Intracardiac recording by catheter electrode of accessory pathway depolarization.

At electrophysiologic study in a patient with the Wolff-Parkinson-White syndrome, intracardiac catheter recordings demonstrated a deflection that occurred 30 ms before ventricular activation. The rapid deflection was present during ventricular preexcitation but not during normal atrioventricular conduction. All QRS complexes were preexcited to varying degrees during atrial fibrillation, yet the deflection consistently preceded ventricular activation by 30 ms. This deflection most likely represents the rare recording of a Kent bundle depolarization with an intracardiac electrode catheter.

Electrophysiologic effects and clinical efficacy of oral propafenone therapy in patients with ventricular tachycardia.

The effects of the antiarrhythmic agent propafenone were evaluated in 25 patients with recurrent symptomatic ventricular tachycardia. Oral propafenone was given to a maximal dose of 300 mg every 8 hours. Ten of the 25 patients developed side effects or had inadequate suppression of spontaneous ventricular arrhythmias during propafenone therapy. Electrophysiologic studies were performed before and during drug therapy on the 15 patients who had a satisfactory clinical response. Propafenone increased the PR interval from 168 +/- 46 to 188 +/- 25 ms (p less than 0.007), the HV interval from 47 +/- 10 to 65 +/- 13 ms (p less than 0.005), the shortest atrial pacing cycle length to maintain 1:1 atrioventricular (AV) nodal conduction from 385 +/- 44 to 436 +/- 42 ms (p less than 0.005), the ventricular effective refractory period from 231 +/- 17 to 255 +/- 19 ms (p less than 0.001) and the ventricular functional refractory period from 260 +/- 15 to 278 +/- 17 ms (p less than 0.002). Before propafenone therapy, all 15 patients had ventricular tachycardia induced by programmed ventricular stimulation. During propafenone treatment, 12 patients still had ventricular tachycardia induced, and the tachycardia cycle length significantly increased from 236 +/- 44 to 374 +/- 103 ms (p less than 0.001). Ten patients were considered to have satisfactory electrophysiologic response to propafenone on the basis of either the inability to initiate ventricular tachycardia or a marked increase in ventricular tachycardia cycle length associated with lack of symptoms during the induced tachycardia. These patients were discharged receiving propafenone.(ABSTRACT TRUNCATED AT 250 WORDS)

Initial experience with reuse of coronary angioplasty catheters in the United States.

OBJECTIVES: We sought to evaluate the performance of angioplasty catheters, restored under a strict manufacturing process, in patients with coronary artery disease. BACKGROUND: Most countries outside the United States routinely reuse disposable medical equipment, resulting in significant cost savings. Because of quality and legal concerns, reuse in the United States has been limited. We investigated the reuse of percutaneous transluminal coronary angioplasty (PTCA) balloon catheters, restored by a process strictly controlled for bioburden and sterility, in patients undergoing PTCA. METHODS: Used PTCA balloon catheters were shipped to a central facility and were decontaminated, cleaned and tested for endotoxin using the limulus amebocyte lystate (LAL) gel clot method. Physical testing and quality assurance were performed. The products were packaged and sterilized with ethylene oxide. Catheter performance was assessed in a pilot study powered to detect a 5% difference in the angiographic failure rates of new and reused balloons (beta 0.8). RESULTS: The study enrolled 107 patients. The indication for PTCA was stable angina pectoris in 69 patients, unstable angina in 22 and acute myocardial infarction in 16. Of the 107 patients enrolled, 106 had a successful laboratory outcome, and 1 required coronary artery bypass graft surgery after failed rescue stenting. There were 122 lesions attempted (American College of Cardiology/American Heart Association classification A, n = 32; B1, n = 43; > or = B2, n = 35; C, n = 12). Of the 110 lesions initially approached with restored PTCA catheters, 108 were crossed and dilated. Sixty-four required no further procedures. Stenting was performed in 37 patients (29 planned, 8 rescue). Thus, the angiographic failure rate was 7% (10 of 108, 95% confidence interval 2% to 12%), comparable to the 10% rate seen with new balloons in other studies. CONCLUSIONS: Restoration of disposable coronary angioplasty catheters using a highly controlled process appears to be safe and effective, with success rates similar to those of new products and no detectable sacrifice in performance. Cost analysis suggests that implementation of reuse technology for expensive disposable equipment may offer cost savings for U.S. hospitals, without sacrifice of quality.

