Minimal Coronary Artery Disease Research Articles

Using Dipyridamole–Thallium Imaging to Reduce Cardiac Risk in Aortic Reconstruction

Cardiac morbidity and mortality remain the major operative risk following aortic reconstruction (AR) performed for aneurysmal and occlusive disease. We reviewed the preoperative cardiac evaluation and outcome in 209 patients who had AR between 1987 and 1992. Dipyridamole–thallium stress test (DTST) was performed in 147 (70.3%) patients. Fifty-six of these patients had a normal DTST and only 1 (1.8%) had a perioperative myocardial infarction (MI). Forty-six patients had a fixed defect on their DTST and 3 (6.5%) had perioperative MI. Forty-five patients had reversible defects on their DTST and 2 (4.4%) had perioperative MI with 1 cardiac death. Following DTST, 29 coronary catheterizations were performed. Ten catheterizations were normal or had minimal one-vessel coronary artery disease with an associated postoperative death in 1 patient due to cardiac dysrhythmia. Nineteen patients had abnormal coronary angiography, 1 of whom had a perioperative myocardial infarction and 5 of whom underwent coronary artery revascularization (CABG) (3) or percutaneous transluminal angioplasty (2) prior to AR without subsequent cardiac events. Forty-three (20.6%) had either no cardiac symptoms (40) or prior CABG (3) precluding invasive cardiac evaluation. There was one fatal perioperative myocardial infarction (2.3%), resulting in a cardiac mortality of 2.3% in this group. The remaining 19 patients who did not have a DTST (9.1%) had coronary angiography based on evidence of significant cardiac disease resulting in one CABG and one percutaneous transluminal angioplasty. There was one (5.3%) perioperative myocardial infarction in this group and no cardiac deaths. Thirty-day mortality was 3.8%, perioperative MI rate was 3.8%, and perioperative cardiac mortality was 1.0%. During the follow-up period (median, 18 months; range, 1–89), there were 19 deaths (10%) and the 5-year cumulative survival was 76%. Conclusion: Selective use of DTST can direct further evaluation, intervention, and subsequent perioperative care. This algorithm has enabled us to perform AR even in patients with defined perfusion abnormalities with acceptable morbidity. The true sensitivity, specificity, and predictive value of DTST can only be determined by a prospective trial.

Recurrence of angina after coronary artery bypass surgery: Predictors and prognosis (CASS registry)

This study sought to define the predictors and prognosis of postoperative angina in patients undergoing coronary artery bypass surgery. Angina recurs in the first postoperative year in 20% to 30% of patients after coronary artery bypass surgery. The Coronary Artery Surgery Study Registry provides an opportunity to study the predictors and prognosis of postoperative angina in a large sample. All patients with isolated coronary artery bypass surgery in the registry were identified, and anginal status was determined on a yearly basis. The influence of angina on mortality, recurrent myocardial infarction and need for reoperation was determined. Angina recurred in the first year in 24% of patients and by the sixth year in 40%. The significant predictors in a multivariate analysis were minimal coronary artery disease, preoperative angina, use of vein grafts only, previous myocardial infarction, incomplete revascularization, female gender, smoking and younger age. In subsequent years important predictors were angina in the first postoperative year, female gender, younger age and incomplete revascularization. The presence of angina in the first postoperative year was associated with more frequent myocardial infarction (p = 0.04) and greater need for reoperation (p = 0.003) but did not affect survival during the 6-year follow-up period. These findings show that the predictors of postoperative angina are features that are or could be predicted before bypass surgery. Thus, patients with these features before bypass surgery could be advised that they would be more likely to experience postoperative angina than those without these features. Postoperative angina is associated with an increased risk of late myocardial infarction and reoperation.

Vasotonic angina: A spectrum of ischemic sysdroms involving function abnormalities of the epicardial and microvascular coronary circulation

