Efficacy and safety of inclisiran in patients with established cerebrovascular disease: pooled, post hoc analysis of the ORION-9, ORION-10 and ORION-11, phase 3 randomised clinical trials

Background

Patients (pts) with hyperlipidaemia and established cerebrovascular disease (CeVD) are at an increased risk of future strokes or other cardiovascular events.[1] In ischaemic stroke survivors, statins and inhibitors of proprotein convertase subtilisin-kexin type 9 (PCSK9) reduce recurrent cardiovascular events including stroke.[2–4] With guidelines increasingly advocating lower LDL-C goals, add-on lipid lowering therapies to statins may be needed. Inclisiran, a first-in-class small interfering RNA (siRNA) targeting PCSK9 messenger RNA, when added to maximally tolerated statin therapy, may provide further LDL-C lowering with a convenient, infrequent dosing schedule in pts with established CeVD.

Purpose

To assess efficacy and safety of inclisiran in pts with established CeVD.

Methods

Pts with HeFH, ASCVD or its risk equivalents from ORION-9 (NCT03397121]), ORION-10 (NCT03399370), and ORION-11 (NCT03400800) were randomised 1:1 to receive inclisiran sodium 300 mg (equivalent to 284 mg inclisiran) or placebo (pbo) at Days 1, 90 and 6-monthly thereafter to Day 540. This post hoc analysis included pts with established CeVD (ischaemic stroke, and/or carotid artery stenosis by angiography or ultrasound >70%, and/or prior percutaneous or surgical carotid artery revascularisation). Percentage LDL-C change from baseline to Day 510 and corresponding time-averaged percentage change from baseline after Day 90 to Day 540 were evaluated. Safety was assessed over 540 days.

Results

Of 202 pts with established CeVD, 110 and 92 received inclisiran and pbo, respectively. At baseline, 90.0% (99/110) of pts in inclisiran and 84.8% (78/92) in pbo group reported prior ischaemic stroke(s); others had carotid artery stenosis and/or carotid revascularisation (Table 1). Mean (95% CI) pbo-corrected LDL-C percentage change from baseline at Day 510 with inclisiran was −55.2% (−64.5 to −45.9); corresponding time-averaged change from baseline after Day 90 to Day 540 was −55.2% (−62.4 to −47.9) (P<0.0001 for each; Table 2). Treatment-emergent adverse event (TEAE) and treatment-emergent serious adverse event (TESAE) were more frequent in the inclisiran vs pbo group but were consistent with the overall pooled (N=3655) population of the combined trials. Clinically relevant TEAEs at the injection site were reported more frequently with inclisiran (3.6% [4/110]) vs pbo (0% [0/92]), but none were severe. Percentage of pts with clinically relevant laboratory measurements was low and similar between treatment groups and consistent with the overall pooled population (Table 2).

Conclusions

In pts with established CeVD, a twice-yearly dosing with inclisiran (after the initial and 3-month doses) provided sustained additional LDL-C reduction of ∼55%. A modest excess of mild/moderate TEAEs at the injection site were reported with inclisiran. The cardiovascular benefits of inclisiran among patients with established CeVD are being evaluated in ongoing trials.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Novartis Pharma AG, Basel, Switzerland.

Efficacy and safety of inclisiran in patients with polyvascular disease: pooled, post hoc analysis of the ORION-9, ORION-10 and ORION-11, phase 3 randomised controlled trials

Background

Approximately 25% of patients (pts) with atherosclerotic cardiovascular disease (ASCVD) have polyvascular disease (PVD), which involves ≥2 coronary, cerebrovascular, and peripheral artery beds. PVD is an independent predictor of major adverse cardiovascular (CV) events (MACE) and death.[1,2] Agents that inhibit proprotein convertase subtilisin-kexin type 9 (PCSK9) resulted in reduced low-density lipoprotein cholesterol (LDL-C) concentration and MACE incidence in pts with PVD.[3,4] Inclisiran is a small interfering RNA (siRNA) agent targeting PCSK9 messenger RNA that provided effective and sustained reduction in LDL-C concentration and was well tolerated.[5]

Purpose

To describe the effect inclisiran versus placebo (pbo) in pts with and without PVD.

Methods

This was a post hoc analysis from the ORION-9 (NCT03397121), ORION-10 (NCT03399370) and ORION-11 (NCT03400800) trials. Pts with heterozygous familial hypercholesterolaemia, ASCVD or risk equivalents were randomised 1:1 to receive 300 mg inclisiran sodium (equivalent to 284 mg inclisiran) or pbo at baseline, Day 90, and 6-monthly thereafter. LDL-C percentage change from baseline to Day 510 and corresponding time-averaged change from Day 90 and to Day 540 were evaluated by presence or absence of PVD (intention-to-treat population). Safety was assessed over 540 days (safety population).

Results

Of 3454 pts, 470 (13.6%) had PVD and 2984 (86.4%) did not. Baseline characteristics were generally balanced between treatment arms in both groups (Table 1). A greater proportion of pts with vs without PVD had CV risk factors at baseline. Mean LDL-C concentration at baseline was lower in pts with vs without PVD (Table 1). Mean (95% CI) pbo-corrected LDL-C percentage change from baseline to Day 510 with inclisiran was −48.9 (−55.6 to −42.2) in pts with PVD and −51.5 (−53.9 to −49.1) in pts without PVD (Table 2). Proportions of pts with treatment-emergent adverse events (TEAE) and treatment-emergent serious adverse events (TESAE) were similar between treatment arms irrespective of PVD status although reported TESAEs were numerically greater in both treatment arms for pts with PVD (Table 2). Clinically relevant TEAEs at the injection site were reported more frequently with inclisiran vs pbo in both groups but all were mild or moderate (Table 2). Proportions of pts with clinically relevant laboratory measurements were low and similar between treatment arms for both groups (Table 2).

Conclusions

Twice-yearly dosing with inclisiran (after the initial and 3-month doses) provided effective and sustained LDL-C lowering in pts, irrespective of their PVD status, with a safety profile similar to pbo, except for a modest excess of mainly mild TEAEs at the injection site. Notably, TESAEs were reported more frequently in pts with PVD, which was likely due to their more advanced disease. Since pts with PVD are at high risk of CV events, intensive LDL-C lowering may be beneficial to reduce this risk.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Novartis Pharma AG, Basel, Switzerland

4945Inclisiran-mediated reductions in Lp(a) in the ORION-1 trial

Background

PCSK9 inhibitors and statins both lower LDL-C by increasing LDL-receptor (LDLR) function. PCSK9 inhibitors lower Lp(a) by 20–30%, whereas statins do not lower Lp(a). The mechanism by which PCSK9 inhibitors lower Lp(a) is unclear. We assessed the role of the LDLR in Lp(a) reductions produced by inclisiran, an siRNA which prevents hepatic synthesis of PCSK9.

