Adenosine deaminase augments SARS-CoV-2 specific cellular and humoral responses in aged mouse models of immunization and challenge

Despite numerous clinically available vaccines and therapeutics, aged patients remain at increased risk for COVID-19 morbidity. Furthermore, various patient populations, including the aged can have suboptimal responses to SARS-CoV-2 vaccine antigens. Here, we characterized vaccine-induced responses to SARS-CoV-2 synthetic DNA vaccine antigens in aged mice. Aged mice exhibited altered cellular responses, including decreased IFNγ secretion and increased TNFα and IL-4 secretion suggestive of TH2-skewed responses. Aged mice exhibited decreased total binding and neutralizing antibodies in their serum but significantly increased TH2-type antigen-specific IgG1 antibody compared to their young counterparts. Strategies to enhance vaccine-induced immune responses are important, especially in aged patient populations. We observed that co-immunization with plasmid-encoded adenosine deaminase (pADA)enhanced immune responses in young animals. Ageing is associated with decreases in ADA function and expression. Here, we report that co-immunization with pADA enhanced IFNγ secretion while decreasing TNFα and IL-4 secretion. pADA expanded the breadth and affinity SARS-CoV-2 spike-specific antibodies while supporting TH1-type humoral responses in aged mice. scRNAseq analysis of aged lymph nodes revealed that pADA co-immunization supported a TH1 gene profile and decreased FoxP3 gene expression. Upon challenge, pADA co-immunization decreased viral loads in aged mice. These data support the use of mice as a model for age-associated decreased vaccine immunogenicity and infection-mediated morbidity and mortality in the context of SARS-CoV-2 vaccines and provide support for the use of adenosine deaminase as a molecular adjuvant in immune-challenged populations.

Lipid nanoparticles (LNP) induce activation and maturation of antigen presenting cells in young and aged individuals

Herein, we studied the impact of empty LNP (eLNP), component of mRNA-based vaccine, on anti-viral pathways and immune function of cells from young and aged individuals. eLNP induced maturation of monocyte derived dendritic cells (MDDCs). We further show that eLNP upregulated CD40 and induced cytokine production in multiple DC subsets and monocytes. This coincided with phosphorylation of TANK binding kinase 1 (pTBK1) and interferon response factor 7 (pIRF7). In response to eLNP, healthy older adults (>65 yrs) have decreased CD40 expression, and IFN-γ output compared to young adults (<65 yrs). Additionally, cells from older adults have a dysregulated anti-viral signaling response to eLNP stimulation, measured by the defect in type I IFN production, and phagocytosis. Overall, our data show function of eLNP in eliciting DC maturation and innate immune signaling pathways that is impaired in older adults resulting in lower immune responses to SARS-CoV-2 mRNA-based vaccines.

Aging alters antiviral signaling pathways resulting in functional impairment in innate immunity in response to pattern recognition receptor agonists

The progressive impairment of immunity to pathogens and vaccines with aging is a significant public health problem as the world population shifts to an increased percentage of older adults (> 65). We have previously demonstrated that cells obtained from older volunteers have delayed and defective induction of type I interferons and T cell and B cell helper cytokines in response to TLR ligands when compared to those from adult subjects. However, the underlying intracellular mechanisms are not well described. Herein, we studied two critical pathways important in the production of type I interferon (IFN), the interferon response factor 7 (pIRF7), and TANK-binding kinase (pTBK-1). We show a decrease in pIRF7 and pTBK-1 in cross-priming dendritic cells (cDC1s), CD4⁺ T cell priming DCs (cDC2s), and CD14^dimCD16⁺ vascular patrolling monocytes from older adults (n = 11) following stimulation with pathway-specific agonists in comparison with young individuals (n = 11). The decrease in these key antiviral pathway proteins correlates with decreased phagocytosis, suggesting impaired function in Overall, our findings describe molecular mechanisms which explain the innate functional impairment in older adults and thus could inform us of novel approaches to restore these defects.

Improved Durability to SARS-CoV-2 Vaccine Immunity following Coimmunization with Molecular Adjuvant Adenosine Deaminase-1

Although severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines have demonstrated strong immunogenicity and protection against severe disease, concerns about the duration and breadth of these responses remain. In this study, we show that codelivery of plasmid-encoded adenosine deaminase-1 (pADA) with SARS-CoV-2 spike glycoprotein DNA enhances immune memory and durability in vivo. Coimmunized mice displayed increased spike-specific IgG of higher affinity and neutralizing capacity as compared with plasmid-encoded spike-only-immunized animals. Importantly, pADA significantly improved the longevity of these enhanced responses in vivo. This coincided with durable increases in frequencies of plasmablasts, receptor-binding domain-specific memory B cells, and SARS-CoV-2-specific T follicular helper cells. Increased spike-specific T cell polyfunctionality was also observed. Notably, animals coimmunized with pADA had significantly reduced viral loads compared with their nonadjuvanted counterparts in a SARS-CoV-2 infection model. These data suggest that pADA enhances immune memory and durability and supports further translational studies.

An old problem with new solutions: Strategies to improve vaccine efficacy in the elderly

Vaccination is the most effective measure to protect against infections. However, with increasing age, there is a progressive decline in the ability of the immune system to both protect against infection and develop protective immunity from vaccination. This age-related decline of the immune system is due to age-related changes in both the innate and adaptive immune systems. With an aging world population and increased risk of pandemics, there is a need to continue to develop strategies to increase vaccine responses in the elderly. Here, the major age-related changes that occur in both the innate and adaptive immune responses that impair the response to vaccination in the elderly will be highlighted. Existing and future strategies to improve vaccine efficacy in the elderly will then be discussed, including adjuvants, delivery methods, and formulation. These strategies provide mechanisms to improve the efficacy of existing vaccines and develop novel vaccines for the elderly.

Operation and Performance of a Mass-Selective Cryogenic Linear Ion Trap

We report on the performance of a cryogenic 2D linear ion trap (cryoLIT) that is shown to be mass-selective in the temperature range of 17-295 K. As the cryoLIT is cooled, the ejection voltages during the mass instability scan decrease, which results in an effective mass shift to lower m/z relative to room temperature. This is attributed to a decrease in trap radius caused by thermal contraction. Additionally, the cryoLIT generates reproducible mass spectra from day-to-day, and is capable of performing stored waveform inverse Fourier transform (SWIFT) mass isolation of fragile N₂-tagged ions for the purpose of background-free infrared dissociation spectroscopy. Graphical Abstract ᅟ.

Pif1 helicase unfolding of G-quadruplex DNA is highly dependent on sequence and reaction conditions

In addition to unwinding double-stranded nucleic acids, helicase activity can also unfold noncanonical structures such as G-quadruplexes. We previously characterized Pif1 helicase catalyzed unfolding of parallel G-quadruplex DNA. Here we characterized unfolding of the telomeric G-quadruplex, which can fold into antiparallel and mixed hybrid structures and found significant differences. Telomeric DNA sequences are unfolded more readily than the parallel quadruplex formed by the c-MYC promoter in K⁺ Furthermore, we found that under conditions in which the telomeric quadruplex is less stable, such as in Na⁺, Pif1 traps thermally melted quadruplexes in the absence of ATP, leading to the appearance of increased product formation under conditions in which the enzyme is preincubated with the substrate. Stable telomeric G-quadruplex structures were unfolded in a stepwise manner at a rate slower than that of duplex DNA unwinding; however, the slower dissociation from G-quadruplexes compared with duplexes allowed the helicase to traverse more nucleotides than on duplexes. Consistent with this, the rate of ATP hydrolysis on the telomeric quadruplex DNA was reduced relative to that on single-stranded DNA (ssDNA), but less quadruplex DNA was needed to saturate ATPase activity. Under single-cycle conditions, telomeric quadruplex was unfolded by Pif1, but for the c-MYC quadruplex, unfolding required multiple helicase molecules loaded onto the adjacent ssDNA. Our findings illustrate that Pif1-catalyzed unfolding of G-quadruplex DNA is highly dependent on the specific sequence and the conditions of the reaction, including both the monovalent cation and the order of addition.

