Randomized trial of contrast media utilization in high-risk PTCA: the COURT trial.

BACKGROUND: Previous in vitro and in vivo studies have suggested an association between thrombus-related events and type of contrast media. Low osmolar contrast agents appear to improve the safety of diagnostic and coronary artery interventional procedures. However, no data are available on PTCA outcomes with an isosmolar contrast agent. METHODS AND RESULTS: A multicenter prospective randomized double-blind trial was performed in 856 high-risk patients undergoing coronary artery intervention. The objective was to compare the isosmolar nonionic dimer iodixanol (n=405) with the low osmolar ionic agent ioxaglate (n=410). A composite variable of in-hospital major adverse clinical events (MACE) was the primary end point. A secondary objective was to evaluate major angiographic and procedural events during and after PTCA. The composite in-hospital primary end point was less frequent in those receiving iodixanol compared with those receiving ioxaglate (5.4% versus 9.5%, respectively; P=0.027). Core laboratory defined angiographic success was more frequent in patients receiving iodixanol (92.2% versus 85. 9% for ioxaglate, P=0.004). There was a trend toward lower total clinical events at 30 days in patients randomized to iodixanol (9.1% versus 13.2% for ioxaglate, P=0.07). Multivariate predictors of in-hospital MACE were use of ioxaglate (P=0.01) and treatment of a de novo lesion (P=0.03). CONCLUSIONS: In this contemporary prospective multicenter trial of PTCA in the setting of acute coronary syndromes, there was a low incidence of in-hospital clinical events for both treatment groups. The cohort receiving the nonionic dimer iodixanol experienced a 45% reduction in in-hospital MACE when compared with the cohort receiving ioxaglate.

Paclitaxel stent coating inhibits neointimal hyperplasia at 4 weeks in a porcine model of coronary restenosis.

BACKGROUND: Despite limiting elastic recoil and late vascular remodeling after angioplasty, coronary stents remain vulnerable to restenosis, caused primarily by neointimal hyperplasia. Paclitaxel, a microtubule-stabilizing drug, has been shown to inhibit vascular smooth muscle cell migration and proliferation contributing to neointimal hyperplasia. We tested whether paclitaxel-coated coronary stents are effective at preventing neointimal proliferation in a porcine model of restenosis. METHODS AND RESULTS: Palmaz-Schatz stents were dip-coated with paclitaxel (0, 0.2, 15, or 187 microgram/stent) by immersion in ethanolic paclitaxel and evaporation of the solvent. Stents were deployed with mild oversizing in the left anterior descending coronary artery (LAD) of 41 minipigs. The treatment effect was assessed 4 weeks after stent implantation. The angiographic late loss index (mean luminal diameter) decreased with increasing paclitaxel dose (P<0.0028 by ANOVA), declining by 84.3% (from 0.352 to 0.055, P<0.05) at the highest level tested (187 microgram/stent versus control). Accompanying this change, the neointimal area decreased (by 39.5%, high-dose versus control; P<0.05) with increasing dose (P<0.040 by ANOVA), whereas the luminal area increased (by 90.4%, high-dose versus control; P<0.05) with escalating dose (P<0.0004 by ANOVA). Inflammatory cells were seen infrequently, and there were no cases of aneurysm or thrombosis. CONCLUSIONS: Paclitaxel-coated coronary stents produced a significant dose-dependent inhibition of neointimal hyperplasia and luminal encroachment in the pig LAD 28 days after implantation; later effects require further study. These results demonstrate the potential therapeutic benefit of paclitaxel-coated coronary stents in the prevention and treatment of human coronary restenosis.

Improved diagnostic performance of exercise thallium-201 single photon emission computed tomography over planar imaging in the diagnosis of coronary artery disease: a receiver operating characteristic analysis.

