Stanley M. Lewis

Silent myocardial ischemia and infarction in diabetics with peripheral vascular disease: Assessment by dipyridamole thallium-201 scintigraphy

We investigated the incidence of silent myocardial ischemia and infarction as assessed by dipyridamole thallium scintigraphy in 30 diabetic patients with peripheral vascular disease and without clinical suspicion of coronary artery disease. Seventeen patients (57%) had thallium abnormalities, with reversible thallium defects compatible with ischemia in 14 patients (47%) and evidence of prior, clinically silent myocardial infarction in 11 patients (37%). Thallium abnormalities were most frequent in patients with concomitant hypertension and cigarette smoking (p = 0.001). These results suggest that unsuspected coronary artery disease is common in this particular group of patients with diabetes mellitus.

Hemodynamic effects of intravenous amiodarone

Amiodarone is a potent antiarrhythmic agent that is effective in controlling both atrial and ventricular arrhythmias. Recently, intravenous administration was demonstrated to be effective in the acute management of rhythm disorders and, in addition, appeared to shorten the loading period normally required for oral drug administration. This investigation examined the hemodynamic effects of amiodarone after both acute intravenous bolus and continuous intravenous administration. Patients with a left ventricular ejection fraction greater than 0.35 experienced improved cardiac performance due to both acute and chronic peripheral vasodilation. However, patients with a lower ejection fraction developed a 20% decrease in cardiac index and clinically significant elevation of right heart pressures after acute bolus administration; these changes were variably compensated for by peripheral vasodilation when the drug was administered intravenously over 3 to 5 days continuously. Therefore, intravenous amiodarone can result in significant impairment of left ventricular performance in patients with preexisting left ventricular dysfunction.

Frequency, risk factors, and outcome for bacteremia after percutaneous transluminal coronary angioplasty

The objectives of this study were to examine bacteremias after percutaneous transluminal coronary angioplasty (PTCA) with respect to incidence, outcome, and risk factors. Patients undergoing PTCA from January 1990 through April 1994 were studied; during this period a total of 4,217 PTCAs were performed in 3,473 patients. With use of predefined clinical and microbiologic criteria, bacteremias were divided into 3 categories according to the relation to the PTCA procedure: PTCA-related, unrelated, and indeterminate. Ninety-one patients with at least 1 positive blood culture during a 7-week period after PTCA were identified. The bacteremia was classified as unrelated to the PTCA procedure in 32 patients, PTCA-related in 27, and indeterminant in the remaining 32 patients. The attack rate of PTCA-related bacteremia during the 52-month period was 0.64%. The most common organisms causing PTCA-related bacteremia were Staphylococcus aureus (14 patients), coagulase-negative staphylococci (9 patients) and group B streptococci (6 patients). Septic complications, which included femoral artery mycotic aneurysm, septic arthritis, and septic thrombosis, occurred in 10 patients (0.24%). Independent risk factors for PTCA-related bacteremia included duration of procedure (odds ratio [OR] 2.9; p = 0.04), number of catheterizations at the same site (OR 4.0; p = 0.015), difficult vascular access (OR 14.9; p = 0.007), arterial sheath in place > 1 day (OR 6.8; p = 0.025), congestive heart failure (OR 43.3; p = 0.002). Thus, PTCA-related bacteremia is an infrequent complication of PTCA but can be associated with significant morbidity, particularly when the infecting organism is S. aureus. Four of the 5 risk factors for PTCA-related bacteremia appear to correlate directly with increased vascular injury or maintenance of the arterial entry for the procedure.

