Progression of coronary atherosclerosis. Clues to pathogenesis from serial coronary arteriography

On the Natural History of Coronary Artery Disease: A Longitudinal Nationwide Serial Angiography Study

Background

The long‐term course of coronary atherosclerosis has not been studied in large nationwide cohorts. Understanding the natural history of coronary atherosclerosis could help identify patients at risk for future coronary events.

Methods and Results

All coronary artery segments with <50% luminal stenosis in patients with a first‐time coronary angiogram between 1989 and 2017 were identified (n=2 661 245 coronary artery segments in 248 736 patients) and followed until a clinically indicated angiography within 15 years was performed or until death or end of follow‐up (April 2018) using SCAAR (Swedish Coronary Angiography and Angioplasty Registry). The stenosis progression and incidence rates were 2.6% and 1.45 (95% CI, 1.43–1.46) per 1000 segment‐years, respectively. The greatest progression rate occurred in the proximal and middle segments of the left anterior descending artery. Male sex and diabetes were associated with a 2‐fold increase in risk, and nearly 70% of new stenoses occurred in patients with baseline single‐vessel disease (hazard ratio, 3.86 [95% CI, 3.69–4.04]). Coronary artery segments in patients with no baseline risk factors had a progression rate of 0.6% and incidence rate of 0.36 (95% CI, 0.34–0.39), increasing to 8.1% and 4.01 (95% CI, 3.89–4.14) per 1000 segment‐years, respectively, in patients with ≥4 risk factors. The prognostic impact of risk factors on stenosis progression was greatest in younger patients and women.

Conclusions

Coronary atherosclerosis progressed slowly but more frequently in the left coronary artery in men and in the presence of traditional risk factors. Coronary artery segments in patients without risk factors had little or no risk of stenosis progression, and the relative impact of risk factors appears to be of greater importance in younger patients and women. These findings help in the understanding the long‐term course of coronary atherosclerosis.

Five-year follow-up of angiographic disease progression after medicine, angioplasty, or surgery

Background

Progression of atherosclerosis in coronary artery disease is observed through consecutive angiograms. Prognosis of this progression in patients randomized to different treatments has not been established. This study compared progression of coronary artery disease in native coronary arteries in patients undergoing surgery, angioplasty, or medical treatment.

Methods

Patients (611) with stable multivessel coronary artery disease and preserved ventricular function were randomly assigned to CABG, PCI, or medical treatment alone (MT). After 5-year follow-up, 392 patients (64%) underwent new angiography. Progression was considered a new stenosis of ≥ 50% in an arterial segment previously considered normal or an increased grade of previous stenosis > 20% in nontreated vessels.

Results

Of the 392 patients, 136 underwent CABG, 146 PCI, and 110 MT. Baseline characteristics were similar among treatment groups, except for more smokers and statin users in the MT group, more hypertensives and lower LDL-cholesterol levels in the CABG group, and more angina in the PCI group at study entry. Analysis showed greater progression in at least one native vessel in PCI patients (84%) compared with CABG (57%) and MT (74%) patients (p < 0.001). LAD coronary territory had higher progression compared with LCX and RCA (P < 0.001). PCI treatment, hypertension, male sex, and previous MI were independent risk factors for progression. No statistical difference existed between coronary events and the development of progression.

Conclusion

The angioplasty treatment conferred greater progression in native coronary arteries, especially in the left anterior descending territories and treated vessels. The progression was independently associated with hypertension, male sex, and previous myocardial infarction.

Relative spatial distributions of coronary artery bypass graft insertion and acute thrombosis: a model for protection from acute myocardial infarction

BACKGROUND

Randomized trials have demonstrated coronary artery bypass surgery (CABG) to be superior to percutaneous coronary intervention with respect to long-term mortality and morbidity from myocardial infarction within specific high-risk cohorts. The purpose of this study was to analyze the spatial distribution of coronary artery bypass graft anastomoses relative to acute thromboses in native coronary arteries. We hypothesized that insertion sites of bypass grafts are located distal to sites of acute thrombosis and consequently decrease cardiac morbidity and mortality associated with plaque rupture.

METHODS

We analyzed 168 patients with prior CABG and 208 patients with ST-segment elevation myocardial infarctions (STEMI) presenting to the Brigham and Women's Hospital who underwent coronary angiography. We constructed a spatial map of the coronary arterial bypass graft insertion sites and compared these locations to sites of acute thrombosis leading to STEMI.

RESULTS

Graft insertion sites were consistently located distal to acute thrombosis sites (left anterior descending artery median graft insertion versus median thrombosis site = 72 versus 34 mm, right coronary artery 91 versus 42 mm, left circumflex artery 44 versus 37 mm). Greater than 97% of thrombosis sites were located proximal to 75% of graft insertion sites.

CONCLUSIONS

Coronary arterial bypass grafts provide the coverage of anatomic zones at risk for STEMI. The superior performance of CABG in high risk patients may be attributed to targeting of proximal coronary locations where thrombosis risk is clustered.

Disease progression and adverse events in patients listed for elective percutaneous coronary intervention

OBJECTIVE

To record disease progression and the timing of adverse events in patients on a waiting list for elective percutaneous coronary intervention (PCI).

DESIGN

Observational prospective study.

SETTINGS

A UK tertiary cardiothoracic centre, at a time when waiting lists for PCI were up to 18 months.

PATIENTS

145 patients (116 men, median age 59.5 years) placed on an elective waiting list for PCI between October 1998 and September 1999.

MAIN OUTCOME MEASURES

Adverse events recorded were death, myocardial infarction, need for urgent hospital admission because of unstable angina, and need for emergency revascularisation while waiting for PCI.

RESULTS

During a median follow up of 10 months (range 1-18 months), nine (6.2%) patients experienced an adverse event. Eight (5.52%) patients were admitted with unstable angina as emergencies. One was admitted with a myocardial infarction. Twenty nine (20.0%) patients had significant disease progression at the time of the repeat angiogram before PCI. In 10 (7%), disease had progressed so that PCI was no longer feasible and patients were referred for coronary artery bypass graft. Sixteen (11%) were removed from the PCI waiting list because of almost complete resolution of their anginal symptoms.

CONCLUSION

Adverse coronary events and clinically significant disease progression occur commonly in patients waiting for PCI. Despite the presence of severe coronary lesions, myocardial infarction was rare and no patients died while on the waiting list. Resolution of anginal symptoms was also comparatively common. The pathophysiology of disease progression frequently necessitates a change in the treatment of patients waiting for PCI.

