Restenosis after transluminal coronary angioplasty detected with exercise-gated radionuclide ventriculography

QT dispersion plus ST-segment depression: a new predictor of restenosis after successful percutaneous transluminal coronary angioplasty

BACKGROUND

ST-segment depression during exercise testing is frequently observed in the absence of restenosis after percutaneous transluminal coronary angioplasty (PTCA).

HYPOTHESIS

With the goal of improving the prediction of restenosis after PTCA, we evaluated the usefulness of ST-segment depression plus QT dispersion (QTd = QTmax - QTmin) during treadmill stress test.

METHODS AND RESULTS

Fifty-six patients (37 men, 19 women, mean age 51 +/- 14 years) were evaluated with treadmill exercise testing and coronary angiography 7 +/- 5 months after PTCA. Treadmill test was positive in 30 patients and negative in 26 patients. At coronary angiography, restenosis was present in 16 patients with positive exercise electrocardiogram (ECG) and in 6 patients with negative exercise ECG. Fourteen patients with a positive stress test did not have restenosis. There was no difference in QTd values between groups at baseline (p > 0.05). Exercise QTd was 63 +/- 9 ms in patients with positive exercise test, 54 +/- 18 ms in patients with negative exercise test (p = 0.003), 71 +/- 13 ms in patients with restenosis, and 53 +/- 17 ms in patients without restenosis (p = 0.001). ST-segment depression during the stress test determined restenosis with a sensitivity of 80% and a specificity of 58%. Sensitivity and specificity of QTd of > or = 60 ms for prediction of restenosis were 83 and 61%, respectively. When QTd of > or = 60 ms was added to ST-segment depression as a condition for positive test, the sensitivity and specificity increased to 91 and 78%, respectively. QT dispersion plus ST-segment depression had higher sensitivity and specificity than either QTd or ST-segment depression alone (p < 0.05).

CONCLUSION

The addition of QTd to ST-segment depression during exercise test improves the diagnostic value and can be used as a noninvasive tool in the diagnosis of restenosis after PTCA.

Exercise stress testing, myocardial perfusion imaging and stress echocardiography for detecting restenosis after successful percutaneous transluminal coronary angioplasty: a review of performance

When chest symptoms recur in a patient who underwent percutaneous transluminal coronary angioplasty (PTCA), it is necessary to rule out restenosis (R). Three main noninvasive tests suggest the presence of R: exercise stress test (XT), myocardial perfusion imaging (MPI) and stress echocardiography (s-echo). The objectives of this review were: (1) to estimate the pretest probability of R as a function of time after PTCA in symptomatic patients and (2) to obtain an approximation of the diagnostic parameters of the XT, MPI and s-echo for detecting R. A MEDLINE search (English-language, years: 1980-2001) was conducted to identify studies examining post-PTCA functional testing for diagnosing R. Data from the studies were pooled. Comparing studies was often difficult due to varying methodology in the studies. Pretest probability of R in symptomatic patients increases in a nonlinear fashion from 20% or less at 1 month, to nearly 90% at 1-year postangioplasty. The approximated accuracy of the XT, MPI, and s-echo for detecting R was 62, 82 and 84%, respectively. During the first month after PTCA, none of the noninvasive modalities is able to accurately detect R. Late (7-9 months) after PTCA, the pretest probability of R is high and therefore the noninvasive measure may be spared. Our analysis suggests that MPI and s-echo should be preferred over the XT for diagnosing R.

[Diagnostic efficacy of myocardial tomographic imaging in the detection of restenosis after coronary angioplasty]

INTRODUCTION AND OBJECTIVES

To analyze the efficacy of single photon emission tomography (SPET) with 99mTc-compounds for the diagnosis of restenosis of previous percutaneous transluminal coronary angioplasty (PTCA).

PATIENTS AND METHODS

Seventy-one patients (16 women, median age: 60 years, 35 with multivessel disease, 78 arteries with PTCA) with previous PTCA and with coronary angiography performed after scintigraphy were studied. 99mTc-SPET exercise (53 with MIBI and 18 with tetrofosmin) was performed, for clinical reasons, to all patients between one month and 4 years after PTCA. Intravenous dipyridamole was administered simultaneously to 16 patients who had insufficient exercise.

RESULTS

SPET sensitivity, specificity, positive predictive values, negative predictive values and global values were all significantly higher than those obtained with exercise tests (80% vs 63%; p = 0.05; 83% vs 37%; p = 0.001; 91% vs 69%; p = 0.007; 64% vs 31%; p = 0.009, and 81% vs 55%; p = 0.0006, respectively). These results were significantly superior in patients with one vessel disease than in patients with multivessel disease.

CONCLUSIONS

SPET exercise with 99mTc-compounds is a test with a high efficacy for the diagnosis of post-PTCA restenosis, mainly in patients with one vessel disease.

Increase in the delta ST/delta heart rate (HR) index: a new predictor of restenosis after successful percutaneous transluminal coronary angioplasty

With the goal of improving the prediction of restenosis after percutaneous transluminal coronary angioplasty (PTCA), we evaluated the usefulness of the delta ST/delta heart rate (HR) index derived from serial exercise treadmill tests. Exercise treadmill tests were performed by 125 patients with single-vessel coronary artery disease before and several days after PTCA, and just before follow-up angiography 3 to 12 months later. Simple HR-adjusted indexes of ST-segment depression during exercise (delta ST/delta HR index) were derived. We compared the usefulness of the increase in delta ST/delta HR index at follow-up over the value obtained several days after PTCA for prediction of restenosis with that of a positive exercise treadmill test and a positive thallium scintigram at follow-up. At follow-up, 47 of the 125 patients showed restenosis. The delta ST/delta HR index increased in 43 of 47 patients in the restenosis group and in 18 of 78 patients without restenosis (p < 0.0001). Separate analysis of each criterion revealed the following respective values for sensitivity, specificity, and positive and negative predictive values for prediction of restenosis; increased delta ST/delta HR index of follow-up: 91%, 77%, 70%, and 94%; positive exercise treadmill test: 83%, 65%, 59%, and 86%; and positive thallium scintigram: 79%, 78%, 69%, and 86%. The increased delta ST/delta HR index had a significantly (p < 0.05) higher sensitivity than the positive thallium scintigram and a significantly (p < 0.01) higher specificity than the positive exercise treadmill test. An increased delta ST/delta HR index at follow-up identifies subgroups of patients who are at high risk for restenosis after PTCA.