Clinical efficacy and electrophysiologic effects of cibenzoline therapy in patients with ventricular arrhythmias.

Cibenzoline, a new antiarrhythmic agent, was tested in 26 patients who had symptomatic ventricular tachycardia (24 patients) or premature ventricular complexes (2 patients) unresponsive to conventional drugs. Cibenzoline was given orally every 8 hours to maximal doses of 65 mg in 2 patients, 81.25 mg in 22 patients and 97.5 mg in 2 patients. Cibenzoline abolished spontaneous episodes of ventricular tachycardia in 8 of 16 patients with ventricular tachycardia during a 72 hour control electrocardiographic recording, and 7 of 22 patients had greater than 83% decrease in premature ventricular complexes compared with control. The PR interval increased 14% (p less than 0.001), QRS duration increased 17% (p less than 0.001), QT interval did not change and mean ejection fraction in 10 patients did not change. Electrophysiologic studies were performed on 10 patients in the control period and during maximal cibenzoline dosage. Cibenzoline did not affect electrophysiologic properties of the atrium or atrioventricular (AV) node. It prolonged the ventricular effective (223 +/- 16 to 241 +/- 22 ms, p less than 0.02) and functional (247 +/- 18 to 264 +/- 25 ms, p less than 0.02) refractory periods. At control electrophysiologic studies, ventricular tachycardia was induced in 9 of 10 patients (mean cycle length 210 +/- 31 ms). Cibenzoline therapy prevented ventricular tachycardia induction in two patients, and in the other seven patients the mean ventricular tachycardia cycle length increased from 210 to 260 ms. The one patient with no ventricular arrhythmia induced during the control study still had no arrhythmia induced while receiving cibenzoline.(ABSTRACT TRUNCATED AT 250 WORDS)

Implications of recurrent ischemia after reperfusion therapy in acute myocardial infarction: a comparison of thrombolytic therapy and primary angioplasty.

OBJECTIVES: The purpose of this study was to examine the incidence and implications of recurrent ischemia after different reperfusion strategies in acute myocardial infarction. BACKGROUND: The rates and effects of recurrent ischemia after reperfusion with thrombolytic therapy and with primary percutaneous transluminal coronary angioplasty have not been compared. METHODS: At 12 centers 395 patients presenting within 12 h of the onset of acute myocardial infarction were prospectively randomized to receive recombinant tissue-type plasminogen activator (rt-PA) or primary coronary angioplasty. Sixteen clinical variables were examined by using univariate and multiple logistic regression analysis to identify the predictors of recurrent ischemia. The relation of recurrent ischemic events to patient outcome was analyzed. RESULTS: Recurrent ischemia developed in 76 patients (19.2%) before hospital discharge, resulting in reinfarction in 18 patients (4.6%) and death in 5 (2.6%). Recurrent ischemia occurred in 56 patients (28.0%) after rt-PA but in only 20 patients (10.3%) after coronary angioplasty (p < 0.0001), directly contributing to a higher rate of death or reinfarction (7.5% vs. 3.1%, p = 0.05), catheterization and revascularization procedures and prolonged hospital stay after thrombolysis. By multivariate analysis, treatment with coronary angioplasty rather than rt-PA was the strongest predictor of freedom from recurrent ischemia. Although the incidence of recurrent ischemia after angioplasty and after rt-PA was similar within the 1st 2 days of admission (9.2% vs. 14.5%, p = 0.11), after hospital day 2 recurrent ischemia occurred in only 2 patients who received primary angioplasty compared with 27 patients who received rt-PA (1.1% vs. 13.5%, p < 0.0001). CONCLUSIONS: The development of recurrent ischemia adversely affects patient outcome, increasing morbidity, mortality and resource utilization. The much lower rate of recurrent ischemia after primary coronary angioplasty than after rt-PA results in improved survival without reinfarction and allows a shorter, less complicated hospital stay. Given the extremely low rate of recurrent ischemia after hospital day 2, safe early discharge on day 3 after primary coronary angioplasty should be feasible in selected patients with acute myocardial infarction.