Finding Vulnerable Atherosclerotic Plaques

Techniques to identify and treat vulnerable plaques are the focus of enormous research. Some have questioned the benefit of locating individual vulnerable plaque in a multifocal disease. On autopsy, it is found that most deaths are caused by thrombotic occlusion of a single plaque; simultaneous occurrence of 2 occlusive thrombi is rare, but a second vulnerable plaque is common, particularly in acute myocardial infarction (MI). Angiographic progression is poorly predicted by risk factors, and angiographic progression is a weak predictor of MI or death. Intravascular ultrasonography (intravascular ultrasound [IVUS]) studies find plaque rupture in most MI patients and in approximately half with unstable angina, but in only a minority of patients with stable angina. IVUS identifies a second vulnerable plaque in many patients with unstable angina, and in most MI patients. Angioscopy reveals a very low incidence of a second vulnerable plaque compared with angiography and IVUS, but identifies additional yellow plaques in many patients with stable angina and in most patients with unstable angina or MI. Using thermography catheters and a temperature cutoff of 0.1 degrees C, approximately half the patients with stable angina have >1 hot lesion; however, if the cutoff is 0.2 degrees C, only approximately 15% have a second hot lesion. New imaging techniques may detect additional characteristics of plaques and new predictive models may assess the risk of vulnerable plaques and patients. This approach enables physicians to "buy time" by application of local therapies until systemic therapies stabilize plaques. This may also reduce the risk in subjects in whom systemic therapies do not work.

Animal models of spontaneous plaque rupture: the holy grail of experimental atherosclerosis research

Throughout the history of atherosclerosis research we have sought animal models of the disease process that exhibit high frequencies of the features that make human plaque a clinical risk: plaque rupture, mural thrombosis, and intra-plaque hemorrhage. This type of model is needed to determine the mechanisms by which plaques rupture and to design and test therapeutic interventions for stabilizing plaques. Studies of domestic and exotic animals have shown that most species will spontaneously develop fatty streaks and in some cases atheromatous lesions with sufficient time, but that rupture and thrombosis is exceedingly rare. Even with addition of fat and cholesterol to the diet, lesion development is accelerated but does not increase the frequency with which plaques rupture in most animal models. However, recently we have observed high frequencies of intra-plaque hemorrhage in the innominate/brachiocephalic arteries of older, chow-fed, hyperlipidemic, apolipoprotein E-deficient mice, and high frequencies of plaque rupture with mural thrombus in younger apolipoprotein E-deficient mice fed a high-fat diet. This suggests that plaque rupture and secondary thrombosis are frequent and reproducible occurrences at specific sites in apolipoprotein E-deficient mice, and that the timing and pathobiology of the ruptures are influenced by lipid status in this murine model.

Angiographic patterns and the natural history of the vulnerable plaque

Coronary angiography is the gold standard for the identification of obstructive coronary artery disease (CAD). The use of this diagnostic test in the evaluation of many clinical syndromes of CAD has yielded a wealth of angiographic data relative to the vulnerable atherosclerotic plaque. This chapter reviews these important data including the limitations of the angiogram in vulnerable plaque detection, angiographic patterns of complex plaques or "culprit lesions," and the natural history of the complex angiographic lesion.

Detection of atherosclerosis using a novel positron-sensitive probe and 18-fluorodeoxyglucose (FDG)

Inflammation contributes to atherosclerotic plaque remodeling, enlargement and rupture. Non-invasive imaging of coronary artery inflammation could help target therapy to 'vulnerable' atheromata, but is limited because of small tissue mass and arterial motion. Local radiopharmaceutical imaging may overcome some of these limitations. We used a positron-sensitive fiberoptic probe, which can distinguish positron emissions from annihilation photons, to identify diseased from healthy endothelium in an atherosclerotic model. New Zealand White rabbits underwent Fogarty-catheter injury of an iliac artery and then were fed a high-fat diet for 3 weeks. Fasted animals received 90-180 MBq of 18-fluorodeoxyglucose (FDG) 2-4 h before sacrifice and harvest of injured and uninjured iliacs. Arteries were incised longitudinally and the probe was placed in contact with the arterial intima. Multiple measurements were obtained along 1 cm artery segments in 60 s intervals, and corrected for 18F decay and background. Measurements were recorded over 93 injured and normal artery segments in 11 animals. Mean probe Z-scores were 4.8-fold higher (CI 3.4-6.3) over injury atherosclerosis compared with uninjured normal iliac artery segments (P<0.001). Gamma counting confirmed that injured artery segments accumulated more FDG per gram than did normal segments (0.203% x kg injected dose per gram of tissue versus 0.042, P<0.001). Non-arterial tissue also accumulated FDG avidly, particularly reticuloendothelial tissues and blood. Delayed sacrifice, 4 h compared with 2 h after animal FDG injection, further reduced blood background counts and improved the signal-to-noise ratio. Histopathology confirmed that injured iliac artery had significantly higher intimal and medial cross-sectional area compared with uninjured artery. Injured artery also had significantly higher macrophage and smooth muscle cell density. Positron-sensitive probe counts correlated with the intima to media ratio (r =0.63, P = 0.03). Our positron-sensitive probe distinguishes atherosclerotic from healthy artery in a blood-free field. Intravascular study of plaque biology may be feasible using FDG and a positron-sensitive probe.

Morphologic correlation between atherosclerotic lesions of the carotid and coronary arteries in patients with angina pectoris

The morphology of atherosclerosis between the carotid and coronary artery systems was studied in 63 patients with ischemic heart disease to determine if there was a correlation with coronary heart disease. The sclerotic lesions of the carotid and coronary artery systems were imaged with ultrasonography and coronary arteriography, respectively, and divided into 4 types. Hemodynamic variables, serum lipid levels, and serum uric acid concentration were not different among the groups, but the serum C-reactive protein (CRP) concentration in patients without significant atheroma in the carotid artery system was lower than the mean concentration of the other 3 groups with carotid atheroma. The morphological stability of carotid arterial plaques correlated well to coronary artery stenosis. Morphologically unstable plaques of the carotid artery predicted unstable forms of coronary obstruction with a sensitivity of 68%, specificity of 85%, predictive power of 72% and a likelihood ratio of 4.5. These results suggest that ultrasonic examination of the carotid artery is useful for predicting the presence or absence of unstable lesions in coronary arteries.

Angiographic evaluation of culprit lesions in acute coronary syndrome: relation to the original site on previous coronary angiography

Culprit lesions in acute coronary syndrome [acute myocardial infarction (AMI) and unstable angina pectoris (UAP)] were examined angiographically in 222 patients who had previously undergone coronary angiography (CAG). The observation period lasted 5 years after primary CAG in medically treated patients (group M, 127 cases) and after final follow-up CAG in patients treated by percutaneous transluminal coronary angioplasty (PTCA) (group B, 95 cases). There were 33 AMIs, including 5 deaths (22/127, 17.3%, in group M vs 11/95, 11.6%, in group B; p<0.01) and 189 UAPs (105/127, 82.7%, in group M vs 84/95, 88.4%, in group B; NS). High-grade stenoses (>75%) were found in 76 (59.8%) patients in group M, of which 41 lesions (54%) resulted in acute coronary syndromes (ACSs). In group M, ACSs resulted from insignificant stenosis (< or =50%) in 67 (53%) patients and from significant stenosis (>50%) in 60 (47%) patients. In group B, ACSs resulted from insignificant stenosis in 78 (82%) patients and from significant stenosis in 17 (18%) patients. Out of 95 PTCA sites, high-grade restenosis occurred in 3 lesions and ACSs (2 AMI, 14 UAP) in 16 (16.8%). We conclude that ACSs are more likely to develop from insignificant lesions than from significant lesions. High-grade stenoses are prone to become occlusive lesions and PTCA reduces this potential risk. Most target sites of PTCA that escaped restenosis were stable in the long term.

