Cryoballoon Ablation for Persistent Atrial Fibrillation in a Patient with a Left Pneumonectomy

Pulmonary vein (PV) isolation (PVI) is the most important component of catheter ablation of atrial fibrillation (AF) and can be achieved by radiofrequency or cryoballoon ablation (CBA). The CBA system has shown excellent efficacy and safety in a number of clinical trials and is independent of the PV anatomy. However, pneumonectomy can significantly alter the anatomy posing a challenge to CBA. Few cases of PVI accomplished by CBA have been described in patients with lobectomy, but none in the pneumonectomy population. We describe a case of successful CBA for paroxysmal AF in a patient with a left total pneumonectomy.

Ventricular Fibrillation Cardiopulmonary Arrest Following Micra™ Leadless Pacemaker Implantation

Leadless cardiac pacemakers such as the Micra™ transcatheter leadless pacing system (Medtronic, Minneapolis, MN, USA) are an alternative to traditional transvenous pacemakers. Implantation of leadless pacemakers, albeit safe, may be associated with complications, including cardiac tamponade; high capture thresholds; and, rarely, ventricular arrhythmias. We report a case of ventricular fibrillation arrest following the implantation of a Micra™ leadless pacemaker.

Body Piercing with a Metallic Tongue Stud Resulting in Ineffective Implantable Cardioverter-defibrillator Shocks: "Heart to Mouth"

Left ventricular assist devices (LVADs) provide circulatory support to patients with severe left ventricular systolic dysfunction. Many such patients have a pre-existing implantable cardioverter-defibrillator (ICD) at the time of their LVAD surgery. LVAD implantation can alter the ICD lead parameters, including R-wave sensing, right ventricular capture threshold, and impedance. These changes can in turn affect the ability of the ICD to successfully treat malignant ventricular arrhythmias. In most patients who present with ineffective ICD shocks, the failed shock is assumed to be secondary to the patient’s severe cardiomyopathy. Especially, the role of physical examination in such patients is often minimized. In our patient, a thorough history-taking and history-guided physical examination led us to the root cause of the failed ICD shocks. Our patient was noted to have a metal tongue piercing, which was the likely cause of his ineffective ICD shocks. Our case highlights the importance of a comprehensive history-taking and physical examination.

Azygous Vein Coil Implantation in Left Ventricular Assist Device Patients: A Hands-on Approach

Recently, there have been reports of left ventricular assist device (LVAD) patients presenting with multiple ineffective implantable cardioverter-defibrillator (ICD) shocks. In such patients, the placement of an azygous vein coil by providing an alternative anteroposterior trajectory of the electrical shock vector can enable successful defibrillation. This review discusses a hands-on approach to azygous vein coil implantation. Additionally, we compare our tools and technique to those that have been previously described by other operators. From 2018 to 2021, eight patients were identified who underwent azygous vein coil implantation at MedStar Washington Hospital Center using a specific technique and tools. Demographic and procedural data were obtained by a retrospective review of patient charts, procedure logs, fluoroscopy, and venography performed during coil implantation. The indication for azygous vein coil implantation was ineffective ICD shocks in seven patients. The presenting rhythm was ventricular fibrillation in six (75%) cases and sustained ventricular tachycardia in two (25%) cases. Using the approach described, we were able to successfully implant an azygous vein coil in all eight (100%) patients. There were no procedure-related complications. Postimplantation, defibrillation threshold (DFT) testing was successfully performed in six of eight (75%) patients. One patient failed DFT testing despite placement of an azygous vein coil. In another patient, DFT testing was not performed because the patient was in atrial fibrillation and was not systemically anticoagulated. In conclusion, the placement of an azygous vein coil in LVAD patients with failed ICD shocks using the tools and technique described in this report is safe and highly efficacious (successful in 100% of cases).

"Retained wire femoral lead removal and fibroplasty" for obtaining venous access in patients with refractory venous obstruction

BACKGROUND

Patients with wire and catheter refractory venous occlusion are traditionally referred for pectoral transvenous lead extraction (TLE) to obtain venous access. TLE causes 1-2 mm circumferential mechanical or laser destruction of tissue surrounding the lead(s). This not only exposes the patient to the risk of major complications but also can damage nontargeted leads. We present a series of patients where retained wire femoral lead removal and fibroplasty was used to obtain venous access in patients with refractory obstruction.

METHODS

Between 2008 and 2021, we identified 17 patients where retained wire lead removal followed by fibroplasty was used to retain venous access. Demographic and procedural data were obtained by retrospective review of patient charts.