Predictors of in-hospital and 6-month outcome after acute myocardial infarction in the reperfusion era: the Primary Angioplasty in Myocardial Infarction (PAMI) trail.

OBJECTIVES: This study examined the predictors of in-hospital and 6-month outcome after different reperfusion strategies in acute myocardial infarction. BACKGROUND: Thrombolytic therapy and primary angioplasty are both widely applied as reperfusion modalities in patients with myocardial infarction. Although it is accepted that restoration of early patency of the infarct-related artery can reduce mortality and salvage myocardium, the optimal reperfusion strategy remains controversial, and the predictors of outcome in the reperfusion era have been incompletely characterized. METHODS: At 12 centers, 395 patients presenting within 12 h of onset of acute transmural myocardial infarction were prospectively randomized to receive tissue-type plasminogen activator (t-PA) or undergo primary angioplasty without antecedent thrombolysis. Sixteen clinical variables were examined with univariate and multiple logistic regression analysis to identify the predictors of clinical outcome. RESULTS: By univariate analysis, in-hospital mortality was increased in the elderly, women, patients with diabetes and in patients treated with t-PA as opposed to angioplasty. Only advanced age and treatment by t-PA versus angioplasty independently correlated with increased in-hospital mortality (6.5% vs. 2.6%, respectively, p = 0.039 by multiple logistic regression analysis). Similarly, the only variables independently related to in-hospital death or nonfatal reinfarction were advanced age and treatment by t-PA versus angioplasty (12.0% vs. 5.1%, p = 0.02). The reduction in in-hospital death or reinfarction with angioplasty versus t-PA was particularly marked in patients > or = 65 years of age (8.6% vs. 20.0%, p = 0.048). Furthermore, primary management with angioplasty versus t-PA was the most powerful multivariate correlate of freedom from recurrent ischemic events (10.3% vs. 28.0%, p = 0.0001). The independent beneficial effect of angioplasty on freedom from death or reinfarction was maintained at 6-month follow-up (8.2% vs. 17.0%, p = 0.02). CONCLUSIONS: In the reperfusion era, the two most powerful determinants of freedom from death, reinfarction and recurrent ischemia after myocardial infarction are young age and treatment by primary angioplasty.

Adverse reactions of low osmolality contrast media during cardiac angiography: a prospective randomized multicenter study.

A multicenter study was performed to determine the incidence of adverse reactions to two contrast media with similar low osmolality during cardiac angiography. The study was of a randomized double-blind design comparing ioxaglate (an ionic dimer) and iopamidol (a nonionic compound) and included 500 patients; 250 patients received ioxaglate and 250 iopamidol. There were 58 adverse reactions attributed to the contrast media in the ioxaglate group and 29 in the iopamidol group (p less than 0.001). Chest pain occurred in 11 patients in the ioxaglate group compared with 5 in the iopamidol group (p = 0.123). Nausea or vomiting was present in 20 and 2 patients, respectively (p less than 0.0003). Allergic adverse reactions, such as bronchospasm, urticaria and itching, occurred in 15 of the ioxaglate group and only 1 of the patients receiving iopamidol (p less than 0.0007). Fifty-two patients in the ioxaglate group had a known allergic history (not to contrast medium) or asthma, whereas 77 receiving iopamidol had a similar history. Seven of the 52 ioxaglate-treated patients developed an allergic adverse reaction compared with none of the 77 in the iopamidol group (p = 0.001). Of 41 patients receiving ioxaglate who were premedicated with diphenhydramine, 4 had an allergic adverse event. In the iopamidol group 45 patients received similar premedication and none had an allergic adverse reaction (p less than 0.03). Thus, this multicenter study shows that adverse reactions occur more often with ioxaglate than with iopamidol and that patients with an allergic history have a greater risk with ioxaglate therapy compared with iopamidol.