Asymptomatic coronary artery disease detection: update 1996. A screening protocol using 16-lead high-resolution ECG, ultrafast CT, exercise testing, and radionuclear imaging

The authors have proposed a new four-step screening algorithm to detect asymptomatic coronary artery disease (CAD) in flight school candidates, cadets, and rated flyers of the Unites States Air Force (USAF). In step 1, the USAF Armstrong Laboratory (USAF/AL) risk profile and improved 16-lead high-resolution electrocardiogram/vectorcardiogram will be recorded at baseline. On routine follow-up evaluations, quantitative serial comparisons will be performed by the method of Kornreich. In step 2, beginning with flight school candidates and cadets, all three groups will be studied by the ultrafast computed tomograph (CT) protocol. Those candidates positive for coronary calcium will be studied by coronary angiography and ventriculography, and their eligibility for continued rated flight status will be determined by present criteria. In step 3, those candidates negative for coronary calcium by ultrafast CT will then be screened by the newly defined and improved high-sensitivity treadmill exercise test criteria. In step 4, candidates with a positive treadmill exercise test result, or who are also found in the upper quintile of the USAF/AL risk profile, wild also have exercise nuclear wall motion studies and perfusion scans. If these are abnormal and suggestive of myocardial ischemia, this subset will also be studied by heart catheterization and coronary angiography, and their eligibility for continued rated flight status will be determined by present criteria. The incidence of coronary calcium/no calcium for each degree of stenosis in the 6,000 flyers in each quintile was used to develop the following projections: (1) that more than 3 of 4 rated flyers with unsuspected CAD, and (2) more than 9 of 10 with severe flow-limiting CAD can be identified by these upgraded screening procedures. Evidence is herein presented that these enhancements will result in a major (5-8-fold) increase in case finding of this disease. Based on the estimate of four lost high-performance aircrafts per year from sudden incapacitation of the pilot due to CAD, when this four-step screen is fully operational, it can be expected to reduce the $80 million annual losses to the United States government from CAD by 85%, a savings of $68 million per year.

Rapid angiographic progression of coronary artery disease in patients with angina pectoris. The role of complex stenosis morphology

BACKGROUND

Rapid disease progression commonly underlies acute coronary events, and "complex" stenosis morphology may play a role in this phenomenon.

METHODS AND RESULTS

We studied the role of complex stenosis morphology in rapid disease progression in 94 consecutive patients awaiting routine coronary angioplasty. Coronary arteriography was repeated at 8 +/- 3 months' follow-up, immediately preceding angioplasty (68 patients) or after an acute coronary event (26 patients). Disease progression of 217 stenoses, of which 79 (36%) were "complex" and 138 (64%) were "smooth," was assessed by computerized angiography. At presentation, 63 patients had stable angina pectoris and 31 had unstable angina that settled rapidly with medical therapy. At follow-up, 23 patients (24%) had progression of preexisting stenoses and 71 (76%) had no progression. Patients with progression were younger (55 +/- 12 years) than those without (58 +/- 9 years) but did not differ with regard to risk factors, previous myocardial infarction, or severity and extent of coronary disease. Twenty-three lesions (11%) progressed, 15 to total occlusion (11 complex and 4 smooth; 65%). Progression occurred in 17 of the 79 complex stenoses (22%) and in 6 of the 138 smooth lesions (4%) (P = .002). Mean stenosis diameter reduction was also significantly greater in complex than in smooth lesions (11.6% versus 3.9% change; P < .001). Acute coronary events occurred in 57% of patients with progression compared with 18% of those without progression (P < .001) and were more frequent in patients who presented with unstable angina (P = .002).

CONCLUSIONS

Rapid stenosis progression is not uncommon, and complex stenoses are at risk more than smooth lesions.

Rapid angiographic progression of "target" and "nontarget" stenoses in patients awaiting coronary angioplasty

OBJECTIVES

Our aim was to compare the short-term evolution of "target" versus "nontarget" stenoses in patients awaiting coronary angioplasty.

BACKGROUND

Coronary angioplasty is effective therapy for angina pectoris, but coronary events occur after successful angioplasty that are caused by both restenosis and progression of mild preexisting nontarget stenoses.

METHODS

We prospectively studied 161 consecutive patients with stable angina (124 men and 37 women). After diagnostic angiography, target stenoses for angioplasty and nontarget lesions were identified. Patients were put on a routine waiting list and followed up regularly until repeat coronary arteriography was performed (mean +/- SD 7 +/- 3 months), either immediately before angioplasty (138 patients) or soon after an acute coronary event (23 patients), if one occurred. Stenosis diameter was measured by using computerized arteriography. Progression of disease was defined as > or = 20% lesion diameter reduction, new total occlusion or development of a "new" stenosis > or = 30%.

RESULTS

At study entry, the mean diameter of target (n = 207) and nontarget (n = 184) lesions was 68 +/- 9% and 38 +/- 9%, respectively (p < 0.001). Disease progression occurred in 33 patients (20%). Seven new lesions (one total occlusion) developed. Eighteen target (9%) and 15 nontarget (8%) stenoses progressed. The power of the study to detect a difference of 1% between the risks of progression of target and nontarget stenoses with a 90% probability was < 0.1. Total occlusion developed in 15 (83%) of the 18 target and 6 (40%) of the 15 nontarget stenoses (p = 0.03). During follow-up, a myocardial infarction developed in 3 patients (2%) and unstable angina in 20 (12%). These coronary events were associated with progression of target stenoses in 10 patients and nontarget stenoses in 7 and with the development of new lesions in 1. In five patients coronary events were not associated with stenosis progression.

CONCLUSIONS

Despite differences in baseline severity, a similar proportion of target and nontarget lesions progressed rapidly. However, target stenoses were more likely than nontarget lesions to progress to total occlusion. Progression of nontarget stenoses may contribute to recurrence of angina and new coronary events after successful angioplasty and should be considered when developing strategies aimed at improving outcome after angioplasty.

Angiographic stenosis progression and coronary events in patients with 'stabilized' unstable angina

BACKGROUND

Recent studies suggest that angiographically complex coronary stenoses are associated with an adverse short-term outcome. It is not known, however, if this applies to unstable angina patients who stabilize on medical therapy.