Objectives. The present study was undertaken to investigate the response of large and small coronary arteries in a subgroup of patients with no or minimal coronary artery disease found to have objective signs of myocardial ischemia.Background. Many patients apparently have normal coronary arteries despite abnormal electrocardiographic (ECG) changes during spontaneous angina attacks or exercise stress testing.Methods. Twenty-five patients with no or minimal (<30% stenosis) coronary artery disease were chosen from a pool initially selected on the basis of spontaneous anginal attacks and ST segment shifts in the anterior leads. Of these, 10 were grouped as having variant angina (at least one episode of ST elevation) and the remaining 15 as having syndrome X (exercise-induced anginal pain, ST depression and reversible thallium abnormalities). Data were compared with those obtained in 10 patients with stable angina and documented coronary artery disease. Eighteen patients with supraventricular arrhythmias and normal coronary arteries served as control patients. Patients showing focal spasm during ergonovine testing were not included in the subsequent angiographic analysis. Great cardiac vein blood flow, aortic pressure and changes in coronary artery diameter were measured at rest and 2 to 4 min after hyperventilation in the remaining study group. The same procedure was repeated after sublingual administration of 0.3 mg of nitroglycerin in eight patients (four with syndrome X and four with variant angina).Results. Hyperventilation induced diffuse epicardial coronary diameter reduction, which was marginal in control patients (9 ± 4%) and those with coronary artery disease (5 ± 3%) but severe (p < 0.001) in those with variant angina (28 ± 14%) or syndrome × (25 ± 13%). Concomitant determination of coronary flow showed significant (p < 0.001) decreases in those with variant angina (25 ± 11%) and syndrome × (28 ± 10%) but not in control patients (5 ± 8%) or those with coronary artery disease (4 ± 5%), Changes in great cardiac vein blood flow during hyperventilation were similar before and after nitroglycerin.Conclusions. These indicate vasoconstrictor stimuli may trigger a diffuse abnormal response of both epicardial and resistance vessels in some patients with chest pain and angiographicaily normal coronary arteries. Patients showing such diffuse vasoconstrictor abnormalities are suggested to have a single pathogenetic entity with a spectrum of ECG manifestations ranging from ST depression to ST elevation.

Interstudy variability of coronary flow reserve. Influence of heart rate, arterial pressure, and ventricular preload.

To define the long-term variability of serial coronary flow reserve (CFR) measurements in humans and to evaluate the influence of changes in heart rate, mean arterial pressure, and left ventricular preload on CFR, 45 patients with normal left ventricular function (38 cardiac allograft recipients, five patients with normal coronary arteries, and two patients with minimal coronary artery disease [less than 50% diameter stenosis]) were studied. CFR (ratio of peak hyperemic [h] to resting [r] coronary blood flow velocity [CBFV]) was measured with a 3F coronary Doppler catheter and intracoronary papaverine. Initial CFR measurements were highly correlated with repeat measurements obtained 11 +/- 0.6 months later (r = 0.95; mean absolute difference, 0.3 +/- 0.1; n = 17). Differences in CFR between studies were related to changes in heart rate (r = 0.61, p = 0.01) but not to changes in mean arterial pressure (r = 0.25, p = 0.33). To define the effects of rapid changes in heart rate, mean arterial pressure, and preload on CFR, these variables were altered by atrial pacing, handgrip exercise, and volume expansion, respectively. Atrial pacing produced a rate-related increase in rCBFV but did not change hCBFV. Consequently, CFR was significantly reduced as heart rate was increased progressively from 76 +/- 2 in sinus rhythm (4.5 +/- 0.2) to 100 (3.8 +/- 0.2, p less than 0.05, n = 32) to 120 beats/min (3.2 +/- 0.1, p less than 0.05, n = 7). Despite a 19 +/- 2 mm Hg rise in mean arterial pressure during handgrip exercise, CFR was unchanged from baseline (3.7 +/- 0.3 vs. 3.7 +/- 0.4, p = NS, n = 7) because rCBFV rose proportionally with hCBFV. When pulmonary capillary wedge pressure was increased from 9 +/- 1 to 16 +/- 1 mm Hg after volume expansion, CFR was significantly decreased (from 3.8 +/- 0.2 to 2.9 +/- 0.2, p less than 0.05, n = 9) because rCBFV was increased while hCBFV remained unchanged. Hence, serial CFR measurements in humans are highly reproducible in the absence of conditions known to affect resting or hyperemic coronary blood flow. Increases in heart rate or preload reduced CFR because rCBFV was increased while hCBFV was unchanged. In contrast, changes in mean arterial pressure did not alter CFR. Proper interpretation of CFR measurements should take into account the hemodynamic conditions at which they are obtained.