RESULTS

We were able to successfully obtain venous access in all 17 patients in whom this technique was attempted. In two patients the target lead was less than or equal to 1 year old. In the remaining 15 patients, the average dwell time of the target lead(s) was 6 years. There were no procedure-related complications, and no changes in the parameters of other leads were noted.

CONCLUSION

Retained wire femoral lead removal and fibroplasty is safe and highly efficacious at obtaining venous access in patients with refractory venous occlusion. If the target lead(s) is less than or equal to 1 year old, this technique can help obtain venous access at the time of the initial surgery, hence avoiding the need for TLE. Furthermore, in patients referred for TLE to obtain venous access, this technique by avoiding the use of TLE tools spares the patient of the associated risks.

The combination of coronary sinus ostial atresia/abnormalities and a small persistent left superior vena cava-Opportunity for left ventricular lead implantation and unrecognized source of thromboembolic stroke

BACKGROUND

Coronary sinus (CS) ostial atresia/abnormalities prevent access to the CS from the right atrium (RA) for left ventricular (LV) lead implantation. Some patients with CS ostial abnormalities also have a small persistent left superior vena cava (sPLSVC).

OBJECTIVE

The purpose of this study was to describe CS ostial abnormalities and sPLSVC as an opportunity for LV lead implantation and unrecognized source of stroke.

METHODS

Twenty patients with CS ostial abnormalities and sPLSVC were identified. Clinical information, imaging methods, LV lead implantation techniques, and complications were summarized.

RESULTS

Forty percent had at least 1 previously unsuccessful LV lead placement. In 70%, sPLSVC was identified by catheter manipulation and contrast injection in the left brachiocephalic vein, and in 30% by levophase CS venography. In 30%, sPLSVC was associated with drainage from the CS into the left atrium (LA). When associated with CS ostial abnormalities, the sPLSVC diameter averaged 5.6 ± 3 mm. sPLSVC was used for successful LV lead implantation in 90% of cases. In 80%, the LV lead was implanted down sPLSVC, and in 20%, sPLSVC was used to access the CS from the RA. Presumably because of unrecognized drainage from the CS to the LA, 1 patient had a stroke during implantation via sPLSVC.

CONCLUSION

When CS ostial abnormalities prevent access to the CS from the RA, sPLSVC can be used to successfully implant LV leads. In some, the CS partially drains into the LA and stroke can occur spontaneously or during lead intervention. It is important to distinguish sPLSVC associated with CS ostial abnormalities from isolated PLSVC.

Interventional device implantation, Part I: Basic techniques to avoid complications: A hands-on approach

Introduction

The essence of cardiac resynchronization therapy (CRT) is biventricular (BiV) pacing, which involves implanting pacing leads in both the right ventricle (RV) and left ventricle (LV). Unlike traditional RV pacing, many hurdles lie ahead of successful LV lead implantation.

Methods and Results

In this review, we first highlight the importance of optimizing the patient and the tools. Next, we describe the CRT tools developed over several decades, to facilitate successful implantation. Thereafter, we provide a streamlined step‐by‐step summary of the basic BiV implantation procedure. Lastly, we discuss some commonly encountered challenges during implantation and the techniques to tackle them.

Conclusion

A systematic approach to every step of the implantation process can reduce procedure time, decrease patient exposure to radiation and contrast, and minimize complications. The use of right tools and techniques can enable all implanters to become more successful with BiV implantation.

Challenging Implants Require Tools and Techniques Not Tips and Tricks

The EP Clinics article "How to implant CRT devices in a busy clinical practice" describes the basics of the "interventional telescoping technique". This article focuses on specific circumstances where the tools and techniques are invaluable: (1) inability to locate the coronary sinus (CS), (2) inability to advance a catheter into the CS, (3) patients with CS atresia, (4) unstable CS access, (4) angulated target veins, (5) small and/or tortuous target veins, (6) target veins into which a wire cannot be advanced, (7) target veins with a drain pipe takeoff, (8) target veins close to the CS ostium.

Venous System Interventions for Device Implantation

Subclavian obstruction is common after lead implantation and the need to add or replace a lead is increasing. Subclavian venoplasty (SV) is a safe and effective option for venous occlusion. Peripheral venography overestimates the severity of the obstruction. A wire can usually be advanced into the central circulation for SV. Compared with dilators, SV improves the quality of venous access, providing unrestricted catheter manipulation for His bundle pacing and left ventricular lead implantation. SV preserves venous access and reduces lead burden. SV can easily be added to the implanting physicians lead management options.