METHODS AND RESULTS

We prospectively studied 85 consecutive patients with unstable angina who stabilized on medical therapy but were found to require angioplasty for treatment of obstructive coronary disease. Angiography was carried out at admission, and patients were restudied 8 +/- 4 months (mean +/- SD) after the first angiogram. Ischemia-related stenoses were identified and classified as "complex" (irregular borders, overhanging edges, or thrombus) or "smooth" (absence of complex features). Stenosis progression (> or = 20% diameter reduction or new total occlusion) was assessed by automated edge detection. At initial angiography, there were 198 stenoses (> or = 50%, 102), of which 85 (54 complex and 31 smooth) were ischemia related. At restudy, 21 ischemia-related stenoses and 8 non-ischemia-related stenoses progressed (25% versus 7%, P = .001). Seventeen of the 21 ischemia-related stenoses that progressed developed into total occlusion compared with 3 of the 8 non-ischemia-related stenoses (P = .02). Changes in average stenosis severity and in absolute stenosis diameter were significantly larger in ischemia-related stenoses than in non-ischemia-related stenoses (P = .03). Eighteen (34%) complex stenoses progressed, compared with 3 (10%) smooth lesions (P = .02). During follow-up, 1 patient died (myocardial infarction) and 25 patients had nonfatal coronary events that were associated with progression of ischemia-related stenoses in 14 (56%).

CONCLUSIONS

In unstable angina patients who stabilize medically, subsequent short-term stenosis progression and coronary events are common. The unstable coronary lesion (particularly complex stenoses) is often not stabilized and will continue to progress over the ensuing months.

Coronary artery spasm. Multiple causes and multiple roles in heart disease

Myocardial infarction and sudden cardiac death may be initiated by a sudden intense localized contraction of coronary artery smooth muscle. When this event occurs around a vulnerable eccentric lipid-filled plaque, rupture and extrusion of plaque contents and exposure of collagen occur. This may sometimes be a silent and self-limiting event; other times it leads to thrombus formation. A second wave of spasm due to accumulated platelet and inflammatory mediators may compound the contractile consequences of the initiating event. Spasm involves intrinsic smooth muscle cell electrical mechanisms, hyper-responsive cells, and multiple agonists that synergize their actions, and the involvement of each mechanism varies at different times in the sequence of vascular occlusion. Study of spasm requires vascular systems that adequately model coronary artery responses of the ageing human heart. As previously emphasized, tissues obtained postmortem, and when possible from recipients during heart transplants, must be integral to theory building, alongside animal models, despite the experimental limitations such tissues impose. A multidisciplinary approach, at all levels of vascular physiology and pharmacology, will be necessary to understand coronary motor activity and human heart disease.

Differential progression of complex and smooth stenoses within the same coronary tree in men with stable coronary artery disease

OBJECTIVES

We sought to compare the evolution of complex and smooth stenoses within the same coronary tree in patients with stable coronary artery disease.

BACKGROUND

Progression of coronary stenosis has prognostic significance and may be influenced by local and systemic factors. Stenosis morphology is a determinant of disease progression, but no previous study has systematically assessed progression of complex and smooth stenoses within the same patient.

METHODS

We studied 50 men with stable angina who 1) had one complex coronary stenosis and one smooth stenosis in different noninfarct-related coronary vessels at initial coronary angiography, and 2) had a second angiogram after a median interval of 9 months (range 3 to 24). Patients with lesions > or = 10 mm long, at a major branching point or with > 85% diameter reduction were not included. Coronary lesions were measured quantitatively from comparable end-diastolic frames. Stenosis morphology was determined qualitatively by two independent observers.

RESULTS

All patients remained in stable condition during follow-up. Progression, defined as an increase in diameter stenosis by > or = 15% was seen in only eight complex stenosis (16%) but in no smooth lesions (p < 0.01). The severity of complex stenoses changed more than that of corresponding smooth stenoses (mean +/- 1 SD 5.8 +/- 13% vs. -0.06 +/- 6%, p < 0.01). On average, the annual rate of growth was 11.4 +/- 28% and 1.5 +/- 14% for complex and smooth lesions, respectively (p < 0.01).

CONCLUSIONS

Few coronary stenoses progress rapidly in stable angina. Complex and smooth coronary stenoses progress at different rates within the same coronary tree. complex stenosis morphology itself is an important determinant of progression of stenosis in patients with apparently clinically stable coronary artery disease.

Identification of patients at high risk for adverse coronary events while awaiting routine coronary angioplasty

BACKGROUND

Identification of patients at risk for progression of coronary stenosis and adverse clinical events while awaiting coronary angioplasty is desirable.

OBJECTIVE

To determine the standard clinical or angiographic variables, or both, present at initial angiography associated with the development of adverse coronary events (unstable angina, myocardial infarction, and angiographic total coronary occlusion) in patients awaiting routine percutaneous transluminal coronary angioplasty (PTCA).

PATIENTS AND METHODS

Consecutive male patients on a waiting list for routine PTCA. Routine clinical details were obtained at initial angiography. Stenosis severity was measured using computerised angiography.

OUTCOME MEASURES

Development of one or more of myocardial infarction, unstable angina, or angiographic total coronary occlusion while awaiting PTCA were recorded as an adverse event.

RESULTS

Some 214 of 219 patients underwent a second angiogram. One had a fatal myocardial infarction and four (2%) were lost to follow up. Fifty patients (23%) developed one or more adverse events (myocardial infarction five, unstable angina 35, total coronary occlusion 23) at a median (range) interval of 8 (3-25) months. Twenty (57%) of the 35 patients with unstable angina developed adverse events compared with 30 (17%) of the 180 with stable angina (P = 0.0001). Plasma triglyceride concentration was 2.6 (1.2) mmol/l in patients with adverse coronary events compared with 2.2 (1.1) mmol/l in those without such events (P < 0.05). Patients with adverse events were younger than those without (54 (9) years v 58 (9) years, P < 0.01). The relative risk of an adverse event in patients with unstable angina and increased plasma triglyceride concentrations was 6.9 compared with those presenting with stable angina and a normal triglyceride concentration (P < 0.02).

CONCLUSIONS

The study shows that adverse events are not uncommon in patients awaiting PTCA. Patients at high risk for adverse events may be predicted by the presence of acute coronary syndrome, increased concentration of plasma triglyceride, and younger age at the time of the first angiogram.

Angiographic predictors of new coronary occlusions

To determine whether coronary angiography is predictive of the future site of coronary occlusion, we analyzed the coronary angiograms of 246 consecutive patients having two or more angiograms without therapeutic invasive intervention in the interval between angiograms. The average interval between studies was 46 months. Of 2183 normal segments at the first angiogram, 51 (2.3%) were occluded at the second angiogram, whereas in segments with minimal disease (1% to 25% diameter stenosis) 33 (8%) of 411 were occluded (p < 0.05). There was a further stepwise increase in the occlusion ratio, with increasing stenosis reaching a 31% occlusion ratio in lesions with critical (91% to 99%) stenosis at the first angiogram. For any given degree of stenosis, the occlusion ratio of "long" lesions (5 to 20 mm) was on the average more than twice that of "short" lesions (< 5 mm, p < 0.01), except in lesions with critical stenosis (91% to 99%) where length was no longer important. Occlusion of segments judged free of disease on the first angiogram was highest in the right coronary artery, 4.7%, versus 2.7% in the left anterior descending and 0.6% in the circumflex artery (p < 0.01). History of recent myocardial infarction was a good clinical predictor of occlusion and deterioration of ventricular function.