Long-term outcome after primary angioplasty: report from the primary angioplasty in myocardial infarction (PAMI-I) trial.

OBJECTIVES: This study sought to compare the two-year outcome after primary percutaneous coronary angioplasty or thrombolytic therapy for acute myocardial infarction. BACKGROUND: Primary angioplasty, that is, angioplasty without antecedent thrombolytic therapy, has been shown to be an effective reperfusion modality for patients suffering an acute myocardial infarction. This report reviews the two-year clinical outcome of patients randomized in the Primary Angioplasty in Myocardial Infarction trial. METHODS: At 12 clinical centers, 395 patients who presented within 12 h of the onset of myocardial infarction were randomized to undergo primary angioplasty (195 patients) or to receive tissue-type plasminogen activator (t-PA) (200 patients) followed by conservative care. Patients were followed by physician visits, phone call, letter and review of hospital records for any hospital admission at one month, six months, one year and two years. RESULTS: At two years, patients undergoing primary angioplasty had less recurrent ischemia (36.4% vs. 48% for t-PA, p = 0.026), lower reintervention rates (27.2% vs. 46.5% for t-PA, p < 0.0001) and reduced hospital readmission rates (58.5% vs. 69.0% for t-PA, p = 0.035). The combined end point of death or reinfarction was 14.9% for angioplasty versus 23% for t-PA, p = 0.034. Multivariate analysis found angioplasty to be independently predictive of a reduction in death, reinfarction or target vessel revascularization (p = 0.0001). CONCLUSIONS: The initial benefit of primary angioplasty performed by experienced operators is maintained over a two-year follow-up period with improved infarct-free survival and reduced rate of reintervention.

Analysis of the relative costs and effectiveness of primary angioplasty versus tissue-type plasminogen activator: the Primary Angioplasty in Myocardial Infarction (PAMI) trial. The PAMI Trial Investigators.

OBJECTIVES: We sought to determine the relative cost and effectiveness of two different reperfusion modalities in patients with acute myocardial infarction (AMI). BACKGROUND: Recent studies have found superior clinical outcomes after reperfusion by primary percutaneous transluminal coronary angioplasty (PTCA) compared with thrombolytic therapy. The high up-front costs of cardiac catheterization may diminish the relative advantages of this invasive strategy. METHODS: Detailed in-hospital charge data were available from all 358 patients with AMI randomized to tissue-type plasminogen activator (t-PA) or primary PTCA in the United States from the Primary Angioplasty in Myocardial Infarction trial. Resource consumption during late follow-up was estimated by assessment of major clinical events and functional status. RESULTS: Compared with t-PA, primary PTCA resulted in reduced rates of in-hospital mortality (2.3% vs. 7.2%, p = 0.03), reinfarction (2.8% vs. 7.2%, p = 0.06), recurrent ischemia (11.3% vs. 28.7%, p < 0.0001) and stroke (0% vs. 3.9%, p = 0.02) and a shorter hospital stay (7.6 +/- 3.3 days vs. 8.4 +/- 4.7 days, p = 0.04). Despite the initial costs of cardiac catheterization in all patients with the invasive strategy, total mean (+/- SD) hospital charges were $3,436 lower per patient with PTCA than with t-PA ($23,468 +/- $13,410 vs. $26,904 +/- $18,246, p = 0.04), primarily due to the reduction in adverse in-hospital outcomes. However, professional fees were higher after primary PTCA ($4,185 +/- $3,183 vs. $3,322 +/- $2,728, p = 0.001), and thus total charges, although favoring PTCA, were not significantly different ($27,653 +/- $13,709 vs. $30,227 +/- 18,903, p = 0.21). At a mean follow-up time of 2.1 +/- 0.7 years, no major differences in postdischarge events or New York Heart Association functional class were present between PTCA- and t-PA-treated patients, suggesting similar late resource consumption. Including in-hospital events, 83% of PTCA-treated patients were alive and free of reinfarction at late follow-up, compared with 74% of t-PA-treated patients (p = 0.06). CONCLUSIONS: Compared with t-PA, reperfusion by primary PTCA improves clinical outcomes with similar or reduced costs. These findings have important clinical implications in an increasingly cost-conscious health care environment.