Fatty acid exercise scintigraphy after percutaneous transluminal coronary angioplasty

We performed a sequential fatty acid exercise-rest scintigraphy in 18 patients with an initially successful percutaneous transluminal coronary angioplasty (PTCA) to study the concordance of trends in symptoms, exercise tolerance and myocardial metabolism. Eleven patients stopped the exercise because of angina pectoris in the preoperative test; 2 days after PTCA this number decreased to two, but again increased to eight 3 months later. Exercise time (9.7 +/- 0.6 min, mean +/- SEM) and maximum exercise heart rate (128 +/- 4 beats min-1) were at least as good immediately after the operation as originally (8.8 +/- 0.6 min and 121 +/- 4 beats min-1, respectively). After 3 months both parameters were significantly (P < 0.05) better (10.3 +/- 0.6 min and 136 +/- 4 beats min-1, respectively) than originally. Some relative improvement in washout was noticed in 61% 2 days and in 56% of cases 3 months after PTCA. Fatty acid exercise uptake was more homogeneous in 72% of cases immediately after angioplasty and in 44% 3 months later. The trend in fatty acid uptake, exercise characteristics, and also in symptoms was most favourable among the eight patients with a dilatated left anterior descending coronary artery. Although the gamma camera technique possibly underestimated the effects of angioplasty, the impaired fatty acid metabolism could be linked with persistent symptoms after the operation. We conclude that most patients can safely participate in a symptom-limited (maximal) ergometry test already 2 days after PTCA, and that postoperatively myocardial perfusion and metabolism improve rapidly. However, this advantage is eventually lost to some degree, even if exercise tolerance continues to improve.

Current status of myocardial perfusion imaging after percutaneous transluminal coronary angioplasty

Controversy exists with regard to the diagnostic accuracy and optimal technique of myocardial perfusion imaging after coronary angioplasty. Exercise treadmill testing is inexpensive, with adequate predictive value for restenosis and clinical events in patients with single-vessel coronary angioplasty with a normal rest electrocardiogram (ECG). Myocardial tomography has advantages for assessing patients with multivessel coronary angioplasty. Exercise stress imaging is generally preferable to pharmacologic stress in patients without physical limitations after angioplasty. Delayed thallium-201 imaging and reinjection protocols may be useful to reconcile whether residual ischemia exists in "fixed" perfusion defects. Appropriately timed stress myocardial perfusion imaging 2 to 4 weeks after procedurally successful coronary angioplasty can document improved cardiac functional capacity and reduced ECG and imaging evidence of myocardial ischemia. Although routine serial postangioplasty evaluations cannot be recommended, stress myocardial imaging may be valuable in subjects with defective anginal nociception or extensive myocardium at risk in the area subtended by the angioplasty vessel.

Early decrease in minimal luminal diameter after successful percutaneous transluminal coronary angioplasty predicts late restenosis

Eighty-eight patients underwent serial coronary arteriography before, immediately after, 24 hours after and 7 +/- 2 months after successful percutaneous transluminal coronary angioplasty (PTCA) of 102 lesions. Severity of coronary obstruction was measured using quantitative digital angiography. Three groups of lesions were defined when comparing angiograms recorded immediately after and 24 hours after PTCA: group I--lesions with either no change or < or = 10% increase in arterial diameter stenosis after PTCA (n = 71); group II--lesions with > 10% increase in diameter stenosis after PTCA (n = 19); and group III--patients with total occlusion (n = 12). There were no significant differences in the severity of stenosis before or immediately after PTCA among the 3 groups of lesions. Twenty-four hours after PTCA the diameter stenosis was 14.2 +/- 6.3% in group I, 34.7 +/- 8.1% in group II and 100 in group III (p < 0.0001). At 7.1 +/- 2 months after PTCA the diameter stenosis was 21.2 +/- 16.8% in group I, 61.3 +/- 1.1% in group II, and 98.5 +/- 1.3% in group III (p < 0.0001). Restenosis (> or = 50% stenosis diameter) at follow-up per lesion was significantly greater in group II than in group I (73.6 vs 9.8%) (p < 0.0001). Thus, early angiographic study after successful PTCA stratifies lesions into angiographic subsets with low (group I) and high (group II) risk of coronary restenosis.

Exercise echocardiography for the evaluation of patients after nonsurgical coronary artery revascularization

OBJECTIVES

The purpose of this study was to demonstrate the accuracy of stress echocardiography for detecting the progression of coronary artery disease after nonsurgical revascularization.

BACKGROUND

The expanding role of nonsurgical coronary revascularization procedures mandates the development of sensitive noninvasive techniques for the detection of recurrent ischemia.

METHODS

Bicycle stress echocardiography was performed in a series of 86 patients 6.5 +/- 1.3 months after a revascularization procedure. Seven patients were excluded from analysis because of poor echocardiographic image quality.

RESULTS

Digital analysis achieved a sensitivity of 83% for the entire group and a specificity of 85% for stress echocardiographic detection of significant coronary artery disease. Sensitivity was greater in patients with (88%) than in those without (75%) prior myocardial infarction, but this difference did not reach statistical significance. Additional analysis using an increase in end-systolic volume index or a decrease in ejection fraction during stress as an additional marker for ischemia tended to enhance sensitivity (90% for the entire group and 93% for the subgroup with prior myocardial infarction).

