The Intentional Spring: A Strategy for Modeling Systems That Learn to Perform Intentional Acts

In motor task learning by instruction, the instructor's skill and intention, which, initially, are extrinsic constraints on the learner's perceiving and acting, eventually become internalized as intrinsic constraints by the learner. How is this process to be described formally? This process takes place via a forcing function that acts both as an anticipatory (informing) influence and a hereditary (controlling) influence. A mathematical strategy is suggested by which such intentions and skills might be dynamically learned. A hypothetical task is discussed in which a blindfolded learner is motorically instructed to pull a spring to a specific target in a specific manner. The modeling strategy involves generalizing Hooke's law to the coupled instructor-spring-Learner system. Specifically, dual Volterra functions express the anticipatory and hereditary influences passed via an instructor-controlled forcing function on the shared spring. Boundary conditions (task goals) on the instructor-spring system, construed as a mathematical (self-adjoint) operator, are passed to the learner-spring system. Psychological interpretation is given to the involved mathematical operations that are passed, and mathematical (Hilbert-Schmidt's and Green's function) techniques are used to account for the release of the boundary conditions by the instructor and their absorption by the learner, and an appropriate change of their power spectra.

Emergency coronary artery bypass surgery following failed balloon angioplasty: role of the internal mammary artery graft

During a 4-year period (1986-1989), 3,502 patients had percutaneous transluminal coronary angioplasty (PTCA) in our institution. One hundred nineteen (3.4%) patients required emergency coronary artery bypass graft surgery (CABG) because of abrupt vessel closure following PTCA. Factors associated with vessel closure included lesion angulation greater than or equal to 90 degrees (p less than 0.007), the presence of thrombus (p less than 0.02), or a long (greater than or equal to 2 cm) lesion (p less than 0.03). Of these 119 emergency CABG patients, 108 (91%) arrived in the operating room in a stable condition (group I) and 11 (9%) were in cardiogenic shock (group II). Five (45%) of the group II patients were admitted to the hospital with an acute myocardial infarction and all 11 patients had a higher incidence of multivessel disease (p less than 0.05) and lower left ventricular ejection fraction (p less than 0.001) than group I patients. The overall surgical mortality was 10.1%; however, in group I the mortality was 5.6% and in group II it was 54.5% (p less than 0.001). The vessel that abruptly closed ("culprit vessel") was the left anterior descending (LAD) in 60%, the right coronary artery in 27%, and the left circumflex in 13%. The internal mammary artery was utilized to bypass the culprit artery in 51 (43%) patients, including 50% of the culprit LADs. With group I culprit LAD patients, when the left IMA was the bypass conduit, there were no hospital deaths nor strokes and there was a 6.3% incidence of perioperative infarction.

Causes and correlates of death after unsupported coronary angioplasty: implications for use of angioplasty and advanced support techniques in high-risk settings

To better understand the factors predisposing a patient to death after elective percutaneous transluminal coronary angioplasty (PTCA) and to gain insight into indications for high-risk PTCA both with and without adjunctive use of support devices, the outcomes of 8,052 consecutive procedures were reviewed. Death occurred after 32 procedures (0.4%) and was directly related to coronary artery closure in 26 (81%) of these cases. Left ventricular failure due to vessel closure at the dilated site, the most common cause of death, was independently correlated with female sex (p less than 0.001), "jeopardy score" (p less than 0.001) and PTCA of a proximal right coronary artery site (p = 0.002), but not with left ventricular ejection fraction or presence of multivessel disease. Right ventricular failure after closure of the proximal right coronary artery, and left main coronary dissection accounted for the majority of the remaining deaths. Systolic blood pressure immediately after coronary artery closure was also closely correlated with jeopardy score, and cardiogenic shock was frequent in women with scores greater than or equal to 3.5 and in men with scores greater than or equal to 5.0. These data highlight the superiority of the jeopardy score versus ejection fraction in the determination of risk, stress the importance of gender in determining outcome and point to the need for better means of right ventricular protection from severe ischemia. Therefore, an initial framework for rational use of PTCA and support devices in the high-risk setting is established.