Methods

ORION-1 was a phase 2 trial of inclisiran in subjects at high ASCVD risk with elevated LDL-C on optimized statin therapy. Subjects received one dose of inclisiran (200, 300, or 500 mg) or two doses at days 1 and 90 (100, 200, or 300 mg). We assessed the correlations between % change in Lp(a) and LDL-C at Day 180 for the inclisiran groups using Spearman correlation coefficients. We additionally assessed the correlation between % change in Lp(a) and absolute change in LDL-C as a proxy for LDLR expression. Lp(a) was measured using an isoform-independent assay and LDL-C with β-quantification.

Results

ORION-1 included 501 subjects; mean age 63; 65% male; 73% on statins. Median baseline Lp(a) was 37.0 nmol/l (IQR: 11.5–142.0 nmol/l), median LDL-C was 117.0 (IQR: 92.5–149.5 mg/dL). Inclisiran dose-dependently lowered Lp(a) by 14% to 26%. Overall, there was a significant but weak correlation between % change in Lp(a) LDL-C (Spearman coefficient 0.35, p<0.001). This correlation appeared to be stronger at higher inclisiran doses and with repeat dosing (table), as well as in statin-users versus non-users (Spearman coefficient 0.37 vs. 0.21). The correlation between % Lp(a) change and absolute LDL-C change was weaker (0.27, p<0.001).

Correlation coefficients LDL-C – Lp(a) Single-dose groups Two-dose groups Inclisiran overall 200 mg (n=60) 300 mg (n=60) 500 mg (n=60) 100 mg (n=59) 200 mg (n=60) 300 mg (n=59) Lp(a) ∼ % change LDL-C 0.22 0.26 0.22 0.29 0.47 0.51 0.35 Lp(a) ∼ absolute change LDL-C 0.35 0.12 0.04 0.22 0.45 0.24 0.27 Lp(a) ∼ % change LDL-C - Statin users 0.16 0.28 0.28 0.31 0.45 0.55 0.37 Lp(a) ∼ % change LDL-C - Non statin users 0.80 -0.08 0.09 0.10 0.63 0.09 0.21

Conclusion

The dose-dependent correlation between % changes in LDL-C and Lp(a) suggests that the LDLR may be partially responsible for Lp(a) reductions produced by inclisiran. The numerically stronger correlation in statin-users supports the idea that LDL-C may compete with Lp(a) for LDLR binding especially at low LDL-C levels.

Acknowledgement/Funding

The Medicines Company

Multiple Influences on Cognitive Function Among Urban-Dwelling African Americans

This study examined multiple influences on cognitive function among African Americans, including education, literacy, poverty status, substance use, depressive symptoms, and cardiovascular disease (CVD) risk factors. Baseline data were analyzed from the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study. Participants were 987 African Americans (mean age 48.5 years, SD = 9.17) who completed cognitive measures assessing verbal learning and memory, nonverbal memory, working memory, verbal fluency, perceptuo-motor speed, attention, and cognitive flexibility. Using preplanned hierarchical regression, cognitive performance was regressed on the following: (1) age, sex, education, poverty status; (2) literacy; (3) cigarette smoking, illicit substance use; (4) depressive symptoms; and (5) number of CVD risk factors. Results indicated that literacy eliminated the influence of education and poverty status in select instances, but added predictive utility in others. In fully adjusted models, results showed that literacy was the most important influence on cognitive performance across all cognitive domains (p < .001); however, education and poverty status were related to attention and cognitive flexibility. Depressive symptoms and substance use were significant predictors of multiple cognitive outcomes, and CVD risk factors were not associated with cognitive performance. Overall, findings underscore the need to develop cognitive supports for individuals with low literacy, educational attainment, and income, and the importance of treating depressive symptoms and thoroughly examining the role of substance use in this population.

Perceived Control Predicts Pulse Pressure in African American Men: The Baltimore Study of Black Aging

OBJECTIVE

Poorer health profiles among African American men throughout the life course evince greater rates of cardiovascular disease (CVD) and significantly earlier mortality compared with other groups. Despite growing emphasis on identifying how psychosocial factors influence disparate disease risk, little of this research has focused intently on African American men.

METHODOLOGY

Using hierarchical linear regression, we explored the additive influence of stress, depression, and perceived control on pulse pressure, an established marker of CVD risk, in a sample (N = 153) of African American men (mean age = 66.73 ± 9.29) from the Baltimore Study of Black Aging (BSBA).

RESULTS

After accounting for age and health status indicators, perceived control emerged as a significant predictor of pulse pressure.

DISCUSSION

These findings suggest that greater belief in one's own efficacy is a protective factor for cardiovascular health among African American men. Future research should examine whether enhancing perceived control can have an appreciable impact on the immense CVD burden in this and other at-risk populations.

Fasting glucose and glucose tolerance as potential predictors of neurocognitive function among nondiabetic older adults

INTRODUCTION

Significant evidence has demonstrated that Type 2 diabetes mellitus and related precursors are associated with diminished neurocognitive function and risk of dementia among older adults. However, very little research has examined relations of glucose regulation to neurocognitive function among older adults free of these conditions. The primary aim of this investigation was to examine associations among fasting glucose, glucose tolerance, and neurocognitive function among nondiabetic older adults. The secondary aim was to examine age, gender, and education as potential effect modifiers.

METHOD

The study employed a cross-sectional, correlational study design. Participants were 172 older adults with a mean age of 64.43 years (SD = 13.09). The sample was 58% male and 87% White. Participants completed an oral glucose tolerance test as part of a larger study. Trained psychometricians administered neuropsychological tests that assessed performance in the domains of response inhibition, nonverbal memory, verbal memory, attention and working memory, visuoconstructional abilities, visuospatial abilities, psychomotor speed and executive function, and motor speed and manual dexterity. Linear multiple regressions were run to test study aims.

RESULTS

No significant main effects of fasting glucose and 2-hour glucose emerged for performance on any neurocognitive test; however, significant interactions were present. Higher fasting glucose was associated with poorer short-term verbal memory performance among men, but unexpectedly better response inhibition and long-term verbal memory performance for participants over age 70. Higher 2-hour glucose values were associated with reduced divided attention performance among participants with less than a high school education.

CONCLUSIONS

Mixed findings suggest that glucose levels may be both beneficial and deleterious to neurocognition among nondiabetic older adults. Additional studies with healthy older adults are needed to confirm this unexpected pattern of associations; however, findings have implications for the importance of maintaining healthy glucose levels in older adulthood.