CONCLUSIONS

Stress echocardiography is a useful and sensitive method for the follow-up of patients undergoing nonsurgical revascularization procedures. The addition of volume determination to routine wall motion analysis may be helpful in patients with prior infarction who have scar tissue that may be difficult to distinguish from an adjacent exercise-induced wall motion abnormality.

The role of scintigraphic techniques in the evaluation of functional results of coronary bypass grafting and percutaneous transluminal coronary angioplasty

Scintigraphic techniques can be used first, to guide appropriate referral for interventional procedures, and second to predict the effect of revascularization on regional perfusion and function prior to the intervention, thereby being able to assess efficacy of revascularization and to assess whether ischemia is the origin of recurrence of symptoms. Of increasing importance is the ability of nuclear techniques to identify those myocardial regions with abnormal function which might benefit from revascularization by showing improvement in regional wall motion. Positron emission tomography is considered to be the gold standard to assess regional myocardial perfusion and metabolism. The introduction of the reinjection technique makes 201Tl-scintigraphy the method of choice to detect jeopardized myocardium and to guide appropriate referral for revascularization procedures in those institutes where PET is not available. Even when the costly PET-instrumentation is available, cost-benefit analysis is indicated to assess the additional value of PET compared with 201Tl reinjection imaging.

Clinical assessment following coronary revascularization

There remains a need to establish adequate protocols for investigating the short- and long-term follow-up of revascularization procedures. For coronary angioplasty the most reliable basis for decision-making in managing patients is the symptomatology of the patient. For bypass surgery a protocol should be established to evaluate patients late, at 5 to 10 years following bypass surgery, in particular those with saphenous vein grafting, as graft and patient survival begins to fall after this period. Investigation after this may be too late for many patients who may already have several occluded grafts and poor left ventricular function, two of the most important prognostic factors post bypass surgery. The improvement and refinement of non-invasive investigations has led to a better understanding of the value and limitations of many of these tests, but it is particularly important that the limitations of many investigation are fully appreciated when they are used to influence clinical decisions. In this regard, a study comparing and integrating the predictive value of the persistence or return to symptoms, a positive non-invasive test, and a positive invasive test would surely prove invaluable.

Detection of restenosis with dobutamine stress test after coronary angioplasty

Dobutamine ECG tests were serially performed before, at 15 days, and at 2 and 6 months after successful coronary angioplasty in 58 patients. The dose of dobutamine was progressively increased from 5 micrograms/kg/min to a maximum of 40 micrograms/kg/min every 5 minutes, with ECG and blood pressure control. Coronary angiography was performed at the end of the study. At 15 days after coronary angioplasty, the dobutamine test was of little value for the diagnosis or prediction of restenosis. At the end of the study, both the presence of angina and the results of the dobutamine test were related to coronary angiography, and their accuracy was calculated for the detection of mild (> or = 50%) and severe (> or = 70%) restenosis or new coronary lesions. The accuracy of angina was 68% for the detection of mild lesions and 70% for that of severe lesions, whereas the accuracy of the dobutamine test was 78% for mild lesions and 80% for severe lesions. It is concluded that the dobutamine stress test is a simple and useful method for the detection of restenosis when it is performed at 2 and 6 months after coronary angioplasty. However, it cannot distinguish between restenosis or new coronary lesions.

Midterm outcome of patients with asymptomatic restenosis after coronary balloon angioplasty

Although many patients with restenosis after balloon coronary angioplasty have recurrence of angina, others remain asymptomatic. To assess the clinical implications of asymptomatic coronary restenosis, we analyzed clinical and angiographic characteristics of 277 consecutive patients with restenosis, 133 (48%) of whom were asymptomatic (group I) and 144 (52%) symptomatic (group II). Restenosis was documented 6 to 9 months after the index procedure, or earlier if angina recurred, and was defined as a greater than 50% lumen narrowing (visual estimation). Group I (asymptomatic group) included fewer female (9% vs. 18%, p less than 0.05) and hypertensive patients (38% vs. 56%, p less than 0.005) and more patients with a previous myocardial infarction (48% vs. 28%, p less than 0.05) and single-vessel disease (67% vs. 55%, p less than 0.05). Before angioplasty, symptoms had lasted for a shorter period (10 +/- 25 vs. 23 +/- 42 months, p less than 0.001), ischemia after a recent infarction was a more frequent indication (21% vs. 10%, p less than 0.05) and total revascularization more frequently obtained (74% vs. 63%, p less than 0.05) in group I than in group II patients. Only a normal blood pressure, previous myocardial infarction, single-vessel disease and a shorter duration of symptoms were independent correlates of asymptomatic restenosis. No differences were found in stenosis severity before angioplasty (90% in both groups) or after angioplasty (22% +/- 12% vs. 24% +/- 16%).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary restenosis: what have we learned from angiography?

Coronary restenosis remains a major problem for interventional cardiology not only by virtue of its frequency, but also because of the current inability to prevent it. Symptomatic status and non-invasive evaluation have been used to study restenosis, but both lack specificity and sensitivity, particularly in patients with multivessel disease. Angiography remains the reference standard. Several arbitrary definitions have been used, some related to visual estimates of coronary stenosis and others to quantitative angiographic techniques. In another approach, linear modeling is used to assess minimal luminal diameter of lesions on restudy. Although angiographic studies have been essential in the study of restenosis, questions concerning the underlying mechanism and pathophysiology remain. The development of animal models that closely resemble human restenosis should allow evaluation of pathophysiologic mechanisms and development of new strategies to prevent the problem.