Coronary angioplasty in octogenarians: comparisons to coronary bypass surgery

Coronary angioplasty was performed in 74 patients 80 years of age and older (mean 83 +/- 3). Single vessel coronary disease was present in 34% and multivessel coronary disease in 66%. Angioplasty of a single vessel was performed in 51 patients (69%), while 23 (31%) had angioplasty of multiple vessels. Angioplasty was successful in 59 of 74 patients (80%). Angioplasty was unsuccessful but uncomplicated in 12 (16%) due to (unyielding) calcified lesions or (impassable) old occlusions. Of these 12, 8 were discharged on medical therapy and 4 underwent elective uncomplicated bypass surgery prior to discharge. Three (4%) patients required emergency coronary bypass surgery due to abrupt vessel closure during the angioplasty procedure, with one hospital death (1.4%). Follow-up (mean 24 +/- 22 months) was obtained in all patients. Of the 59 successful angioplasty patients, late mortality was 10% (cardiac 7% and non-cardiac 3%). Survival and survival without myocardial infarction were both 90%; survival without either infarction or bypass surgery was 86%. Actuarial 3-year survival was 91% and 3-year freedom from death, infarction or bypass surgery was 87% by life-table analysis. Repeat angioplasty for restenosis was performed in 7 patients (12%) without complications.

Usefulness of tomographic thallium-201 imaging for detection of restenosis after percutaneous transluminal coronary angioplasty

The role of tomographic thallium-201 exercise and redistribution imaging in the detection of restenosis after percutaneous transluminal coronary angioplasty (PTCA) was evaluated in 116 patients: 61 (53%) with 1- and 55 (47%) with multivessel PTCA, with a total of 185 dilated vessels. Complete revascularization was performed in 89 (77%) and partial revascularization in 27 (23%) of the patients. Restenosis was angiographically demonstrated in 69 (60%) of the patients and 85 (46%) of the vessels 6.4 +/- 3.1 months after PTCA. Disease progression in previously normal vessels was noted in 11 patients. The results were: (1) for detection of restenosis in the group of patients, single-photon emission computed tomographic (SPECT) versus exercise electrocardiographic sensitivity was 93 vs 52% (p less than 0.001), specificity 77 vs 64%, and accuracy 86 vs 57% (p less than 0.001). The results were similar in the complete and partial revascularization groups. (2) SPECT was 86% sensitive, specific and accurate for restenosis detection in specific vessels with comparable results for 1-versus multivessel PTCA and complete versus partial revascularization. Sensitivity, specificity and accuracy were: 89, 95 and 92% for the left anterior descending coronary artery; 88, 79 and 82% for the right coronary artery; and 76, 83 and 85% for the left circumflex coronary artery. Eighty-one percent of the diseased nondilated vessels were correctly identified. (3) Disease progression to greater than 50% stenosis was detected with 91% sensitivity, 84% specificity and 85% accuracy. SPECT thallium-201 imaging is an excellent tool for the detection of restenosis and disease progression after PTCA in the settings of 1- and multivessel angioplasty and complete and partial revascularization.

Coronary angioplasty in young adults: initial results and late outcome

The initial and late outcome of coronary angioplasty was studied in 148 patients less than 40 years of age (mean 36.4 +/- 3). Angioplasty was performed on a single vessel in 70% of patients and on multiple vessels in 30%; it was performed on a totally occluded vessel in 20%. Angioplasty was successful in 90.5% of patients, unsuccessful but uncomplicated in 7.4% and complicated by myocardial infarction in 0.7%, emergency bypass surgery in 0.7% and death in 0.7%. At late (mean 3.7 +/- 3 years; range 0.5 to 11.5) follow-up study after successful angioplasty, 94% of patients were alive, 79% were free of angina and 85% had returned to work; late myocardial infarction occurred in 4%. Actuarial survival at 5 years was 95%, and 85% of patients were free from death, infarction or bypass surgery. A second angioplasty was performed in 29 patients (22%) (mean 6.1 +/- 8.4 months) and was successful in 27 (93%), with no deaths. Elective coronary bypass surgery was performed in 8.5% of patients, with perioperative infarction in 9% and no deaths. By univariate analysis, late death was more likely to occur in hypertensive patients (15% versus 2.5%; p less than 0.01) and diabetic patients (21.4% versus 3.6%; p less than 0.01). Cox proportional hazard regression analysis identified hypertension (p = 0.007) and diabetes (p = 0.04) as independent time-related predictors of subsequent death. Thus, early and late results after coronary angioplasty in young adults are favorable, but certain risk factors are important predictors of outcome. Late revascularization procedures (repeat angioplasty or surgery) for restenosis or disease progression are common.