A new look at coronary angiograms: plaque morphology as a help to diagnosis and to evaluate outcome

Characterization of plaque morphology can provide useful information beyond those generally yielded by the more traditional methods of interpretation of coronary angiograms based on assessment of severity of stenoses and number of diseased vessels. Focus on the culprit coronary lesion in acute myocardial infarction and in unstable angina allows recognition of the complex plaque and of presence of endoluminal thrombi that are closely associated to the mechanisms of the disease. Response to treatment in these clinical situations, and the healing process can be assessed by repeated opacifications of the lesion. The presence of a residual thrombus is associated with a worse clinical outcome and also a higher risk of complication if coronary angioplasty is performed. The prognostic information derived from the morphologic analysis extends to the chronic phase of the disease. The extent score of disease, defined as the sum of coronary artery segments showing a narrowing of any severity marks more severe disease and predicts future progression. Severity of stenosis is also a predictor. More severe lesions will occlude more frequently but most often without clinical consequences. Occlusion of less severe stenosis, on the other hand, leads to acute myocardial infarction or to the other manifestations of acute coronary syndromes. Other morphologic features are also associated with a higher risk of myocardial infarction. These include a geometry favoring blood flow separation and turbulence such as acute inflow and outflow angles of the stenosis and presence of a division within its vicinity. This new look at coronary angiograms may help orient therapy. Patients with angina and a significant stenosis will profit from a corrective intervention. Others with a high extent score should receive a comprehensive program for control of risk factors. Patients with a lesion of borderline significance at risk of activation should be closely monitored, and when clinical symptoms evolve, receive more intensive antithrombotic therapy. Quantification of the morphologic characteristics of the plaque, coupled to new techniques for endovascular imaging should lead in the future to better diagnostic and better risk stratification.

Toward the quiescent coronary plaque

The treatment of coronary atherosclerosis requires an understanding of the pathophysiology of plaque rupture. The rupture of lipid-laden, macrophage-rich plaques initiates unstable angina, acute myocardial infarction and sudden cardiac death. Plaque rupture occurs when the circumferential tension on a plaque exceeds its tensile strength, an event that cannot be predicted by coronary angiography. The incidence of plaque rupture appears to be reduced in patients receiving cholesterol-lowering therapy, beta-adrenergic blocking agents and, possibly, angiotensin-converting enzyme inhibitors and antioxidants. Not all ruptured coronary plaques produce an acute coronary syndrome. The consequences of plaque rupture depend on the extent of thrombus formation over the fissured plaque. This is determined by flow characteristics within the vessel as well as the activity of the thrombotic and fibrinolytic systems. Recent advances in cardiovascular molecular biology, coronary diagnostic techniques and cardiac therapeutics have opened windows of opportunity to study and modify the factors leading to plaque rupture. The local modification of gene expression to alter plaque composition and to elucidate and subsequently inhibit the prothrombotic and fibrinolytic defects that promote coronary thrombosis may, in future, prevent plaque rupture and its consequences. The application of such a concerted interdisciplinary approach promises a paradigm shift in the management of coronary artery disease toward the prevention of plaque rupture and its sequelae.

Various intensities of leisure time physical activity in patients with coronary artery disease: effects on cardiorespiratory fitness and progression of coronary atherosclerotic lesions

OBJECTIVES

This study was designed to define the effect of different levels of leisure time physical activity on cardiorespiratory fitness and progression of coronary atherosclerotic lesions in unselected patients with coronary artery disease.

BACKGROUND

It has been shown in various studies that regression of coronary atherosclerotic lesions can be achieved by means of lipid-lowering drugs, reduction of fat consumption and physical exercise.

METHODS

Patients were prospectively randomized either to an intervention group (n = 29) participating in regular physical exercise or to a control group (n = 33) receiving usual care. Energy expenditure in leisure time physical activity was estimated from standardized questionnaires and from participation in group exercise sessions. After 12 months of participation, repeat coronary angiography was performed; coronary lesions were measured by digital image processing.

RESULTS

After 1 year, patients in the intervention group achieved an increase in oxygen uptake at a ventilatory threshold of 7% (p < 0.001) and peak exercise of 14% (p < 0.05), whereas a significant decrease was observed in patients in the control group. To achieve significant improvement in cardiorespiratory fitness, approximately 1,400 kcal/week had to be expended in the form of leisure time physical activity (p < 0.001). The mean energy expended in such activity was 1,876 +/- 163 kcal/week in the intervention group and 1,187 +/- 97 kcal/week in the control group (p < 0.001). In the intervention group, regression of coronary artery disease was noted in 8 patients (28%), progression of disease in 3 (10%) and no change in coronary morphology in 18 (62%). In contrast, coronary artery disease progressed at a significantly faster rate in patients in the control group (progression in 45%, no change in 49% and regression in 6%) (p < 0.001 vs. intervention). When the two groups were combined, the lowest level of leisure time physical activity was noted in patients with progression of disease (1,022 +/- 142 kcal/week) as opposed to patients with no change (1,533 +/- 122 kcal/week) or regression of disease (2,204 +/- 237 kcal/week) (p < 0.005).

CONCLUSIONS

Measurable improvement in cardiorespiratory fitness requires approximately 1,400 kcal/week of leisure time physical activity; higher work loads are necessary to halt progression of coronary atherosclerotic lesions (1,533 +/- 122 kcal/week), whereas regression of coronary lesions is observed only in patients expending an average of 2,200 kcal/week in leisure time physical activity, amounting to approximately 5 to 6 h/week of regular physical exercise.

Progression of coronary artery disease is dependent on anatomic location and diameter. The INTACT investigators

OBJECTIVES

This study represents the first prospective, quantitative analysis of the association of progression of coronary atherosclerosis with anatomic site and diameter.

BACKGROUND

The progressive course of coronary artery disease has been documented in many angiographic follow-up trials.

METHODS

The data of 348 patients with coronary artery disease from the International Nifedipine Trial on Antiatherosclerotic Therapy (INTACT) were reviewed. Standardized coronary angiograms were taken 3 years apart and were analyzed quantitatively. The coronary tree was subdivided into 25 segments. The progression of 1,063 preexisting coronary stenoses and the appearance of 247 newly formed stenoses was assessed in relation to the mean diameter of segments (< 2 mm, 2 to 3 mm, > 3 mm) and to their position in the coronary tree (proximal, mid, distal) and in the three major coronary arteries.

RESULTS

Decreases in the minimal diameter of preexisting stenoses were largest in segments that were > 3 mm in diameter (mean +/- SD 0.23 +/- 0.5 mm vs. 0.10 +/- 0.4 mm and 0.02 +/- 0.3 mm, p < 0.001), in a proximal position (0.14 +/- 0.5 mm vs. 0.09 +/- 0.4 mm and 0.06 +/- 0.3 mm, p = 0.081) and in the right coronary artery (0.14 +/- 0.4 mm vs. 0.07 +/- 0.4 mm and 0.07 +/- 0.3 mm, p < 0.01). Changes in percent diameter stenosis of preexisting stenoses were lowest in segments that were < 2 mm in diameter and in a distal position (p = NS). The number of new stenoses/segment was lowest in segments that were < 2 mm in diameter (44 of 1,756 vs. 139 of 1,967 and 64 of 1,125, p < 0.001) and in a distal position (77 of 2,370 vs. 84 of 1,193 and 86 of 1,285, p < 0.001) and was highest in segments of the right coronary artery (100 of 1,546 vs. 66 of 1,496 and 72 of 1,492, p = 0.044).