Qualitative interpretation of tomographic and planar scintigrams, a five point rating scale and receiver operating characteristic analysis were utilized to compare single photon emission computed tomography and conventional planar imaging of myocardial thallium-201 uptake in the accuracy of the diagnosis of coronary artery disease and individual vessel involvement. One hundred twelve patients undergoing cardiac catheterization and 23 normal volunteers performed symptom-limited treadmill exercise, followed by stress and redistribution imaging by both tomographic and planar techniques, with the order determined randomly. Paired receiver operating characteristic curves revealed that single photon emission computed tomography was more accurate than planar imaging over the entire range of decision thresholds for the overall detection and exclusion of coronary artery disease and involvement of the left anterior descending and left circumflex coronary arteries. Tomography offered relatively greater advantages in male patients and in patients with milder forms of coronary artery disease, who had no prior myocardial infarction, only single vessel involvement or no lesion greater than or equal to 50 to 69%. Tomography did not appear to provide improved diagnosis in women or in detection of disease in the right coronary artery. Although overall detection of coronary artery disease was not improved in patients with prior myocardial infarction, tomography provided improved identification of normal and abnormal vascular regions, particularly of the left anterior descending and circumflex artery regions. These results indicate that single photon emission computed tomography provides improved diagnostic performance compared with planar imaging in many clinical subgroups, and suggest that it represents the diagnostic imaging procedure of choice in exercise thallium-201 perfusion studies.

Is atrial activation beneficial in heart transplant recipients?

Because of the distortion of atrial morphology that occurs during cardiac allograft transplantation in humans, the beneficial effects of properly sequenced atrial and ventricular activation are unclear in these patients. To evaluate the atrial contribution to ventricular pump performance in heart transplant recipients, arterial pressure and cardiac output during pacing from either chamber were measured in nine patients 10 +/- 1 days after transplantation. Systolic, diastolic and mean systemic arterial pressures were significantly higher during atrial pacing compared with ventricular pacing: 143 +/- 23 versus 125 +/- 20 mm Hg, 73 +/- 15 versus 66 +/- 14 mm Hg and 94 +/- 17 versus 84 +/- 16 mm Hg, respectively (p less than 0.05 for all). In addition, cardiac output decreased from 5.5 +/- 1.4 to 4.6 +/- 1.5 liters/min (p less than 0.005) for atrial versus ventricular pacing. Thus, there is a significant atrial contribution to cardiac performance in patients after heart transplantation. This may have clinical implications in those patients who later require a permanent pacemaker.

Percutaneous balloon valvuloplasty of the pulmonary valve: role of right to left shunting through a patent foramen ovale.

Percutaneous balloon valvuloplasty was performed on a patient with pulmonary stenosis. Right to left shunting through a patent foramen ovale during balloon inflation was documented by contrast two-dimensional echocardiography. Right and left ventricular pressures recorded during balloon inflation showed a decrease in left ventricular end-diastolic pressure and equilibration with right ventricular end-diastolic pressure. Systemic hypotension was minimal during balloon inflation, possibly due to persistent filling of the left ventricle via the patent foramen ovale. Persistent right ventricular systolic hypertension immediately after valvuloplasty may have been due to infundibular narrowing and resolved on restudy 2 weeks later.

Net costs from three perspectives of using low versus high osmolality contrast medium in diagnostic angiocardiography.