Restenosis after coronary angioplasty: an overview

Despite substantial basic and clinical efforts to address the problem of restenosis after percutaneous coronary intervention, effective preventive therapies have not yet been developed. Nevertheless, the accumulated information has provided much insight into the process of restenosis in addition to allowing standards to be developed for adequate clinical trials. The pathophysiology of restenosis increasingly appears to be distinct from that of primary atherosclerosis. Restenosis involves elastic recoil, incorporation of thrombus into the lesion and fibrocellular proliferation in varying degrees in different patients. Lack of an animal model that satisfactorily mimics restenosis is a major impediment to further understanding of the process. Clinical studies are hampered by difficulties in finding a single unifying definition of restenosis and by variable methods of reporting follow-up. Reporting of clinical outcomes of all patients in angiographic substudies would allow a more satisfactory interpretation of the results of clinical trials. Current noninvasive test results are not accurate enough to substitute for angiographic and clinical outcome data in intervention trials. In the majority of observational studies, only diabetes and unstable angina have emerged as consistently associated with restenosis; whereas most of the standard risk factors for atherosclerosis have a less consistent relation. Disappointingly, the new atherectomy and laser technologies have not affected restenosis rates. The one possible exception is coronary stenting, as a result of the larger luminal diameter achieved by the placement of the stent. In conclusion, although substantial continued effort is necessary to explore the basic aspects of cellular proliferation and mechanical alteration of atherosclerotic vessels, attention to the principles of clinical trials and observation are required to detect the impact of risk factors and interventions on the multifactorial problem of restenosis. Adequate sample sizes, collection of clinical and angiographic outcomes and factorial study designs hold promise for unraveling this important limitation of percutaneous intervention.

Clinical efficacy of PTCA and identification of restenosis: evaluation by serial body surface potential mapping

We used serial body surface potential mapping (BSPM) with the departure map technique to evaluate the clinical efficacy of percutaneous transluminal coronary angioplasty (PTCA) in various pathophysiologic stages of coronary artery disease, and to detect restenosis. The BSPM was performed prior to, 1 week after, and 1 month after PTCA. A follow-up coronary angiography was performed 3 to 6 months after PTCA, and BSPM was also performed at the same time. The results of BSPM were compared with those of thallium-201 single-photon emission computed tomography (Tl-201 SPECT) and radionuclide ventriculography. After PTCA, BSPM showed a significant reduction in the departure area, the Tl-201 SPECT also showed a significant reduction in the extent and severity scores, and the left ventricular ejection fraction improved significantly. In the cases with restenosis, the departure area, which had decreased in size after PTCA, showed an increase in size. After successful re-PTCA, the size of the departure area again became smaller. We concluded that BSPM, which is a simple, noninvasive, and inexpensive method, is useful in the evaluation of the clinical efficacy of PTCA and in the detection of restenosis after successful PTCA.

Radionuclide methods to evaluate percutaneous transluminal coronary angioplasty

Radionuclide angiocardiography and myocardial perfusion imaging with exercise are valuable methods to assess patients undergoing percutaneous transluminal coronary angioplasty. Successful angioplasty results in improvement in ventricular systolic and diastolic function and regional perfusion. Complications of angioplasty, such as periprocedural infarction and side branch occlusion, can be documented noninvasively. Radionuclide methods have also been demonstrated to be of prognostic value in predicting coronary artery restenosis and recurrent cardiac symptoms. However, to avoid underestimating the success of coronary revascularization, studies must be scheduled long enough following angioplasty to allow transient abnormalities associated with artery dilation to resolve.

Role of radionuclide ventriculography in evaluating cardiac function

The role of nuclear cardiology techniques for evaluating cardiac function has become increasingly important among other diagnostic techniques. The current status of radionuclide imaging of left and right ventricular function allows accurate diagnosis of cardiac patients with both coronary and noncoronary disease. The combination of gated first-pass and equilibrium radionuclide ventriculography makes it possible to assess more completely cardiac function than by either technique alone. Of particular interest to most imaging physicians is the current position of exercise ventriculography in the diagnostic setting, especially since this test has undergone new scrutiny in its application to broader patient segments. This technique and issues related to its place in the diagnostic environment are discussed in this review article, with emphasis on relevance to the clinical laboratory.

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.

Detection of restenosis after successful coronary angioplasty: improved clinical decision making with use of a logistic model combining procedural and follow-up variables

A prospective study of 111 patients who underwent repeat coronary angiography and exercise thallium-201 scintigraphy 6 +/- 2 months after complete revascularization by percutaneous transluminal coronary angioplasty was performed to assess whether clinical, procedure-related and postangioplasty exercise variables yield independent information for the prediction of angiographic restenosis after angioplasty. Complete revascularization was defined as successful angioplasty of one or more vessels that resulted in no residual coronary lesion with greater than 50% diameter stenosis. Restenosis was defined as a residual stenosis at the time of repeat angiography of greater than 50% of luminal diameter. Restenosis occurred in 40% of the patients. The 111 patients were randomly subdivided into a learning group (n = 84) and a testing group (n = 27). A logistic discriminant analysis was performed in the learning group and the logistic model was used to estimate a logistic probability of restenosis. This probability of restenosis was validated in the testing group. In the learning group of 84 patients univariate analysis of 39 factors revealed 8 factors related to restenosis: recurrence of angina (p less than 0.0001), postangioplasty abnormal finding on exercise thallium-201 scintigram (p less than 0.0001), exercise thallium-201 scintigram score (p less than 0.0001), difference between exercise and rest ST segment depression (p less than 0.001), postangioplasty exercise ST segment depression (p less than 0.001), absolute postangioplasty stenosis diameter (p less than 0.003), postangioplasty exercise work load (p less than 0.03) and postangioplasty exercise heart rate (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of "silent" restenosis and long-term follow-up after successful angioplasty in single vessel coronary artery disease: the value of quantitative exercise electrocardiography and quantitative coronary angiography