CONCLUSIONS

Progression of coronary artery disease occurs most frequently in coronary segments that are > 2 mm in diameter, in a proximal or midartery position and in the right coronary artery.

Natural history of coronary atherosclerosis using quantitative angiography in men, and implications for clinical trials of coronary regression. The Harvard Atherosclerosis Reversibility Project Study Group

Previous studies of the natural history of coronary disease generally relied on estimates of percent stenosis derived from visual assessment of the coronary angiogram. In a study of 26 patients, serial quantitative angiography was performed 3 years apart to determine changes in both absolute measurements of the luminal diameter and relative percent stenosis. Initially, the mean minimal diameter of 74 coronary obstructions was 1.94 +/- 0.09 mm, the mean "normal" reference diameter was 3.06 +/- 0.11 mm, and the mean percent stenosis was 37%. At follow-up, there was a mild reduction of 0.12 +/- 0.04 mm (6%) in the minimal diameter (p < 0.005), and an increase in percent stenosis to 39% (p = 0.03). The average diameter of 85 arterial segments without a focal obstruction either initially or at follow-up showed mild but significant progression (-0.11 +/- 0.04 mm; p = 0.02). Using a minimal change of 0.27 mm in arterial diameter as a categoric variable, progression occurred in 26% of 74 arterial segments, no significant change in 65%, and regression in 9%. The only significant determinant of disease progression was the initial severity of disease. Obstructed arteries with a larger initial minimal diameter and presumably milder disease progressed more rapidly than did those with a smaller diameter (r = -0.42; p = 0.0002). There was no effect of age on the rate of progression (r = 0.02; p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Role of coronary artery spasm in progression of organic coronary stenosis and acute myocardial infarction in a swine model. Importance of mode of onset and duration of coronary artery spasm

BACKGROUND

Coronary spasm may play an important role in progression of organic coronary stenosis and myocardial infarction, but the mechanisms responsible for these complications are not known. This study aimed to examine whether the mode of onset and the duration of coronary spasm influenced progression of organic coronary stenosis and acute myocardial infarction in a swine model of coronary spasm.

METHODS AND RESULTS

Göttingen miniature pigs were subjected to cholesterol feeding, balloon-induced coronary arterial denudation, and x-ray irradiation. Five months later, coronary spasm was induced by intracoronary injection of serotonin. In 10 pigs, coronary spasm was provoked abruptly and maintained for 25 minutes by five repeated intracoronary injections of serotonin (10 micrograms/kg) every 5 minutes (group A, abrupt onset and short duration). In group B, coronary spasm was provoked gradually by intracoronary injections of serotonin at graded doses of 0.1, 0.3, and 0.6 microgram/kg every 5 minutes and was then maintained for 25 minutes in four pigs (group B1, gradual onset and short duration) and for 120 minutes in six pigs (group B2, gradual onset and long duration) by repeated intracoronary injections of serotonin (10 micrograms/kg) every 5 minutes. Intramural hemorrhage was noted histologically at the spastic site more frequently in group A with abrupt onset (nine of 10 pigs) than in group B with gradual onset (two of 10 pigs) (p < 0.01). Progression of organic coronary stenosis due to intramural hemorrhage was noted in seven pigs (six pigs in group A and one pig in group B), including three cases of total coronary occlusion. Evidence for the evolution of acute myocardial infarction (serial ECG findings, left ventriculograms, and histological findings) was noted in one pig (7%) of group A or B1 with short duration and in five of six pigs (83%) in group B2 with long duration (p < 0.01 versus group A and B1).

CONCLUSIONS

These results indicate that: 1) intramural hemorrhage was frequently induced by coronary spasm of abrupt but not of gradual onset, 2) intramural hemorrhage resulted in acute progression of coronary stenosis and sometimes resulted in persistent total coronary occlusion leading to acute myocardial infarction, and 3) prolonged coronary spasm resulted in acute myocardial infarction without progression of organic coronary stenosis.

Clinical risk assessment after first myocardial infarction--is additional noninvasive testing necessary?

In order to assess whether the outcome of MI can be predicted by clinical data alone or whether and how much noninvasive testing is necessary to predict cardiac events or death, 361 patients were prospectively evaluated and followed for up to five years. A recursive partitioning analysis indicated that high-risk patients can be identified clinically after MI with a high degree of accuracy; to separate low-risk patients who need no further investigation or therapy, however, one additional noninvasive test is necessary which allows quantification of myocardial damage as well as exercise-induced ischemia. Additional tests added little to this risk prediction, indicating that multiple noninvasive testing should not be performed.

Regular physical exercise and low-fat diet. Effects on progression of coronary artery disease

BACKGROUND

Significant regression of coronary and femoral atherosclerotic lesions has been documented by angiographic studies using aggressive lipid-lowering treatment. This study tested the applicability and effects of intensive physical exercise and low-fat diet on coronary morphology and myocardial perfusion in nonselected patients with stable angina pectoris.

METHODS AND RESULTS

Patients were recruited after routine coronary angiography for stable angina pectoris; they were randomized to an intervention group (n = 56) and a control group on "usual care" (n = 57). Treatment comprised intensive physical exercise in group training sessions (minimum, 2 hr/wk), daily home exercise periods (20 min/d), and low-fat, low-cholesterol diet (American Heart Association recommendation, phase 3). No lipid-lowering agents were prescribed. After 12 months of participation, repeat coronary angiography was performed; relative and minimal diameter reductions of coronary lesions were measured by digital image processing. Change in myocardial perfusion was assessed by 201Tl scintigraphy. In patients participating in the intervention group, body weight decreased by 5% (p less than 0.001), total cholesterol by 10% (p less than 0.001), and triglycerides by 24% (p less than 0.001); high density lipoproteins increased by 3% (p = NS). Physical work capacity improved by 23% (p less than 0.0001), and myocardial oxygen consumption, as estimated from maximal rate-pressure product, by 10% (p less than 0.05). Stress-induced myocardial ischemia decreased concurrently, indicating improvement of myocardial perfusion. Based on minimal lesion diameter, progression of coronary lesions was noted in nine patients (23%), no change in 18 patients (45%), and regression in 13 patients (32%). In the control group, metabolic and hemodynamic variables remained essentially unchanged, whereas progression of coronary lesions was noted in 25 patients (48%), no change in 18 patients (35%), and regression in nine patients (17%). These changes were significantly different from the intervention group (p less than 0.05).

CONCLUSIONS

In patients participating in regular physical exercise and low-fat diet, coronary artery disease progresses at a slower pace compared with a control group on usual care.