Multicenter reperfusion trial of intravenous anisoylated plasminogen streptokinase activator complex (APSAC) in acute myocardial infarction: controlled comparison with intracoronary streptokinase.

The recent establishment of a firm therapeutic role for reperfusion in acute myocardial infarction has stimulated interest in the development of more ideal thrombolytic agents. Anisoylated plasminogen streptokinase activator complex (APSAC) is a new plasminogen activator possessing properties that are promising for intravenous thrombolytic application in acute myocardial infarction. To assess the reperfusion potential of intravenous APSAC, a multi-center, angiographically controlled reperfusion trial was performed. An approved thrombolytic regimen of intracoronary streptokinase served as a control. Consenting patients with clinical and electrocardiographic signs of acute myocardial infarction were studied angiographically and 240 qualifying patients with documented coronary occlusion (flow grade 0 or 1) were randomized to treatment in less than 6 h of symptom onset (mean 3.4 h, range 0.4 to 6.0) with either intravenous APSAC (30 U in 2 to 4 min) or intracoronary streptokinase (160,000 U over 60 min). Both groups also received heparin for greater than or equal to 24 h. Reperfusion was evaluated angiographically over 90 min and success was defined as advancement of grade 0 or 1 to grade 2 or 3 flow. Rates of reperfusion for the two treatment regimens were 51% (59 of 115) at 90 min after intravenous APSAC and 60% (67 of 111) after 60 min of intracoronary streptokinase (p less than or equal to 0.18). Reperfusion at any time within the 90 min was observed in 55 and 64%, respectively (p less than or equal to 0.16). Time to reperfusion occurred at 43 +/- 23 min after intravenous and 31 +/- 17 min after intracoronary therapy. The success of intravenous therapy was dependent on the time to treatment: 60% of APSAC patients treated within 4 h exhibited reperfusion compared with 33% of those treated after 4 h (p less than or equal to 0.01). Reperfusion rates were also dependent on initial flow grade (p less than or equal to 0.0001): 48% (81 of 168) for grade 0 (APSAC = 43%, streptokinase = 54%), but 78% for grade 1 (APSAC = 78%, streptokinase = 77%). APSAC given as a rapid injection was generally well tolerated, although the median change in blood pressure at 2 to 4 min was greater after APSAC than after streptokinase (-10 versus -5 mm Hg). Mean plasma fibrogen levels fell more at 90 min after the sixfold higher dose of APSAC than after streptokinase (to 32 versus 64% of control). Reported bleeding events were more frequent after APSAC but occurred primarily at the site of catheter insertion and no event was intracranial.(ABSTRACT TRUNCATED AT 400 WORDS)

Anistreplase versus alteplase in acute myocardial infarction: comparative effects on left ventricular function, morbidity and 1-day coronary artery patency. The TEAM-3 Investigators.