Predictive value of quantitative dipyridamole-thallium scintigraphy in assessing cardiovascular risk after vascular surgery in diabetes mellitus

Cardiac complications represent a major risk to patients undergoing vascular surgery. Diabetic patients may be particularly prone to such complications due to the high incidence of concomitant coronary artery disease, the severity of which may be clinically unrecognized. Attempts to stratify groups by clinical criteria have been useful but lack the predictive value of currently used noninvasive techniques such as dipyridamole-thallium scintigraphy. One hundred one diabetic patients were evaluated with dipyridamole-thallium scintigraphy before undergoing vascular surgery. The incidence of thallium abnormalities was high (80%) and did not correlate with clinical markers of coronary disease. Even in a subgroup of patients with no overt clinical evidence of underlying heart disease, thallium abnormalities were present in 59%. Cardiovascular complications, however, occurred in only 11% of all patients. Statistically significant prediction of risk was not achieved with simple assessment of thallium results as normal or abnormal. Quantification of total number of reversible defects, as well as assessment of ischemia in the distribution of the left anterior descending coronary artery was required for optimum predictive accuracy. The prevalence of dipyridamole-thallium abnormalities in a diabetic population is much higher than that reported in nondiabetic patients and cannot be predicted by usual clinical indicators of heart disease. In addition, cardiovascular risk of vascular surgery can be optimally assessed by quantitative analysis of dipyridamole-thallium scintigraphy and identification of high- and low-risk subgroups.

Radionuclide angiographic exercise left ventricular performance in chronic aortic regurgitation: Relationship to resting echographic ventricular dimensions and systolic wall stress index

Forty-five patients with chronic aortic regurgitation (AR) underwent first-pass radionuclide angiocardiography (RNA) at rest and during upright bicycle exercise, as well as M-mode echocardiography at rest. Abnormal left ventricular (LV) exercise reserve, defined by the absolute change in ejection fraction (EF), was present in 16 of 45 patients (36%). Seven of ten patients with abnormal resting EF (less than 50%) and three of seven symptomatic patients had normal LV exercise responses. Patients with normal LV exercise reserve by RNA had LV dimensions by echo at end diastole (5.9 +/- 0.2 vs 6.5 +/- 0.3 cm, p = NS) and end systole (3.9 +/- 0.2 vs 4.4 +/- 0.3 cm, p = NS) comparable to those in patients wht abnormal LV exercise reserve. However, the mean corrected LV end-diastolic (LVED) radius/wall thickness ratio was significantly greater in AR patients with abnormal LV exercise reserve than in those with normal LV exercise reserve (395 +/- 15 vs 315 +/- 16, p less than 0.01). There data suggest that resting echocardiographic LV dimensions as well as the corrected echo LVED radius/wall thickness ratio have a variable relationship to RNA LV exercise performance in patients with chronic AR.

A Patent Infarct-Related Artery Is Associated With Reduced Long-term Mortality After Percutaneous Transluminal Coronary Angioplasty for Postinfarction Ischemia and an Ejection Fraction <50%

BACKGROUND Prognosis after myocardial infarction (MI) is influenced by the presence of post-MI ischemia and possibly the patency of the infarct-related artery. The purpose of this study was to compare long-term outcome (reinfarction and death) in patients with open versus closed coronary arteries after percutaneous transluminal coronary angioplasty performed for MI complicated by persistent ischemia. METHODS AND RESULTS Between 1981 and 1989, 505 patients underwent percutaneous transluminal coronary angioplasty for post-MI ischemia at the Deaconess Hospital. Long-term incidence (mean follow-up, 34 months) of death, nonfatal reinfarction, repeated coronary angioplasty, and coronary bypass surgery was determined for 479 patients and then compared on the basis of the status of the artery, open versus closed, at the end of angioplasty. The 5-year Kaplan-Meier actuarial mortality rate was 4.9% for 456 patients with open infarct-related arteries and 19.4% for 23 patients with closed infarct-related arteries (P=.0008). Multivariate Cox proportional hazards analyses controlling for age, sex, number of diseased vessels, type and location of MI, and year of coronary angioplasty revealed a hazard ratio for death for closed compared with open arteries of 6.1 (95% CI, 1.8 to 20.0). Among patients with ejection fractions <50%, a closed artery was associated with a higher mortality (p=.0014) compared with patients with open arteries. The status of the artery was not associated with a difference in mortality in patients with ejection fractions > or = 50%. CONCLUSIONS As open artery after coronary angioplasty for post-MI ischemia is associated with significantly lower long-term mortality, particularly in patients with ejection fractions <50%.

