% to 37 +/- 18% after angioplasty and to 8 +/- 8% after stenting (both p < 0.05). CVR was minimally changed from 1.70 +/- 0.79 at baseline to 1.89 +/- 0.56 (p = NS) after angioplasty but increased to 2.49 +/- 0.68 after stent placement (p < 0.01 vs. before and after angioplasty). IVUS lumen cross-sectional area was significantly larger after stenting than after angioplasty (8.39 +/- 2.09 vs. 5.10 +/- 2.03 mm2, p < 0.05). Anatomic variables were related to increasing coronary flow velocity reserve (CVR vs. IVUS lumen area: r = 0.47, p < 0.005; CVR vs. quantitative coronary angiographic percent area stenosis: r = 0.58, p < 0.0001).

CONCLUSIONS

In most cases, increases in CVR were associated with increases in coronary lumen cross-sectional area. These data suggest that impaired CVR after angioplasty is often related to the degree of residual narrowing, which at times may not be appreciated by angiography. A physiologically complemented approach to balloon angioplasty may improve procedural outcome.

Evaluation of patients with diabetes mellitus for coronary artery disease using dobutamine stress echocardiography

BACKGROUND

There is a high prevalence of coronary artery disease (CAD) in patients with diabetes mellitus. Detection of inducible ischaemia using treadmill exercise testing may be limited by the relatively poor inherent predictive accuracy of the test. The purpose of this study was to determine the value of dobutamine stress echocardiography (DSE) for the detection of CAD in patients with diabetes mellitus.

METHODS

Patients with diabetes mellitus referred for cardiac assessment were considered eligible for study. DSE was performed in a standard fashion. Significant CAD was defined as a > 50% luminal diameter stenosis on coronary angiography.

RESULTS

A total of 52 patients (mean age 59 years) with diabetes mellitus were studied prospectively using DSE. Risk factors for CAD included hypertension in 19, family history in 21, hypercholesterolaemia in 14, history of smoking in 38. The sensitivity, specificity, positive and negative predictive values of DSE for detection of CAD were 82, 54, 84 and 50% respectively.

CONCLUSION

The specificity of DSE for CAD in patients with diabetes mellitus is low. Whether this reflects an underdetection of small vessel disease by contrast coronary angiography or whether it relates to test performance is unclear.

Safety of dobutamine stress echocardiography in 474 consecutive studies

BACKGROUND

With expanding applications and increasingly aggressive stress protocols, concerns about the safety of dobutamine stress echocardiography (DSE) have arisen. The purpose of this study was to analyse prospectively the safety, adverse event profile and complication rate of DSE.

METHODS

Prospective data were recorded in a consecutive series of 474 patients undergoing DSE. Dobutamine was administered intravenously in graded infusion, each stage over 3 min, at 10, 20, 40 and, if required, 50 micrograms/kg/min. Atropine (1 mg) was administered thereafter if the response remained suboptimal.

RESULTS

The mean dose of dobutamine was 42 micrograms/kg/min, with 111 patients (23%) receiving 50 micrograms/kg/min. Atropine was required for 27 patients (6%). No patient died or suffered a myocardial infarction. Sustained ventricular tachycardia occurred in one patient, angina pectoris in 127 (27%), non-sustained ventricular tachycardia in eight (2%) and supraventricular tachycardia in 19 (4%). Profound bradycardia requiring cessation of the test occurred in one patient. Pulmonary oedema developed in one patient. A hypotensive response requiring cessation of the test was seen in one patient. Test termination because the patient complained of nausea, tremor or headache was not required.

CONCLUSION

DSE is safe. Side effects are rare and when they occur, are usually minor. Ischaemic pain is effectively treated by termination of the test and sublingual administration of nitrates.