OBJECTIVES: This double-blind, randomized, multicenter trial was designed to compare the effects of treatment with anistreplase (APSAC) and alteplase (rt-PA) on convalescent left ventricular function, morbidity and coronary artery patency at 1 day in patients with acute myocardial infarction. BACKGROUND: Anistreplase (APSAC) is a new, easily administered thrombolytic agent recently approved for treatment of acute myocardial infarction. Alteplase (rt-PA) is a rapidly acting, relatively fibrin-specific thrombolytic agent that is currently the most widely used agent in the United States. METHODS: Study entry requirements were age less than or equal to 75 years, symptom duration less than or equal to 4 h, ST segment elevation and no contraindications. The two study drugs, APSAC, 30 U/2 to 5 min, and rt-PA, 100 mg/3 h, were each given with aspirin (160 mg/day) and intravenous heparin. Prespecified end points were convalescent left ventricular function (rest/exercise), clinical morbidity and coronary artery patency at 1 day. A total of 325 patients were entered, stratified into groups with anterior (37%) or inferior or other (63%) acute myocardial infarction, randomized to receive APSAC or rt-PA and followed up for 1 month. RESULTS: At entry, patient characteristics in the two groups were balanced. Convalescent ejection fraction at the predischarge study averaged 51.3% in the APSAC group and 54.2% in the rt-PA group (p less than 0.05); at 1 month, ejection fraction averaged 50.2% versus 54.8%, respectively (p less than 0.01). In contrast, ejection fraction showed similar augmentation with exercise at 1 month after APSAC (+4.3% points) and rt-PA (+4.6% points), and exercise times were comparable. Coronary artery patency at 1 day was high and similar in both groups (APSAC 89%, rt-PA 86%). Mortality (APSAC 6.2%, rt-PA 7.9%) and the incidence of other serious clinical events, including stroke, ventricular tachycardia, ventricular fibrillation, heart failure within 1 month, recurrent ischemia and reinfarction were comparable in the two groups; and mechanical interventions were applied with equal frequency. A combined clinical morbidity index was determined and showed a comparable overall outcome for the two treatments. CONCLUSIONS: Convalescent rest ejection fraction was high after both therapies but higher after rt-PA; other clinical outcomes, including exercise function, morbidity index, and 1-day coronary artery patency, were favorable and comparable after APSAC and rt-PA.

Adenosine as an adjunct to thrombolytic therapy for acute myocardial infarction: results of a multicenter, randomized, placebo-controlled trial: the Acute Myocardial Infarction STudy of ADenosine (AMISTAD) trial.

OBJECTIVES: The Acute Myocardial Infarction STudy of ADenosine (AMISTAD) trial was designed to test the hypothesis that adenosine as an adjunct to thrombolysis would reduce myocardial infarct size. BACKGROUND: Reperfusion therapy for acute myocardial infarction (MI) has been shown to reduce mortality, but reperfusion itself also may have deleterious effects. METHODS: The AMISTAD trial was a prospective, open-label trial of thrombolysis with randomization to adenosine or placebo in 236 patients within 6 h of infarction onset. The primary end point was infarct size as determined by Tc-99 m sestamibi single-photon emission computed tomography (SPECT) imaging 6+/-1 days after enrollment based on multivariable regression modeling to adjust for covariates. Secondary end points were myocardial salvage index and a composite of in-hospital clinical outcomes (death, reinfarction, shock, congestive heart failure or stroke). RESULTS: In all, 236 patients were enrolled. Final infarct size was assessed in 197 (83%) patients. There was a 33% relative reduction in infarct size (p = 0.03) with adenosine. There was a 67% relative reduction in infarct size in patients with anterior infarction (15% in the adenosine group vs. 45.5% in the placebo group) but no reduction in patients with infarcts located elsewhere (11.5% for both groups). Patients randomized to adenosine tended to reach the composite clinical end point more often than those assigned to placebo (22% vs. 16%; odds ratio, 1.43; 95% confidence interval, 0.71 to 2.89). CONCLUSIONS: Many agents thought to attenuate reperfusion injury have been unsuccessful in clinical investigation. In this study, adenosine resulted in a significant reduction in infarct size. These data support the need for a large clinical outcome trial.

Prolongation of the Q-T interval in man during sleep.

Parasympathetic blockade shortens the duration of the Q-T interval and ventricular effective refractory period independent of heart rate change. Since relative parasympathetic effect increases during sleep, it was determined whether sleep was associated with a change in the Q-T interval. Fifteen patients receiving no drugs underwent 3 to 6 days of continuous electrocardiographic recordings. Tracings were sampled every 30 minutes and recorded at a paper speed of 25 mm/s. This provided 12,000 Q-T and R-R intervals that were measured. Comparison of R-R intervals that had similar durations during sleep and awake states revealed that the duration of the Q-T interval was longer during sleep in all 15 patients (p less than 0.001). Eight patients had sufficient range of overlap of R-R intervals to compare linear regression lines of Q-T intervals recorded while awake with Q-T intervals recorded while asleep. The regression lines during sleep exhibited a mean intercept change of 38 +/- 37 ms and mean slope change of -0.021 +/- 0.040 ms when compared with the regression lines during the awake state. The difference in Q-T interval between awake and sleep states was 19 +/- 7 ms when calculated at a heart rate of 60 beats/min. These statistical comparisons of the relationship of the Q-T interval to R-R interval indicate that the Q-T interval is longer during sleep than during the awake state at the same heart rate. Prolongation of the Q-T interval during sleep may reflect increased vagal tone or sympathetic withdrawal. These changes in repolarization may be related to the diurnal variation of some ventricular arrhythmias.

