Frederic R. Kahl

Can coronary angiography predict the site of a subsequent myocardial infarction in patients with mild-to-moderate coronary artery disease?

To help determine if coronary angiography can predict the site of a future coronary occlusion that will produce a myocardial infarction, the coronary angiograms of 42 consecutive patients who had undergone coronary angiography both before and up to a month after suffering an acute myocardial infarction were evaluated. Twenty-nine patients had a newly occluded coronary artery. Twenty-five of these 29 patients had at least one artery with a greater than 50% stenosis on the initial angiogram. However, in 19 of 29 (66%) patients, the artery that subsequently occluded had less than a 50% stenosis on the first angiogram, and in 28 of 29 (97%), the stenosis was less than 70%. In every patient, at least some irregularity of the coronary wall was present on the first angiogram at the site of the subsequent coronary obstruction. In only 10 of the 29 (34%) did the infarction occur due to occlusion of the artery that previously contained the most severe stenosis. Furthermore, no correlation existed between the severity of the initial coronary stenosis and the time from the first catheterization until the infarction (r2 = 0.0005, p = NS). These data suggest that assessment of the angiographic severity of coronary stenosis may be inadequate to accurately predict the time or location of a subsequent coronary occlusion that will produce a myocardial infarction.

Evaluation of the associations between carotid artery atherosclerosis and coronary artery stenosis. A case-control study.

To evaluate the consistency, strength, and independence of the relation of carotid atherosclerosis to coronary atherosclerosis, we quantified coronary artery disease risk factors and extent of carotid atherosclerosis (B-mode score) in 343 coronary artery disease patients and 167 disease-free control patients. In univariable analyses, there was a strong association between coronary status and extent of carotid artery disease in men and women older than and younger than 50 years (p less than 0.001 for men and women greater than 50 years, p less than 0.001 for women less than or equal to 50 years, p = 0.045 for men less than or equal to 50). The relation remained strong after control for age in men and women older than 50 years and in women younger than 50 (p less than 0.001 for men and women greater than 50 years, p = 0.003 for women less than or equal to 50) but did not persist after control for age in men younger than 50. Logistic models that included coronary disease risk factors, with or without B-mode score, as independent variables and presence or absence of coronary disease as the outcome variable indicated that the extent of carotid atherosclerosis was a strong, statistically significant independent variable in models for men and women older than 50 years of age. Next, we examined the usefulness of B-mode score as an aid in screening for coronary artery disease in men and women older than 50 years. Classification rules, both including and excluding B-mode score, were developed based on logistic regression and, for comparison, recursive partitioning (decision trees). The performance of these rules and the bias of their performance statistics were estimated. The improved classification of the study sample when B-mode score was incorporated in the rule was statistically significant only for men (p = 0.015). However, the addition of B-mode score was found to 1) increase the median discrimination score for both sex groups based on the logistic model, and 2) yield better sensitivities and specificities for rules based on recursive partitioning. Thus B-mode score is strongly, consistently, and independently associated with coronary artery disease in patients older than 50 and is at least as useful as well-known risk factors for identifying patients with coronary artery disease.

Risk factors for extracranial carotid artery atherosclerosis.

We related risk factors, cardiovascular symptoms, and coronary status to the extent of extracranial carotid atherosclerosis as measured by B-mode ultrasonography in 376 volunteers hospitalized for elective coronary angiography. In a first analysis, we correlated risk factors and cardiovascular symptoms with carotid atherosclerosis. Univariate analysis showed that relations between many continuous risk factors and carotid atherosclerosis were graded and consistent for men and women. Multivariate analysis identified 6 significant variables (age, hypertension, pack-years smoked, and inversely, plasma concentrations of high density lipoprotein cholesterol and uric acid, and Framingham Type A score) that together accounted for 35% of the variability in extent of carotid atherosclerosis. In a second multivariate analysis, addition of coronary status (presence or absence of coronary stenosis as evaluated by coronary angiography) to the roster of candidate independent variables produced a new equation that accounted for an additional 5% of the variability in carotid atherosclerosis extent. Although much of the variability in extent of carotid atherosclerosis remains unexplained, these data define an association between coronary and carotid atherosclerosis that depends partly on shared exposure of both arteries to the same risk factors. They are also consistent with the concept that as yet undiscovered risk factors and/or genetic (e.g., arterial wall) factors common to both arterial beds also contribute to the relation between coronary and carotid atherosclerosis in human beings.