Exercise electrocardiographic (ECG) testing during follow-up after coronary angioplasty is widely applied to evaluate the efficacy of angioplasty, even in asymptomatic patients. One hundred forty-one asymptomatic patients without previous myocardial infarction underwent quantitative exercise ECG testing and quantitative coronary angiography 1 to 6 months after successful angioplasty in single vessel coronary artery disease to 1) determine the value of exercise ECG testing to detect "silent" restenosis, and 2) assess the long-term prognostic value of exercise ECG testing and coronary angiography. The prevalence of restenosis (defined as greater than or equal to 50% luminal narrowing at the dilation site) was 12% in this selected study group. Of 26 patients with an abnormal exercise ECG (ST segment depression greater than or equal to 0.1 mV), only 4 (15%) showed recurrence of stenosis. Sensitivity and specificity for detection of restenosis were 24% and 82%, respectively. One hundred thirty-four patients (95%) were followed up 1 to 64 months (mean 35) after exercise ECG testing and coronary angiography. Thirty-two patients (24%) experienced a cardiac event: in 25 patients (78%) the initial event was recurrent angina pectoris (New York Heart Association class III or IV) and in 7 patients (22%) it was myocardial infarction, although cardiac death did not occur. The mean interval between exercise ECG testing and the initial cardiac events was 14 months (range 1 to 55), whereas 47% of the initial events took place less than or equal to 6 months after exercise ECG testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Sustained improvement in left ventricular function after successful coronary angioplasty

The short and long term effects of successful percutaneous transluminal coronary angioplasty on left ventricular function, at rest and on exercise were investigated in 49 patients. Thirty-four had had no previous infarction (group 1) and 15 had (group 2). Technetium-99m gated blood pool images were obtained at rest and during exercise before, six weeks after, and a mean of fifteen months after successful angioplasty. Before angioplasty the mean (SD) ejection fraction fell significantly on exercise in both groups from 58 (10)% to 53 (13)% in group 1 and from 48 (10)% to 40 (16)% in group 2. This change was paralleled by a worsening wall motion score (from 0.6 (0.4) to 1.6 (1.2) in group 1 and from 2.3 (1.9) to 3.3 (2.4) in group 2). Six weeks after the procedure there was little change in resting ejection fraction but it increased significantly on exercise (to 62 (11)% in group 1 and to 53 (13)% in group 2). There was a concomitant significant improvement in the exercise wall motion score (to 0.4 (0.6) in group 1 and to 1.8 (1.1) in group 2). This improvement in exercise ejection fraction and wall motion was maintained at later follow up with no significant deterioration in either variable and a clearly sustained improvement in ejection fraction (60 (10)% in group 1 and 51 (10)% in group 2) and wall motion score (0.2 (0.2) in group 1 and 1.3 (0.8) in group 2) compared with values before angioplasty. The initial improvement in left ventricular function on exercise after successful angioplasty was maintained for at least 9-24 months both in patients with previous myocardial infarction and in those without.

Restenosis following coronary angioplasty

The last decade has witnessed an enormous increase in the use and success of percutaneous transluminal coronary angioplasty. During this time, our knowledge of the mechanisms of angioplasty and of how it relates to the pathophysiology of restenosis has also grown. Despite our better understanding of the mechanisms responsible for it, restenosis remains a significant problem in coronary angioplasty, affecting approximately one third of patients. A variety of factors can affect the measured rate of restenosis, such as the symptomatic status of the patient and the timing of restenosis studies. Certain clinical, anatomic, and procedural factors are associated with increased rates of restenosis. Pharmacologic interventions are ineffective in preventing restenosis. A variety of new mechanical devices are being developed, but their efficacy at this time does not appear to be superior to angioplasty alone. While attempts at preventing restenosis have thus far been unsuccessful, the information gained through the various studies has added tremendously to our knowledge base of angioplasty. Through this better understanding of the mechanisms of angioplasty and restenosis, it is likely that the problem of restenosis will be improved, either through existing technology or by methods yet to be discovered.

Very early prediction of restenosis after successful coronary angioplasty: anatomic and functional assessment

To investigate the time course of restenosis, serial treadmill exercise testing was performed in the absence of medical therapy by 31 patients with single vessel coronary disease who underwent successful angioplasty. Exercise tests were performed before angioplasty and at 3 days and 1, 3 and 6 months after angioplasty; if the test was positive, it was repeated after administration of 10 mg of intravenous verapamil. At arteriography 6 months after coronary angioplasty, 17 patients (group 1) showed no restenosis but 14 patients (group 2) did. Before angioplasty all 31 patients had a positive exercise test with ST segment depression greater than or equal to 1 mm. At 3 days after angioplasty, three patients in group 1 had a positive exercise test compared with 11 patients in group 2 (p = 0.08). At 1, 3 and 6 months, 1 patient in group 1 had a positive exercise test compared with 14 patients in group 2 (p less than 0.01). The heart rate-blood pressure product (beats/min.mm Hg) calculated at 1 mm ST segment depression, or at peak exercise if the test was negative, was used as an index of the ischemic threshold. In group 1 (no restenosis) the ischemic threshold increased progressively from 14,840 +/- 1,075 (mean value +/- SEM) before angioplasty to 21,210 +/- 1,049 at 3 days and to 25,140 +/- 1,177 (p less than 0.001) at 6 months. In group 2 (restenosis) the ischemic threshold increased from 16,270 +/- 828 before angioplasty to 20,400 +/- 984 (p less than 0.0004) at 3 days but decreased to 16,090 +/- 1,298 (p less than 0.006) at 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of restenosis after elective percutaneous transluminal coronary angioplasty using the exercise treadmill test