Rationale and design of a randomized trial to assess the safety and efficacy of MultiPoint Pacing (MPP) in cardiac resynchronization therapy: The MPP Trial

BACKGROUND

Although the majority of Class III congestive heart failure (HF) patients treated with cardiac resynchronization therapy (CRT) show a clinical benefit, up to 40% of patients do not respond to CRT. This paper reports the design of the MultiPoint Pacing (MPP) trial, a prospective, randomized, double-blind, controlled study to evaluate the safety and efficacy of CRT using MPP compared to standard biventricular (Bi-V) pacing.

METHODS

A maximum of 506 patients with a standard CRT-D indication will be enrolled at up to 50 US centers. All patients will be implanted with a CRT-D system (Quartet LV lead Model 1458Q with a Quadra CRT-D, Abbott) that can deliver both MPP and Bi-V pacing. Standard Bi-V pacing will be activated at implant. At 3 months postimplant, patients in whom the echocardiographic parameters during MPP are equal or better than during Bi-V pacing are randomized (1:1) to either an MPP or Bi-V arm.

RESULTS

The primary safety endpoint is freedom from system-related complications at 9 months. Each patient's response to CRT will be evaluated using a heart-failure clinical composite score, consisting of a change in NYHA functional class, patient global assessment score, HF events, and cardiovascular death. The primary efficacy endpoint is the proportion of responders in the MPP arm compared with the Bi-V arm between 3 and 9 months.

CONCLUSION

This trial seeks to evaluate whether MPP via a single quadripolar LV lead improves hemodynamic and clinical responses to CRT, both in clinical responders and nonresponders.

Biventricular pacing for atrioventricular block and systolic dysfunction

BACKGROUND

Right ventricular pacing restores an adequate heart rate in patients with atrioventricular block, but high percentages of right ventricular apical pacing may promote left ventricular systolic dysfunction. We evaluated whether biventricular pacing might reduce mortality, morbidity, and adverse left ventricular remodeling in such patients.

METHODS

We enrolled patients who had indications for pacing with atrioventricular block; New York Heart Association (NYHA) class I, II, or III heart failure; and a left ventricular ejection fraction of 50% or less. Patients received a cardiac-resynchronization pacemaker or implantable cardioverter-defibrillator (ICD) (the latter if the patient had an indication for defibrillation therapy) and were randomly assigned to standard right ventricular pacing or biventricular pacing. The primary outcome was the time to death from any cause, an urgent care visit for heart failure that required intravenous therapy, or a 15% or more increase in the left ventricular end-systolic volume index.

RESULTS

Of 918 patients enrolled, 691 underwent randomization and were followed for an average of 37 months. The primary outcome occurred in 190 of 342 patients (55.6%) in the right-ventricular-pacing group, as compared with 160 of 349 (45.8%) in the biventricular-pacing group. Patients randomly assigned to biventricular pacing had a significantly lower incidence of the primary outcome over time than did those assigned to right ventricular pacing (hazard ratio, 0.74; 95% credible interval, 0.60 to 0.90); results were similar in the pacemaker and ICD groups. Left ventricular lead-related complications occurred in 6.4% of patients.

CONCLUSIONS

Biventricular pacing was superior to conventional right ventricular pacing in patients with atrioventricular block and left ventricular systolic dysfunction with NYHA class I, II, or III heart failure. (Funded by Medtronic; BLOCK HF ClinicalTrials.gov number, NCT00267098.).

Goose neck snare for LV lead placement in difficult venous anatomy

Venous anatomy frequently impairs placement of the left ventricular (LV) lead. In some cases, the wire will not advance into the vein and in others wire position is lost as the lead is advanced. This article describes how a commonly available goose neck snare is used to gain access to the distal end of the wire as it re-enters the coronary sinus retrograde via collaterals through an adjacent vein. The snare is advanced into the coronary sinus through the same catheter as the wire. The snare opens perpendicular to the long axis of the coronary sinus due to which the wire must pass through the open loop, provided the diameter of the snare is approximately the same as the coronary sinus. Thus no time-consuming manipulation of the snare is required. With access to both ends of the wire the vein is approached either retrograde (over the distal end) or antegrade (over the proximal end) while the other end of the wire is secured by the operator. Gaining control of both ends of the wire with a snare is another example of adapting interventional techniques for the device implantation. Unlike venoplasty, the snare does not evoke credentialing concerns and can be easily implemented by most implanting physicians.

Irrigated Radiofrequency Catheter Ablation Guided by Electroanatomic Mapping for Recurrent Ventricular Tachycardia After Myocardial Infarction

Background— Recurrent ventricular tachycardia (VT) is an important cause of mortality and morbidity late after myocardial infarction. With frequent use of implantable cardioverter-defibrillators, these VTs are often poorly defined and not tolerated for mapping, factors previously viewed as relative contraindications to ablation. This observational multicenter study assessed the outcome of VT ablation with a saline-irrigated catheter combined with an electroanatomic mapping system.