OBJECTIVES: We conducted an economic analysis to assess the extent to which a reduction in adverse drug reactions induced by low osmolality compared with high osmolality contrast media during diagnostic angiocardiography would result in savings to hospitals, society and third-party payers that would offset the substantially higher price of low osmolality contrast medium. BACKGROUND: Substitution of low osmolality for high osmolality contrast media in the approximately 1 million diagnostic angiocardiographic procedures performed each year in the United States could substantially increase health care costs. Cost-effectiveness estimates should include savings that might occur through reduced costs of managing adverse drug reactions. METHODS: In a randomized clinical trial of 505 persons under-going diagnostic angiography with either high osmolality or low osmolality contrast medium, we measured and compared 1) material costs of contrast media, and 2) costs from three perspectives of incremental resources used to manage contrast-related adverse drug reactions. We also performed sensitivity analyses to examine the effect of different assumptions with regard to relative risk, absolute risk and costs of adverse drug reactions on estimates of net cost of use of high osmolality and low osmolality contrast media. RESULTS: One-hundred thirty-seven (54.2%) of 253 patients receiving high osmolality contrast medium and 44 (17.5%) of 252 patients receiving low osmolality contrast medium experienced adverse drug reactions. The average cost (from society's perspective) of resources used to manage adverse drug reactions per patient undergoing angiography was significantly (p = 0.0001) greater for high osmolality (mean $249) versus low osmolality (mean $92) contrast medium. Differential costs (from the hospital's perspective) were $67 greater for high osmolality contrast medium. Charges and professional fees (from the payer's perspective) were $182 greater for high osmolality (mean $312) than for low osmolality (mean $130) contrast medium (p = 0.42, NS). The higher differential and average costs of managing adverse drug reactions with high osmolality contrast medium offset 33% and 75%, respectively, of the $207 difference in mean material costs, but these estimates are sensitive to infrequent high cost cases. CONCLUSIONS: Although low osmolality contrast medium is not cost-saving in diagnostic angiocardiography, its higher price is partially offset by lower management costs of adverse drug reactions. The cost offset for the hospital is lower than that for society and may not be realized by third-party payers. These methods and results may be useful in establishing clinical and payment guidelines for use of alternative contrast media in diagnostic angiocardiography.

A multicenter randomized trial comparing a percutaneous collagen hemostasis device with conventional manual compression after diagnostic angiography and angioplasty.

OBJECTIVES: A new percutaneous collagen hemostasis device was compared with conventional compression techniques after diagnostic catheterization and angioplasty. BACKGROUND: Peripheral vascular complications after diagnostic catheterization or more complex interventional procedures, as well as the discomfort of manual compression and prolonged bed rest, represent significant morbidity for invasive cardiac procedures. METHODS: A prospective, multicenter, randomized trial was designed to compare the hemostasis time in minutes and the incidence of vascular complications in patients receiving a vascular hemostasis device with those undergoing conventional compression techniques. RESULTS: After diagnostic catheterization, hemostasis time was significantly less with the vascular hemostasis device than with conventional manual compression (4.1 +/- 2.8 min [n = 90 patients] vs. 17.6 +/- 9.2 min [n = 75], p < 0.0001). This difference was greater in patients undergoing angioplasty and was unrelated to the anticoagulation status (4.3 +/- 3.7 min [n = 71 not receiving heparin], 7.6 +/- 11.6 min [n = 85 receiving heparin], 33.6 +/- 24.2 min [n = 134 control patients not receiving heparin], p < 0.0001 vs. control patients). The time from the start of the procedure to ambulation was slightly less after diagnostic catheterization in patients treated with the device (13.3 +/- 12.1 h vs. 19.2 +/- 17.8 h, p < 0.05). It was also less in patients who underwent angioplasty when the device was used after discontinuation of anticoagulation (23.0 +/- 11.1 h, without heparin), as compared with control compression techniques (32.7 +/- 18.8 h, p < 0.0001). Time to ambulation was even shorter (16.1 +/- 11.1 h, p < 0.0001) in patients in whom the device was placed immediately after angioplasty while they were still fully anticoagulated with a prolonged activated clotting time (336 +/- 85 s). There were no major complications (surgery or transfusion) after diagnostic catheterization and a low incidence of major complications in patients who underwent angioplasty (0.7% in control patients, 1.4% with the device without heparin, 1.2% with the device and heparin, p = NS). After angioplasty, there was a trend toward fewer hematomas when the device was used in the absence of heparin (4.2% vs. 9.7% in control patients, p = 0.14). CONCLUSIONS: A new vascular hemostasis device can significantly reduce the puncture site hemostasis time and the time to ambulation without significantly increasing the risk of peripheral vascular complications. The role of this technology in reducing complications, length of hospital stay and cost remains to be determined.