Quantitative thallium-201 myocardial exercise scintigraphy in normal subjects and patients with normal coronary arteries

Quantitative thallium-201 myocardial exercise scintigraphy was tested in two patient populations representing alternative standards for cardiac normality: group I comprised 18 male uncatheterized patients with a low likelihood of coronary artery disease (CAD); group II contained 41 patients with normal coronary arteriograms. Group I patients were younger, they achieved a higher rate-pressure product than group II patients; all had normal findings by physical examination and electrocardiography at rest and exercise. Group II patients comprised 21 females, 11 patients showed abnormal electrocardiography at rest, and five patients showed ischemic ST depression during exercise. Twelve patients had signs of minimal CAD. Twelve patients revealed abnormal visual and quantitative thallium findings, three of these patients had minimal CAD. Profiles of uptake and washout of thallium-201 were derived from both patient groups, and compared with normal limits developed by Maddahi et al. Furthermore, low likelihood and angiographically normal patients may differ substantially, and both sets of normal patients should be considered when establishing criteria for abnormality in exercise thallium imaging. When commercial software containing normal limits for quantitative analysis of exercise thallium-201 imaging is used in clinical practice, it is mandatory to compare these with normal limits of uptake and washout of thallium-201, derived from the less heterogeneous group of low-likelihood subjects, which should be used in selecting a normal population to define normality.

Depression of systolic and diastolic myocardial reserve during atrial pacing tachycardia in patients with dilated cardiomyopathy.

Previous reports have shown that increases in heart rate may result in enhanced left ventricular (LV) systolic and diastolic performance. To assess whether this phenomenon occurs in the presence of depressed LV function, the effects of pacing on LV pressure and volume were compared in seven patients with dilated cardiomyopathy (LV ejection fraction 0.19 +/- 0.11) and six patients with no or minimal coronary artery disease (LV ejection fraction 0.69 +/- 0.11). Patients with normal LV function demonstrated significant increases in LV peak-positive dP/dt, LV end-systolic pressure-volume ratio, LV peak filling rate, and a progressive leftward and downward shift of their pressure-volume diagrams, compatible with increased contractility and distensibility in response to pacing tachycardia. There was no change in LV peak-negative dP/dt or tau. Patients with dilated cardiomyopathy, in contrast, demonstrated no increase in either LV peak-positive dP/dt or the end-systolic pressure-volume ratio, and absence of a progressive leftward shift of their pressure-volume diagrams. Moreover, cardiomyopathy patients demonstrated no increase in LV peak-negative dP/dt or LV peak filling rate and a blunted downward shift of the diastolic limb of their pressure-volume diagrams. Tau, as determined from a derivative method, became abbreviated although never reaching control values. We conclude that patients with dilated cardiomyopathy may demonstrate little or no significant enhancement in systolic and diastolic function during atrial pacing tachycardia, suggesting a depression of both inotropic and lusitropic reserve.

DNA polymorphisms in the apolipoprotein C-III and insulin genes and atherosclerosis

A total of 167 patients undergoing investigation for suspected coronary artery disease (CAD) were genotyped for restriction fragment length polymorphisms (RFLP) at the apo A-1/C-III locus and the insulin gene locus using cloned human apo A-1 and insulin gene probes. The study group was subdivided into patients with absent or minimal CAD, intermediate CAD and severe obstructive CAD. An Sst-1 polymorphism located in the 3′ non-coding region of the apo C-III gene identifies two alleles. One of the alleles (S2) showed a significantly increased frequency in the subjects with severe obstructive CAD (18%) compared with patients with minimal or absent CAD (6%) ( P < 0.025) and normolipidaemic control subjects. This A-1/C-III polymorphism may be a marker for an abnormality in the A-1/C-III genes predisposing to atherosclerosis. In contrast to a previous report, we found no increase in the frequency of the Class 3 insulin alleles in subjects with severe CAD.

Factors associated with progression of coronary artery disease in patients with normal or minimally narrowed coronary arteries

This study was performed to identify the subset of patients with normal or with minimal (49% or less) stenosis of the coronary vessels who may be prone to progressive coronary artery disease (CAD). Data were collected from 51 patients (19 men, 32 women, mean age 48 years) with normal coronary arteries (20 patients) or with minimal narrowing (31 patients) on a first angiogram, who underwent repeat catheterization 4 to 120 months later (mean 52) because of persistent chest pain. Three classic lifestyle-related risk factors (systemic hypertension, cigarette smoking status and hypercholesterolemia) were noted; the number of diseased segments on the first angiogram was counted according to a 15-segment coding system. Progression of CAD required the consensus of 3 observers on a 30% or greater decrease in luminal diameter. Progression was recorded in 16 of 31 patients with minimal CAD and in 3 of 20 patients with normal coronary arteries (p < 0.01). By multivariate logistic regression, progression was predicted by (1) number of diseased segments (p = 0.001), (2) age (p < 0.01), (3) smoking status (p < 0.05) and (4) initial cholesterol level (p < 0.05). Using the probability computed by the logistic model, we could separate the 51 patients in groups with low (0 of 18), medium (9 of 23) and high (10 of 10) risk of progression. Thus, patients with normal or minimally narrowed coronary arteries at angiography form a heterogenous population including both normal or borderline subjects and patients with CAD at its early stage. The latter condition was associated with presence of risk factors and to the angiographic extent of the disease.