Early clinical experience with a hot tip laser wire in patients with chronic coronary artery occlusions

Chronic coronary artery occlusions remain one of the problems limiting the use of percutaneous transluminal coronary angioplasty (PTCA). We have studied the use of an 0.018 inch laser hot tip wire. It was coupled either to a continuous wave argon or Nd-YAG laser generator and introduced through a balloon catheter to try and cross and dilate a series of chronic coronary artery occlusions in which initial conventional attempts had failed. Four LAD and 6 RCA occlusions were attempted; we successfully crossed and dilated 6 (60%) lesions, 4 (40%) using the laser wire alone to recanalize the occlusion and in 2 a combination of laser wire and conventional means.

Coronary angioplasty after coronary bypass surgery: initial results and late outcome in 422 patients

From 1978 to 1988, coronary angioplasty was performed in 422 patients with prior coronary artery bypass surgery (264 patients with native coronary artery angioplasty and 158 patients with graft angioplasty). Angioplasty was successful in 84%, unsuccessful but uncomplicated in 11% and complicated by one or more major cardiac events in 5% (myocardial infarction 5%, emergency bypass surgery 2% and death 0.2%). Follow-up data were obtained in 99% of 356 patients with successful angioplasty. At a mean of 33 +/- 26 months, 92% were alive, 73% had improvement in angina and 61% were free of angina. One or more of the following late events occurred in 67 patients (19%): myocardial infarction (6%), elective reoperation (13%) and cardiac death (6%). Repeat angioplasty was performed in 27%, with a success rate of 89% and no deaths. Initial success rates were equal in native vessel versus graft angioplasty, but late outcome was less favorable with the latter because of a higher rate of infarction (11% versus 4%, p less than 0.05) and need for reoperation (19% versus 10%, p less than 0.05). The initial success rate was higher in vein grafts less than 1 year old compared with grafts 1 to 4 years or greater than 4 years after operation (92% versus 85% versus 83%, respectively) and adverse late events were less frequent after angioplasty in recent vein grafts (less than 1 year 13%, 1 to 4 years 35%, greater than 4 years 29%; less than 1 versus greater than 1 year, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Does percutaneous transluminal coronary angioplasty accelerate atherosclerotic lesions?

Recent reports have suggested that angioplasty may cause or accelerate coronary arterial stenoses secondary to traumatic injury. Ninety-four coronary angiograms performed in a 1 yr period were reviewed in patients who had successful coronary angioplasty 6 to 30 mo (mean 10.7) prior to restudy. Restenosis was found in 43 of 140 dilated lesions (31%) and in 41 of 94 patients (44%). Thirty-three (35%) patients had new or progressive lesions outside the angioplasty site. New or progressive lesions occurred with similar frequency in the arteries that did not have angioplasty (23/155 = 15%) as in the arteries that did (13/127 = 10%; chi-square n.s.). In the arteries which underwent angioplasty, new or progressive lesions occurred as commonly proximal to the PTCA site (7/14, 50%) as distal (6/13, 46%). New or progressive lesions occurred in 29% of patients with concomitant restenosis, and 40% of those without restenosis (chi-square n.s.). No clinical, angiographic, or procedural factors distinguished patients with new and progressive lesions in target vessels from those without these lesions in target vessels. Patients with progressive lesions anywhere in the coronary tree were more likely to have had a shorter duration of anginal symptoms before angioplasty and a family history of coronary disease when compared with patients without progressive atherosclerosis. In conclusion, new and progressive lesions outside the angioplasty site occur after the procedure but appear unrelated to the restenosis process or traumatic injury by angioplasty instrumentation.