Functional bundle branch block: discordant response of right and left bundle branches to changes in heart rate.

Faster heart rates shorten refractoriness more in some tissues than in others. This study investigates whether faster heart rates shorten relative refractoriness more in the right than left bundle branch in humans. Premature atrial stimulation at 2 or more basic cycle lengths was performed in 314 patients with no evidence of atrioventricular conduction system disease. In 10 patients, both functional right and left bundle branch block (BBB) developed with premature atrial stimulation. Functional right BBB occurred at the longer basic cycle length, and functional left BBB at the shorter cycle length in 8 patients. In 2 patients functional right and functional left BBB were present at the same cycle length, but functional left BBB occurred at a shorter premature atrial coupling interval. For all patients, the mean functional right bundle branch relative refractoriness was 438 ms at a basic cycle length of 847 ms, and functional left bundle branch relative refractoriness was 357 ms at a cycle length of 622 ms (p less than 0.01). The HV interval was 45 +/- 15 ms at control and increased with functional left BBB to 77 +/- 19 ms (p less than 0.01), but not with functional right BBB. Thus, relative refractoriness of the right and left bundle branches are rate-dependent and discordant. At longer cycle lengths, relative refractoriness of the right bundle branch is greater than that of the left bundle branch, and at shorter cycle lengths relative refractoriness of the left bundle branch is greater than that of the right bundle branch. The relative refractory period curves "cross over" and can explain the presence of both functional right and left BBB in the same patient.

Comparison of in-hospital outcome in men versus women treated by either thrombolytic therapy or primary coronary angioplasty for acute myocardial infarction.

At 12 centers, 395 patients, including 288 men (73%) and 107 women (27%) with acute myocardial infarction (AMI), were prospectively randomized to treatment with tissue plasminogen activator (t-PA) or primary percutaneous transluminal coronary angioplasty (PTCA). Compared with men, women were older (65.7 vs 57.7 years, p < 0.0001), more often had diabetes mellitus (19% vs 10%, p = 0.03), systemic hypertension (54% vs 39%, p = 0.005), prior congestive heart failure (5% vs 0%, p = 0.002), and presented later after symptom onset (229 vs 174 minutes, p = 0.0004). The in-hospital mortality in women was 3.3-fold higher than men (9.3% vs 2.8%, p = 0.005). After adjustment for comorbid baseline characteristics, however, only advanced age independently correlated with mortality. Among t-PA-treated patients, mortality was significantly higher in women than in men (14.0% vs 3.5%, p = 0.006). Intracranial hemorrhage after t-PA was also more common in women than in men (5.3% vs 0.7%, p = 0.037). In contrast, women and men had similar in-hospital mortality after primary PTCA (4.0% vs 2.1%, respectively, p = 0.46). No intracranial bleeding occurred in PTCA-treated patients. A univariate trend was present for reduced in-hospital mortality in women treated with PTCA rather than t-PA (4.0% vs 14.0%, p = 0.07). By multiple logistic regression analysis of 15 clinical variables, treatment with PTCA rather than t-PA, as well as younger age, were independently predictive of in-hospital survival in women.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of acute myocardial infarction location on in-hospital and late outcome after primary percutaneous transluminal coronary angioplasty versus tissue plasminogen activator therapy.