Significance of exercise-induced ventricular arrhythmia in stable coronary artery disease: A coronary artery surgery study project

This retrospective study examines the prognostic significance of exercise-induced ventricular arrhythmia in patients with stable coronary artery disease (CAD) who were included in the multicenter patient registry of the Coronary Artery Surgery Study. The population is composed of 1,486 patients selected from 1975 to 1979 and followed an average of 4.3 years. All underwent a standard Bruce exercise test and had CAD by cardiac catheterization at entry. Patients were classified into group I or II depending on whether they had minimal or significant CAD. (Significant CAD was defined as 70% or greater diameter reduction in any major coronary artery or 50% or greater narrowing in the left main artery.) They were further subclassified into groups A or B depending on whether or not they had exercise-induced ventricular arrhythmia. Groups IA (16 patients) and IB (229 patients) had similar clinical and angiographic characteristics except for the average ejection fraction (EF), which was 50% for group IA and 64% for group IB (p less than 0.05). Group IIA (130 patients) had a higher prevalence of previous myocardial infarction, a lower mean EF and a higher proportion of patients with at least 2 coronary arteries significantly narrowed than group IIB (1,111 patients). The 5-year event-free survival was not influenced by the presence of exercise-induced ventricular arrhythmia; it was 76 and 88% in groups IA and IB, respectively (difference not significant), and 71 and 76% in groups IIA and IIB, respectively (difference not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between cortisol and cholesterol in men with coronary artery disease and type A behavior.

To further understand the hormonal mechanisms linking behavior pattern and coronary artery disease (CAD), we investigated the relationship between 0930-hour plasma cortisol and cholesterol in relatively young males who had undergone coronary angiography and in a subgroup of individuals who had undergone the structured interview for classification of behavior pattern. A statistically significant association (p less than 0.05) was found between cortisol and cholesterol for individuals who had either minimal CAD (20% to 49% narrowing) or significant CAD (greater than or equal to 50% narrowing), but not for subjects without CAD. An association between cortisol and cholesterol was also found to be significant for the subgroup of individuals with Type A-1 behavior pattern, but not for those with Type A-2, X, or B behavior patterns. The findings suggest that hormonal mechanisms involving cortisol and cholesterol metabolism may be operative in individuals with CAD as well as in individuals with Type A-1 behavior.

The relationship between vasectomy and angiographically determined atherosclerosis in men

Long-term prospective studies in monkeys have shown that vasectomy is associated with an increase in atherosclerotic disease. The purpose of the present investigation is to evaluate whether vasectomy in men is associated with atherosclerotic disease in the coronary arteries. In this study information was obtained on the vasectomy status in a series of 7,420 men who had previously been referred for coronary angiography because of cardiovascular symptomatology and have been followed for as long as 9 years to evaluate coronary artery bypass surgery and the natural history of the disease. It was found that 5.0% had a vasectomy prior to angiography. Two different data analysis procedures were used to determine whether the vasectomized men had a greater degree of angiographically determined coronary occlusive disease than the nonvasectomized men. Subgroups with minimal and extensive coronary artery disease were also analyzed. Results of all analyses show that the vasectomized men did not have more coronary occlusive disease. Possible patient selection biases in this study are discussed.

Variant angina--correlation of clinical, electrocardiographic and angiographic features: results of medical and surgical management.

Angiographic coronary artery disease (CAD) was correlated with clinical features, electrocardiographic (ECG) findings and the results of medical management or aortocoronary bypass in 42 patients with angina at rest associated with transient ST segment elevation (variant angina). Patients were divided into three sub-sets based on the coronary arteriographic findings. On the basis of greater than 75% luminal diameter narrowing, 28 patients had multiple vessel, ten had single vessel and four had minimal (less than 50% narrowing) CAD. The angiographic sub-sets did not differ significantly in age, sex, coronary risk factors, time from onset of rest pain to coronary angiography, or in the presence of arrhythmias during ischaemic episodes. Patients with multiple vessel CAD more commonly had prior coronary events (P less than 0.01), an abnormal baseline ECG (P less than 0.05) or both (P less than 0.001). These features did not distinguish patients with single vessel from those with minimal CAD. ST elevation in the inferior leads during episodes of myocardial ischaemia was more common (P less than 0.005) in patients with minimal CAD. Twenty--four patients with multiple vessel and six with single vessel CAD underwent aortocoronary by-pass surgery and relief of variant angina was achieved in all 25 long-term survivors during an average follow-up period of 36 months. Twelve patients (four of each subset) were treated medically. Among those with multiple vessel CAD, the small medically treated numbers precluded valid comparison of medical and surgical results. Patients with single vessel CAD followed for an average period of 17 months compared unfavourably with the operated group. Calcium antagonists with the operated group. Calcium antagonists or nitrates controlled variant angina in patients with minimal CAD followed for an average of 27 months.