The Combined Influence of Psychological Factors on Biomarkers of Renal Functioning in African Americans

OBJECTIVE

African Americans are disproportionately affected by chronic kidney disease (CKD). Recent research has documented that psychological-factors have a significant influence on the progression and treatment of CKD. However, extant evidence exists that has examined the link between psychological factors and renal function in African Americans. The purpose of the study was to determine if psychological factors were associated with several biomarkers of renal functioning in this group.

PARTICIPANTS

129 African American participants, with a mean age of 44.4 years (SD = 12.25).

DESIGN AND SETTING

Data were analyzed from a cross-sectional study entitled Stress and Psychoneuroimmunological Factors in Renal Health and Disease. MAIN PREDICTOR MEASURES: Participants completed the Beck Depression Inventory-II, Cook Medley Scale, and Perceived Stress Scale-10.

MAIN OUTCOME MEASURES

Systolic blood pressure, as well as blood and urine samples, were collected and served as biomarkers of renal functioning.

RESULTS

Our findings indicated that psychological factors were not associated with renal functioning. Age, sex, and systolic blood pressure emerged as significant predictors of renal functioning.

CONCLUSIONS

Depressive symptomatology, perceived stress, and hostility did not influence renal functioning in this sample. This unexpected finding may be attributed to the fact that this sample population was not elevated on depressive symptoms, perceived stress, or hostility. Elevated levels of these psychological factors, as well as other psychological factors associated with the CKD, may be more influential on renal functioning in African Americans.

Low-dose nesiritide in human anterior myocardial infarction suppresses aldosterone and preserves ventricular function and structure: a proof of concept study

BACKGROUND

B-type natriuretic peptide (BNP, nesiritide) has anti-fibrotic, anti-hypertrophic, anti-inflammatory, vasodilating, lusitropic and aldosterone-inhibiting properties but conventional doses of BNP cause hypotension, limiting its use in heart failure.

OBJECTIVE

To determine whether infusion of low-dose BNP within 24 h of successful reperfusion for anterior acute myocardial infarction (AMI) would prevent adverse left ventricular (LV) remodelling and suppress aldosterone.

METHODS

A translational proof-of-concept study was carried out to determine tolerability and biological activity of intravenous BNP at 0.003 and 0.006 microg/kg/min, without bolus started within 24 h of successful reperfusion for anterior AMI. 24 patients with first anterior wall ST elevation AMI and successful revascularisation were randomly assigned to receive 0.003 (n = 12) or 0.006 (n = 12) microg/kg/min of IV BNP for 72 h in addition to standard care during hospitalisation for anterior AMI.

RESULTS

Baseline characteristics, drugs and peak cardiac biomarkers for myocardial damage were similar between both groups. Infusion of BNP at 0.006 microg/kg/min resulted in greater biological activity than infusion at 0.003 microg/kg/min as measured by higher mean (SEM) plasma cGMP levels (8.6 (1) vs 5.5 (1) pmol/ml, p<0.05) and suppression of plasma aldosterone (8.0 (2) to 4.6 (1) ng/dl, p<0.05), which was not seen in the 0.003 microg/kg/min group. LV ejection fraction (LVEF) improved significantly from baseline to 1 month (40 (4)% to 54 (5)%, p<0.05) in the 0.006 group but not in the 0.003 group. Infusion of BNP at 0.006 microg/kg/min was associated with a decrease of LV end-systolic volume index (61 (9) to 43 (8) ml/m(2), p<0.05) at 1 month, which was not seen in the 0.003 group. No drug-related serious adverse events occurred in either group.

CONCLUSIONS

72 h infusion of low BNP at the time of anterior AMI is well tolerated and biologically active. Patients treated with low-dose BNP had improved LVEF and smaller LV end-systolic volume at 1 month.

Improved survival after acute myocardial infarction in patients with advanced Killip class

BACKGROUND

The continuing applicability of the Killip classification system to the effective stratification of long-term and short-term outcome in patients with acute myocardial infarction (MI) and its influence on treatment strategy calls for reanalysis in the setting of today's primary reperfusion treatments.

HYPOTHESIS

Our study sought to test the hypothesis that Killip classification, established on admission in patients with acute MI, is an effective tool for early prediction of in-hospital mortality and long-term survival.

METHODS

A series of 909 consecutive Olmsted County patients admitted with acute MI to St. Marys Hospital, Mayo Clinic, between January 1988 and March 1998 was analyzed. Killip classification was the primary variable. Endpoints were in-hospital death, major in-hospital complications, and post-hospital death.

RESULTS

Patients analyzed included 714 classified as Killip I, 170 classified as Killip II/III, and 25 classified as Killip IV. Increases in in-hospital mortality and prevalence of in-hospital complications correspond significantly with advanced Killip class (p < 0.01), with in-hospital mortality 7% in class I, 17.6% in classes II/III, and 36% in class IV patients (p < 0.001). Killip classification was strongly associated with mode of therapy administered within 24 h of admission (p < 0.01). Killip IV patients underwent primary angioplasty most commonly and were less likely to receive medical therapy.

CONCLUSIONS

Killip classification remains a strong independent predictor of in-hospital mortality and complications, and of long-term survival. Early primary angioplasty has contributed to a decrease in mortality in Killip IV patients, but effective adjunctive medical therapy is underutilized.

Obesity is associated with premature occurrence of acute myocardial infarction

BACKGROUND

The American Heart Association has classified obesity as a major modifiable risk factor for coronary artery disease, but its relationship with age at presentation with acute myocardial infarction (AMI) is poorly documented.

HYPOTHESIS

The study was undertaken to evaluate the impact of obesity on age at presentation, and on in-hospital morbidity and mortality in patients with AMI.

METHODS

Our analysis includes a consecutive series of 906 Olmsted County patients (mean age 67.7 years, 51% male) admitted with AMI to the Mayo Clinic Coronary Care Unit (CCU). The patients were entered into the Mayo CCU Database, a prospective registry of data pertaining to patients admitted to the Mayo Clinic CCU with AMI. Age at AMI occurrence and in-hospital morbidity and mortality were noted.

RESULTS

Obese patients (body mass index [BMI] >30) with AMI were significantly younger than patients with AMI in the overweight (BMI 25-30) and normal-weight (BMI < 30) groups (62.3+/-13.1 vs. 66.9+/-13.2 and 72.9+/-13.4, respectively. p < 0.001). Obesity and overweight status were associated with male gender, diabetes mellitus, hypercholesterolemia, and smoking history; however, after multivariate adjustment for these risk factors, excess weight and premature AMI remained significantly associated. Compared with normal-weight patients, overweight patients presenting with AMI were 3.6 years younger (p < 0.001, confidence interval [CI] 1.9-5.4) and obese patients 8.2 years younger (p < 0.001, Cl 6.2-10.1). No significant increase in in-hospital morbidity and mortality was seen.