To determine the value of a 6-month exercise treadmill test for detecting restenosis after elective percutaneous transluminal coronary angioplasty (PTCA), 303 consecutive patients with successful PTCA and without a recent myocardial infarction were studied. Among the 228 patients without interval cardiac events, early repeat revascularization or contraindications to treadmill testing, 209 (92%) underwent follow-up angiography, and 200 also had a follow-up treadmill test and formed the study population. Restenosis (greater than or equal to 75% luminal diameter stenosis) occurred in 50 patients (25%). Five variables were individually associated with a higher risk of restenosis: recurrent angina (p = 0.0002), exercise-induced angina (p = 0.0001), a positive treadmill test (p = 0.008), more exercise ST deviation (p = 0.04) and a lower maximum exercise heart rate (p = 0.05). However, only exercise-induced angina (p = 0.002), recurrent angina (p = 0.01) and a positive treadmill test (p = 0.04) were independent predictors of restenosis. Using these 3 variables, patient subsets could be identified with restenosis rates ranging from 11 to 83%. The exercise treadmill test added independent information to symptom status about the risk of restenosis after elective PTCA. Nevertheless, 20% of patients with restenosis had neither recurrent angina nor exercise-induced ischemia at follow-up. For more accurate detection of restenosis, the exercise treadmill test must be supplemented by a more definitive test.

Role of single photon wall motion and perfusion studies in the evaluation of patients with suspected coronary artery disease

Cardiovascular nuclear medicine procedures are useful to characterize coronary artery disease by measuring changes in perfusion, myocardial metabolism, cellular integrity, and regional or global function. Coronary angiography, while an excellent indicator of anatomic changes in arterial lumenal diameter, is a poor predictor of downstream perfusion, since neither the length of the stenosis nor absolute lumenal diameter is considered. Even if the anatomy is known, perfusion measurements provide information about ischaemia and ventricular dysfunction that is helpful for planning therapy. New technetium 99m-labelled perfusion agents are likely to improve the certainty of diagnosis due to their higher photon flux. The development of techniques for continuous ventricular function monitoring during daily activities provides an opportunity for detecting the impact of silent ischaemia on cardiac function. The role of the radionuclide imaging procedures in classifying patients with coronary disease is discussed in light of the pathophysiology of ischaemia and necrosis.

A randomized trial of corticosteroids for the prevention of restenosis in 102 patients undergoing repeat coronary angioplasty

To examine the effect of corticosteroid therapy on the development of restenosis following successful percutaneous transluminal coronary angioplasty (PTCA), we randomized 102 patients with restenosis following prior PTCA to receive high-dose steroids (n = 52) or no steroids (n = 50). The steroid regimen consisted of 125 mg methylprednisolone I.M. the night before and morning of the PTCA, and prednisone 60 mg p.o. Q.D. for 1 week. post-PTCA. Angiographic follow-up at 6 months was available in 27 steroid-treated patients (52%) and 27 controls (54%). The per lesion incidence of restenosis was similar in the two groups (36% vs. 40%, respectively, P = NS). Clinical follow-up was available in the remaining patients at a mean interval of 1.2 years. The clinical correlates of restenosis (incidence and severity of angina, positive treadmill exercise test, nonfatal infarction or death) were similar in the steroid treated and control groups (24% vs. 39%, respectively, P = .56). At late follow-up, 30 steroid-treated patients (58%) and 26 control patients (52%) had no clinical or angiographic evidence of restenosis (P = NS). In conclusion, a short course of high-dose corticosteroid therapy does not significantly reduce the frequency of restenosis following PTCA.

Quantitative exercise thallium-201 scintigraphy for predicting angina recurrence after percutaneous transluminal coronary angioplasty

The aim of this prospective study was to determine the value of quantitative exercise thallium-201 scintigraphy for predicting short-term outcome in patients after percutaneous transluminal coronary angioplasty (PTCA). Quantitative exercise thallium-201 scintigraphy was performed 2.2 +/- 1.2 weeks after successful PTCA in 68 asymptomatic patients, 64 (94%) of whom had class III or IV angina before the procedure. Clinical follow-up was obtained in all patients at a mean of 10 +/- 2 months and all were followed for at least 6 months; 45 patients (66%) remained asymptomatic during follow-up and 23 (34%) developed recurrent class III or IV angina at a mean of 2.6 +/- 1.2 months. Multivariate analysis of 22 clinical, angiographic and exercise test variables revealed that thallium-201 redistribution, any thallium scan abnormality, presence of a distal stenosis and treadmill time were the only significant predictors of recurrent angina after PTCA. Using a stepwise discriminant function model, thallium-201 redistribution was the only significant independent predictor. Despite its prognostic value relative to other variables as a predictor, thallium redistribution at 2 weeks after PTCA was only detected in 9 of the 23 patients (39%) who subsequently developed recurrent angina, although only 2 of the 45 patients (9%) who remained asymptomatic during follow-up demonstrated thallium-201 redistribution at the time of early testing. After repeat angiography was performed in 17 of the 23 patients with recurrent angina, 14 (82%) demonstrated restenosis and 3 (18%) had worse narrowing distal to or remote from the site of dilatation.(ABSTRACT TRUNCATED AT 250 WORDS)

Stress thallium-201 imaging after coronary angioplasty predicts restenosis and recurrent symptoms