In the Primary Angioplasty in Myocardial Infarction trial, 395 patients with acute myocardial infarction (AMI) were prospectively randomized to tissue plasminogen activator (tPA) or primary percutaneous transluminal coronary angioplasty (PTCA). In 138 patients with anterior wall AMI, in-hospital mortality was significantly reduced by treatment with PTCA compared with tPA (1.4% vs 11.9%, p = 0.01). PTCA also resulted in lower rates of death or reinfarction (1.4% vs 18.0%, p = 0.0009), recurrent myocardial ischemia (11.3% vs 28.4%, p = 0.01), and stroke (0.0% vs 6.0%, p = 0.037) in anterior wall AMI. The independent beneficial effect of treatment with primary PTCA rather than tPA in anterior wall AMI was confirmed by multivariate analysis and interaction testing. The in-hospital mortality of 257 patients with nonanterior wall AMI was similar after PTCA and tPA (3.2% vs 3.8%, p = 0.82). Compared with tPA, however, primary PTCA resulted in a markedly lower rate of recurrent myocardial ischemia (9.7% vs 27.8%, p = 0.0002), fewer unscheduled catheterization and revascularization procedures, and a shorter hospital stay (7.0 vs 8.6 days, p = 0.01) in nonanterior wall AMI. Thus, compared with tPA, primary PTCA in patients with anterior wall AMI results in significantly improved survival, with lower rates of stroke, reinfarction, and recurrent myocardial ischemia. In nonanterior wall AMI, treatment with PTCA and tPA results in similar early mortality, although PTCA-treated patients have a more stable hospital course characterized by reduced recurrent ischemia, fewer subsequent invasive procedures, and earlier discharge.

Intra-aortic balloon counterpulsation in an experimental model of myocardial infarction.

The efficacy of intra-aortic balloon counterpulsation for heart failure during acute myocardial infarction has been controversial, and early intervention has been suggested as crucial. We have examined this type of therapy in the intact anesthetized dog during complete occlusion of the proximal left anterior descending coronary artery with a balloon-tipped catheter. Group 1 (n = 8) represented untreated animals undergoing four hours of ischemia. Group 2 (n = 7) consisted of animals undergoing counterpulsation with an intra-aortic balloon after 15 minutes of ischemia. Initially, stroke volume and the mean rate of left ventricular fiber shortening were similarly diminished in both groups, while filling pressure rose proportionately. After four hours, the mean rate of fiber shortening, stroke volume, and left ventricular filling pressure rose to a greater extent in untreated compared to treated animals (p less than 0.01). The degree of swelling in ischemic tissue and the number of sites with ST-segment elevation and their sums were comparable in the two groups. Thus, intra-aortic counterpulsation applied early in the course of ischemia can improve global left ventricular dysfunction without affecting the extent of myocardial injury.

Worse six-month outcome for patients with multiple stents in a single coronary artery.

BACKGROUND: Before the "era" of optimal stent deployment, very few data concerning multiple stents in a single coronary artery showed restenosis rates up to 60%. OBJECTIVE: To evaluate the 6-month outcome of patients receiving multiple Palmaz-Schatz stents (> or =2 stents) in a single coronary artery compared to those receiving single stents. METHODS: Three hundred and forty-eight patients having multiple stents were compared to 174 patients receiving single stents during a 6-month follow-up. RESULTS: Repeat target lesion revascularization (RTLR), either repeat PTCA or CABG, was 10.4% in the single-stent group, 22.6% in the two-stent group, and 23.1% in the > or =2 stent group (p = 0.001, single versus 2 or > or =2 stents). There was not a significant difference between single stent and multiple stent groups in myocardial infarction and death during 6-month follow-up. Multivariate analysis showed multiple stents, diabetes mellitus, and type C lesion to be predictors of RTLR. CONCLUSIONS: Placement of two or more stents was associated with a significantly higher RTLR compared with single stent placement. The optimal approach to diffuse coronary artery disease remains to be defined.

Five-hour balloon inflation to resolve recurrent reocclusion during coronary angioplasty.

A 63-year-old male presented with an acute inferior myocardial infarction with initial clinical reperfusion following thrombolysis. Due to recurrent reocclusion, emergency catheterization was performed, demonstrating a 90% stenosis in the mid right coronary artery. Angioplasty was complicated by multiple reocclusions, ultimately requiring 5-h autoperfusion balloon inflation to maintain patency.