CORONARY ARTERY DISEASE IN THE OCTOGENARIAN : ANGIOGRAPHIC SPECTRUM AND SUITABILITY FOR REVASCULARIZATION

The angiographic findings of 84 consecutive octogenarians presenting with symptoms of coronary artery disease (CAD) were examined to determine the extent of CAD as well as suitability for both coronary artery bypass grafting (CABG) and percutaneous transluminal coronary angioplasty (PTCA). The frequency of 0-, 1-, 2-, and 3-vessel and left main CAD was 7, 14, 21, 57 and 13%, respectively. Based on angiographic criteria, 69 of 78 patients (88%) with significant CAD had suitable coronary anatomy for CABG. Only 24 patients (31%) had coronary anatomy amenable to PTCA. CABG was performed in 19 patients with an operative mortality of 16% and major complication rate of 37%. PTCA was performed in 12 patients with a clinical success rate of 83%, mortality of 8% and major complication rate of 8%. It is concluded that in octogenarians with CAD, cardiac catheterization will often reveal coronary anatomy that is suitable for CABG but less suitable for PTCA. The morbidity and mortality associated with these interventions are high.

Usefulness of dipyridamole-thallium-201 perfusion scanning for distinguishing ischemic from nonischemic cardiomyopathy

To determine noninvasively the etiology of left ventricular (LV) dysfunction, 22 patients with a diagnosis of cardiomyopathy determined via cardiac catheterization and 5 normal control subjects underwent radionuclide ventriculography and intravenous dipyridamole-thallium-201 perfusion scanning. Both ischemically and nonischemically induced LV dysfunction had comparable global LV ejection fractions (24 +/- 6 vs 23 +/- 8%, respectively) and extent of segmental wall motion abnormalities. Right ventricular ejection fraction was significantly better in the group with an ischemic etiology of LV dysfunction (41 +/- 26 vs 13 +/- 10%, p less than 0.005) but significant group overlap was present. However, computer-assisted analysis of dipyridamole-thallium-201 myocardial perfusion scanning demonstrated more homogeneous myocardial perfusion in idiopathic cardiomyopathy (mean perfusion defect 25 +/- 11 vs 6 +/- 6%, p less than 0.001) and successfully predicted the correct etiology of LV dysfunction in 20 of 22 (91%) patients.

Plaque disruption and thrombus in Ambrose’s angiographic coronary lesion types

Lesion eccentricity with irregularities on coronary angiography is associated with ruptured plaques and thrombus based on postmortem and clinical angiographic studies. However, the predictive value of such angiographic markers of plaque disruption and thrombus remains to be determined in vivo. The purpose of this study was to establish whether Ambroses angiographic coronary lesion types and other angiographic criteria predict the presence of disrupted plaques and thrombus using intracoronary angioscopy. Angioscopy was performed before angioplasty in 60 patients with various coronary syndromes and culprit lesions that were not totally occlusive. Lesions were classified angiographically according to Ambroses criteria as concentric, type I and II eccentric, and multiple irregularities, or as complex or noncomplex, and then compared with the corresponding angioscopic findings. Disruption and/or thrombus were seen in 17 of 19 type II eccentric lesions and 21 of 23 angiographically complex lesions and had the highest positive predictive value to detect complicated atherosclerotic plaques (type II eccentric lesions: positive predictive value 89%, 95% confidence intervals 67% to 99%; complex lesions: 91%, 95% confidence intervals 72% to 99%). We conclude that Ambroses type II eccentric stenoses and angiographically complex lesions are strongly associated with disrupted plaques and/or thrombus as assessed by angioscopy in patients and represent unstable plaque substrates.

Angioscopy of Culprit Coronary Lesions in Unstable Angina Pectoris and Correlation of Clinical Presentation With Plaque Morphology

This study demonstrates that plaque disruption and thrombus are absent in a considerable number of patients with unstable angina and that culprit lesion morphologies as assessed by angioscopy may differ among the various clinical subsets of patients. Although plaque disruption and thrombus undoubtedly play an important role in the pathogenesis of unstable angina, alternative mechanisms may be responsible for ischemia in some patients.