The predictive accuracy of thallium imaging for the diagnosis of restenosis after angioplasty was evaluated in 121 patients who had undergone a successful procedure. Patients were evaluated three times over a 1 year follow-up period for symptoms, electrocardiographic (ECG) changes during exercise and the presence of reversible ischemia on exercise thallium imaging. At initial evaluation (4 to 6 weeks after angioplasty), 104 patients (86%) were asymptomatic. Of the 17 patients with chest pain symptoms, 9 had reversible ischemia on thallium imaging and all had restenosis. Of the 104 asymptomatic patients, 26 (25%) had a positive thallium scan (reversible ischemia) and this sign identified a high risk group. Evidence of restenosis was present by 6 months in 22 (85%) and by 1 year in 25 (96%) of these 26 patients. The largest group of patients manifested symptoms by the second evaluation (between 3 and 6 months after angioplasty). Of 28 patients with symptoms and a positive thallium scan at this evaluation, 26 had restenosis; on initial evaluation, 22 of these 26 patients had no symptoms but had had a positive thallium study. Ten of the 65 patients in the asymptomatic group had a positive thallium scan, but the scans of this group were not as predictive for recurrent symptoms as were those of the same group at initial evaluation. The 74 patients who had a negative thallium scan at 3 to 6 months with or without associated symptoms had a low likelihood of developing restenosis or symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Restenosis after successful percutaneous transluminal coronary angioplasty: serial angiographic follow-up of 229 patients

To further understand the temporal mode and mechanisms of coronary restenosis, 229 patients were studied by prospective angiographic follow-up on day 1 and at 1, 3 and 6 months and 1 year after successful percutaneous transluminal coronary angioplasty. Quantitative measurement of coronary stenosis was achieved by cinevideodensitometric analysis. Actuarial restenosis rate was 12.7% at 1 month, 43.0% at 3 months, 49.4% at 6 months and 52.5% at 1 year. In 219 patients followed up for greater than or equal to 3 months, mean stenosis diameter was 1.91 +/- 0.53 mm immediately after coronary angioplasty, 1.72 +/- 0.52 mm on day 1, 1.86 +/- 0.58 mm at 1 month and 1.43 +/- 0.67 mm at 3 months. In 149 patients followed up for greater than or equal to 6 months, mean stenosis diameter was 1.66 +/- 0.58 mm at 3 months and 1.66 +/- 0.62 mm at 6 months. In 73 patients followed up for 1 year, mean stenosis diameter was 1.65 +/- 0.56 mm at 6 months and 1.66 +/- 0.57 mm at 1 year. Thus, stenosis diameter decreased markedly between 1 month and 3 months after coronary angioplasty and reached a plateau thereafter. In conclusion, restenosis is most prevalent between 1 and 3 months and rarely occurs beyond 3 months after coronary angioplasty.

Clinical significance of perfusion defects by thallium-201 single photon emission tomography following oral dipyridamole early after coronary angioplasty

The clinical significance of myocardial perfusion defects present early after angiographically successful percutaneous transluminal coronary angioplasty was assessed in 53 patients using thallium-201 single photon emission computed tomography combined with pharmacologic vasodilation induced by a large dose (300 mg) of orally administered dipyridamole. Myocardial tomographic images were obtained at a mean of 20 +/- 6 h (SD) before and 2.9 +/- 2.7 days after angioplasty. Before angioplasty, 15 (28%) of the 53 patients developed angina after dipyridamole administration, in contrast to only 3 (7.5%) of 40 patients after angioplasty (p less than 0.001). The mean percent luminal area stenosis decreased from 93 +/- 6% before angioplasty to 34 +/- 17% after angioplasty (p less than 0.001). Myocardial perfusion defects, present in 49 (93%) of the 53 patients before angioplasty, were reversible in 44 patients (83%), all of whom underwent dilation of arteries supplying the ischemic areas. After angioplasty, 26 (65%) of 40 patients had no ischemic defects, whereas 14 (35%) of the patients still had an ischemic defect in the vascular territory of the dilated artery. After a mean follow-up period of 21.7 months, 13 (33%) of 39 patients developed restenosis, 10 of whom had an ischemic defect early after angioplasty. Restenosis developed in 10 (71%) of 14 patients with an ischemic defect after angioplasty, but in only 3 (11.5%) of the patients without an ischemic defect (p = 0.007). In conclusion, thallium-201 tomography after oral dipyridamole affords convenient assessment of the physiologic significance of coronary stenosis present before angioplasty and the residual stenosis after angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous transluminal coronary angioplasty

The relief of coronary obstruction by surgical grafting was the first effective treatment to be directed at the cause of ischemic heart disease. PTCA represents the second major step in relieving coronary stenosis. It seems timely to review where this second step has led in order to understand how percutaneous transluminal coronary angioplasty (PTCA) relates to surgery and to understand future implications of this procedure. This review will reflect many of the authors biases and prejudices derived from their experience at Mayo Clinic. It will also be a somewhat practical assessment. Such a pragmatic approach can be defended because PTCA itself is built on pragmatism. It is more of the world of craftsmen than of the world of scientists. We are still waiting for science to "catch up" to help solve important remaining problems such as the issue of acute rethrombosis and restenosis. Our ability to review the Mayo Clinic experience is made possible only by having a dedicated team of colleagues in the catheterization laboratory and a dedicated support group managing our PTCA Registry. Experience with other large registries (the NHLBI CASS Registry and the PTCA Registry) has taught us that this is a valuable method of collecting and reviewing the experience with a new procedure as it develops. This approach is likely to be more widely applied in the future.

Incidence of restenosis after successful coronary angioplasty: a time-related phenomenon. A quantitative angiographic study in 342 consecutive patients at 1, 2, 3, and 4 months

Data from experimental, clinical, and pathologic studies have suggested that the process of restenosis begins very early after coronary angioplasty. The present study was performed to determine prospectively the incidence of restenosis with use of the four National Heart, Lung, and Blood Institute and the 50% or greater diameter stenosis criteria, as well as a criterion based on a decrease of 0.72 mm or more in minimal luminal diameter. Patients were recatheterized at 30, 60, 90, or 120 days after successful percutaneous transluminal coronary angioplasty (PTCA). After PTCA all patients received 10 mg nifedipine three to six times a day and aspirin once a day until repeat angiography. Of 400 consecutive patients in whom PTCA was successful (less than 50% diameter stenosis), 342 underwent quantitative angiographic follow-up (86%) by use of an automated edge-detection technique. A wide variation in the incidence of restenosis was found dependent on the criterion applied. The incidence of restenosis proved to be progressive to at least the third month for all except NHLBI criterion II. At 4 months a further increase in the incidence of restenosis was observed when defined as a decrease of 0.72 mm or more in minimal luminal diameter, whereas the criteria based on percentage diameter stenosis showed a variable response. The lack of overlap between the different restenosis criteria applied affirms the arbitrary nature of angiographic definitions currently in use. Restenosis should be assessed by repeat angiography, and preferably ascertained according to the change in absolute quantitative measurements of the luminal diameter.