Reduction of ischemia with a new flow-adjustable hemoperfusion pump during coronary angioplasty. The Coronary Hemoperfusion Ischemia Prevention Study (CHIPS) Investigators.

A new flow-adjustable pump for coronary hemoperfusion to prevent ischemia during routine coronary angioplasty was evaluated in a multicenter prospective study of 110 patients. The protocol included patients who had angina or ST segment elevation during a control balloon inflation of less than or equal to 3 min. Hemoperfusion was performed by means of a new large lumen angioplasty catheter utilizing the patient's renal vein or femoral artery blood. Vessels perfused were the left anterior descending coronary artery (n = 74), right coronary artery (n = 39), left circumflex artery (n = 9) and coronary vein grafts (n = 15). Mean (+/- SD) perfusion flow was 41 +/- 9 ml/min (range 17 to 70); mean perfusion time was 9.3 +/- 4 min (median 8.5, range 2 to 30). Chest pain score (0 to 4) decreased from 2.9 +/- 1 to 1.4 +/- 1 during hemoperfusion (p less than 0.001); ST segment elevation score (0 to 4) decreased from 2.6 +/- 1 to 0.7 +/- 1 (p less than 0.005) and inflation time increased from 1.3 +/- 0.9 to 7 +/- 4 min, (p less than 0.001). At least a 50% increase in tolerated inflation time was obtained in 104 patients (95%). Free plasma hemoglobin and creatine kinase levels did not increase significantly over baseline values. Angioplasty was successful in 107 patients (97%), with mean stenosis reduced from 87 +/- 11% to 20 +/- 17%; 3 patients had urgent bypass surgery, 2 (1.8%) had a myocardial infarction (1 Q wave, 1 non-Q wave) and 2 (1.8%) died later in the hospital of probable noncoronary causes.(ABSTRACT TRUNCATED AT 250 WORDS)

Contrast echocardiographic mapping of collateralized myocardium in humans before and after coronary angioplasty.

Conventional coronary arteriography is able to demonstrate the presence of coronary collateral vessels but cannot delineate the specific region of myocardium to which they supply blood. To test the hypothesis that contrast echocardiography can specifically identify collateralized myocardium, contrast echocardiographic perfusion "maps" were compared in patients with (n = 12) and without (n = 12) angiographic evidence of coronary collateral flow, both before and after coronary angioplasty. Contrast echocardiographic images of the mid-left ventricle in the short-axis view at end-diastole were obtained after separate injections of a sonicated contrast agent into both the right and the left coronary arteries. A computer-based contouring system was used to determine the individual areas of myocardium perfused by each of the two coronary arteries and then to superimpose the images of the two perfusion beds. The resulting area of overlapping perfusion represented myocardium receiving blood flow from both coronary systems and was defined as collateralized myocardium. To normalize for heart size, overlap area was expressed as a percent of total myocardial area, which was the area between endocardium and epicardium in the short-axis view. To adjust for differences in vascular distribution, overlap area was expressed as a percent of the perfusion area of the recipient vessel. In patients with angiographic collateral flow, the recipient vessel was that vessel receiving the collateral flow. In patients without angiographic collateral flow, the right coronary artery was considered the recipient vessel. Overlap area was 1.3 +/- 0.4% of total myocardial area and 6.6 +/- 1.7% of recipient vessel area in patients without angiographic evidence of collateral flow compared with 30.6 +/- 2.5% and 89.2 +/- 6.4%, respectively, in patients with angiographic collateral flow (p less than 0.001 for both). In four patients in whom angiographic collateral flow was abolished by angioplasty, overlap area decreased from 30.3 +/- 5.3% to 6.8 +/- 2.7% of total myocardial area and from 100% to 18.5 +/- 5.4% of recipient vessel area (p less than 0.05 for both). Thus, contrast echocardiography is able to map the specific myocardial territory perfused by coronary collateral flow and document an immediate reduction in perfusion in this territory when collateral flow is abolished by angioplasty.