CONCLUSION

In this population-based study, overweight and obese status are independently associated with the premature occurrence of AMI, but not with an increased incidence of in-hospital complications.

A new simplified immediate prognostic risk score for patients with acute myocardial infarction

BACKGROUND

Immediate risk stratification of patients with myocardial infarction in the emergency department (ED) at the time of initial presentation is important for their optimal emergency treatment. Current risk scores for predicting mortality following acute myocardial infarction (AMI) are potentially flawed, having been derived from clinical trials with highly selective patient enrollment and requiring data not readily available in the ED. These scores may not accurately represent the spectrum of patients in clinical practice and may lead to inappropriate decision making.

METHODS

This study cohort included 1212 consecutive patients with AMI who were admitted to the Mayo Clinic coronary care unit between 1988 and 2000. A risk score model was developed for predicting 30 day mortality using parameters available at initial hospital presentation in the ED. The model was developed on patients from the first era (training set--before 1997) and validated on patients in the second era (validation set-during or after 1997).

RESULTS

The risk score included age, sex, systolic blood pressure, admission serum creatinine, extent of ST segment depression, QRS duration, Killip class, and infarct location. The predictive ability of the model in the validation set was strong (c = 0.78).

CONCLUSION

The Mayo risk score for 30 day mortality showed excellent predictive capacity in a population based cohort of patients with a wide range of risk profiles. The present results suggest that even amidst changing patient profiles, treatment, and disease definitions, the Mayo model is useful for 30 day risk assessment following AMI.

Strong predictive value of TIMI risk score analysis for in-hospital and long-term survival of patients with right ventricular infarction

BACKGROUND

While right ventricular myocardial infarction is associated with increased in-hospital morbidity and mortality, prognostic risk factors for in-hospital and long-term mortality are poorly defined.

OBJECTIVES

To evaluate the prognostic value of TIMI (Thrombolysis in Myocardial Infarction) risk score analysis in patients with right ventricular myocardial infarction (RVI).

DESIGN

Retrospective analysis of a community population.

SETTING

Mayo Clinic Coronary Care Unit.

PATIENTS

One hundred and two patients with RVI from 580 consecutive patients from Rochester, Minnesota admitted to the Coronary Care Unit with acute inferior or lateral wall myocardial infarction from January 1988 through March 1998.

MEASUREMENT

Combined TIMI risk score analysis with in-hospital and long-term mortality.

RESULTS

In-hospital morbidity (RVI: 54.9% vs non-RVI: 22.2%; P<0.001) and mortality (RVI: 21.6% vs non-RVI: 6.9%;P <0.001) were increased in patients with RVI. The TIMI risk score predicted risk (per one point increase in TIMI score) for in-hospital mortality (OR 1.23, 95% CI 1.02-1.51, P=0.037) and long-term mortality (OR 1.57, 95% CI 1.25-1.96, P<0.001). Patients with RVI whose TIMI risk score was >or=4 had significantly worse long-term survival compared to those patients with RVI and TIMI score <4 (P=0.006).

CONCLUSIONS

In-hospital morbidity and mortality, and long-term mortality are increased by right ventricular infarction and can be accurately predicted by the initial TIMI risk score.

A new method to incorporate age and gender into the criteria for the detection of acute inferior myocardial infarction

Recent studies have shown that younger women are more likely to die during and after hospitalization for acute myocardial infarction (MI) than older women and men of all ages. This may be partly due to incorrect diagnosis or late detection of acute MI in younger women. At high specificity levels (>98%), the sensitivity of the initial ECG to detect acute MI may be as low as 30% when using traditional criteria by both physicians and computerized interpretation programs. This study examines if women of different age groups have a similar ECG presentation to men during acute inferior MI and if the diagnostic accuracies of the initial ECG are comparable. We analyzed chest pain ECGs from Mayo Clinic and Medical College of Wisconsin, which included 1,339 patients with acute inferior MI and 1,169 age-matched controls with noncardiac chest pain. We subdivided all groups by age (below and above 60 years) and compared ECG parameters (ST elevation, ST depression, QRS duration, R-wave amplitude, Q-wave duration and amplitude, QT interval) between genders. For inferior MI patients under age 60, women had lower ST elevations at the J point in lead II than men (57 +/- 91 microV vs. 86 +/- 117 microV, P < .02). This trend was reversed for patients over age 60 (lead a VF: 102 +/- 126 microV vs. 84+/-117 microV, P < .04; Lead III: 130+/-146 microV vs. 103+/-131 microV, P < .007). A neural network method was used to identify the most significant group of ECG parameters for detecting acute MI. An adaptive fuzzy logic method was developed for adapting to the threshold differences among the different gender and age groups. The new algorithm improved the sensitivity of acute inferior MI detection by more than 25% relative to old algorithm, while maintaining the high specificity around 98% for noncardiac chest pain patients.

Impact of community-based education on health care evaluation in patients with acute chest pain syndromes: the Wabasha Heart Attack Team (WHAT) project

BACKGROUND

Community education programmes focused on raising public awareness of the symptomatology of acute coronary syndromes have had mixed results.

OBJECTIVES

The Wabasha Heart Attack Team project, a unique multidisciplinary public education effort in Minnesota, sought to educate area citizens about signs and symptoms of acute myocardial infarction (MI).

METHODS

After an intensive 1-month education period, we compared presentations for emergency evaluation of chest pain during the study period with baseline data from the same seasonal period of the preceding year.

RESULTS

Visits to the Emergency Room for symptomatic heart disease increased significantly during the study period (56 patients versus 46 patients during the baseline period), as did the percentage of patients presenting with acute MI (18% versus 12%, P < 0.05). Use of emergency medical services for pre-hospital evaluation was significantly increased (41% versus 27%, P < 0.05).

CONCLUSION

A community education campaign can significantly increase use of pre-hospital emergency medical service resources and may increase the number of patients presenting with acute chest pain symptoms, including MI.