Infrared ion spectroscopy: an analytical tool for the study of metabolites

Vibrational ion spectroscopy techniques coupled with mass spectrometry are applied to standard metabolites as a proof-of-principle demonstration for the structural identification of unknown metabolites. The traditional room temperature infrared multiple photon dissociation (IRMPD) spectroscopy technique is shown to differentiate chemical moieties in isobaric and isomeric variants. These results are compared to infrared spectra of cryogenically cooled analyte ions, showing enhanced spectral resolution, and thus also improved differentiation between closely related molecules, such as isomers. The cryogenic spectroscopy is effected in a recently developed mass-selective cryogenic linear ion trap, which is capable of high sensitivity and the ability to measure the IR spectra of multiple analytes simultaneously.

Infrared ion spectroscopy inside a mass-selective cryogenic 2D linear ion trap

We demonstrate operation of the first cryogenic 2D linear ion trap (LIT) with mass-selective capabilities. This trap presents a number of advantages for infrared ion "action" spectroscopy studies, particularly those employing the "tagging/messenger" spectroscopy approach. The high trapping efficiencies, trapping capacities, and low detection limits make 2D LITs a highly suitable choice for low-concentration analytes from scarce biological samples. In our trap, ions can be cooled down to cryogenic temperatures to achieve higher-resolution infrared spectra, and individual ions can be mass selected prior to irradiation for a background-free photodissociation scheme. Conveniently, multiple tagged analyte ions can be mass isolated and efficiently irradiated in the same experiment, allowing their infrared spectra to be recorded in parallel. This multiplexed approach is critical in terms of increasing the duty cycle of infrared ion spectroscopy, which is currently a key weakness of the technique. The compact design of this instrument, coupled with powerful mass selection capabilities, set the stage for making cryogenic infrared ion spectroscopy viable as a bioanalytical tool in small molecule identification.

Evidence That G-quadruplex DNA Accumulates in the Cytoplasm and Participates in Stress Granule Assembly in Response to Oxidative Stress

Cells engage numerous signaling pathways in response to oxidative stress that together repair macromolecular damage or direct the cell toward apoptosis. As a result of DNA damage, mitochondrial DNA or nuclear DNA has been shown to enter the cytoplasm where it binds to "DNA sensors," which in turn initiate signaling cascades. Here we report data that support a novel signaling pathway in response to oxidative stress mediated by specific guanine-rich sequences that can fold into G-quadruplex DNA (G4DNA). In response to oxidative stress, we demonstrate that sequences capable of forming G4DNA appear at increasing levels in the cytoplasm and participate in assembly of stress granules. Identified proteins that bind to endogenous G4DNA in the cytoplasm are known to modulate mRNA translation and participate in stress granule formation. Consistent with these findings, stress granule formation is known to regulate mRNA translation during oxidative stress. We propose a signaling pathway whereby cells can rapidly respond to DNA damage caused by oxidative stress. Guanine-rich sequences that are excised from damaged genomic DNA are proposed to enter the cytoplasm where they can regulate translation through stress granule formation. This newly proposed role for G4DNA provides an additional molecular explanation for why such sequences are prevalent in the human genome.

Making Mass Spectrometry See the Light: The Promises and Challenges of Cryogenic Infrared Ion Spectroscopy as a Bioanalytical Technique

The detailed chemical information contained in the vibrational spectrum of a cryogenically cooled analyte ion would, in principle, make infrared (IR) ion spectroscopy a gold standard technique for molecular identification in mass spectrometry. Despite this immense potential, there are considerable challenges in both instrumentation and methodology to overcome before the technique is analytically useful. Here, we discuss the promise of IR ion spectroscopy for small molecule analysis in the context of metabolite identification. Experimental strategies to address sensitivity constraints, poor overall duty cycle, and speed of the experiment are intimately tied to the development of a mass-selective cryogenic trap. Therefore, the most likely avenues for success, in the authors' opinion, are presented here, alongside alternative approaches and some thoughts on data interpretation.

Risk factors for Nipah virus encephalitis in Bangladesh

Patients in Goalando were likely infected by direct contact with fruit bats or their secretions, rather than through contact with an intermediate host.

Nipah virus (NiV) is a paramyxovirus that causes severe encephalitis in humans. During January 2004, twelve patients with NiV encephalitis (NiVE) were identified in west-central Bangladesh. A case–control study was conducted to identify factors associated with NiV infection. NiVE patients from the outbreak were enrolled in a matched case-control study. Exact odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by using a matched analysis. Climbing trees (83% of cases vs. 51% of controls, OR 8.2, 95% CI 1.25–∞) and contact with another NiVE patient (67% of cases vs. 9% of controls, OR 21.4, 95% CI 2.78–966.1) were associated with infection. We did not identify an increased risk for NiV infection among persons who had contact with a potential intermediate host. Although we cannot rule out person-to-person transmission, case-patients were likely infected from contact with fruit bats or their secretions.

Hemorrhagic and vascular complications after percutaneous coronary intervention with adjunctive abciximab

OBJECTIVES

To examine the frequency and nature of hemorrhagic and peripheral vascular complications associated with use of abciximab during percutaneous coronary intervention and to characterize high-risk patients.

PATIENTS AND METHODS

We report the frequency and severity of bleeding and vascular complications recorded prospectively in 2,559 consecutive nonselected patients who underwent percutaneous coronary intervention at Mayo Clinic, Rochester, Minn, between July 1, 1996, and April 30, 1998, 831 of whom received abciximab and 1,728 did not. Abciximab and heparin were administered according to guidelines of the Evaluation of PTCA [percutaneous transluminal coronary angioplasty] to Improve Long-Term Outcome With Abciximab GP IIb/IIIa Blockade (EPILOG).

RESULTS

Patients who received abciximab were more likely to be men, were more often treated within 12 hours of an acute myocardial infarction, and were more likely to have received heparin after the procedure (8.7 % vs 4.5%, P<.001). Major bleeding occurred in 18 patients (2.4%) who received abciximab and in 10 patients (0.6%) who did not receive abciximab (P<.001). Minor bleeding occurred in 108 patients (14.3%) and in 92 patients (5.9%), respectively (P<.001). Both major bleeding and minor bleeding were more frequent among patients within 12 hours of an acute myocardial infarction and were more frequent if abciximab had been used. Multivariate analysis revealed that use of abciximab was independently associated with major and minor bleeding.

CONCLUSION

In this clinical setting, use of adjunctive abciximab during percutaneous coronary intervention was associated with a significantly increased risk of both major and minor bleeding.

Effect of abciximab on the outcome of emergency coronary artery bypass grafting after failed percutaneous coronary intervention

OBJECTIVE

To evaluate the outcome of coronary artery bypass grafting (CABG) for failed percutaneous coronary intervention (PCI) in patients who had received abciximab.

PATIENTS AND METHODS

In this retrospective study, we analyzed the records of patients who had PCI at our institution between January 1994 and December 1998 and identified those who had urgent or emergency CABG within 48 hours after PCI. CABG was performed for failed PCI in patients who had ongoing ischemia, hemodynamic compromise, or both. These patients were categorized into 2 groups depending on whether they had been given abciximab during PCI. We compared blood product transfusion requirements, bleeding complications, and frequency of in-hospital adverse events of the 2 groups.

RESULTS

Of 5636 patients who had PCI, 77 (1.4%) had urgent or emergency CABG within 48 hours, including 11 who were given abciximab (abciximab group) during PCI and 66 who were not given abciximab (no abciximab group). The 2 groups had similar baseline characteristics. The mean +/- SD time to surgery was 8.4 +/-8.0 hours (median, 6 hours) for the abciximab group vs 12.1 +/- 12.5 hours (median, 4 hours) for the no abciximab group. Major bleeding (Thrombolysis in Myocardial Infarction criteria) occurred in 9 (90%) of 10 patients in the abciximab group vs 48 (77%) of 62 patients in the no abciximab group. The total volumes of intraoperative autotransfusion and transfusion of red blood cells and fresh frozen plasma tended to be higher for the abciximab group. Also, this group received a mean of 13.9 U of platelets vs 3.2 U for the no abciximab group (P<.001). However, no in-hospital deaths occurred among patients in the abciximab group, and adverse events were infrequent and comparable between the 2 groups. No difference was noted between the 2 groups in the frequency of surgical reexploration for bleeding.