Carotid sinus reflex in patients undergoing coronary angiography: relationship of degree and location of coronary artery disease to response to carotid sinus massage.

Heart rate and blood pressure responses during and after carotid sinus massage were examined in 66 patients just before coronary angiography. A significant relationship was found between heart rate and blood pressure responses and (1) angina pectoris class, (2) total coronary artery disease score and (3) presence of high-grade (> 90%) stenosis of any of the three major coronary arteries. Only patients with contraction abnormalities of the anterolateral left ventricular region had greater cardionhibitory responses than patients with normal left ventricular angiograms. Among patients with normal left ventricular angiograms, those with more than 50% stenosis of one or more vessels had significantly (p < 0.01) greater responses than those with no or minimal coronary artery disease. All 21 hypersensitive (asystole longer than 3 seconds) patients had significant multivessel coronary artery stenoses or single-vessel high-grade stenosis (greater than or equal to 90%) proximal to the atrioventricular nodal artery. None of the 11 patients with normal coronary arteries had an exaggerated response to carotid sinus massage. These data support the association of an exaggerated response to carotid sinus massage in the presence of symptomatic coronary artery disease and suggest that the magnitude of response is influenced by the severity of the disease.

The relationship between coronary artery lesions and myocardial infarcts: Ulceration of atherosclerotic plaques precipitating coronary thrombosis

A review of 494 myocardial lesions at least 3 cm. in one dimension reveal 418 (85 per cent) related to atherosclerotic coronary lesions, 55 (11 per cent) related to coronary emboli of various types, 18(3.5 per cent) without specific coronary lesions but related to clinical events associated with coronary hypoperfusion, and 3 (0.5 per cent) associated with miscellaneous coronary lesions. In 399 of 418 (96 per cent) atherosclerotic coronary lesions of all ages complete occlusion (remote of fresh) or histological evidence of lumenal recanalization was present. These coronary lesions were situated within extramural coronary artery segments one to several centimeters proximal to the myocardial lesions which were confined to the distribution of the respective partially or totally occluded coronary segments. In the atherosclerotic cornary lesions less than 2 weeks of age partially or totally occlusive thrombus was found in 67 of 69 (97 per cent) cases and a underlying plaque ulceration, erosion, or rupture was present in 64 of 69 (93 per cent) instances. These endothelial and intimal injuries were generally focal in nature, often extending over a length of only 100 to 200 mu. In no instance could it be stated with certainty that the oldest portion of the atherosclerotic ulceration-thrombus complex was younger in age than its associated myocardial lesion. On the contrary, in 10 of 69 (14 per cent) of the cases portion of the coronary thrombus, usually at the site of plaque ulceration, were histologically older than the myocardial lesion. In addition, the presence of thrombus and plaque debris admixtures further suggested the antecedent nature of the coronary lesion in relation to the myocardial lesion. Atherosclerotic coronary lesions associated with myocardial lesions of 2 to 8 weeks of age had identifiable thromboses in all instances and underlying plaque ulceration, erosions, or ruptures in 17 of 21 (80 per cent). Endothelial injuries were more difficult to assess due to the obscuring features of organizing lumenal thrombus. Interface i.e., plaque ulceration, erosions, or ruptures, were reliably detectable up to approximately on month of age. Coronary arter thromboemboli accounted for a significant percentage of myocardial lesions, were usually associated with normal or minimal coronary artery disease, and frequently involved smaller intramural coronary vessels of the heart. Organization and recanalization of thromboemboemboli tended to be rapid and complete so that in the late stages the residual intimal plaque was sometimes difficult to identify. Myocardial lesions related to clinical events associated with coronary artery hypoperfusion centric, and not confined to the distribution of a single coronary artery. They were unassociated with acute coronary lesions and histologically displayed contraction band necrosis more frequently than the embolic and atherosclerotic related lesions. An explanation was found for the overwhelming majority of myocardial lesions...