Methods and Results— Two hundred thirty-one patients (median LV ejection fraction, 0.25; heart failure in 62%) with recurrent episodes of monomorphic VT (median, 11 in the preceding 6 months) caused by prior myocardial infarction were enrolled. All inducible monomorphic VTs with a rate approximating or slower than any spontaneous VTs were targeted for ablation guided by electroanatomic mapping during sinus rhythm and/or VT. Patients were not excluded for multiple VTs (median, 3 per patient) or unmappable VT (present in 69% of patients). Ablation abolished all inducible VTs in 49% of patients. The primary end point of freedom from recurrent incessant VT or intermittent VT after 6 months of follow-up was achieved for 123 patients (53%). In 142 patients with implantable cardioverter-defibrillators before and after ablation for intermittent VT who survived 6 months, VT episodes were reduced from a median of 11.5 to 0 ( P <0.0001). The 1-year mortality rate was 18%, with 72.5% of deaths attributed to ventricular arrhythmias or heart failure. The procedure mortality rate was 3%, with no strokes.

Conclusions— Catheter ablation is a reasonable option to reduce episodes of recurrent VT in patients with prior myocardial infarction, even when multiple and/or unmappable VTs are present. This population remains at high risk for death, warranting surveillance and further study.

Implant venoplasty: dilation of subclavian and coronary veins to facilitate device implantation: indications, frequency, methods, and complications

Subclavian vein (SV) obstruction occurs in 13-35% of patients with prior leads, resulting in use of proximal venous access, the other vein, laser lead extraction, or surgery. Surgery is required for optimal left ventricle lead placement in 10-15% of cardiac resynchronization therapy candidates because of small or stenotic veins. Published data describe the safe and successful balloon dilation of both subclavian and coronary veins (CV); however, implant venoplasty is rarely performed because many implanting physicians are not familiar with the use of balloons. This article outlines how we use venoplasty to facilitate implantation in our laboratory. The indications, frequency, observed and potential complications that have evolved with our experience are also discussed.

Catheter cryoablation of supraventricular tachycardia: results of the multicenter prospective “frosty” trial

OBJECTIVE

To study the safety, efficacy, and mapping utility of a new cryoablation catheter.

BACKGROUND

The CryoCath Technologies Freezor catheter has been used successfully for cryoablation of supraventricular tachycardia (SVT), but has not been evaluated in a large clinical trial.

METHODS

A multicenter clinical trial to evaluate the safety, efficacy, and cryomapping utility of this cryoablation catheter was conducted in 166 subjects. The target of ablation was the slow pathway in patients with SVT due to AV nodal reentry (AVNRT, n = 103), an accessory pathway in patients with AV reentrant SVT (AVRT, n = 51) and the AV junction in patients with atrial fibrillation (AF, n = 12).

RESULTS

Acute procedural success (APS) was achieved in 83% of the overall group (95% CI, 76% to 88%). APS in the AVNRT group was 91% (98.3% CI, 82% to 97%), compared to 69% for AVRT (98.3% CI, 51% to 84%) and 67% for AF (98.3% CI, 29% to 93%), a highly significant difference (P < .001 by stepwise logistic regression). In patients with APS, long-term success after 6 months was 91% overall (95% CI, 86% to 96%) and 94% for AVNRT subjects (98.3% CI, 87% to 100%). None of the AVNRT or AVRT subjects required a permanent pacemaker. Cryomapping successfully identified ablation targets in 64% of patients in whom it was attempted. The electrophysiologic effects of cryomapping were completely reversible within minutes in 94% of such attempts.

CONCLUSIONS

Catheter cryoablation of SVT is a safe alternative to RF ablation and is clinically effective in patients with AVNRT. Cryomapping can reversibly identify targets for ablation and can help minimize the risk of inadvertent AV block during ablation.

Cardiac resynchronization therapy for the treatment of heart failure in patients with intraventricular conduction delay and malignant ventricular tachyarrhythmias

OBJECTIVES

This study was conducted to assess the safety and effectiveness of cardiac resynchronization therapy (CRT) when combined with an implantable cardioverter defibrillator (ICD).

BACKGROUND

Long-term outcome of CRT was measured in patients with symptomatic heart failure (HF), intraventricular conduction delay, and malignant ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) requiring therapy from an ICD.

METHODS

Patients (n = 490) were implanted with a device capable of providing both CRT and ICD therapy and randomized to CRT (n = 245) or control (no CRT, n = 245) for up to six months. The primary end point was progression of HF, defined as all-cause mortality, hospitalization for HF, and VT/VF requiring device intervention. Secondary end points included peak oxygen consumption (VO(2)), 6-min walk (6 MW), New York Heart Association (NYHA) class, quality of life (QOL), and echocardiographic analysis.