CONCLUSION

Transfusion requirements are higher for patients who undergo emergency or urgent CABG after having received abciximab during PCI. However, in-hospital adverse events are infrequent and comparable to those for patients who do not receive abciximab.

Alveolar hemorrhage as a complication of treatment with abciximab

STUDY OBJECTIVE

The use of abciximab, a chimeric monoclonal antibody Fab fragment specific for platelet glycoprotein IIb/IIIa receptors, is associated with improved outcome after angioplasty and stent placement. Major complications include bleeding, but pulmonary hemorrhage has been reported rarely. This study was done to identify patients with pulmonary hemorrhage following abciximab infusion and to define, if possible, any specific risk factors.

DESIGN

Retrospective review of institutional coronary angiography and bronchoscopy databases to identify patients who received abciximab and developed pulmonary hemorrhage.

SETTING

Tertiary-care teaching hospital.

PATIENTS

All patients who underwent coronary angiography and received abciximab between June 1995 and March 2000.

INTERVENTION

None.

MEASUREMENTS AND RESULTS

Seven of 2,553 patients (0.27%) had documented severe pulmonary hemorrhage associated with chest radiographic abnormalities, impaired oxygenation, and the need for blood product transfusions. The initial symptom was hemoptysis in four of the seven patients. There were two early deaths and one late death. No cases of pulmonary hemorrhage were identified in 5,412 patients who underwent coronary procedures without abciximab infusion. No other risk factors predicting hemorrhage were identified.

CONCLUSIONS

Severe pulmonary hemorrhage is a complication of abciximab use. Although hemoptysis is an important alerting symptom, it may not be present initially and the diagnosis may be missed or considered late, with the potential for inappropriate treatment until the diagnosis is established. Lesser degrees of bleeding are potentially easily missed, and this report should alert physicians to this complication so that it can be considered early in the evaluation of patients presenting with pulmonary events after abciximab use.

Infarct artery reocclusion after primary angioplasty, stent placement, and thrombolytic therapy for acute myocardial infarction

BACKGROUND

The benefits of thrombolytic therapy for acute myocardial infarction (AMI) are limited by reocclusion of the infarct-related artery, which occurs in 25% to 30% of patients after successful reperfusion. The frequency of reocclusion after balloon angioplasty and stenting in this setting is less well documented. The aim of this study was to analyze the frequency and timing of reocclusion after percutaneous transluminal coronary angioplasty (PTCA) and stent placement during AMI from all available studies compared with previously published reocclusion rates after thrombolysis.

METHODS AND RESULTS

The previously published thrombolysis data included 4231 patients in 19 studies with > or = 75 patients. Only PTCA studies with > or = 50 patients and stent studies with > or = 30 patients, in which routine angiographic follow-up was obtained in > or = 60% of patients, were included. Ten PTCA studies with a total of 1943 patients were analyzed, with follow-up angiography in 1391 (72%). Reocclusion rates ranged from 5% to 16.7%. The stent studies included 698 patients from 7 studies, with follow-up angiography in 92%. Reocclusion rates ranged from 0% to 6%. With the use of logistic regression analysis with allowance for overdispersion, there was a significantly lower rate of reocclusion after PTCA (odds ratio, 0.38; confidence interval, 0.24 to 0.57; P <.0001) and stent placement (odds ratio, 0.11; confidence interval, 0.05 to 0.22; P <.0001) compared with thrombolysis. Reocclusion after stent placement was lower than after PTCA (odds ratio, 0.28; confidence interval, 0.13 to 0.6; P <.0001).

CONCLUSIONS

Reocclusion after PTCA and stent placement during AMI is less frequent than after thrombolysis. This may contribute to the superior outcome of patients treated with PTCA and stent placement in this setting.

Evaluation of the coronary venous system using electron beam computed tomography

New therapeutic strategies in interventional cardiology and electrophysiology involve the coronary veins. This study examines the potential usefulness of electron beam computed tomography to obtain detailed noninvasive definition of the coronary venous anatomy and of arteriovenous relationships. Electron beam computed tomography allows acquisition and three-dimensional reconstruction of tomographic images of the beating heart with high spatial and temporal resolution. Contrast-enhanced, thin-section electron beam computed tomographic coronary arteriographic images of 34 patients (21 men and 13 women, age 60+/-10 years) were analyzed. The visibility of the coronary veins and their spatial relationship to the coronary arteries were assessed qualitatively on two- and three-dimensional displays. The coronary sinus was visible in 91%, the great cardiac vein in 100%, the middle cardiac vein in 88%, at least one vein overlying the lateral surface of the left ventricle in 97%, the anterior interventricular vein in 97%, and the small cardiac vein in 68%. A left marginal and a left posterior vein were seen in 44%, one of the two in 38%, and neither in 3%. The course of the anterior interventricular vein was parallel to the left anterior coronary artery in 79% and a crossover between the two vessels at an obtuse angle occurred in 12%. Contrast-enhanced electron beam computed tomography imaging of the heart noninvasively provides information on the coronary venous system and arteriovenous relationships that may help guide new interventional procedures.

Immediate and one-year outcome of intracoronary stent implantation in small coronary arteries with 2.5-mm stents

BACKGROUND

The role of coronary stenting in the treatment of stenoses in small coronary arteries with use of 2.5-mm stents is not well defined.

METHODS AND RESULTS

Between January 1995 and August 1999, 651 patients with stenoses in small coronary arteries were treated with 2.5-mm stents (n = 108) or 2.5-mm conventional balloon angioplasty (BA) (n = 543). Patients who received treatment with both 2.5-mm and > or =3.0-mm stent placement or balloons were excluded. Procedural success and complication rates as well as 1-year follow-up outcomes were examined. Baseline clinical characteristics were similar between the two groups, except patients in the stent group were more likely to have hypertension and a family history of coronary artery disease and less likely to have prior myocardial infarction. Angiographic success rates were higher in the stent group (97.2% vs 90.2%, P =.02). In-hospital complication rates were comparable between the two groups. Among successfully treated patients, 1-year follow-up revealed no significant differences in the survival (96.2% vs 95.2%, P =.89) or the frequency of Q-wave myocardial infarction (0% vs 0.4%, P =.60) or coronary artery bypass grafting (8.4% vs 6.8%, P =.89) between the stent and BA groups, respectively. However, patients in the stent group were more likely to have adverse cardiac events (35.4% vs 22.1%, P =.05). Stent use after excluding GR II stent use, however, was not independently associated with reduced cardiac events at follow-up (relative risk 1. 3 [95% confidence interval 0.8-2.3], P =.30).

CONCLUSIONS

Intracoronary stent implantation of stenoses in small coronary arteries with 2.5-mm stents can be carried out with high success and acceptable complication rates. However, compared with BA alone, stent use was not associated with improved outcome through 1 year of follow-up.

The PARAGON stent study: a randomized trial of a new martensitic nitinol stent versus the Palmaz-Schatz stent for treatment of complex native coronary arterial lesions

A new martensitic nitinol stent with improved flexibility and radiopacity was tested to evaluate whether these differences improve initial or long-term outcome. Patients who underwent percutaneous revascularization of a discrete native coronary lesion were randomly assigned to the new stent (PARAGON, n = 349) or to the first-generation Palmaz-Schatz (PS) stent (n = 339). The primary end point was target vessel failure at 6 months (a composite of cardiac or noncardiac death, any infarction in the distribution of the treated vessel, or clinically indicated target vessel revascularization). Secondary end points were, among others, device and procedural success and angiographic restenosis. Mean age was 62 years; diabetes was present in 21% of patients, prior bypass surgery in 6%, and recent infarction in 22% (p = NS for comparison between the 2 randomized arms). The PARAGON stent group had smaller reference vessels (2.97 vs 3.05 mm, p = 0.05), more prior restenosis (8.0% vs 4.5%, p = 0.07), and a longer average stent length (21.3 vs 19.4 mm, p < 0.05). Device success was significantly higher in the PARAGON arm (99.1% vs 94.3%, p < 0.05). Death and infarction at 6-month follow-up were infrequent in both groups. There was no significant difference in death (2.0% vs 1.2%, p = 0.546), but a higher rate of infarction for the PARAGON cohort (9.2% vs 4.7%, p = 0.025). Although target vessel failure (20.3% vs 12.4%, p = 0.005) and target lesion revascularization (12.0% vs 5.9%, p = 0.005) were higher in the PARAGON group, there was no significant difference in 6-month follow-up in in-stent minimal lumen diameter or in the rate of binary angiographic restenosis. Both PARAGON and PS stents are safe and associated with infrequent adverse events. The PARAGON stent can be delivered more frequently than the first-generation PS stent. Although there was no significant difference in in-stent minimal lumen diameter or the frequency of angiographic restenosis, clinical restenosis was more frequent in the PARAGON group.