Unstable angina and coronary angioplasty

Of 2,122 consecutive patients undergoing elective coronary angioplasty from 1982 to 1985, 62% had stable angina pectoris (SAP), and 38% had unstable angina pectoris (UAP). There were differences between the two groups in clinical and morphological factors and in initial and late results of angioplasty. UAP patients were more likely than SAP patients to be smokers and to have had prior myocardial infarctions. Lesions in UAP patients were more severe, longer, more eccentric, more irregular, and more likely to have intracoronary thrombi than were lesions in SAP patients. Coronary angioplasty success was achieved in 84% of UAP and in 88% of SAP patients (p less than 0.05), and complications occurred in 6.7% of UAP and in 4.7% of SAP patients (p less than 0.05). Hospital death rates were low and similar, 0.2% for both groups. Follow-up (mean, 37 months) showed recurrent Canadian Cardiovascular Society (CCVS) class III/IV angina in 30.1% of UAP and in 25.2% of SAP patients (p less than 0.05). There was a return to work in 86% of UAP and in 91% of SAP patients (p less than 0.05). When UAP patients' durations of symptoms were further fractionated, it was found that the earlier angioplasty was performed after onset of angina, the lower was the success rate and the higher the complication rate and incidence of late follow-up untoward events. When coronary angioplasty was performed within 1 week of onset of angina ("early"), success was 79.1%; when angioplasty was performed 2 weeks or more after onset of angina ("later"), success was 86.3%. Major cardiac events occurred in 11.5% in the early group and in 4.8% in the later group (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Intra-aortic balloon counterpulsation support for elective coronary angioplasty in the setting of poor left ventricular function: a two center experience

A two-center elective coronary angioplasty experience with intra-aortic balloon pump support for patients with severe left ventricular dysfunction is reported. To prevent hemodynamic collapse, an intra-aortic balloon pump was inserted percutaneously before coronary angioplasty in 97 patients with a left ventricular ejection fraction less than 35% (26% of whom had ejection fractions less than 25%). The cohort was predominantly male (71%) with a mean age of 64 +/- 9 years. Angioplasty was successfully performed in 83 (85.6%) patients and 80 (82.5%) of these successful patients were discharged from the hospital. Seven patients had unsuccessful angioplasty without a major cardiac event. Seven patients (7.2%) suffered a major cardiac event; 4 had emergent coronary bypass surgery with q-wave infarction, 2 had uneventful emergency coronary bypass surgery, and one patient died in the operating room after a failed angioplasty. Using logistic regression analysis, the presence of multivessel disease and a history of prior myocardial infarction were associated with more complications during angioplasty (p less than 0.05). Intra-aortic balloon pump placement did not interfere with the angioplasty procedure. Two patients had limb ischemia which resolved when the intra-aortic balloon pump was removed. Of the 80 successful patients discharged, 72 were followed for a mean of 22 months. At the latest follow-up, 52 had not suffered a myocardial infarction and were alive. Of the 20 late deaths, 16 were cardiac and 4 non-cardiac.(ABSTRACT TRUNCATED AT 250 WORDS)

Bidirectional crossover and late outcome after coronary angioplasty and bypass surgery: 8 to 11 year follow-up