Bundle branch block as a predictor of long-term survival after acute myocardial infarction

Using a community-based population of patients with acute myocardial infarction (AMI), we sought to: (1) determine the prevalence of bundle branch block (BBB) on the presenting electrocardiogram (ECG), (2) compare the clinical characteristics and the treatment administered to patients with and without BBB, and (3) determine the association of BBB with mortality. We analyzed the admission ECGs of 894 consecutive patients with AMI from Olmsted County, Minnesota, seen at our institution from January 1988 to March 1998. Of these, 53 had left BBB (LBBB) (5.9%) and 60 had right BBB (RBBB) (6.7%). Patients with BBB were more likely to be older, have a history of AMI or hypertension, and to be in Killip class >I at presentation. They were less likely to receive primary reperfusion therapy, beta blockers, or heparin, but more likely to receive angiotensin-converting enzyme inhibitors. They had lower mean predischarge ejection fractions (38 +/- 16% vs 50 +/- 15%, p <0.0001). In-hospital mortality was 13.3%, 17.0%, and 9.1% for patients with RBBB, LBBB, and no BBB, respectively (p = 0.11). Respective postdischarge survival at 1, 3, and 5 years was 80%, 60%, and 50% in the RBBB group, 78%, 56%, and 51% in the LBBB group, and 92%, 85%, and 76% in the group without BBB (p <0.0001). Although BBB was not an independent predictor of mortality on multivariate analysis, the presence of transient or persistent BBB with AMI is an easily recognized clinical marker of increased mortality. Our conclusion from this study is that in a community-based population, patients who had LBBB or RBBB at the time of AMI had lower predischarge ejection fractions and higher in-hospital and long-term unadjusted mortality.

Annual recertification program for audit standards used in the EPA PM2.5 Performance Evaluation Program

This paper describes procedures used to perform 152 annual recertifications of temperature, pressure, and flow rate audit standards. It discusses the metrology laboratories and the uncertainty of their recertifications. It describes the data base for the standards that tracks their recertifications and shipments. Finally, it presents some illustrative recertification results and describes what these results reveal about the audit standards and the recertifications.

Length of stay in myocardial infarction

OBJECTIVE

We evaluated the association between length of hospital stay (LOS) and clinical factors, treatment intensity, and use of percutaneous coronary revascularization from 1988 to 1997.

BACKGROUND

Multiple factors contribute to the observed reduction in LOS for patients with myocardial infarction.

METHODS

We studied a series of 849 consecutive patients admitted with acute myocardial infarction to the Mayo Clinic Coronary Care Unit within three time periods: period I (1988-1990), period II (1991-1993), and period III (1994-1997).

RESULTS

Median LOS decreased significantly between 1988 and 1997 (9 days to 5 days, 36% reduction, p < 0.0001), with significant reductions (p < 0.001) associated with certain therapies: primary reperfusion (6 days vs 7 days), b-blockers (6 days vs 8 days), and aspirin (6 days vs 8 days). Hospitalizations were lengthened by coronary artery bypass grafting (12 vs 6 days) and by serious complications (10 vs 6 days). The era of the admission (period I vs II vs III) is a significant, powerful predictor of LOS, even after adjustment for other key variables.

CONCLUSION

The 36% reduction in LOS for acute myocardial infarction between 1988 and 1997 is related both to therapeutic modalities and temporal trends. Further study is needed to clarify whether the trend for decreasing LOS persists and influences outcome and health care quality variables.

False-negative and false-positive ECG diagnoses of Q wave myocardial infarction in the presence of right bundle-branch block

Right bundle-branch block (RBBB) has not traditionally been seen as an obstacle to ECG diagnosis of Q wave myocardial infarction (MI)--in clinical electrocardiography and vectorcardiography--because this conduction disturbance is not believed to cause significant alterations in the spatial orientation of initial excitation wavefronts. In the era of large-scale clinical trials, however, where serial ECG analysis is among the major diagnostic tools in MI classification, both false-positive and false-negative diagnoses of MI in the presence of RBBB have become increasingly evident. Because of the limited detectability of Q wave MI by ECG in the presence of RBBB, the electrocardiographic finding of Q wave MI should not be regarded as an independent diagnostic tool. It is best to utilize independent corroboration to establish the diagnosis of transmural infarction when RBBB is present. Further investigations are warranted to better delineate sensitivity, specificity, and predictive value of Q wave MI in the presence of RBBB.

Characteristics of presenting electrocardiograms of acute myocardial infarction from a community-based population predict short- and long-term mortality

To investigate the relevance of presenting electrocardiographic (ECG) patterns to short- and long-term mortality in nonreferral patients with acute myocardial infarction (AMI), 6 ECG patterns were analyzed. A consecutive series of 907 patients from Olmsted County, Minnesota, admitted to the Mayo Clinic Cardiac Care Unit from January 1, 1988 to March 31, 1998 for acute myocardial infarction comprised the study population. ECG patterns and distribution in the population were: (1) ST elevation alone (20.8%), (2) ST elevation with ST depression (35.2%), (3) normal or nondiagnostic electrocardiograms (18.5%), (4) ST depression alone (11.8%), (5) T-wave inversion only (10.7%), and (6) new left bundle branch block (LBBB) (3.0%). Seven- and 28-day mortalities varied significantly (p <0.01) among the 6 ECG groups. Respective mortalities were 3.0% and 6.0% for patients with normal or nondiagnostic electrocardiograms, 3.1% and 5.2% for T-wave inversion only, 7.4% and 10.6% for ST elevation alone, 9.4% and 13.1% for ST depression alone, 10.3% and 13.8% for ST elevation with ST depression, and 18.5% and 22.2% for new LBBB. Length of hospital stay (LOS) also varied among the ECG pattern groups (p <0.001) with the longest average LOS being in the new LBBB group (12.5 days). Long-term survival was similar among 5 ECG pattern groups (45% to 55% at 8 years from discharge) with the exception of LBBB (20% at 8 years). Among non-LBBB groups, ST-segment depression with or without ST elevation was associated with increased short-term mortality. Also, in this community-based population, 18.5% of patients had normal or nondiagnostic electrocardiograms.

Idiopathic short QT interval: a new clinical syndrome?

In this first clinical report of an idiopathic familial persistently short QT interval (QTI), we describe three members of one family (a 17-year-old female, her 21-year-old brother, and their 51-year-old mother) demonstrating this ECG phenomenon, associated in the 17-year-old with several episodes of paroxysmal atrial fibrillation requiring electrical cardioversion. Similar ECG changes seen in an unrelated 37-year-old patient were associated with sudden cardiac death. Our report also describes other manifestations of abnormal shortening of the QTI and considers the possible arrhythmogenic potential of the short QTI.

Effect of concomitant or very early statin administration on in-hospital mortality and reinfarction in patients with acute myocardial infarction

In a retrospective analysis, 66 patients identified as having received a statin drug within 24 hours of admission for acute myocardial infarction were matched 3:1 with a control group of 198 patients not treated with a statin agent. End points of in-hospital mortality and in-hospital reinfarction were significantly lower in the statin-treated group, pointing to a benefit from very early statin treatment in acute myocardial infarction.