Decreasing mortality with primary percutaneous coronary intervention in patients with acute myocardial infarction: the Mayo Clinic experience from 1991 through 1997

OBJECTIVE

To characterize and determine the overall impact of changes in primary percutaneous coronary intervention (PCI) on the clinical outcome of patients presenting within 24 hours of acute myocardial infarction (AMI).

PATIENTS AND METHODS

We retrospectively analyzed a prospective PCI registry for 1073 consecutive patients undergoing primary PCI for AMI at the Mayo Clinic in Rochester, Minn, from 1991 through 1997. The primary outcome measure was mortality from any cause within 30 days and 1 year.

RESULTS

The number of patients treated for AMI by primary PCI per year increased from 119 in 1991 to 193 in 1997. Intracoronary stent use increased from 1.7% in 1991 to 64.8% in 1997 (P < .001). This coincided with an increase in ticlopidine use from 3.6% in 1994 to 62.1% in 1997 (P < .001) and in abciximab use from 2.7% in 1995 to 63.2% in 1997 (P < .001). An increase in beta-blocker (58.3% to 75.3%; P < .001), angiotensin-converting enzyme inhibitor (0.9% to 40.0%; P < .001), and 3-hydroxy-3-methylglutaryl coenzyme A reductase use (1.9% to 40.5%; P < .001) as well as a decrease in calcium channel antagonist (34.3% to 8.4%; P < .001) use occurred on discharge. From 1991 through 1997, there was a significant decrease in the 30-day mortality rate (10.1% to 5.2%; P = .05). The 1-year mortality rate also decreased (13.4% in 1991 to 10.4% in 1997) (P = .09). After adjustment for other confounding variables, treatment in more recent years was associated with a significant decrease in death at 30 days (odds ratio, 0.89; 95% confidence interval, 0.79-1.00; P = .05) and during long-term follow-up (odds ratio, 0.93; 95% confidence interval, 0.87-1.00; P = .04).

CONCLUSIONS

Percutaneous coronary intervention methods of reperfusion for AMI, along with adjuvant pharmacotherapy, have changed over recent years and have been associated with improved short- and long-term survival.

Improving outcome over time of percutaneous coronary interventions in unstable angina

OBJECTIVE

This study was performed to evaluate the recent changes in the outcome of coronary interventions in patients with unstable angina (UA).

BACKGROUND

An early invasive strategy has not been shown to be superior to conservative treatment in patients with UA. Earlier studies had utilized older technology. Interventional approaches have changed in the recent past, but to our knowledge, no large studies have addressed the impact of these changes on the outcome of coronary interventions.

METHODS

We analyzed the in-hospital and intermediate-term outcome in 7,632 patients with UA who underwent coronary interventions in the last two decades. The study population was divided into three groups: group 1, n = 2,209 who had coronary intervention from 1979 to 1989; group 2, n = 2,212 with interventions from 1990 to 1993; and group 3, n = 3,211 treated from 1994 to 1998.

RESULTS

Group 2 and 3 patients were older and sicker compared with group 1 patients. The clinical success improved significantly in group 3 (94.1%) compared with group 2 (87%) and group 1 (76.5%) (p < 0.001). There was a significant reduction in in-hospital mortality, Q-wave myocardial infarction and need for emergency bypass surgery in group 3 compared with the earlier groups. One-year event-free survival was also significantly higher in the recent group compared with the earlier groups: 77% in group 3, 70% in group 2 and 74% in group 1 (p < 0.001). With the use of multivariate models to adjust for clinical and angiographic variables, treatment during the most recent era was found to be independently associated with improved in-hospital and intermediate-term outcomes.

CONCLUSIONS

There has been significant improvement in the in-hospital and intermediate-term outcome of coronary interventions in patients with UA in recent years; newer trials comparing conservative and invasive strategies are therefore needed.

Application of the New York State PTCA mortality model in patients undergoing stent implantation

BACKGROUND

This study applied the New York State conventional coronary angioplasty (PTCA) model of clinical outcomes to evaluate whether it has relevance in the current era of stent implantation. The model was developed in 62 670 patients treated with conventional PTCA from 1991 to 1994 to risk adjust mortality and bypass surgery after PTCA. Since then, stents have become the dominant form of intervention. Whether that model remains relevant is uncertain.

METHODS AND RESULTS

All patients undergoing stenting at the Mayo Clinic from 1995 to 1998 were analyzed for in-hospital mortality, bypass surgery performed after attempted stenting, and longer-term mortality. No patients were excluded. The New York model was used to risk adjust and predict in-hospital and follow-up mortality. There were 3761 patients with 4063 procedural admissions for stenting; 6,472 target vessel segments were attempted, and 96.1% of procedures were successful. With the New York multivariable risk factor equation, 79 in-hospital deaths were expected (1.95%); 66 deaths (1.62%) were observed. The New York model risk score in a logistic regression model was the most significant factor associated with in-hospital mortality (OR, 1.86; P<0.001). During a mean follow-up of 1.2+/-1.0 years, there were 154 deaths. Multivariable analysis documented 6 factors associated with subsequent mortality; New York risk score was the most significant (chi(2)=16.64, P=0.0001).

CONCLUSIONS

Although the New York mortality model was developed in an era of conventional angioplasty, it remains relevant in patients undergoing stenting. The risk score derived from that model is the variable most significantly associated with not only in-hospital but also longer-term outcome.

Prediction of death after percutaneous coronary interventional procedures

BACKGROUND

The prediction and comparison of procedural death after percutaneous coronary interventional procedures is inherently difficult because of variations in case mix and practice patterns. The impact of modern, expanded patient selection criteria, and newer technologic approaches is unknown. Our objective was to determine whether a risk equation based on patient-related variables and derived from an independent data set can accurately predict procedural death after percutaneous coronary intervention in the current era.

METHODS AND RESULTS

An analysis was made of the Mayo Clinic Coronary Interventional Database January 1, 1995, to October 31, 1997. Expected mortality rate was calculated with the use of the New York State multivariate risk score. In 3387 patients, 3830 procedures (55.1% stents) were performed, with an expected mortality rate of 2.32% and observed mortality rate of 2.38% (P = not significant). The risk score derived from the New York multivariate model was highly predictive of death (chi-square = 213.8; P <.0001). The presence of a high-risk lesion characteristic such as calcium, thrombus, or type C lesion was modestly associated with death.

CONCLUSIONS

The New York State multivariate model accurately predicted procedural death in our database.

Capacity of the low-photon-rate direct-detection optical pulse-position-modulation channel in the presence of noise photons

We derive expressions for the capacity of the pulse-position-modulated (PPM) direct-detection photon-counting channel in the presence of noise photons in addition to the signal-dependent shot noise that is normally considered in studying photon counting at low photon rates. We note that even a small mean number of noise photons per PPM count bin significantly decreases the capacity of the channel. These results are useful for comparisons of performance that are obtained by use of real coding and synchronization algorithms with photon-counting PPM schemes that are currently being considered for deep-space optical communications.

Immediate and long-term outcome of intracoronary stent implantation for true bifurcation lesions

OBJECTIVES

The aim of this study was to evaluate the immediate and long-term outcome of intracoronary stent implantation for the treatment of coronary artery bifurcation lesions.

BACKGROUND

Balloon angioplasty of true coronary bifurcation lesions is associated with a lower success and higher complication rate than most other lesion types.