RESULTS

A 15% reduction in HF progression was observed, but this was statistically insignificant (p = 0.35). The CRT, however, significantly improved peak VO(2) (0.8 ml/kg/min vs. 0.0 ml/kg/min, p = 0.030) and 6 MW (35 m vs. 15 m, p = 0.043). Changes in NYHA class (p = 0.10) and QOL (p = 0.40) were not statistically significant. The CRT demonstrated significant reductions in ventricular dimensions (left ventricular internal diameter in diastole = -3.4 mm vs. -0.3 mm, p < 0.001 and left ventricular internal diameter in systole = -4.0 mm vs. -0.7 mm, p < 0.001) and improvement in left ventricular ejection fraction (5.1% vs. 2.8%, p = 0.020). A subgroup of patients with advanced HF (NYHA class III/IV) consistently demonstrated improvement across all functional status end points.

CONCLUSIONS

The CRT improved functional status in patients indicated for an ICD who also have symptomatic HF and intraventricular conduction delay.

Prospective randomized comparison of cooled radiofrequency versus standard radiofrequency energy for ablation of typical atrial flutter

In patients with atrial flutter, conventional RF ablation may not result in complete isthmus block. This prospective, randomized study tested the hypothesis that the cooled RF ablation is safe and facilitates the achievement of isthmus block with fewer RF applications than with standard ablation for typical atrial flutter. Isthmus ablation was performed in 59 patients (40 men, 64 +/- 14 years) with type I atrial flutter using standard RF (n = 31) or cooled RF (n = 28) catheters with crossover after 12 unsuccessful RF applications. The endpoint was bidirectional isthmus block or a total of 24 unsuccessful RF applications. After the first 12 RF applications, 17 (55%) of 31 standard RF and 22 (79%) of 28 cooled RF patients had bidirectional isthmus block (P < 0.05). After the remaining patients crossed over to the alternate RF ablation system and underwent up to 12 more RF applications, bidirectional isthmus block had been demonstrated in 27 (87%) of 31 standard RF and 25 (89%) of 28 cooled RF patients (P = NS). Isthmus block was not achieved within 24 RF applications in four standard and three cooled RF patients. Mean measured tip temperatures for cooled RF were lower than for standard RF (38.5 degrees C +/- 6.98 degrees C vs 57.2 degrees C +/- 7.42 degrees C, P < 0.0001). Peak temperatures were also lower for cooled RF compared to standard RF (45.7 degrees C +/- 22.7 degrees C vs 63.4 degrees C +/- 9.87 degrees C, P < 0.0001). Importantly, mean power delivered was significantly higher for cooled than for standard RF (42.3 +/- 9.48 vs 34.0 +/- 14.0 W, P < 0.0001). There were no serious complications for either ablation system. During a 12.8 +/- 3.76-month follow-up, there were two atrial flutter recurrences in the cooled RF group and four in the standard RF group (P = NS). In patients with type I atrial flutter, ablation with the cooled RF catheter is as safe as, and facilitates creation of bidirectional isthmus block more rapidly than, standard RF ablation.

Signal averaging in Wolff-Parkinson-White syndrome: evidence that fractionated activation is not necessary for body surface high-frequency potentials

It is commonly assumed that the presence of high frequency components in body surface potentials implies that fractionated activation fronts, caused by heterogeneously viable tissue, are present in the heart. However, it is possible that non-fractionated activation fronts can also give rise to high frequency surface potentials and that the relative amount of high frequency power is related to the complexity of the activation sequence. In a test of this idea, averaged body surface potentials were recorded during the entire QRS complex of nine Wolff-Parkinson-White (WPW) patients in situations in which fractionated activation fronts should not have been present, but which represent increasing degrees of complexity of ventricular activation: (1) postoperative ectopic pacing from subepicardial wires placed during surgery, when a single coherent activation front was present throughout most of the QRS; (2) Preoperative preexcited rhythm, when a single coherent activation front was present for one portion of the QRS (the delta wave); and (3) postoperative normal rhythm, when two or more activation fronts were present in the ventricles throughout most of the QRS. For comparison, averaged body surface potentials were also analyzed during the last 40 ms of the QRS complex and the ST segment of 14 postinfarction patients with chronic ventricular tachycardia. In the patients with WPW syndrome, relatively high frequency content increased (attenuation -36.7 vs -27.2 vs -18.3 dB) and QRS width decreased (160.7 vs 125.9 vs 94.1 ms) significantly from paced to preoperative to postoperative beats. Significant high frequency content was present in all cases, showing that coherent activation fronts can give rise to high frequencies. Interestingly, the postoperative QRS of WPW patients contained a larger proportion of high frequency power than did the late potentials of the patients with ventricular tachycardia. Thus, while the presence of late fractionated body surface potentials may be a marker for ventricular tachycardia, these potentials by themselves do not necessarily signify that the underlying cardiac activation giving rise to these signals is fractionated.