Exercise-induced ST segment elevation in Q wave leads in postinfarction patients: defining its meaning and utility in today's practice

Most attempts to identify qualitative and quantitative techniques for assessing myocardial viability and the likelihood of improved function after revascularization in patients with healed myocardial infarcts have focused on treatment strategies and prognosis. This review examines the true value of the electrocardiographic phenomenon of exercise-induced ST segment elevation (EISTE) in Q wave leads as a diagnostic tool for the assessment of myocardial viability. The prognostic potential and clinical utility of the EISTE phenomenon are inhibited both by the heart's electrophysiologic response to exercise-induced metabolic and hemodynamic changes, and by the ECG's limited facility in assessing myocardial preservation. The use of EISTE as an independent indicator for surgical intervention is proscribed by these limitations. The EISTE phenomenon could serve as a useful tool in the first line of discrimination in patients with healed Q wave myocardial infarction, and may justify further diagnostic work-up in patients under consideration for a revascularization procedure. In the era of sophisticated nuclear and echo techniques, accurate imaging studies should not be replaced by ECG analysis alone in the search for viable tissue, except when financial costs are of major importance.

Update on intravenous fibrinolytic therapy for acute myocardial infarction

Intravenous fibrinolytic therapy is used widely in the treatment of ST-elevation acute myocardial infarction. Advances in this therapeutic modality during the past 5 years include new third-generation fibrinolytic agents and creative strategies to enhance administration and efficacy of fibrinolytic therapy. Several of the new agents allow for single- or double-bolus injection. A number of ongoing large randomized trials are attempting to determine whether the combination of fibrinolytic therapy with low-molecular-weight heparin or a glycoprotein IIb/IIIa antagonist enhances coronary reperfusion and reduces mortality and late reocclusion. One large prospective trial is investigating the potential benefit of prehospital administration of fibrinolytic therapy. This article summarizes recent safety and efficacy data on fibrinolytic therapy, with particular emphasis on the new third-generation fibrin-specific agents; reviews the preliminary data on facilitated fibrinolysis; and discusses the rationale for prehospital administration of fibrinolytic therapy.

Cardiac catheterization reduces resource utilization in patients with chronic chest pain

The evaluation of patients with recurrent chest pain accounts for a significant proportion of the $274 billion annual cost of cardiovascular services in the United States. Our investigation examines the impact of coronary angiography on subsequent use of medical resources for evaluation of chest pain symptoms. The study seeks to determine whether a finding of noncritical coronary artery disease on cardiac catheterization leads to a reduced use of resources for subsequent evaluation and treatment of chest pain syndromes. Our study included 22 consecutive patients who had sought evaluation for chest pain symptoms, and who had persistence of symptoms after functional testing. Cardiac catheterization demonstrated angiographically mild coronary artery disease (stenosis less than 50%) in these patients. The patient cohort accounted for 22 emergency room evaluations and 41 ambulatory clinic evaluations in the 2.5 years before cardiac catheterization. In the 2.5-year period after catheterization, these patients had only 3 emergency room visits and 1 ambulatory clinic visit for chest pain evaluation (P < 0.001). There was a significant reduction in the number of prescriptions written for topical and oral nitrates (32% precatheterization vs. 5% postcatheterization, P < 0.04), but not of beta-blockers (26% vs. 21%, P = 0.53) or calcium blockers (32% vs. 32%, P = 1.0). Furthermore, most of the 21 surviving patients were found subsequently to have a noncardiac basis for their pain: pericarditis was felt to be the cause of chest pain in 4 patients, pulmonary disease in 7 patients, and gastrointestinal conditions in 8 patients. Diagnostic coronary arteriography may identify a subset of patients in whom a finding of noncritical coronary artery disease leads to a reduction in physician visits for evaluation of chest pain syndromes and reduced use of nitrates. In addition, when coronary artery disease is known to be mild, a noncardiac etiology for the chest pain can be sought. These results may decrease the use of expensive medical resources and encourage full occupational and lifestyle rehabilitation.

Hypersensitivity pneumonitis from Pezizia domiciliana. A case of El Niño lung

A previously healthy woman developed severe dyspnea and was found to have restrictive lung disease and evidence of alveolitis. Open lung biopsy revealed extrinsic allergic alveolitis (hypersensitivity pneumonitis). The etiology was not initially apparent, but a home inspection showed an unusual mushroom growing in the patient's basement. Air sampling and serum precipitins against the fungal antigens confirmed that Pezizia domiciliana was the cause of the patient's hypersensitivity pneumonitis. This is the first described case of hypersensitivity pneumonitis cause by P. domiciliana. We speculate that unprecedented rainfall and flooding of the patient's basement as a result of El Niño rains produced ideal factors for the growth of this fungus.

Evaluation of pollution prevention options to reduce styrene emissions from fiber-reinforced plastic open molding processes

Pollution prevention (P2) options to reduce styrene emissions, such as new materials and application equipment, are commercially available to the operators of open molding processes. However, information is lacking on the emissions reduction that these options can achieve. To meet this need, the U.S. Environmental Protection Agency's (EPA) Air Pollution Prevention and Control Division, working in collaboration with Research Triangle Institute, measured styrene emissions for several of these P2 options. In addition, the emission factors calculated from these test results were compared with the existing EPA emission factors for gel coat sprayup and resin applications. Results show that styrene emissions can be reduced by up to 52% by using controlled spraying (i.e., reducing overspray), low-styrene and styrene-suppressed materials, and nonatomizing application equipment. Also, calculated emission factors were 1.6-2.5 times greater than the mid-range EPA emission factors for the corresponding gel coat and resin application. These results indicate that facilities using existing EPA emission factors to estimate emissions in open molding processes are likely to underestimate actual emissions. Facilities should investigate the applicability and feasibility of these P2 options to reduce their styrene emissions.

Polymyalgia, hypersensitivity pneumonitis and other reactions in patients receiving HMG-CoA reductase inhibitors: a report of ten cases

Ten patients who take hydroxy-methylglutaryl coenzyme A reductase inhibitors, or statin medications, and experience adverse reactions are described. All patients experienced various manifestations of hypersensitivity while receiving the drugs. One patient is described with hypersensitivity pneumonitis, which was graphically demonstrated by both high resolution computerized axial tomography and open lung biopsy.

Evaluation of a portable Fourier transform infrared gas analyzer for measurements of air toxics in pollution prevention research

A portable Fourier transform infrared gas analyzer with a photoacoustic detector performed reliably during pollution prevention research at two industrial facilities. It exhibited good agreement (within approximately 6%) with other analytical instruments (dispersive infrared and flame ionization) when analyte concentrations were high and relatively steady. It did not show good agreement when analyte concentrations were low (approximately 10 parts per million [ppm]) or were varying rapidly (less than 1.5 min). The precision for total acetates measurements was estimated to be approximately 40 ppm for measurements in the 0- to 700-ppm region. The precision for styrene measurements was estimated to be approximately 10 ppm for measurements in the 0- to 90-ppm region.