METHODS

We treated 131 patients with bifurcation lesions with > or =1 stent. Patients were divided into two groups; Group (Gp) 1 included 77 patients treated with a stent in one branch and percutaneous transluminal coronary angioplasty (PTCA) (with or without atherectomy) in the side branch, and Gp 2 included 54 patients who underwent stent deployment in both branches. The Gp 2 patients were subsequently divided into two subgroups depending on the technique of stent deployment. The Gp 2a included 19 patients who underwent Y-stenting, and Gp 2b included 33 patients who underwent T-stenting.

RESULTS

There were no significant differences between the groups in terms of age, gender, frequency of prior myocardial infarction (MI) or coronary artery bypass grafting (CABG), or vessels treated. Procedural success rates were excellent (89.5 to 97.4%). After one-year follow-up, no significant differences were seen in the frequency of major adverse events (death, MI, or repeat revascularization) between Gp 1 and Gp 2. Adverse cardiac events were higher with Y-stenting compared with T-stenting (86.3% vs. 30.4%, p = 0.004).

CONCLUSIONS

Stenting of bifurcation lesions can be achieved with a high success rate. However, stenting of both branches offers no advantage over stenting one branch and performing balloon angioplasty of the other branch.

Immediate and late outcomes after direct stent implantation without balloon predilation

OBJECTIVES

The aim of our study was to compare the in-hospital and long-term clinical outcomes of direct coronary stenting with balloon predilation followed by stent placement.

BACKGROUND

With improvement in stent designs, the practice of direct stenting without balloon predilation has become more widespread.

METHODS

We analyzed the Mayo Clinic Coronary Intervention data base between January 1, 1995 and March 5, 1999 and identified 777 patients who were treated with direct stenting (DS) and 3,176 patients treated with balloon angioplasty plus stenting (BA+S).

RESULTS

The procedural success rates between the DS and BA+S groups were not significantly different (96.3% vs. 96.4%). The ability to deliver the stent in a subgroup of patients who had DS was 95%, with 5% requiring crossover to predilation. Multivariate analysis showed no significant differences with respect to in-hospital death (odds ratio [OR] 0.9, 95% confidence interval [CI] 0.5 to 1.8), in-hospital myocardial infarction (OR 0.9, 95% CI 0.6 to 1.2) or revascularization (OR 0.7, 95% CI 0.4 to 1.5) in the DS compared with the BA+S group. Long-term outcomes were not significantly different between the DS and BA+S groups. The procedural duration was significantly shorter in the DS group, and there was a decreased utilization of contrast agent, balloons and wires.

CONCLUSIONS

The in-hospital and long-term clinical outcomes in patients undergoing a coronary intervention are equivalent when comparing stenting without balloon predilation with balloon angioplasty followed by stenting. Direct stenting is associated with decreased utilization of contrast agent and equipment and shorter procedure times. A randomized study should be performed to better determine the impact of this technique on short- and long-term procedural outcomes.

Effect of age on the outcome of angioplasty for acute myocardial infarction among patients treated at the Mayo Clinic

PURPOSE

Elderly patients, especially those 80 years of age and older, have been excluded from most studies of thrombolysis or primary coronary angioplasty in patients with acute myocardial infarction. We compared the outcomes of elderly patients who underwent coronary angioplasty with the outcomes of younger patients and determined whether there were any temporal trends in survival.

PATIENTS AND METHODS

We reviewed the outcomes of 1,597 consecutive patients who underwent primary coronary angioplasty between 1979 and 1997, including 127 patients who were 80 years of age or older (mean [+/-SD] age, 83 +/- 3 years, 47% male). Their in-hospital and long-term outcomes were compared with those of 524 patients who were 70 to 79 years old, 527 patients who were 60 to 69 years old, and 419 patients who were 50 to 59 years old. The oldest group of patients was divided into two groups, based on whether they had intervention through the end of 1993 (n = 56) or between 1994 and 1997 (n = 71). The survival rate of the patients who had no complications and left the hospital was compared with expected survival based on age- and sex-adjusted data.

RESULTS

Patients 80 years of age or older had more adverse baseline characteristics, including risk factors and comorbid conditions, than the younger patients. The clinical success rate of primary angioplasty in this group was lower than those in the other three groups (61% versus 74% in those aged 70 to 79 years, 73% in those aged 60 to 69 years, and 81% in those aged 50 to 59 years, P < 0.001). The in-hospital mortality rate among patients 80 years of age or older was significantly greater than among patients in the other three groups (21% in those aged 80 years or older, 13% in those aged 70 to 79 years, 9% in those aged 60 to 69 years, and 4% in those aged 50 to 59 years, P < 0.001 ). The clinical success rate of the angioplasty improved significantly in the more recent period (75% versus 45%, P = 0.0006) and in-hospital mortality declined (16% versus 29%, P = 0.07). During follow-up, mortality in the oldest age group in whom angioplasty was successful was significantly greater than in the three younger groups, but was similar to the expected survival in the general US population.

CONCLUSIONS

The mortality associated with primary angioplasty for acute myocardial infarction in octogenarians remains high, although there has been significant improvement in the clinical success rate. The long-term prognosis following a successful angioplasty is not different from that in an age- and sex-adjusted U.S. white population.

The iron (Fe) and atherosclerosis study (FeAST): a pilot study of reduction of body iron stores in atherosclerotic peripheral vascular disease

BACKGROUND

Levels of body iron stores, represented by the serum ferritin concentration, rise with age after adolescence in men and menopause in women. This rise has been implicated mechanistically and epidemiologically in the pathogenesis of atherosclerosis through iron-induced oxygen free radical-mediated lipid oxidation. However, the precise contribution of iron stores to atherosclerosis and its complications are unknown because prospective randomized trials designed to test effects of reduction of iron stores on clinical outcomes in this disease have not been performed.

METHODS AND RESULTS

In preparation for a prospective randomized trial, a randomized pilot study was conducted to evaluate the feasibility, safety, and methodologic accuracy of calibrated reduction in iron stores by phlebotomy in a cohort of patients with advanced peripheral vascular disease. Phlebotomy resulted in a significant reduction in serum ferritin concentration to near targeted levels. Thus the formula for calculating the volume of blood to be removed to achieve a predetermined decrement in serum ferritin concentration was accurate and phlebotomy was not associated with any adverse laboratory or clinical effects.

CONCLUSIONS

Reduction of body iron stores to a predetermined level is feasible and can be achieved in a timely manner with excellent patient compliance. Prospective randomized trials of calibrated reduction of body iron stores may be undertaken to define their pathophysiologic significance in atherosclerosis and other diseases in which excessive iron-induced oxidative stress has been implicated.

Clopidogrel versus ticlopidine after intracoronary stent placement

OBJECTIVES

The study compared the safety and efficacy of ticlopidine with clopidogrel in patients receiving coronary stents.

BACKGROUND

Stent thrombosis is reduced when ticlopidine is administered with aspirin. Clopidogrel is similar to ticlopidine in chemical structure and function but has fewer side effects; few data are available about its use in stent patients.

METHODS

We compared 30-day event rates in 500 consecutive coronary stent patients treated with aspirin and clopidogrel (300 mg loading dose immediately prior to stent placement, and 75 mg/day for 14 days) to 827 consecutive stent patients treated with aspirin and ticlopidine (500 mg loading dose and 250 mg twice daily for 14 days).

RESULTS

Patients treated with clopidogrel had more adverse clinical characteristics including older age, more severe angina, and more frequent infarction within the prior 24 h. Nonetheless, mortality was 0.4% in clopidogrel patients versus 1.1% in ticlopidine patients; nonfatal myocardial infarction occurred in 0% versus 0.5%, stent thrombosis in 0.2% versus 0.7%, bypass surgery or repeat angioplasty in 0.4% versus 0.5%, and any event occurred in 0.8% versus 1.6% of patients, respectively (p = NS). Based on the observed 30-day event rate of 1.6% with ticlopidine, the statistical power of the study was 43% to detect an even rate of 0.5% with clopidogrel, and 75% to detect an event rate with of 4% with clopidogrel, with a p value of 0.05.