Use of a real-time three-dimensional magnetic navigation system for radiofrequency ablation of accessory pathways

Using conventional technology, accessory pathway ablation often requires prolonged exposure of the team and patient to ionizing radiation. Further, although the primary success rate (approximately 90%) and the rate of recurrence (approximately 10%) are acceptable, there is room for improvement. Finally, inadvertent ablation of the compact node and AV/His-Purkinje system still occurs particularly with septal accessory pathways. The Biosense CARTO Nonfluoroscopic Mapping and Navigation System (CARTO System) when used to locate the accessory pathway and guide delivery of radio frequency energy to the accessory pathway, has the potential to reduce radiation exposure, improve primary ablation success, and reduce the rate of recurrence and improve safety. This article describes our experience with the CARTO Biosense System relating to setting up the CARTO System specifically for WPW mapping/ablation, and features of the CARTO System, which are particularly advantageous for mapping and ablation of accessory pathways.

Assessment of coronary reperfusion after thrombolysis with a model combining myoglobin, creatine kinase-MB, and clinical variables. TAMI-7 Study Group. Thrombolysis and Angioplasty in Myocardial Infarction-7

BACKGROUND

Several biochemical markers have been investigated for the noninvasive assessment of reperfusion after myocardial infarction. Because myoglobin is released very soon after myocardial injury and clears rapidly after reperfusion, it may prove to be an excellent marker of occlusion and reperfusion.

METHODS AND RESULTS

We examined the relation between various myoglobin measures and Thrombolysis In Myocardial Infarction (TIMI) flow grade in 96 patients enrolled in a study of front-loaded thrombolysis who underwent 90-minute angiography. We also combined myoglobin measures with models that include clinical and creatine kinase-MB variables. The myoglobin level measured within 10 minutes of acute angiography showed the best overall performance and was used for later analyses. Of the clinical variables examined, only time from symptom onset to thrombolysis and chest pain grade at angiography discriminated among TIMI flow grades. Combining the 90-minute myoglobin level and these clinical variables showed a significant difference (P<.0001) between both TIMI 3 versus TIMI 0 through 2 and TIMI 2 or 3 versus TIMI 0 or 1 flow. When the 90-minute myoglobin level was added to an established predictive model containing clinical variables and creatine kinase-MB measures, its contribution remained significant (P=.044). The area under the receiver operator characteristic curve for this combined model was .88.

CONCLUSIONS

A single myoglobin measurement obtained 90 minutes after the start of thrombolysis, combined with select clinical variables and creatine kinase-MB levels, enhances the noninvasive prediction of reperfusion after myocardial infarction.

Combined accelerated tissue-plasminogen activator and platelet glycoprotein IIb/IIIa integrin receptor blockade with Integrilin in acute myocardial infarction. Results of a randomized, placebo-controlled, dose-ranging trial. IMPACT-AMI Investigators

BACKGROUND

Platelet activation and aggregation may be key components of thrombolytic failure to restore and maintain perfusion in acute myocardial infarction. We performed a placebo-controlled, dose-ranging trial of Integrilin, a potent inhibitor of platelet aggregation, with heparin, aspirin, and accelerated alteplase.

METHODS AND RESULTS

We assigned 132 patients in a 2:1 ratio to receive a bolus and continuous infusion of one of six Integrilin doses or placebo. Another 48 patients were randomized in a 3:1, double-blind fashion to receive the highest Integrilin dose from the first phase or placebo. All patients received accelerated alteplase, aspirin, and intravenous heparin infusion; all but two groups also received an intravenous heparin bolus. The highest Integrilin dose group from the nonrandomized phase and the randomized patients were pooled for analysis and compared with placebo-treated patients. The primary end point was Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow at 90-minute angiography. Secondary end points were time to ST-segment recovery, an in-hospital composite (death, reinfarction, stroke, revascularization procedures, new heart failure, or pulmonary edema), and bleeding variables. The highest Integrilin dose groups had more complete reperfusion (TIMI grade 3 flow, 66% versus 39% for placebo-treated patients; P = .006) and a shorter median time to ST-segment recovery (65 versus 116 minutes for placebo; P = .05). The groups had similar rates of the composite end point (43% versus 42% for placebo-treated patients) and severe bleeding (4% versus 5%, respectively).