Persistent cauda equina syndrome following bilateral aortoiliac dissection as a complication of cardiac angiography

Cardiac angiography is accepted as an invasive yet safe procedure with well-characterized complications. We present a complication heretofore not described to our knowledge, in which a patient experienced the cauda equina syndrome following bilateral aortoiliac dissection during cardiac angiography. Similarities are noted between this complication and those documented in abdominal aortic aneurysm repair surgery.

C-type natriuretic peptide-mediated coronary vasodilation: role of the coronary nitric oxide and particulate guanylate cyclase systems

OBJECTIVES

We tested the hypothesis that C-type natriuretic peptide (CNP) mediates coronary vasodilation through activation of cyclic guanosine monophosphate (cGMP) by way of particulate guanylate cyclase.

BACKGROUND

CNP has known peripheral vasodilator properties, and preliminary data have suggested that it can function as a coronary vasodilator.

METHODS

The actions of CNP were studied in instrumented dogs and in organ chamber rings in the presence and absence of a known antagonist to particulate guanylate cyclase, HS-142-1. Additionally, the actions of HS-142-1 were tested on acetylcholine-mediated coronary vasodilation, and immunohistochemical staining was utilized to localize the presence of CNP in the coronary endothelium.

RESULTS

CNP relaxed isolated coronary arteries with (mean +/- SEM 45.9 +/- 7%*) and without (72.0 +/- 7%*) an endothelium (*p < 0.05 for CNP effect alone, p < 0.05 for endothelium vs. no endothelium with CNP). Intracoronary infusions increased coronary blood flow (baseline, 64.6 +/- 5.1 ml/min; CNP-5, 79.9 +/- 6.1*; CNP-20, 103.3 +/- 13.6* [*p < 0.05 vs. baseline value]) and reduced coronary vascular resistance (baseline, 1.6 +/- 0.3 mm Hg/ml per min; CNP-5, 1.4 +/- 0.3*; CNP-20, 1.2 +/- 0.3*). Intracoronary injections increased coronary blood flow (delta baseline coronary flow, 30 +/- 9* ml/min [*p < 0.05]). HS-142-1 significantly attenuated these increases (delta coronary flow, 30 +/- 9* ml/min [CNP] to 14 +/- 6 [CNP + HS-142-1] [p < 0.05 CNP vs. CNP + HS-142-1]) and the relaxation of organ chamber rings (56 +/- 7% [CNP] to 18 +/- 6% [HS-142-1 + CNP]). Finally, CNP was localized to the coronary endothelium and smooth muscle by immunohistochemical staining.

CONCLUSIONS

CNP functions as a coronary vasodilator through activation of cGMP by way of particulate guanylate cyclase. CNP-mediated coronary vasodilation is attenuated by intracoronary HS-142-1. Intracoronary HS-142-1 does not affect acetylcholine-mediated coronary vasodilation. These observations support a role for exogenous CNP as a potent coronary vasodilator.

Pleural effusion associated with ipsilateral breast and arm edema as a complication of subclavian vein catheterization and arteriovenous fistula formation for hemodialysis

A 38-year-old woman with end-stage kidney disease presented with a pleural effusion and profound edema of the ipsilateral arm and breast. A patent hemodialysis arteriovenous fistula access was present in the involved extremity. Brachiocephalic vein stenosis, as a result of previous dialysis catheter placement in the subclavian vein, was demonstrated by ultrasound imaging and Doppler analysis. Takedown of the arteriovenous fistula in the edematous arm along with living-related kidney transplantation caused immediate resolution of the breast and arm edema and rapid clearing of the effusion. An anatomic explantation for the findings is offered.

Interrelationships between pulmonary and extrapulmonary involvement in systemic sclerosis. A longitudinal analysis

PURPOSE

(1) To evaluate the relationship between the degree of pulmonary involvement by systemic sclerosis (SSc) and the degree of involvement of other organ systems by SSc at baseline. (2) To assess the degree of impairment in lung function at presentation and the annual rate of change in lung function to predict the rate of progression of involvement of extrapulmonary organ systems by SSc over time. (3) To determine whether survival in patients with SSc can be predicted from the degree of lung function impairment at baseline or from the annual rate of change in lung function.

METHODS

Semiquantitative indices of pulmonary and extrapulmonary involvement and pulmonary function tests (PFTs) were analyzed and compared in 62 nonsmoking scleroderma patients enrolled in a 3-year prospective drug trial, vs 47 in a "study group" who underwent serial evaluation. The other 16 "early withdrawals" withdrew prior to the second evaluation. The indices of organ system involvement were based on clinical, physiologic, and biochemical findings as previously published. The PFTs included total lung capacity (TLC), forced vital capacity (FVC), FEV1, and single-breath diffusing capacity for carbon monoxide (Dsb). Annualized rates of change in PFTs and indices of extrapulmonary involvement were calculated for each subject from data collected on at least 2 separate occasions at least 6 months apart. Spearman rank correlations were performed between individual baseline PFTs (expressed as percent predicted) and (a) indices of extrapulmonary involvement at baseline, (b) annualized rates of change in PFTs, and (c) annualized rates of change in indices of extrapulmonary involvement. Correlations also were performed between the rate of change in each lung function measure and rates of change in indices of extrapulmonary involvement. The ability of PFTs at baseline and their rates of change to predict cumulative survival was assessed by Cox stepwise regression.

RESULTS

The degree of impairment in baseline PFTs was related to involvement of the right side of the heart but not to other extrapulmonary system involvement. Baseline PFTs were not related to the rate of subsequent decline of lung function or worsening of extrapulmonary organ system involvement. Subsequent annual rates of decline in lung function were related to worsening skin and upper gastrointestinal involvement. Cumulative survival may be related to the rate of decline in DCO, TLC, and FVC, but was not predicted by impairment in any measure of lung function.

CONCLUSION

With the exception of involvement of the right side of the heart consistent with cor pulmonale, the degree of pulmonary involvement by SSc was not correlated with the extent of extrapulmonary involvement. The degree of pulmonary involvement by SSc did not predict subsequent worsening of either pulmonary or extrapulmonary involvement. Worsening pulmonary involvement by SSc, in general, does not correlate with worsening involvement of extrapulmonary organ systems, except for the skin and upper gastrointestinal tract. A rapid decline in DCO or lung volumes may predict poor survival.