CONCLUSIONS

These data indicate that clopidogrel can be safely substituted for ticlopidine in patients receiving coronary stents.

Clinical, angiographic, and procedural correlates of abrupt vascular closure during coronary intervention: a 10-year experience at Mayo Clinic

A large matched-cohort study was carried out to determine correlates of in-hospital abrupt vascular closure (AC). Univariate analysis identified current cigarette smoking (P = 0.021), myocardial infarction within 24 hr prior to procedure (P = 0.0035), emergency procedure (P = 0.02), lesion thrombus (P = 0.0001), and lesion angulation (P = 0.021) as significant clinical and angiographic variables. Relative to balloon angioplasty (PTCA), use of atherectomy (P = 0.015) and laser devices (P = 0.018) but not elective stent placement (P = 0.97) were associated with increased risk of AC. In the multivariate model, current cigarette smoking (P = 0.0474), lesion thrombus (P = 0.0001), lesion angulation (P = 0.0124), use of atherectomy devices (P = 0.001), and laser devices (P = 0.0037) remained as significant correlates of increased AC events. In conclusion, the risk of AC appears associated primarily with lesion characteristics and use of nonballoon devices other than stents. Elective stent placement did not appear to reduce AC risk over conventional PTCA; the small number of patients studied may have prevented any benefit from being observed.

Validation of minimally invasive measurement of myocardial perfusion using electron beam computed tomography and application in human volunteers

OBJECTIVES

To measure myocardial perfusion using an estimate of intramyocardial vascular volume obtained by electron beam computed tomography (EBCT) in an animal model; to assess the feasibility and validity of measuring regional myocardial perfusion in human volunteers using the techniques developed and validated in the animal studies.

METHODS

Measurements of myocardial perfusion with EBCT employing intravenous contrast injections were compared with radioactive microsphere measurements (flow 57 to 346 ml/100 g/min) in seven closed chest dogs. Fourteen human volunteers then underwent EBCT scans using intravenous contrast injections.

RESULTS

Mean (SEM) global intramyocardial vascular volume by EBCT was 7.6 (1.1)%. The correlation between global EBCT (y) and microsphere (x) perfusion was y = 0.59x + 15.56 (r = 0.86) before, and y = 0.72x + 6. 06 (r = 0.88) after correcting for intramyocardial vascular volume. Regional perfusion correlation was y = 0.75x + 23.84 (r = 0.82). Corresponding improvements in agreement between the two techniques were also seen using Bland-Altman plots. In the human subjects, mean resting global myocardial flow was 98 (6) ml/100 g/min, with homogeneous flow across all regions. In 10 of these subjects, perfusion was studied during coronary vasodilatation using intravenous adenosine. Global flow increased from 93 (5) ml/100 g/min at rest to 250 (19) ml/100 g/min during adenosine (p < 0.001), with an average perfusion reserve ratio of 2.8 (0.2). Similar changes in regional perfusion were observed and were uniform throughout all regions, with a mean regional perfusion reserve ratio of 2.8 (0.3).

CONCLUSIONS

Accounting for intramyocardial vascular volume improves the accuracy of EBCT measurements of myocardial perfusion when using intravenous contrast injections. The feasibility of providing accurate measurements of global and regional myocardial perfusion and perfusion reserve in people using this minimally invasive technique has also been demonstrated.

Timing of coronary stent thrombosis in patients treated with ticlopidine and aspirin

In patients receiving coronary stents treated with aspirin and coumadin, the peak incidence of stent thrombosis occurs on the fifth and sixth days following the implantation procedure. Little is known about the timing of stent thrombosis in patients treated with aspirin and ticlopidine. We compared the timing of coronary stent thrombosis in patients treated with ticlopidine and aspirin with the timing in those receiving coumadin and aspirin. A retrospective databank analysis was performed and 39 patients were identified who experienced stent thrombosis after successful coronary stent implantation. Of these, 21 had been treated with ticlopidine and aspirin and 18 with coumadin and aspirin therapy. The median time from stent implantation to stent thrombosis in the ticlopidine and aspirin group was 12 hours (interquartile range 6 to 72 hours) compared with 4 days in the coumadin and aspirin group (interquartile range 21 to 68 hours) (p <0.0001). There was no significant difference between the timing of stent thrombosis in patients treated with abciximab in addition to ticlopidine and aspirin (median 17 hours, interquartile range 6 to 29) versus ticlopidine and aspirin patients who did not receive abciximab (median 11 hours, interquartile range 9 to 12, p = 0.57). Thus, in patients who receive coronary stents, stent thrombosis occurs much earlier after the procedure in patients treated with ticlopidine and aspirin than in patients treated with anticoagulation therapy.

Utility of bilateral coronary injections during complex coronary angioplasty

We describe a technique useful in complex coronary interventions wherein timed bilateral contrast injections are given in both coronary arteries. This technique is useful in chronic total occlusions in which the distal coronary vessel is not visualized except by collateral filling via the contralateral artery. This technique was applied in 12 patients; 11 with native coronary occlusion and one in whom the target site was visualized by contrast injections into a vein graft supplying competitive flow to an otherwise patent native vessel. With this technique, the distal coronary artery segment can be better visualized, which helps to aim and track the guide wire across the occluded segment.

Real-time measurement of radiation exposure to patients during diagnostic coronary angiography and percutaneous interventional procedures

OBJECTIVES

The aim of this study was to accurately assess the radiation exposure received by patients during cardiac catheterization in a large sample representative of the current state of practice in cardiac angiography.

BACKGROUND

Radiation exposure to patients and laboratory staff has been recognized as a necessary hazard in coronary angiography. The effects on x-ray exposure of the increased complexity of coronary angiographic procedures and, in particular, the increasing use of coronary artery stenting, have not been adequately addressed in previous studies.

METHODS

X-ray exposure measurements were performed on a consecutive series of 972 patients undergoing 992 diagnostic and interventional studies in the Mayo Clinic catheterization laboratory within an eight week period in late 1997. Data were acquired from 706 diagnostic procedures and 286 interventional procedures using a real-time exposure measurement system to continuously calculate and record the exposure rate and total exposure, reflecting all parameters relevant to the specific patient and procedure situation.

RESULTS

The median exposure for all 992 procedures was 41.8 mC/kg (162.1 R); the corresponding values for diagnostic and interventional procedures were 34.9 and 95.6 mC/kg, respectively (135.3 vs. 370.5 R). There were significant differences in the fluoroscopy exposure time between diagnostic and interventional procedures: 4.7 min vs. 21.0 min. Heavier patients (>83 kg) received x-ray exposures at a significantly higher rate than did lighter patients (<83 kg) during both fluoroscopy and cine; 44.9 mC/kg/min (173.9 R/min) vs. 27.9 mC/kg/min (108.3 R/min) for cine exposure rate and 2.3 mC/kg/min (8.8 R/min) vs. 1.5 mC/kg/min (5.8 R/min) for fluoroscopy exposure rate.

CONCLUSIONS

Changes in practice have led to higher values for patient x-ray radiation exposures during cardiac catheterization procedures. The real-time display and recording of x-ray exposure facilitates the reduction of exposure in the catheterization laboratory.

Safety and efficacy of ticlopidine for only 2 weeks after successful intracoronary stent placement

BACKGROUND

In patients receiving intracoronary stents, stent thrombosis is reduced when ticlopidine therapy is combined with aspirin after the procedure. However, ticlopidine causes neutropenia in 1% of patients when administered for >2 weeks, and little is known about the duration that ticlopidine needs be administered to prevent stent thrombosis.