Between March 1978 and July 1981, 217 symptomatic patients underwent coronary angioplasty as an alternative to coronary bypass surgery. Angioplasty was successful in 143 patients (66%), unsuccessful but uncomplicated in 65 (30%) and complicated in 9 (4%) by one or more of the following criteria: Q wave myocardial infarction (2%), emergency surgery (4%) or death (0.5%). Late follow-up evaluation was obtained in 213 patients at a mean of 9 +/- 1 years. Of patients in whom angioplasty was successful, 59 (42%) of 140 required another revascularization procedure (repeat angioplasty in 26% and bypass surgery in 16%). The actuarial survival rate at 5, 9 and 10 years after successful angioplasty was 98%, 93% and 92%, respectively. Of the 65 patients with unsuccessful and uncomplicated angioplasty (usually as a result of technical factors), 58 underwent elective bypass surgery within 2 months and 56 survived. These 56 surgical patients were compared with the 140 patients with successful angioplasty. Univariate analysis of prognostic factors did not reveal significant differences between these two groups. At late follow-up study, the successful angioplasty and the successful surgical groups had similar rates of survival (93% versus 95%, p = NS) and of death or infarction, or both (11% versus 12.5%, p = NS). Repeat revascularization was required more frequently after successful angioplasty than after surgery (42% versus 18%, p less than 0.001). Crossover from angioplasty to surgery occurred slightly more often than from surgery to angioplasty (16% versus 12.5%, p = NS). The time to crossover from angioplasty to surgery occurred earlier than from surgery to angioplasty (mean 21 versus 76 months, p less than 0.001).

Percutaneous transluminal aortic valvuloplasty--the acute outcome and follow-up of 149 patients who underwent the double balloon technique

Double balloon percutaneous transluminal aortic valvuloplasty (PTAV) was performed on 149 patients (76 male (51%), mean age 76 +/- 11 years) whose symptoms included severe congestive heart failure in 127 cases (82%), syncope in 21 (14%) and angina in six (4%). Significant changes (P less than 0.05) in peak systolic (83 +/- 36 to 38 +/- 30 mmHg) and mean gradient (68 +/- 25 to 36 +/- 21 mmHg), and aortic valve area (0.6 +/- 0.2 to 1.0 +/- 0.4 cm2) were achieved in 130/149 patients (87%). Complications included an overall in-hospital mortality of 13%, (10.0% excluding the six deaths occurring in 18 moribund patients), a neurologic deficit incidence of 3%, and surgical arterial entry site repair 3.0% (14/47) of patients. Multivariate analysis identified congestive heart failure (NYHA Class IV), left ventricular ejection fraction, cardiac output and coronary artery disease as independent variables significantly affecting in-hospital mortality. Predictors of poor long-term survival were degree of heart failure, and coronary artery disease. The cumulative probability of survival at 24 months was 52 +/- 5% (excluding non-cardiac deaths, was 66 +/- 3%). Follow-up (mean time: 16 +/- 7 months) of 130 patients discharged alive revealed 41 late deaths (26 cardiac related). Sixty-two patients (70%) were symptomatically improved; 17 patients had symptom recurrence and underwent repeat valvuloplasty, and 10 patients valve replacement. Follow-up catheterization of 18 asymptomatic patients revealed that 11 patients had silently restenosed. These data indicate that aortic valvuloplasty is a palliative therapy for elderly patients, who are poor surgical candidates, with symptomatic calcific aortic stenosis with reasonable clinical success and long-term survival when considering their clinical status, but with a significant restenosis rate.

The setting of coronary angioplasty in multivessel disease: current status and future directions

In summary, the use of coronary angioplasty in the setting of multivessel coronary disease has become more common in recent years. Reports indicate that, in carefully selected patients, a high initial success rate and low incidence of complications can be achieved. We have presented a schema for the triage of multivessel disease patients. Examples of each subgroup have been presented to illustrate the basis for this categorization. Our experience using this schema at the San Francisco Heart Institute has been valuable in understanding the initial and long-term results of coronary angioplasty in these patients. It is important that this paradigm (or a similar classification schema) be adopted to assist clinicians in making judgments about alternative approaches in patients with multivessel disease and to provide a common organization for the dissemination of research findings and collaboration among members of the medical community.