Results of a randomized prospective trial of intraaortic balloon counterpulsation and intravenous nitroglycerin in patients with acute myocardial infarction.

A randomized prospective clinical trial compared combined treatment with intraaortic balloon pumping and intravenous nitroglycerin for 4 to 5 days with routine clinical management in 20 patients with extensive myocardium at risk for infarction as evidenced by a thallium defect score of 7.0 units or greater. No significant differences in mortality or clinical outcome were observed between the 10 patients receiving the combined treatment and the 10 receiving routine management. In 14 patients two-dimensional echocardiograms obtained 6 to 24 hours after the onset of symptoms and at follow-up 6 to 16 days later (after completion of combined intraaortic balloon pumping plus nitroglycerin therapy) were analyzed to determine whether infarct segment or noninfarct segment lengths were affected by therapy. Among these 14 patients, 5 (3 receiving the combined therapy and 2 receiving routine management) demonstrated an increase in infarct segment length of greater than 1.0 cm. Mean infarct segment length increased 0.30 +/- 0.44 cm in patients receiving the combined therapy and 0.29 +/- 0.36 cm in patients on routine management (p = NS). In contrast, noninfarct segment length increased greater than 1.0 cm (mean increase 1.20 +/- 0.39) in five of seven patients on routine management but in none of 7 patients receiving intraaortic balloon pumping plus nitroglycerin therapy (mean decrease 0.22 +/- 0.20 cm) (p less than 0.05). No significant differences were noted in left ventricular ejection fraction, as measured by gated blood pool scintigraphy, or thallium perfusion defect score in a comparison of day 1 (pretreatment) with day 4 thallium or day 7 to 14 gated blood pool scintigrams. Thus, in patients with extensive myocardium at risk, it is unlikely that a reduction in mortality or a significant improvement in myocardial perfusion or ventricular function can be obtained by early intervention with intraaortic balloon pumping in combination with nitroglycerin. Although this combined therapy failed to prevent infarct segment lengthening (infarct expansion), the combined afterload-lowering effects of intraaortic balloon pumping and nitroglycerin did appear to prevent dilation or remodeling of noninfarcted segments during the first 2 weeks after acute myocardial infarction.

Regional wall motion improvement after coronary thrombolysis with recombinant tissue plasminogen activator: importance of coronary angioplasty.

To evaluate functional recovery in 20 consecutive patients with acute myocardial infarction who received recombinant tissue-type plasminogen activator, serial two-dimensional echocardiograms were performed before and immediately after tissue plasminogen activator administration and at 1 and 10 days postinfarction. Tissue plasminogen activator was administered intravenously (17 patients) or by intracoronary infusion (3 patients) after angiographic confirmation of total occlusion. Reperfusion, documented by angiography, occurred in 13 of the 20 patients. The mean time from onset of chest pain to thrombolysis was 5.1 +/- 1.1 hours. Echocardiograms were evaluated for regional function with a visual semiquantitative scoring system by two independent observers who had no knowledge of patient identity, temporal sequence, therapy or effect of therapy. There was no immediate or 24 hour improvement in wall motion. At day 10 compared with pretreatment, 28 of 33 reperfused infarct zone segments versus 6 of 20 nonreperfused infarct segments demonstrated improved wall motion (p = 0.01). This improvement did not relate to time from onset of chest pain to successful thrombolysis. Of reperfused infarct zone segments in the distribution of coronary artery balloon dilation, 19 of 23 segments exhibited improvement versus 7 of 17 (reperfused, no angioplasty) and 6 of 20 (nonreperfused, no angioplasty) segments (p = 0.001). Infarct zone segments reperfused at the time of ongoing chest pain demonstrated functional recovery compared with segments reperfused in the absence of chest pain (18 of 23 versus 10 of 20, respectively; p = 0.05). Thus, in this uncontrolled series, there was echocardiographically detectable improvement in function of reperfused infarct segments 10 days after coronary thrombolysis with recombinant tissue plasminogen activator.