METHODS AND RESULTS

We analyzed 827 patients undergoing successful stent placement in 1061 coronary segments at Mayo Clinic who were treated between May 1, 1996, and October 31, 1997. Chronic warfarin therapy, cardiogenic shock, and enrollment in research protocols requiring 4 weeks of ticlopidine were exclusion criteria; ticlopidine was discontinued after 14 days in all remaining patients. The mean age of the study population was 64+/-11 years; 49% had suffered a prior infarction, 20% had undergone coronary artery bypass surgery, and 65% had multivessel disease. The indication for stent placement was dissection or abrupt closure in 31% of patients and suboptimal results from balloon angioplasty in 18%. Placement was elective in 51% of patients, and 10.3% of patients were treated within 12 hours of an acute myocardial infarction. Mean nominal stent size was 3.3+/-0.5 mm. High-pressure inflations (>/=12 atm) were performed in all patients (mean, 17+/-4 atm). Intravascular ultrasound was used to facilitate stent placement in 8.8% of patients. Abciximab was administered to 38% of patients; 11% of patients who were at increased risk of stent thrombosis were treated with enoxaparin for 10 to 14 days. Adverse cardiovascular events in the 14 days after stent placement occurred in 11 patients (1.3%). Two patients died of nonischemic causes (sepsis and renal failure) in the 15th through 30th days after ticlopidine was stopped. However, there were no cardiovascular deaths, myocardial infarctions, coronary artery bypass operations, or repeat angioplasty procedures between the 15th and 30th days; stent thrombosis did not occur in any patient after ticlopidine had been stopped. No patient developed neutropenia, although 1.8% of the first 489 patients who were closely monitored for side effects from ticlopidine developed side effects requiring its discontinuation, and milder side effects occurred in 4.7%.

CONCLUSIONS

In patients receiving intracoronary stents, the discontinuation of ticlopidine therapy 14 days after stent placement is associated with a very low frequency of stent thrombosis and other adverse events.

Marked regularity models

We present a generalization of the regularity model, which is a stationary point process model describing how often and how regularly a random "event" occurs. The generalization allows the amplitude of each event to be a sample from a random process. First, we developed closed-form approximations of the power spectra of data segments; then we examined the accuracy of a procedure that estimates the regularity and mark process parameters by minimizing the error between measured spectra and the approximations. We found the following. In the absence of measurement noise, joint estimation of both mark and regularity parameters is accurate only if the ratio of the square of the mean of the marks to the variance of the marks (the SMNPR) is small. Marginal estimation of the regularity process parameters can be accurate if the mark process is taken into account by minimizing overall parameters; the accuracy then depends on both measurement noise and SMNPR. Error in the marginal estimation of the regularity process parameters will be inversely proportional to the SMNPR if the marks are ignored by minimizing only with respect to the regularity parameters, so ignoring the marks can cause a substantial degradation in accuracy when the SMNPR is small. We illustrate these findings with an acoustic scattering example in which simulated ultrasound measurements of tissue samples are characterized by their description in the parameter space.

Usefulness of abciximab for treatment of early coronary artery stent thrombosis

The clinical and angiographic outcomes of 10 patients who received abciximab as part of their therapy for early stent thrombosis was compared with 25 patients (using historical controls) who received conventional therapy. Although the angiographic outcome and the incidence of myocardial infarction in both groups was similar, there were no deaths or referral for emergency coronary bypass surgery in the abciximab-treated group versus 3 deaths and 10 referrals for emergency bypass surgery in the conventionally treated group.

Abciximab administration and outcome after intracoronary stent implantation

Although adjunctive abciximab therapy improves outcome after angioplasty or atherectomy, there are few data demonstrating its benefit for intracoronary stent implantation. We characterized patients receiving abciximab for stent placement in our practice and determined the impact of abciximab on outcome. Abciximab was introduced to our practice in April 1995 for percutaneous revascularization. Demographic, clinical, and angiographic variables that were independently associated with the use of abciximab for stent placement through 1996 (abciximab era) were examined. We then examined among all patients receiving stents from 1992 through 1996 (preabciximab and abciximab eras) whether the use of abciximab was independently associated with improved outcome (death, nonfatal Q-wave myocardial infarction, coronary bypass surgery, or target vessel percutaneous revascularization) in the hospital and at 30 days. The 30-day event rate was 7% for those who did or did not receive abciximab. The following characteristics were independently associated with the use of abciximab for stent placement in the abciximab era: thrombus before stent placement (chi-square 50.5), > or =2 stents implanted (chi-square 10.8), stent in venous graft (chi-square 7.4), calcific lesion (chi-square 5.8), and hypertension (chi-square 5.5). Among all patients receiving stents in the preabciximab and abciximab eras (n=1,859), the presence of these characteristics was independently associated with worse outcome. Abciximab, however, did not improve outcome in the hospital (odds ratio [95% confidence interval]=0.96 [0.58 to 1.58]) or at 30 days (0.87 [0.53 to 1.41]), even after adjusting for these characteristics. Abciximab for stent placement was used in high-risk patients in our practice but was not associated with improved outcome.

Reversible perfusion defects on exercise tomographic thallium imaging in patients with and without collateral flow

A consecutive series of patients underwent exercise thallium imaging and coronary angiography that identified single-vessel right coronary artery disease. Redistribution in the left anterior descending territory was significantly associated with the presence of left-to-right collaterals, whereas collaterals were significantly less frequent in individuals who did not exhibit redistribution.

Cine film replacement: digital archival requirements and remaining obstacles

The acceptance of the Digital Imaging and Communication in Medicine (DICOM) standard and the Compact Disk-Recordable (CD-R) as the interchange medium have been critical developments for laboratories that need to move forward on the cine replacement front, while at the same time retain a means to communicate with other centers. One remaining essential component which has not been satisfactorily addressed is the issue of how digital image data should be archived within an institution. Every laboratory must consider the diverse issues which affect the choice of a digital archiving system. These factors include technical and economic issues, along with the clinical routines prevailing in their laboratory. A complete understanding of the issues will lead to the formulation of multiple options which may prove acceptable and will help to overcome the last obstacle which remains for the complete replacement of cine film in the cardiac catheterization laboratory.

Intravenous electron-beam computed tomographic coronary angiography for segmental analysis of coronary artery stenoses

OBJECTIVES

We sought to identify and localize significant coronary stenoses on a segmental basis by electron-beam computed tomography (EBCT) and intravenous administration of a contrast agent.

BACKGROUND

The clinical applicability and limitations of intravenous EBCT coronary angiography have not been defined.

METHODS

EBCT was performed within 24 h of selective coronary angiography (SCA) in 28 patients (19 men and 9 women, mean [+/-SD] age 60 +/- 10 years). After examination for coronary calcium, EBCT coronary angiography was performed using overlapping slices (in-plane resolution 0.34 to 0.41 mm) with a nominal slice thickness of 1 mm. Based on quantitative analysis of SCA, lumen diameter narrowing > or = 50% (i.e., significant stenoses) was evaluated in 8 (major) or 12 (including side branches) coronary artery segments, using both two-dimensional (tomographic) and three-dimensional (volume) data sets.

RESULTS

Of the 330 segments assessable by SCA, 237 (72%) were visualized by EBCT. The sensitivity (+/-SE) for detection of significant stenoses was 82 +/- 6%; specificity was 88 +/- 2%; positive and negative predictive values were 57 +/- 7% and 96 +/- 2%, respectively; and overall accuracy was 87 +/- 2%. If only eight (major) coronary artery segments were considered, 194 (88%) of 221 segments were visualized, and the overall accuracy was 90 +/- 2%. Seven (18%) of 38 significantly stenotic segments were classified as having < 50% stenoses by EBCT. Six of these segments (86%), but only 9 (29%) of the 31 correctly classified stenotic segments, were severely calcified (area > 20 mm2, p = 0.02). In 23 (12%) of 199 nonstenotic segments falsely classified as having > or = 50% stenosis by EBCT, the lumen diameter was significantly smaller than that of the segments correctly classified as negative (mean [+/-SD] 1.5 +/- 0.8 vs. 2.9 +/- 1.1 mm, p < 0.001).

CONCLUSIONS

Intravenous EBCT coronary angiography allows for accurate segmental evaluation of significant disease in the major coronary arteries and may be of value for ruling out significant disease. The main determinant of false negative results is substantial segmental calcification, whereas the main determinant of false positive results is small vessel size.