Silent ischemia: evaluation by exercise and redistribution tomographic thallium-201 myocardial imaging

To compare the amount of myocardium jeopardized during silent ischemia and painful ischemia, 112 consecutive patients undergoing coronary arteriography with ischemia demonstrated by exercise and redistribution tomographic thallium-201 myocardial imaging (SPECT) were divided into two groups: 84 patients without anginal pain (silent ischemia) and 28 with pain (painful ischemia). The SPECT apical, mid and basal ventricular levels of the short-axis view and the apical portion of the long-axis view were divided into 20 segments. The results were 1) 7.4 +/- 4.7 ischemic segments in silent ischemia and 7.6 +/- 3.7 in painful ischemia (p = NS) with 4.7 +/- 3.6 segments in silent ischemia undergoing total redistribution compared with 5.4 +/- 3.4 in painful ischemia (p = NS); 2) no difference in the incidence of single, double or triple vessel disease between silent and painful ischemic groups; 3) similar anatomic distribution of ischemic segments between the two groups; 4) more positive exercise electrocardiographic (ECG) changes in painful ischemia (70%) than in silent ischemia (32%) (p less than 0.001) with equal amounts of ischemia associated with positive and negative exercise ECG findings.

CONCLUSIONS

1) Patients with silent and painful ischemia during exercise have similar amounts of ischemic myocardium demonstrated by tomographic thallium-201 imaging and similar extent of angiographically documented coronary artery disease despite the absence of pain and the lower incidence of positive exercise ECG findings in silent ischemia. 2) Positive and negative exercise ECG findings were associated with similar amounts of ischemic myocardium.

Risk factors, time course and treatment effect for restenosis after successful percutaneous transluminal coronary angioplasty of chronic total occlusion

Advances in technology and operator experience, and increased use of angiography early after myocardial infarction have led to greater use of percutaneous transluminal coronary angioplasty (PTCA) for chronic, total coronary artery occlusions. To better assess long-term outcome, 257 consecutive patients with successful PTCA of a total occlusion with late angiographic follow-up from 484 patients (53%) with PTCA success were reviewed. The mean +/- standard deviation patient age was 54 +/- 10 years, 79% were men, the duration of total occlusion was 11 +/- 15 weeks and the post-PTCA diameter stenosis was 24 +/- 12%. Eighty-two, 27 and 63% of patients received long-term aspirin, dipyridamole and warfarin therapy, respectively. Angiography at 8 +/- 8 months demonstrated restenosis (greater than or equal to 50% diameter stenosis) in 41% of patients restudied within 6 months and in 66% of patients restudied within 12 months by life table analysis. In multivariate regression analysis of 19 variables, 2 were independently correlated with the occurrence of restenosis: post-PTCA diameter stenosis greater than 30% (p = 0.02) and coronary artery dilated (left anterior descending and right coronary arteries greater than the left circumflex coronary artery) (p = 0.05). In log rank analysis that also considered the timing of angiographic detection of restenosis, dilatation of a proximal left anterior descending stenosis was also a significant predictor of restenosis (p = 0.01), and dilatation within 4 weeks of the presumed time of occlusion was only weakly predictive (p = 0.11).(ABSTRACT TRUNCATED AT 250 WORDS)

Education of patients undergoing coronary angioplasty: factors affecting learning during a structured educational program

A structured educational program for patients undergoing coronary angioplasty was designed and administered to 97 patients undergoing their first procedure. Knowledge, coping style, social support, health locus of control, IQ, and demographic and medical factors were assessed before the procedure. Risk factor knowledge, anxiety, and medical status were assessed before discharge, and at 6 months and 2 years after angioplasty. Total knowledge mean score for all patients was higher at discharge (p less than 0.05). There was no significant difference between knowledge scores at baseline and at either 6 months or 2 years. Analyses revealed that patients with a repressive coping style learned less during hospitalization (p less than 0.05). No factors predicted retention of knowledge at 6 months or 2 years. These results indicate that a structured educational approach may have beneficial effects on immediate knowledge gain, although these results are not sustained. Coping assessment may provide information valuable for understanding differences in knowledge retention.