Analysis of physician and hospital differences in 'negative' coronary angiogram rates.

A direct relationship has been postulated between high "negative" coronary angiogram rates and physician payment. We conducted a prospective study of coronary angiography in a teaching and community hospital staffed, respectively, by cardiologists who were performing cardiac catheterization as salaried or fee-for-service physicians. The lower overall rate of negative angiograms at the teaching hospital correlated with the presence of a cardiac surgery unit and the increased referral of patients with documented coronary artery disease. The percentage of completely normal angiograms did not differ significantly between hospitals. The number of angiograms positive by a 70% occlusion criterion in patients not previously known to have coronary artery disease also did not differ greatly. Negative angiogram rates appeared to vary inversely with physician ability to set preangiogram probabilities of coronary artery disease. Our findings do not discount reimbursement as a strong incentive, but suggest other important determinants of coronary angiographic variation.

Selection of a contrast agent in the cardiac catheterization laboratory.

The evolution of contrast material for intravascular use has been directed toward the development of better-tolerated agents. Currently, a variety of such "dyes" are available for coronary angiography and left ventriculography. Considerable animal and human investigation suggests that significant differences exist between the families of contrast agents that relate to patient tolerance. The newer low osmolality agents (especially the nonionic agents) produce less perturbation of the homeostatic state, which is clinically manifested by a lessened incidence of side effects, including those of a hemodynamic and electrophysiologic nature. While controversy continues over the cost/benefit ratio of the low osmolality contrast agents compared to traditional high osmolality agents, the former are rapidly becoming the community standard for diagnostic and especially therapeutic cardiologic procedures. Accepting the advantages of the low osmolality contrast agents, differences between the ionic dimers and the nonionic agents have been examined. Both experimental and clinical data suggest superiority of the nonionic agents. Although controversy still surrounds the issue of thromboembolism with the nonionic agents, accumulating evidence fails to support a clinically significant relation. The choice of contrast material is the responsibility of the invasive cardiologist. While the benefits of low osmolality agents are most obvious in high-risk patients, experience with large-scale intravenous studies suggests that the choice of contrast agent is a better discriminator of adverse reaction than is preprocedural risk stratification.

Regional coronary blood flow during relief of pacing-induced angina by nitroglycerin. Implications for mechanism of action.

The mechanism for the therapeutic effect of nitroglycerin in stress-induced angina remains controversial; it has been attributed to both increased blood supply to the ischemic myocardium and decreased myocardial oxygen demand. To investigate the contribution of each of these mechanisms, systemic pressures and great cardiac vein flow were measured in 14 patients with single-vessel disease involving the left anterior descending (LAD) coronary artery during the development of pacing-induced angina and after the administration of nitroglycerin while continuing pacing at the angina-provoking rate. Great cardiac vein flow, measured by thermodilution, represents the venous efflux from the LAD territory and therefore provided an index of flow to the poststenotic myocardium. In 11 patients, nitroglycerin was administered systemically (400 to 800 micrograms sublingually or 200 micrograms intravenously); angina was relieved in 10, concomitant with a decrease in both great cardiac vein flow (from 123 +/- 29 to 98 +/- 29 ml/min, p less than 0.001) and mean aortic pressure (from 118 +/- 22 to 104 +/- 22 mm Hg, p less than 0.001). In contrast, when 75 micrograms of nitroglycerin was administered directly into the left main coronary artery of 7 patients, it produced a small increase in great cardiac vein flow (from 108 +/- 32 to 125 +/- 31 ml/min, p = 0.059), no change in aortic pressure, and no relief of angina. This study suggests that nitroglycerin's major beneficial action in pacing-induced angina is unrelated to direct effects on the coronary circulation and is likely related to its cardiac unloading effect.

Limitations of pulmonary wedge V waves in diagnosing mitral regurgitation.