Clinical outcomes after successful percutaneous coronary angioplasty of saphenous vein graft disease and the importance of long-term assessment

We examined the short- and long-term outcome of 327 patients at Mayo Clinic who had undergone coronary angioplasty of saphenous vein graft stenoses to determine whether the traditional 6-month assessment of clinical end points after coronary angioplasty is as useful as it is for patients who have had angioplasty of native vessel disease. Follow-up over 3.3+/-2.7 years was performed. At 6 months, 96+/-1% of the patients were alive, whereas at the 1- and 5-year end points, survival had deteriorated to 92+/-2 and 67+/-3%, respectively. Only 80+/-2% were free of severe angina at 6 months and 62+/-3 and 36+/-3% after 1 and 5 years. Combined event-free rate for death, Q-wave myocardial infarction or repeat coronary artery bypass surgery was 86+/-2% at 6 months, 78+/-2% at 1 year, and 45+/-4% at 5 years. Independent predictors of mortality included advancing age, diabetes mellitus, target vein grafts >5 years old and left ventricular ejection fraction <40%. In conclusion, despite reasonable 6- to 12-month outcomes following vein graft angioplasty, significant attrition in survival and event-free survival was observed. These observations have important implications for the interpretation of results of trials comparing conventional angioplasty and coronary bypass surgery with newer interventional devices if only the traditional 6-month follow-up interval is used.

Frequency of adverse clinical events in the 12 months following successful intracoronary stent placement in patients treated with aspirin and ticlopidine (without warfarin)

Little is known about the frequency of adverse events in the year following stent placement in patients treated with aspirin and ticlopidine, without warfarin. We analyzed the first such 234 consecutive patients treated at our hospital between October 1994 and December 1995. Their mean age was 62+/-12 years; 40% had had a prior myocardial infarction, 22% had undergone coronary artery bypass surgery, and 65% had multivessel disease. The indication for stent placement was dissection or abrupt closure in 24% of patients and suboptimal balloon angioplasty results in 14%; placement was elective in 62% of patients. Three hundred forty-five coronary segments were treated in the 234 patients; 305 stents (1.3 stents/patient) were placed. Palmaz-Schatz coronary stents (75%), Gianturco-Roubin stents (21%), and Johnson & Johnson biliary stents (4%) were used. Mean nominal stent size was 3.4+/-0.4 mm. High-pressure inflations (> or = 14 atm, mean 17+/-2) were performed in all patients. The mean residual stenosis was 3+/-5% by visual estimate. Intravascular ultrasound was utilized to facilitate stent placement in 53% of patients. Mean follow-up was 1.6+/-0.5 years. There were no deaths, Q-wave myocardial infarctions, coronary artery bypass operations, or repeat angioplasty procedures required during the remainder of the hospitalization or in 30 days after stent placement; stent thrombosis did not occur. Kaplan-Meier analysis of adverse events in the 6 months following the procedure revealed a mortality rate of 0.9%; the rate of myocardial infarction (Q-wave or non-Q-wave) was 1.3%. Bypass surgery was performed in 0.9% and angioplasty for in-stent restenosis was performed in 9.5% of patients. Any 1 of these events occurred in 11.7% of patients in the 6 months after the procedure. The corresponding event rates at 1 year were 1.3%, 2.2%, 3.5%, and 12.2%, respectively; any 1 of these events occurred in 16.5% of patients. In patients receiving intracoronary stents of varying designs followed by high-pressure postdeployment inflations in whom an excellent visual angiographic result is achieved, antithrombotic therapy with aspirin and ticlopidine is associated with a very low frequency of adverse cardiovascular events in the 12 months following the procedure regardless of the indication for stent placement.

Clinical outcome of patients undergoing multivessel coronary stent implantation

OBJECTIVES

To evaluate the outcome of patients undergoing multivessel coronary stent implantation.

BACKGROUND

Percutaneous transluminal coronary angioplasty has been shown to be an effective treatment for multivessel coronary artery disease, although the need for repeat revascularization continues to be a limitation. Intracoronary stent placement has been shown to reduce the need for subsequent revascularization.

METHODS

Seventy-seven patients without prior coronary artery bypass grafting (CABG) undergoing multivessel coronary revascularization in which stents were placed in all treated segments over a 5 year period at our institution were identified. Clinical and angiographic characteristics and outcomes were analyzed.

RESULTS

One hundred and eighty-eight coronary lesions were successfully treated (2.1+/-0.3 treated vessels/patient, 2.4+/-0.6 treated lesions/patient) using 2.8+/-1.2 stents/patient (range 2-9) and 1.4+/-0.8 stents/vessel (range 1-6). Procedural success rate [angiographic success without in-hospital death, Q-wave myocardial infarction (Q-wave MI) or CABG] was achieved in 76 of 77 patients (98.7%). Anatomically complete revascularization was achieved in 46 (59.7%) patients. Modified ACC/AHA Type B2 and C lesions comprised 75.5% of the 188 lesions. The left anterior descending artery was treated in 57 (74.0%) patients. The indication for stent placement was dissection or threatened/abrupt closure in 54 segments (28.8%). In-hospital events included death in one patient (1.3%); no patient suffered a Q-wave MI or required CABG. Stent occlusion occurred in two (2.6%) patients, and repeat percutaneous intervention of the target vessel was also required in these two patients. Any of these adverse events occurred in three (3.9%) patients. No further events occurred after hospital discharge in the 30 days after the procedure. Of hospital survivors (n=76), adverse events at 6 months included death in two patients (2.6%), MI in two (2.6%), CABG in six (7.9%); nine (11.8%) patients underwent repeat percutaneous intervention and 15 (19.7%) underwent any revascularization.

CONCLUSIONS

Multivessel coronary stent placement is associated with an excellent procedural success rate despite a high rate of adverse lesion characteristics, and a low rate of death or MI during follow-up. The need for further revascularization compares favorably with published rates with multivessel PTCA and single stent implantation for discrete de novo lesions.

Clinical outcome of patients undergoing endoluminal coronary artery reconstruction with three or more stents

OBJECTIVES

We sought to evaluate the outcome of patients undergoing multiple (three or more), contiguous stent implantation within a single native coronary artery.

BACKGROUND

The implantation of multiple stents within a single coronary artery is increasing in frequency, although the outcome of such patients is not well described.

METHODS

Forty-five patients without previous coronary artery bypass graft surgery (CABG) undergoing multiple, contiguous stent implantation in a single coronary artery were identified. Clinical and angiographic characteristics and outcomes were analyzed.

RESULTS

The angiographic success rate was 97.8%. The procedural success rate was 91.1%; stent occlusion during the initial hospital period occurred in four patients (8.9%). Death, myocardial infarction (MI), CABG, repeat target vessel intervention or severe angina occurred in 10 (23.3%) of 43 hospital survivors at 6-months follow-up. The indication for stent placement was threatened or abrupt closure in 30 patients (66.7%). Of the 25 patients with abrupt or threatened closure whose clinical and angiographic data would have indicated emergent CABG had stents not been available, the frequency of in-hospital death and Q wave MI was similar to that of a matched consecutive series of patients at our institution who underwent emergent CABG after failed angioplasty. At 1 year, the frequency of death, Q wave MI, CABG and severe angina at 1 year was similar in the two groups; the need for repeat percutaneous intervention was more common in the stent group (25% vs. 0%, p = 0.01).

CONCLUSIONS

Implantation of multiple, contiguous intracoronary stents was associated with a high initial success rate, although the incidence of early stent closure was relatively high. Adverse events at 6 months of follow-up were more frequent than previously reported for elective single-stent implantation; however, adverse angiographic characteristics such as dissection and thrombus were frequent in this group. In addition, the strategy of multiple stent implantation in the setting of failed angioplasty is a reasonable alternative to emergent CABG, although the need for further percutaneous intervention must be anticipated.

Determination of ventricular ejection fraction: a comparison of available imaging methods. The Cardiovascular Imaging Working Group

Knowledge of left ventricular ejection fraction has been shown to provide diagnostic and prognostic information in patients with known or suspected heart disease. In clinical practice, the ejection fraction can be determined by using one of the five currently available imaging techniques: contrast angiography, echocardiography, radionuclide techniques of blood pool and first pass imaging, electron beam computed tomography, and magnetic resonance imaging. In this review, we discuss the clinical application as well as the advantages and disadvantages of each of these methods as it relates to determination of ventricular ejection fraction.