Vascular closure devices in patients treated with anticoagulation and IIb/IIIa receptor inhibitors during percutaneous revascularization.

OBJECTIVES The study assessed clinical outcomes of closure device use following percutaneous coronary revascularization using current standards of anticoagulation and antiplatelet therapy. BACKGROUND Evaluation of the outcomes of patients by use of vascular closure devices during coronary interventions employing current standards of anticoagulation and glycoprotein (GP) IIb/IIIa inhibitor therapy is limited. METHODS We evaluated outcomes of 4,525 consecutive patients who underwent percutaneous coronary intervention between July 1997 and April 2000. All patients received anticoagulation with heparin and GP IIb/IIIa inhibitor therapy with abciximab. The closure method was manual in 1,824 patients, Angioseal in 524 patients and Perclose in 2,177 patients. Procedural and hospital vascular outcomes were evaluated. RESULTS Closure device success was 97.1% Angioseal and 94.1% Perclose (p < 0.05). Minor vascular complications occurred in 1.8% of manual patients, 1.1% of Angioseal patients and 1.2% of Perclose patients (p = NS); major complications occurred in 1.3% of manual patients, 1.1% of Angioseal patients and 1.0% of Perclose patients (p = NS). Multivariate logistic regression identified only closure device failure as an independent predictor of a vascular complication. In patients with successful closure with a device, minor complications (0.8% vs. 1.8%, p < 0.05) and any complication (1.5% vs. 2.5%, p < 0.05) were reduced compared to manual compression. CONCLUSIONS Arterial closure following coronary interventions using anticoagulation and GP IIb/IIIa inhibitor therapy can be safely and effectively performed, with vascular complication rates similar to or lower than with manual pressure. Additionally, vascular complication rates using GP IIb/IIIa inhibitor therapy regardless of the method of arterial closure are equivalent to or lower than previously published rates of vascular complications.

Evaluation of a scoring system for extracranial carotid atherosclerosis extent with B-mode ultrasound.

We have developed a scoring system to quantify extent of extracranial carotid artery atherosclerosis using real-time ultrasound (B-mode). To evaluate repeatability of this scoring system we correlated repeat scores obtained within a short interval of one another (6 months) in 52 individuals. We compared repeatability of extent measurements with repeatability of a measure of severity (single most severe lesion). Correlations between first and second studies for severity were weak (r2 = 0.20) but significant (p less than 0.001). Extent scores correlated much better (r2 = 0.77, p less than 0.001). In another group of 22 patients we found that the extent of atherosclerosis decreased following endarterectomy. We used this method to determine changes in extent of carotid atherosclerosis with age in two sets of individuals. One consisted of a cohort of 22 patients who underwent repeat B-mode studies separated by 1 1/2-3 years. This cohort demonstrated an increase in carotid score with age (p less than 0.05). In a second group of volunteers undergoing cardiac catheterization and B-mode evaluation of the carotid system, carotid scores could be compared in individuals with age differences that averaged 15 years. Extent of carotid atherosclerosis was significantly greater in older individuals (p less than 0.01) and differences in extent with age were exaggerated in patients with coronary disease compared to coronary disease free controls.

Trends in Vascular Complications After Diagnostic Cardiac Catheterization and Percutaneous Coronary Intervention Via the Femoral Artery, 1998 to 2007

OBJECTIVES This study sought to evaluate trends in vascular complications after diagnostic cardiac catheterization (CATH) and percutaneous coronary intervention (PCI) from the femoral artery from 1998 to 2007. BACKGROUND Vascular complications have been recognized as an important factor in morbidity after CATH and PCI. Whether strategies to reduce vascular complications performed from the femoral artery in the past decade have improved the safety of these procedures, however, is uncertain. METHODS A total of 35,016 consecutive diagnostic cardiac catheterization (n = 20,777) and percutaneous coronary intervention procedures (n = 14,239) performed via a femoral access at a single site (Wake Forest University Baptist Medical Center) between 1998 and 2007 were evaluated. Annual rates of vascular complications were evaluated. Covariate effects on the risk of vascular complications were evaluated by logistic regression and risk-adjusted trend analysis. RESULTS Overall, the incidence of any vascular complication decreased significantly for CATH, 1.7% versus 0.2%, and PCI, 3.1% versus 1.0%, from 1998 to 2007, both p < 0.001 for trend. Favorable trends in procedural covariates affecting vascular complications were mainly responsible for the decrease in the incidence of vascular complications, including fewer closure device failures and use of smaller sheath sizes. CONCLUSIONS In this large, single-center, contemporary observational study, the safety of CATH and PCI performed from the femoral artery improved significantly from 1998 to 2007. Reductions in the prevalence of adverse procedural factors contributed to the decrease in the incidence of vascular complications, suggesting that strategies to reduce vascular complications can be effective in improving the safety of these procedures.