To study the usefulness of large V waves in pulmonary capillary wedge tracings in establishing the diagnosis of mitral regurgitation, data on 1,021 consecutive cardiac catheterizations were reviewed. Wedge tracings were obtained by Swan-Ganz catheterization in 208 patients, usually because of suspected valve disease. One hundred two patients had no trace of mitral regurgitation angiographically, 69 had mild to moderate and 37 had severe regurgitation. V waves were graded as trivial (less than 5), intermediate (5 to 10) or large (10 or more mm Hg above mean wedge pressure). Of 50 patients with large V waves, 18 (36 percent) had no or trace mitral regurgitation; these included 5 with mitral stenosis, 3 with a mitral valve prosthesis, 4 with coronary disease and congestive failure, 2 with aortic valve disease and congestive failure and 2 with a ventricular septal defect. Of 37 patients with severe mitral regurgitation, 16 (43 percent) had large and 12 (32 percent) had trivial V waves. Thus, mitral regurgitation is the most common cause of large V waves; however, large V waves are neither highly sensitive nor specific for severe regurgitation. Increased left atrial compliance may be associated with trivial V waves in the presence of severe regurgitation. Mitral obstruction, congestive heart failure and ventricular septal defect may all be associated with large V waves in the absence of significant mitral regurgitation.

Ischemic ventricular fibrillation: the importance of being spontaneous.

Although the energy level required to defibrillate normal myocardium is low and constant, as determined from studies of induced ventricular fibrillation, little is known of the specific energy requirements in regionally ischemic hearts for spontaneous or induced ventricular fibrillation. In this study the lowest energy threshold for defibrillation was determined in 10 open chest dogs with reversible 10 minute coronary occlusions at various sites for each of 44 events of ventricular fibrillation, using apical and superior vena caval electrodes with a generator providing variable output of 1 to 30 watt seconds. The ischemic mass, quantitated from postmortem angiographic and planimetric data, was 52 +/- 9 percent (mean +/- standard deviation) of the left ventricle in dogs with induced ventricular fibrillation (Group I), 52 +/- 12 percent in dogs with spontaneous ventricular fibrillation after occlusion (Group II) and 54 +/- 9 percent in dogs with spontaneous ventricular fibrillation after reperfusion (Group III). Defibrillation thresholds in watt seconds were 9 +/- 7 in Group I (n = 12), 19 +/- 10 in Group II (n = 13) and 18 +/- 10 in Group II (n = 19). (Group I versus Groups II and III, probability [p] less than 0.025). In nonischemic hearts, the defibrillation threshold was 3 +/- 2 (n = 32) (p less than 0.001 compared with values in Group I, II or III). Thus, despite similar masses of ischemia, twice as much energy was required for defibrillation of spontaneous ventricular fibrillation (whether after occlusion or reperfusion) as for induced ventricular fibrillation, suggesting that these conditions are caused by different metabolic or pathologic derangements. Such differences should be considered in assessing interventions such as drug therapy designed to inhibit the repetitive ventricular response and in design of implantable defibrillators.

Intracoronary thrombolysis 3 to 13 days after acute myocardial infarction for postinfarction angina pectoris.

The restoration of anterograde coronary flow long after coronary thrombosis may be of benefit to patients with continuing ischemia. To determine whether "old" intracoronary thrombi are susceptible to lysis with thrombolytic agents, 18 patients with angina at rest during evolving acute myocardial infarction (AMI) and total occlusion of the infarct vessel were treated with intracoronary streptokinase 3 to 13 days after onset of AMI. In 12 of the 18 patients (67%), successful recanalization of the artery was achieved 6.9 +/- 2.7 days after AMI. Thrombolysis was followed by coronary angioplasty in 2 patients. To evaluate the efficacy of this approach in reducing post-AMI ischemia, the number of episodes of angina at rest was compared in patients with successful and unsuccessful attempts at recanalization. Even in patients without angioplasty, the mean number of daily episodes decreased from 1.02 +/- 0.6 to 0.09 +/- 0.2 in patients in whom reperfusion was achieved, and from 1.07 +/- 0.8 to 0.88 +/- 0.8 in those in whom it was not (p = 0.027 for the difference between the groups). Thus, in patients with early post-AMI angina, intracoronary streptokinase can restore flow in the occluded artery, may decrease the frequency of angina, and allows angioplasty to be performed.