Relation of the site of acute myocardial infarction to the most severe coronary arterial stenosis at prior angiography

To determine whether the site of acute myocardial infarction (AMI) can be predicted on the basis of a previous coronary angiogram, 184 consecutive angiograms obtained between March 1972 and August 1990 in 92 patients who had undergone coronary angiography both before and after AMI without intervening bypass surgery or angioplasty were evaluated. Median time between the first coronary angiography and AMI was 26 months (range 1 to 144). On the first angiogram, most patients (89%) had 1- or 2-vessel disease, and 56 (61%) had an abnormal ventriculography. Seventy-two segments (78%) responsible for a future AMI were not significantly stenosed. On the second angiogram, AMI was related to the previously most stenotic segments in only 29 patients (32%). For these patients, median time between first coronary angiography and AMI was slightly shorter (22 vs 28 months; p = 0.04). The severity of the narrowing on the first angiogram was a poor predictor of subsequent AMI. It is concluded that in a selected, medically treated cohort, AMI is frequently related to a segment that was not the most stenotic one or was not even significantly stenosed at previous angiography, particularly with a long interval between the first angiogram and AMI.

Rotablator induced "shave" of intraluminal cap exposing intramural plaque crater

A patient with recent onset of unstable angina was found to have a severe, eccentric stenosis of the proximal left anterior descending coronary artery. Rotational atherectomy was performed. After the first passage of the burr across the stenosis, an intraplaque crater was angiographically visualized. It is hypothesized that the patient's clinical presentation may be attributed to plaque rupture and formation of an intraplaque crater which was sealed by a fibrous cap. This cap was "shaved" by the rotating burr, exposing the crater. Adjunctive balloon dilatation expanded the true lumen and compressed the crater.

Myocardial perfusion and regression of coronary artery disease in patients on a regimen of intensive physical exercise and low fat diet

This intervention program tested the applicability and effects of intensive physical exercise and a low fat diet on progression of coronary atherosclerotic lesions and stress-induced myocardial ischemia in patients with stable angina pectoris. Eighteen patients participated in this program for 1 year; they consumed a low fat, low cholesterol diet (less than 20 energy % fat, cholesterol less than 200 mg/day) and exercised for greater than 3 h/week. Change in coronary morphology was assessed by angiography and digital image processing; stress-induced myocardial ischemia was measured by thallium-201 scintigraphy. Results were compared with those in patients receiving "usual care." In the intervention group, significant regression of coronary atherosclerotic lesions was noted in 7 of the 18 patients; no change or progression was present in 11 patients. In patients receiving usual care, regression was detected in only 1, with no change or progression in 11 patients (different from intervention, p less than 0.05). There was a significant reduction in stress-induced myocardial ischemia, which was not limited to patients with regression of coronary atherosclerotic lesions. Thus, regular physical exercise and a low fat diet may retard progression of coronary artery disease; however, improvement of myocardial perfusion may be achieved independently from regression of stenotic lesions.

The severity of atherosclerosis at sites of plaque rupture with occlusive thrombosis in saphenous vein coronary artery bypass grafts

Atherosclerotic plaque rupture with superimposed thrombosis is recognized as the lesion causing late, acute, thrombotic saphenous vein coronary artery bypass graft (CABG) occlusion. To determine the severity of atherosclerosis at the site of plaque rupture, 68 saphenous vein CABGs removed at the time of reoperation or at autopsy were studied. The study population consisted of 57 men, 64 +/- 9 years old, and nine women, 70 +/- 10 years old. The duration of graft implantation was 7.9 +/- 2.7 years (mean +/- S.D.). All CABGs were dissected from the hearts, fixed, decalcified, cut at 2 to 3 mm intervals, and processed routinely for histologic examination. A planimeter was used to measure total vessel, plaque, thrombus, and luminal cross-sectional areas at the site of plaque rupture with thrombosis in sections projected at 13.8 power magnification. At the site of atherosclerotic plaque rupture with superimposed thrombosis, the degree of stenosis due to plaque was: 90 +/- 11% for the right coronary artery grafts (n = 19); 94 +/- 7% for the left anterior descending artery grafts (n = 41), and 90 +/- 14% for the left circumflex artery (n = 8) grafts. Thus in saphenous vein CABGs, atherosclerotic plaque rupture with thrombosis usually occurs at sites of severe narrowing (mean = 93%) by preexisting atherosclerotic plaque.

Segmental analysis of coronary arterial stenoses in patients presenting with angina or first myocardial infarction

The segmental distribution of stenoses within the coronary arteries was analysed in a population of 258 patients with a first myocardial infarction undergoing coronary angiography to evaluate the effect of thrombolytic therapy, and in a population of 466 patients undergoing elective coronary angiography for stable angina. Mean ages were 53.7 and 56.7 years respectively (P = NS). As judged angiographically, coronary arterial disease was more extensive in the group suffering angina, with a greater proportion of patients with two- or three-vessel disease (odds ratio 2.56, 95% confidence interval 1.87 to 3.52) and more patients having stenoses in two or more coronary arterial segments (odds ratio 1.52, 95% confidence interval 1.12 to 2.08). For each coronary vessel, the probability of finding a stenosis greater than 50% in an individual segment was greater in the group presenting with angina. There was a relative deficiency of stenoses within the main stem of the left coronary artery or its proximal left anterior descending branch among the patients suffering myocardial infarction. Within those having angina, subgroups were identified with "isolated" and "diffuse" coronary arterial disease: the latter patients tended to have a lower concentration of total cholesterol in the serum, but an increased prevalence of diabetes mellitus. Patients presenting clinically with a first myocardial infarction, and patients with severe angina, constitute distinct populations selected by different mechanisms from the overall pool of patients with atheromatous coronary arterial disease.

Effects of asymptomatic ischemia on long-term prognosis in chronic stable coronary disease

BACKGROUND

Ischemia on ambulatory electrocardiographic monitoring has been shown to adversely affect short-term prognoses in patients with unstable angina, after myocardial infarction, and with chronic stable angina.

METHODS AND RESULTS

In this long-term study, we followed 138 patients (mean age, 59 +/- 9 years) with chronic stable angina and positive exercise tests for cardiac events (e.g. death, myocardial infarction, percutaneous transluminal coronary angioplasty, or coronary artery bypass graft surgery). In 105 patients, ambulatory electrocardiographic monitoring was performed after all antianginal medication was withheld for 48 hours. In 26 patients, the diagnostic tests were repeated while on their usual medication. In addition to the 105 patients, 33 patients had their monitoring performed only while on their usual medication. During 37 +/- 17 months of follow-up, there were nine deaths, nine myocardial infarctions, and 35 revascularization procedures. In patients monitored off medication, Cox survival analysis showed that the occurrence of ischemia on electrocardiographic monitoring was the most significant predictor of death and myocardial infarction in the subsequent 2 years (p = 0.02) and all adverse events for 5 years (p = 0.009). Patients who were monitored on medication and did not have ischemia (n = 18) appeared to have more adverse events than patients who had no ischemia while being monitored off medication (n = 43).

CONCLUSIONS

Asymptomatic ischemia on ambulatory electrocardiographic monitoring in patients with stable angina predicts death and myocardial infarction for 2 years and all adverse events for 5 years. Monitoring performed while on medication may show no ischemia; however, this may not indicate low risk of future coronary events.