Atrial natriuretic peptide in heart failure

Atrial natriuretic peptide hormone of cardiac origin, which is released in response to atrial distension and serves to maintain sodium homeostasis and inhibit activation of the renin-angiotensin-aldosterone system. Congestive heart failure is a clinical syndrome characterized by increased cardiac volume and pressure overload with an inability to excrete a sodium load, which is associated with increased activity of systemic neurohumoral and local autocrine and paracrine mechanisms. Circulating atrial natriuretic peptide is greatly increased in congestive heart failure as a result of increased synthesis and release of this hormone. Atrial natriuretic peptide has emerged as an important diagnostic and prognostic serum marker in congestive heart failure. In early heart failure, it may play a key role in preserving the compensated state of asymptomatic left ventricular dysfunction. Despite increased circulating atrial natriuretic peptide in heart failure, the kidney retains sodium and is hyporesponsive to exogenous and endogenous atrial natriuretic peptide. The mechanism for the attenuated renal response is multifactorial and includes renal hypoperfusion, activation of the renin-angiotensin-aldosterone and sympathetic nervous systems. Therapeutic strategies to potentiate the biologic actions of atrial natriuretic peptide may prolong the asymptomatic phase and delay progression to overt congestive heart failure.

Cardiorenal and neurohumoral function in a canine model of early left ventricular dysfunction

BACKGROUND

Recent studies have reported that asymptomatic left ventricular dysfunction (ALVD) in humans is characterized by early neurohumoral activation. Specifically, atrial natriuretic factor (ANF) and norepinephrine are activated without activation of the renin-angiotensin-aldosterone system (RAAS). The current study describes hemodynamic and renal function associated with this neurohumoral profile in a canine model of early and presumably "asymptomatic" ventricular dysfunction. We hypothesized that the neurohumoral profile observed in ALVD is associated with preservation of renal function despite significant hemodynamic compromise.

METHODS AND RESULTS

ALVD was produced by ventricular pacing at 180 beats per minute for 10 days. Intravascular volume expansion was performed before and after producing ALVD in eight conscious dogs. The model of ALVD was characterized by decreases in ejection fraction (48 +/- 2 to 29 +/- 4%), cardiac output (4.64 +/- 0.29 to 2.89 +/- 0.17 L/min), and mean arterial pressure (119 +/- 4 to 108 +/- 4 mm Hg). Atrial pressures and systemic vascular resistance were increased. ANF (60 +/- 19 to 165 +/- 27 pg/mL) and norepinephrine (382 +/- 127 to 690 +/- 211 pg/mL) were activated, whereas the RAAS was not. Creatinine clearance and sodium excretion (UNa V) were unchanged after producing ALVD. The natriuretic response to volume expansion in ALVD was completely intact, with increases in UNa V similar to that observed with volume expansion in ALVD was completely intact, with increases in UNa V similar to that observed with volume expansion before producing ALVD.

CONCLUSIONS

The current study demonstrates that significant ventricular dysfunction with peripheral vasoconstriction can be associated with normal renal function and thus suggests an important functional role for the neurohumoral profile of ALVD in preserving sodium balance.

Effects of smoked marijuana of varying potency on ventilatory drive and metabolic rate

Ventilatory responses to hypercapnia in experienced marijuana smokers have previously been shown to decrease, increase, or not change acutely after marijuana. In one study, minute ventilation (VE) and O2 consumption (VO2) increased but hypoxic ventilatory response did not change after smoking marijuana. We further investigated the effects of marijuana of increasing potency (0, 13, and 20 mg THC) on ventilatory and mouth occlusion pressure (P0.1) responses to hypercapnia and hypoxia in 11 young, healthy men who smoked marijuana regularly but refrained from any smoked substance, alcohol, caffeine, or other drugs for greater than or equal to 12 h before study. Ventilatory and P0.1 responses to hypoxia and hypercapnia were measured on 3 separate days before and 5 and 35 min (hypoxia) and 15 and 45 min (hypercapnia) after smoking. In a companion 3-day study, 12 young male habitual marijuana smokers underwent measurements of VE, VO2, and CO2 production (VCO2) before and 5 to 135 min after smoking marijuana containing 0, 15, or 27 mg THC. None of the active marijuana preparations caused significant changes in ventilatory or P0.1 responses to either hypercapnia or hypoxia or in resting VE, VO2 or VCO2. We conclude that smoking marijuana (13 to 27 mg THC) has no acute effect on central or peripheral ventilatory drive or metabolic rate in habitual marijuana smokers. These conclusions cannot be applied to infrequent users of marijuana without further study.

Bilateral tension pneumothoraces after acupuncture

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Propionate inhibits hepatocyte lipid synthesis

Oat bran lowers serum cholesterol in animals and humans. Propionate, a short-chain fatty acid produced by colonic bacterial fermentation of soluble fiber, is a potential mediator of this action. We tested the effect of propionate on hepatocyte lipid synthesis in rats using [1-14C]acetate, 3H2O, and [2-14C]mevalonate as precursors. Propionate produced a statistically significant inhibition of cholesterol biosynthesis from [1-14C]acetate at a concentration of 1.0 mM and from 3H2O and [2-14C]mevalonate at concentrations of 2.5 mM. Propionate also produced a significant inhibition of fatty acid biosynthesis at concentrations of 2.5 mM using [1-14C]acetate as a precursor. The demonstration of propionate-mediated inhibition of cholesterol and fatty acid biosynthesis at these concentrations suggests that propionate may inhibit cholesterol and fatty acid biosynthesis in vivo and may mediate in part the hypolipidemic effects of soluble dietary fiber. Further studies are needed to clarify this action of propionate and to establish the exact mechanisms by which the inhibition occurs.

Ventilatory and diffusion abnormalities in potential heart transplant recipients

Few data are available concerning pulmonary function in patients with severe chronic congestive heart failure. Of 315 patients evaluated for potential cardiac transplantation at UCLA, 132 underwent pulmonary function tests. The latter patients had severe heart failure with a mean left ventricular ejection fraction of 19 percent and mean cardiac index of 2.1 L/min/m2. Diffusion impairment either alone or combined with restrictive and/or obstructive ventilatory defects occurred in 67 percent of the patients evaluated. Diffusion impairment occurred as the sole abnormality in 31 percent of the patients and in combination with a restrictive ventilatory defect in 21 percent. A reduction in diffusing capacity has not been previously described as a frequent finding in patients with chronic congestive heart failure. In contrast to other studies involving patients with acute heart failure, obstructive ventilatory defects were uncommon. None of the lung function abnormalities was associated with smoking status, prior drug use, chest roentgenographic changes, hemodynamic findings, or clinical features, including duration of congestive heart failure. The mechanism for the diffusion impairment is unclear but could be due to chronic passive congestion with pulmonary fibrosis and/or recurrent pulmonary emboli. Recognition of diffusion impairment as a common finding in patients with severe chronic congestive heart failure who are candidates for heart transplantation is important for proper interpretation of possible post-transplant changes in diffusing capacity due to other causes.