Usefulness of early radionuclide angiography for identifying low-risk patients for late restenosis after percutaneous transluminal coronary angioplasty

This study evaluated the ability of exercise radionuclide angiography performed early after percutaneous transluminal coronary angioplasty (PTCA) to predict subsequent restenosis. Forty-eight patients with initially successful PTCA underwent early (less than or equal to 1 month) exercise radionuclide angiography and late (greater than 1 month, mean 8) coronary angiography. Findings on exercise radionuclide angiography were normal in 17 patients (35% of the entire group); none of these 17 patients had restenosis. Of the 31 patients with abnormal radionuclide angiographic findings, 13 had restenosis. When the exercise radionuclide angiogram was used to stratify patients according to risk of restenosis, the negative predictive value of a normal test was 100% (95% confidence limits = 81 to 100%) and the positive predictive value was 42%. By this method, 35% of the entire study population could be classified as low risk for restenosis after PTCA. Early exercise radionuclide angiography identifies subgroups of patients who are at low and high risk for early restenosis after PTCA.

Quantitative radionuclide angiocardiography

Quantitation of cardiac pump function using radionuclide angiocardiography provides objective information for the management of patients with heart disease. Left and right ventricular ejection fraction, stroke volume ratio, ejection rate, diastolic function, ventricular volume, parametric imaging, amplitude and phase analysis, and shunt quantification can be measured from the radionuclide angiocardiogram at rest, during exercise, and during pharmacologic interventions. This review describes these methods and discusses their reliability and their role in the clinical assessment of patients with cardiac disease.

Medical approaches to prevention of restenosis after coronary angioplasty

Although initial success rates for coronary angioplasty have improved, the rate of restenosis within 6 months of the procedure has persisted at 30 to 40%. The relation of restenosis to initial success, recurrence of symptoms and risk factors suggests that high grade or total lesions, long lesions, lesions in the proximal left anterior descending artery or in saphenous grafts, and the absence of intimal dissection after angioplasty are associated with an increased risk of restenosis. Unstable angina, male sex and diabetes are clinical factors associated with a greater risk of restenosis. Pathologic specimens suggest that plaque splitting and disruption are found acutely after angioplasty, but that restenosis occurs as an excessive reparative, proliferative response of smooth muscle cells leading to recurrent luminal narrowing. A prospective analysis of therapeutic interventions to prevent restenosis, such as administering antiplatelet and lipid-lowering agents, intensive diabetic therapy and administration of calcium antagonists, is proposed. Problems with timing of studies, design and sample size are considered. Current recommendations for anti-restenosis therapy include antiplatelet therapy before and after angioplasty, administration of heparin in some patients and intensive risk factor intervention for the 6 months after the procedure.

The efficacy of cardiovascular nuclear medicine exercise studies

Radionuclide stress tests were initially introduced into medicine as new diagnostic tests for coronary artery disease (CAD). These tests are very effective for this purpose when applied to populations with an intermediate pre-test probability of coronary artery disease. Radionuclide stress tests, however, also are used now in guiding many management decisions in patients with established CAD, based on the ability of these tests to assess the extent and severity of myocardial ischemia, the functional significance of coronary stenoses, and myocardial viability. Specific uses beyond diagnosis include decisions regarding whom to catheterize, send to coronary bypass surgery, or angioplasty; risk stratification following myocardial infarction or before noncardiac surgery; and evaluation of the results of therapy. This article reviews both the diagnostic efficacy of radionuclide stress tests and their efficacy in guiding management decisions in patients with known coronary artery disease.

Role of nuclear cardiology in evaluating the total ischemic burden in coronary artery disease

Goals of exercise radionuclide imaging are to: enhance sensitivity, specificity and predictive value of coronary artery disease (CAD) detection; noninvasively assess extent and severity of functionally significant CAD; determine prognosis so that specific therapeutic strategies can be more rationally implemented; detect silent ischemia in asymptomatic subjects or in patients with known CAD with a higher degree of specificity than can be accomplished by electrocardiogram stress testing alone; evaluate the response to therapeutic interventions aimed at enhancing coronary blood flow. Two major radionuclide techniques are currently used in evaluating the total ischemic burden in patients with CAD. These are myocardial perfusion imaging with either thallium-201 or rubidium-82, and radionuclide angiography performed after administration of technetium-99m. Areas of diminished thallium-201 activity on early postexercise images are abnormal and represent either areas of stress-induced ischemia or myocardial scar. To differentiate between the two, delayed images are obtained to determine if the initial postexercise defect either persists or demonstrates redistribution (i.e., delayed defect disappearance or improvement). Defects demonstrating redistribution represent transient ischemia, whereas areas of previous infarction or scar usually appear as persistent defects. Patients with left main or 3-vessel CAD usually show multiple thallium-201 redistribution defects in more than 1 vascular supply region, a phenomenon often associated with abnormal lung thallium-201 uptake. In terms of radionuclide angiography, the normal ventricular response to exercise has been defined as an absolute increment of at least 5% in the left ventricular ejection fraction without the development of regional wall motion abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

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)