CONCLUSIONS

The incidence and speed of reperfusion can be enhanced when a potent inhibitor of the glycoprotein IIb/IIIa integrin receptor, such as Integrilin, is combined with accelerated alteplase, aspirin, and intravenous heparin.

Multicenter comparison of truncated biphasic shocks and standard damped sine wave monophasic shocks for transthoracic ventricular defibrillation. Transthoracic Investigators

BACKGROUND

The most important factor for improving out-of-hospital ventricular fibrillation survival rates is early defibrillation. This can be achieved if small, lightweight, inexpensive automatic external defibrillators are widely disseminated. Because automatic external defibrillator size and cost are directly affected by defibrillation waveform shape and because of the favorable experience with truncated biphasic waveforms in implantable cardioverter-defibrillators, we compared the efficacy of a truncated biphasic waveform with that of a standard damped sine monophasic waveform for transthoracic defibrillation.

METHODS AND RESULTS

The principal goal of this multicenter, prospective, randomized, blinded study was to compare the first-shock transthoracic defibrillation efficacy of a 130-J truncated biphasic waveform with that of a standard 200-J monophasic damped sine wave pulse using anterior thoracic pads in the course of implantable cardioverter-defibrillator testing. Pad-pad ECGs were also examined after transthoracic defibrillation. After the elimination of data for 24 patients who did not meet all protocol criteria, the results from 294 patients were analyzed. The 130-J truncated biphasic pulse and the 200-J damped sine wave monophasic pulse resulted in first-shock efficacy rates of 86% and 86%, respectively (P = .97). ST-segment levels measured 10 seconds after the shock in 151 patients in sinus rhythm were -0.26 +/- 1.58 and -1.86 +/- 1.93 mm for the 130- and 200-J shocks, respectively (P < .0001).

CONCLUSIONS

We found that 130-J biphasic truncated transthoracic shocks defibrillate as well as the 200-J monophasic damped sine wave shocks that are traditionally used in standard transthoracic defibrillators and result in fewer ECG abnormalities after the shock.

Increased risk of non-Q wave myocardial infarction after directional atherectomy is platelet dependent: evidence from the EPIC trial. Evaluation of c7E3 for the Prevention of Ischemic Complications

OBJECTIVES

We sought to determine the effects of platelet glycoprotein IIb/IIIa receptor blockade on adverse outcomes, especially non-Q wave myocardial infarction, in patients undergoing directional atherectomy in the Evaluation of c7E3 for the Prevention of Ischemic Complications (EPIC) trial.

BACKGROUND

Randomized trials comparing directional atherectomy with percutaneous transluminal coronary angioplasty (PTCA) have demonstrated modest benefits favoring atherectomy but at a cost of increased acute ischemic complications, notably non-Q wave myocardial infarction. The mechanism for this excess risk is unknown.

METHODS

Of 2,038 high risk patients undergoing coronary intervention in the EPIC trial, directional atherectomy was performed in 197 (10%). Patients randomly received the chimeric glycoprotein IIb/IIIa antibody 7E3 (c7E3), as a bolus or a bolus and 12-h infusion or placebo. Study end points included death, myocardial infarction, repeat intervention or bypass surgery.

RESULTS

Patients undergoing directional atherectomy had a lower baseline risk for acute complications but had a higher incidence of any myocardial infarction (10.7% vs. 6.3%, p = 0.021) and non-Q wave myocardial infarction (9.6% vs. 4.9%, p = 0.006). Bolus and infusion of c7E3 reduced non-Q wave myocardial infarctions by 71% after atherectomy (15.4% for placebo vs. 4.5% for bolus and infusion, p = 0.046). Non-Q wave myocardial infarction rates after PTCA were not affected by c7E3, although Q wave myocardial infarctions were reduced from 2.6% to 0.8% (p = 0.017).

CONCLUSIONS

The EPIC trial confirmed the increased risk of non-Q wave myocardial infarction with directional atherectomy use compared with PTCA. A bolus and 12-h infusion of the glycoprotein IIb/IIIa receptor inhibitor c7E3 abolished this excess risk. Directional atherectomy-related non-Q wave myocardial infarction appears to be platelet aggregation dependent.