The severity of coronary atherosclerosis at sites of plaque rupture with occlusive thrombosis

Atherosclerotic plaque rupture with superimposed thrombosis is recognized as the lesion causing greater than 90% of acute myocardial infarctions. To determine the severity of atherosclerosis at the site of plaque rupture, 184 coronary arteries from autopsies of 162 patients who died of acute myocardial infarction were studied. There were 102 men, 72 +/- 10 years old (mean +/- SD), and 60 women, 75 +/- 8 years old. All arteries were dissected from the heart, fixed, decalcified, cut at 2 to 3 mm intervals and processed routinely for histologic examination. A planimeter was used to measure artery, plaque, thrombus and luminal cross-sectional area at the site of plaque rupture with thrombosis in sections projected at x13.8 magnification. At the site of atherosclerotic plaque rupture with superimposed thrombosis, the degree of stenosis due to plaque was: 90 +/- 7% for the right (n = 67), 91 +/- 6% for the left anterior descending (n = 79) and 91 +/- 6% for the left circumflex (n = 38) coronary arteries. Plaque rupture in fatal acute myocardial infarction occurs at sites of severe narrowing (mean 91%, range 67% to 99%). Thus, plaque rupture with thrombosis is unlikely to cause the fatal acute myocardial infarction in patients with mild to moderate coronary stenosis.

Experimental induction of spasm, sudden progression of organic stenosis and intramural hemorrhage in the epicardial coronary arteries

Pathogenesis of the so-called "heart attack" still remains to be elucidated. The links between stable effort angina and unstable or acute myocardial infarction, and between asymptomatic and spontaneous angina are all missing. In medicine presently, pathophysiology of ischemic heart disease is considered a consequence of i) the progression of atherosclerotic narrowing of the coronary artery, and ii) dynamic and transient obstruction (coronary spasm), but these mechanisms are traditionally believed to be unrelated. This article demonstrates various experimental evidence indicating that these two mechanisms are related. And, this review article describes how to produce experimental coronary spasm in the presence of atherosclerosis, similar to that seen in patients with variant angina, and that coronary spasm can produce sudden progression of coronary atherosclerotic obstruction due to intramural hemorrhage. Establishment of various animal models to elucidate mechanisms related to various stages of ischemic heart disease are needed.

Angiographic progression to total coronary occlusion in hyperlipidemic patients after acute myocardial infarction. POSCH Group

The progression of coronary artery stenosis to total occlusion was assessed in 413 hyperlipidemic patients with a previous myocardial infarction. Coronary angiograms were recorded at baseline, 3 (n = 312), and 5 years (n = 248) after initial study and analyzed by 2 independent readers. There were 177 (43%) patients with 1-, 130 (31%) with 2-, and 61 (15%) with 3-vessel disease (greater than or equal to 50% diameter narrowing), whereas 45 (11%) did not have significant disease within a major coronary vessel at baseline. A new finding of total occlusion occurred in 4% (30 of 748) and 7% (40 of 605) of major coronary artery segments at 3 and 5 years, respectively. The risk of progression to total occlusion was higher if the initial stenosis was greater than 60% compared to lesions less than or equal to 60% both at 3 years (19 of 143 = 13% vs 11 of 605 = 2%; p less than 0.001) and 5 years (27 of 91 = 30% vs 13 of 514 = 3%; p less than 0.001). The frequency of occlusion was highest for the right coronary artery by 5 years (18 of 167 = 11% for right vs 8 of 225 = 4% for circumflex vs 14 of 213 = 7% for left anterior descending coronary arteries; p less than 0.02). Clinical and laboratory data revealed that myocardial infarction was associated with a new total occlusion in 23% of patients (7 of 30) at 3 years and in 64% (25 of 39) at 5 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiographic assessment of the culprit coronary artery lesion before acute myocardial infarction

Serial angiographic studies of patients with myocardial infarction and unstable angina suggest that the culprit plaque underlying a thrombus need not have produced severe luminal obstruction before onset of the event. An atherosclerotic coronary artery lesion can, therefore, have 2 important characteristics. First, it may be obstructive. Second, it may be "vulnerable" in that it has the potential to become thrombogenic if exposed to the appropriate triggering stimulus. A lesion need not be obstructive to become thrombogenic, nor do all obstructive lesions have thrombogenic potential. The cause of an infarction may thus be rupture of a nonobstructive plaque leading to occlusive thrombus formation. Because it may be difficult to predict the site of a subsequent occlusion from a coronary angiogram, coronary bypass surgery or angioplasty directed only at discernible stenotic lesions may not be effective for preventing subsequent myocardial infarctions. Appropriate therapy may need to be directed at the entire coronary tree. Such therapy might include cholesterol lowering, beta blockade and aspirin.

Coronary angiographic ruptured atheromatous plaque as a predictor of future progression of stenosis

To determine whether or not angiographic coronary morphology can predict future development/progression of narrowing, we reviewed coronary angiograms (CAGs) from 29 patients who underwent CAG studies twice but who had no myocardial revascularization during the period of the studies. The mean age of the patients was 52.9 +/- 8.5 years, and the mean interval between the studies was 25.4 +/- 22.6 months. Mean luminal diameter stenosis of 77 lesions that reduced the diameter by 50% or more on either CAG, but were not totally occluded on the initial CAG, increased from 62% to 79% (p less than 0.01). Progression of stenosis developed in 35 lesions (45%); the progression in 13 lesions of the 35 (37%) was on sites associated with no stenosis or mild stenosis on the initial CAG. No relation was found between the development/progression of stenosis and either its initial severity or elapsed time; however, the prevalence of the development/progression of stenosis was more frequent on sites with possible or probable ruptured atheromatous plaque on the initial CAG than on sites without such plaque (p less than 0.05). The evidence suggests that there is no apparent relation between the future development/progression of coronary narrowing and either the severity of stenosis on the initial CAG or elapsed time but that some of the development/progression can be predicted on the basis of certain specific coronary morphology.

A new method of scoring coronary angiograms to reflect extent of coronary atherosclerosis and improve correlation with major risk factors

We developed a new angiographic score of the extent of coronary disease (extent score), which we compared with conventional stenosis and vessel scores that emphasize the severity of stenosis. Scores were determined in 132 patients (29 women, 103 men with a mean age of 55 +/- 10 years) who underwent elective coronary angiography. Risk factors were more closely related to the extent score than to either the stenosis or vessel scores (Total R2 = 0.35 versus 0.28 (p less than 0.001) and 0.25 (p less than 0.001), respectively). The extent score was more closely related to age (r = 0.30, p less than 0.05), than was either stenosis (r = 0.21 ns) or vessel score (r = 0.26, p less than 0.05). Apolipoprotein B was the strongest predictor of both extent and stenosis scores but was more closely related to the extent score (r = 0.36, p less than 0.05), even after correction for age and gender. This new angiographic score that assesses the extent of coronary disease is simple to perform and correlates better with age and lipoprotein risk factors than conventional scores do.