Iodixanol, a new isosmotic nonionic contrast agent compared with iohexol in cardiac angiography.

Iodixanol, a new ratio 6 nonionic iodinated contrast agent with an osmolality equal to serum, was compared with iohexol in a randomized, double-blind, parallel study. Two hundred patients undergoing elective diagnostic cardiac angiography were randomized to iodixanol (n = 101) or iohexol (n = 99). There were no differences noted between the 2 agents in the mean changes in systolic or diastolic blood pressure or heart rate during or immediately after any angiography. However, significantly more patients had a decrease in diastolic blood pressure of > 20 mm Hg during left coronary angiography with iodixanol. The only significant differences in any electrophysiologic parameter were slightly more PR prolongation during left coronary angiography with iodixanol and more ST-segment depression with iohexol during coronary angiography. Neither was clinically significant. Injection-associated discomfort occurred with both agents, but more patients experienced moderate to severe discomfort with iohexol (52%) than with iodixanol (17%) (p < 0.001). Only 1 potentially serious adverse event, ventricular fibrillation with iohexol, was considered related to contrast, and there were no differences noted between the agents. Overall, angiographic quality was equal with all angiograms being assessed as good or excellent in both groups (p = 0.885). In this low-risk population undergoing cardiac angiography, iodixanol is safe and effective without clinically important differences from iohexol. Additional studies in patients at high risk for complications should help further define the role of iodixanol in cardiac angiography.

Reduced left ventricular cavitary activity ("black hole sign") in thallium-201 SPECT perfusion images of anteroapical transmural myocardial infarction.

Apparently reduced left ventricular (LV) cavitary thallium activity in both planar and tomographic perfusion images has been previously observed by these and other investigators. With single-photon emission computerized tomography, we have clinically noted that this "black hole sign" was associated with an aneurysm in the setting of a transmural anterior or anteroapical perfusion defect. We have now prospectively studied the etiology and predictive value of this sign in 84 consecutive patients with an anterior, anteroapical transmural perfusion defect. Of the 84 patients, 49 had both LV aneurysm (confirmed by contrast ventriculography, echocardiography or gated blood pool studies) and a black hole sign. Only 1 patient with an aneurysm did not have the black hole sign, and 2 without aneurysm did. Thus, it is concluded that this sign is highly accurate in diagnosing LV aneurysm. Because thallium-201 single-photon emission computerized tomography imaging is often performed as one of the first diagnostic tests soon after myocardial infarction, this has important clinical management implications.

Detection of left anterior descending coronary artery disease in patients with left bundle branch block.

The detection of coronary artery disease is difficult if a patient has electrocardiographic evidence of left bundle branch block (BBB). Septal blood flow may be reduced in patients with left BBB, despite no angiographic evidence of left anterior descending (LAD) coronary artery disease. We have developed a new method of quantification of Thallium-201 single-photon emission computed tomographic (SPECT) images with the aim of better separating patients with left BBB and LAD disease from those with left BBB alone. The study cohort comprised 8 normal subjects (group I) and 20 patients with left BBB and chest pain who underwent thallium-201 SPECT imaging and coronary angiography. Eight patients (group II) had < or = 50% LAD stenosis, and 12 (group III) had > or = 70% LAD stenosis. Septal abnormality scores on the second short-axis slice from the base were computed, based on comparison of each subject's short-axis circumferential profile with a normal reference curve. This followed a procedure in which each profile was scaled to minimize differences in its absolute level in relation to the reference curve. Septal abnormality scores on stress images were 0.8 +/- 22 for group I, 27 +/- 43 for group II, and 165 +/- 67 for group III (p = 0.15 for group I vs II, and p < 0.0001 between groups I and III, and II and III).(ABSTRACT TRUNCATED AT 250 WORDS)