In-hospital cardiac mortality after acute closure after coronary angioplasty: analysis of risk factors from 8,207 procedures

Cardiac death consequent to acute vessel closure after coronary angioplasty occurred in 13 of 294 closures from 8,207 consecutive procedures performed at two centers since 1981 (0.16% cardiac mortality rate). To determine the predictors of cardiac death after acute coronary closure, 50 clinical, angiographic and procedural variables were analyzed by an observer unaware of the clinical outcome for each of the 13 patients who died and also 100 patients randomly chosen, in whom vessel closure after angioplasty did not result in death during hospitalization. Univariate analysis found female gender (p less than 0.0001), collateral channels from the vessel dilated (p less than 0.0001), use of balloon counterpulsation (p less than 0.0002), pre- and postprocedural hypotension (p = 0.0003 and p = 0.003, respectively), jeopardy score greater than or equal to 2.5 (p = 0.003), left ventricular hypertrophy (p = 0.013), hypertension (p = 0.02), diabetes (p = 0.02) and multivessel disease (p = 0.03) to be predictive of death. Multivariate analysis found collateral vessels, female gender and multivessel disease to be independent predictors of death. Thus, cardiac death after elective coronary angioplasty is very rare in experienced centers and occurs most often in women with a large amount of potentially ischemic myocardium. Hypotension often precedes the fatal closure event. Close attention to the amount of potentially ischemic myocardium and to the fluid volume status of these patients would seem to be especially warranted.

Transluminal coronary angioplasty in the treatment of silent ischemia

Fifty-four asymptomatic patients with positive thallium exercise tests underwent coronary angiography followed by coronary angioplasty (PTCA), as the primary therapy for silent ischemia. The procedure was technically successful in 89% of these patients. Emergency bypass graft surgery was necessary in 2 (3.6%) and q-wave myocardial infarction occurred in 1 (1.8%) of these. All fifty-four patients have been followed for a mean of 35 months since angioplasty. Of the 48 patients with initially successful PTCA, 12 had either clinical restenosis (9/14 or 19%) or a new lesion (3/48 or 6%) during follow-up, which required a repeat PTCA. At the longest follow-up, 46 (85%) had been successfully treated with on or more PTCA procedures. Two patients (3.6%) had sustained late q-wave myocardial infarction and two additional patients reported angina pectoris. There were no deaths. Angioplasty as a primary therapy for silent ischemia appears efficacious, with success and restenosis rates comparable to those in the symptomatic population. Event-free survival is improved, compared with natural history data for patients with silent ischemia from other studies. Prudent risk/benefit analysis may help to define subgroups most likely to benefit from this intervention.

Recurrence after coronary angioplasty

Recurrence (restenosis) after coronary angioplasty has undermined the initial success of the procedure and has compromised, to some extent, the attractiveness of the technique in the treatment of ischemic heart disease. Assessment of recurrence predictors has been problematic due to lack of coordination of angioplasty recurrence research and includes: incomplete angiographic documentation, variations in definitions of restenosis anatomically and the results of restenosis physiologically (ie, myocardial ischemia), the dirth of morphologic specifications of subsets under investigation and late outcome pathology, limitations in statistical analyses used, and minimal efforts to classify the available data on recurrence. A review of the literature suggests that all findings regarding recurrence after angioplasty can be organized in four categories: clinical, morphologic, technical (or procedural), and pharmacologic. The reported findings with high concordance as risk factors for recurrence after angioplasty include the clinical factors of diabetes mellitus, hyperlipidemia, and angina of short duration or unstable presentation. Morphologic factors which have been corroborated vis-à-vis recurrence include stenoses with diameter reduction of greater than 90% before and greater than 30% after angioplasty, residual trans-stenotic pressure gradients of greater than 20 mmHg after angioplasty, and lesions that are diffuse, long, eccentric, or calcified. Technical factors associated with recurrence include lower balloon/vessel (or graft) ratios and the absence of (uncomplicated) "intimal dissection." The category most deficient in research regarding recurrence after angioplasty is pharmacologic. Since there are statistically documented and reproducible factors predictive of restenosis, to ignore or minimize these findings or resist further evaluation (because of the ease and safety of performing repeat angioplasty) is to deny the opportunity to understand the mechanisms and favorably affect the incidence of recurrence. This review concludes with two major implications of the restenosis research: certain clinical, technical, and pharmacologic factors, if addressed, may predictably decrease the rate of restenosis and certain clinical and morphologic factors may increase the risk of restenosis; these factors may be less readily modified (eg, diabetes, lesion calcification) and thus must be considered in the decision for angioplasty.(ABSTRACT TRUNCATED AT 400 WORDS)