Restick following initial Angioseal use

The Angioseal hemostatic device is currently in widespread use for arterial closure after both diagnostic and interventional procedures. Resticking of the artery in which an Angioseal device has been placed has been discouraged for up to 90 days after the initial device placement because of theoretical concerns of disruption or dislodgment of the hemostatic plug. However, no data are available to address this concern. We evaluated the incidence of vascular complications following restick of the artery in which an Angioseal device had been deployed ≤ 90 days previously in 181 patients. Restick occurred 1–7 days after device placement in 80 patients, 8–30 days in 34 patients, and 31–90 days in 66 patients. There were no major bleeding, vascular repair, vessel occlusion, or embolizations. Three large hematomas (1.7%) were noted. These data suggest that restick can be performed safely after initial Angioseal deployment. Cathet Cardiovasc Intervent 2003;58:181–184.

Evaluation of aortocoronary bypass graft status by computed tomography.

Abstract The efficacy of contrast-enhanced computed tomography to define graft patency status was studied in 42 patients with 100 aortocoronary vein grafts. The status of each graft had been determined earlier by anglography. A rotary fan beam whole body scanner with a 2 second scan duration was used. Initial scans determined the optimal level for study of the graft; patency was assessed by computed tomographic enhancement of the graft after intravenous bolus injection of 30 ml meglumine and sodium diatriazoate. The computed tomographic studies were evaluated without knowledge of the anglographic findings; graft status by computed tomography was interpreted as patent, occluded or equivocal. Overall, computed tomography correctly defined graft patency status in 79 of the 100 grafts and incorrectly identified it in 9; in 12 grafts, the computed tomographic diagnosis was equivocal. Computed tomography correctly identified 61 of 74 patent grafts and 18 of 26 occluded grafts. Patency status was correctly defined by computed tomography in 35 of 37 grafts to the left anterior descending artery, 23 of 30 grafts to circumflex branches and 19 of 31 grafts to the right coronary artery. These data indicate that computed tomography is a promising noninvasive method of determining patency of aortocoronary bypass grafts, especially of grafts to the left anterior descending artery.

Cause of acute myocardial infarction late after successful coronary artery bypass grafting

Coronary artery bypass grafting (CABG) reduces angina and improves exercise tolerance in patients with symptomatic coronary artery disease. Further, it improves survival in selected high-risk patients. Despite these dramatic results CABG has not been shown to reduce the incidence of acute myocardial infarction (AMI). In each of 3 large randomized CABG trials the frequency of nonfatal AMI was not reduced.1–3 The causes of AMI occurring months or years after successful CABG have not been well defined. In patients who have undergone CABG, AMI may potentially result from occlusion of a graft to an artery that has already closed, occlusion of an artery whose graft has previously closed or occlusion of an ungrafted native coronary artery.4 Recently, we observed that AMI in medically treated patients with coronary artery disease frequently was due to occlusion of an artery that previously did not contain an obstruction.5 This suggests that occlusion of unbypassed arteries that did not previously contain obstructions may be an important cause of AMI after CABG.

A microcomputer based automated, quantitative coronary angiographic analysis system

Rapid and accurate assessment of coronary artery stenotic severity is important in therapy and understanding of coronary artery disease. Since automated systems minimize prejudiceand variations in analysis, we developed an automated, quantitative coronary analysis system utilizing an IBM PC-XT computer. Film images (35 mm) were cine-to-video converted and subsequently digitized by an IBM PC-XT computer. Given an approximate center line, the computer automatically detected edges, corrected for X-ray magnification, and calculated arterial dimensions. On objects of known dimensional sizes, the correlation coefficient between actual and calculated dimensions was 0.996 (p<0.01) with a standard error of estimate of 0.07 mm and ±3.0% reproducibility. For objects less than 1 mm in diameter, the standard error of estimate was 0.05 mm with ±4.1% reproducibility. However, with minimal contrast material (25%), the standard error of estimate increased to 0.20 mm with ±7.2% reproducibility. The results indicate that automated, quantitative coronary angiography can be achieved using an inexpensive IBM PC-XT based system, provided that the vessels are adequately opacified.