Frequency, significance, and cost of recurrent ischemia after thrombolytic therapy for acute myocardial infarction. TAMI Study Group

Early postinfarction angina implies an unfavorable prognosis. Most published information on this outcome represents data collected in the prethrombolytic era, in which definitions and populations differed considerably. Our purpose was to evaluate the incidence and importance of recurrent ischemia after administration of thrombolytic therapy. We studied patients enrolled in the Thrombolysis and Angioplasty in Myocardial Infarction studies. Patients were enrolled into 5 studies with similar entry criteria; 552 patients were treated with tissue plasminogen activator (t-PA), 293 were treated with urokinase, and 385 received both thrombolytic agents. Recurrent ischemia was defined as symptoms in association with electrocardiographic changes; reinfarction was defined as a reelevation of creatine kinase myocardial band isoenzyme in an appropriate clinical setting. Both recurrent ischemia and reinfarction occurred in 42 patients (3.4%), recurrent ischemia alone occurred in 226 (18%), whereas neither occurred in 964 (78%). Although baseline characteristics were similar among the 3 groups, in-hospital cardiac events (total 73 deaths, 253 heart failure episodes) were not: in-hospital mortality in patients with reinfarction was 21%; with recurrent ischemia, 11%; and with neither event, 4% (p < 0.0001). The in-hospital heart failure rate of patients with reinfarction was 50%; with recurrent ischemia alone, 31%; and with neither event, 17% (p < 0.0001). As expected, median in-hospital costs were highest in patients with reinfarction ($26,802), intermediate for those with recurrent ischemia alone ($18,422), and lowest in patients with neither event ($15,623). Recurrent myocardial ischemia after thrombolytic therapy is a frequent, important, and expensive adverse clinical outcome, making it a critical target for therapeutic intervention.

Creatine kinase MM and MB isoforms in patients receiving thrombolytic therapy and acute angiography. TAMI Study Group

Creatine kinase isoforms markers, including MB2 concentration, MB2/MB1 and MM3/MM1 ratios, and MT index (based on the "tissue" M subunits), were measured in serial specimens from 207 patients receiving thrombolytic therapy followed by acute angiography. The slope of release showed a significant relation (P < 0.05) between MB2 concentrations and patency, graded as TIMI 0 through TIMI 3; with regard to the precatheterization/baseline ratio, the MB2 concentrations, the MM3/MM1 ratio, and the MT index were all significantly related to graded patency (P < 0.004). Patients having patency graded as either TIMI 2/3 (Open) or TIMI 0/1 (Closed) showed highly significant differences (P < 0.03) in the slope of release and precatheterization/baseline ratio for all markers except the MB2/MB1 ratio. Defining Open as TIMI 3 and Closed as TIMI 0/1/2 showed very similar results. Despite these significant differences between the Open and Closed groups after thrombolytic therapy, none of the C index calculations (areas under ROC curves) for any of the isoform markers--either alone or combined--exceeded 0.70, suggesting that these markers have limited diagnostic utility for assessing patency.

Creatine kinase MM and MB isoforms in patients receiving thrombolytic therapy and acute angiography. TAMI Study Group

Creatine kinase isoforms markers, including MB2 concentration, MB2/MB1 and MM3/MM1 ratios, and MT index (based on the "tissue" M subunits), were measured in serial specimens from 207 patients receiving thrombolytic therapy followed by acute angiography. The slope of release showed a significant relation (P &lt; 0.05) between MB2 concentrations and patency, graded as TIMI 0 through TIMI 3; with regard to the precatheterization/baseline ratio, the MB2 concentrations, the MM3/MM1 ratio, and the MT index were all significantly related to graded patency (P &lt; 0.004). Patients having patency graded as either TIMI 2/3 (Open) or TIMI 0/1 (Closed) showed highly significant differences (P &lt; 0.03) in the slope of release and precatheterization/baseline ratio for all markers except the MB2/MB1 ratio. Defining Open as TIMI 3 and Closed as TIMI 0/1/2 showed very similar results. Despite these significant differences between the Open and Closed groups after thrombolytic therapy, none of the C index calculations (areas under ROC curves) for any of the isoform markers--either alone or combined--exceeded 0.70, suggesting that these markers have limited diagnostic utility for assessing patency.

Multicenter, randomized, double-blind, placebo-controlled trial of the platelet integrin glycoprotein IIb/IIIa blocker Integrelin in elective coronary intervention. IMPACT Investigators

BACKGROUND

Platelet aggregation and thrombosis have been implicated in the pathogenesis of coronary angioplasty complications. Integrelin, a synthetic cyclic heptapeptide with high affinity and marked specificity for platelet integrin glycoprotein IIb/IIIa, effectively blocks ADP-induced platelet aggregation.

METHODS AND RESULTS

In 150 patients undergoing elective percutaneous coronary intervention, random assignment was made to one of three treatment regimens: placebo; a 90-micrograms/kg bolus of Integrelin before angioplasty followed by a 1.0-micrograms.kg-1.min-1 infusion of Integrelin for 4 hours; or a 90-micrograms/kg bolus followed by a 1.0-microgram.kg-1.min-1 infusion of Integrelin for 12 hours. Patients were followed to 30 days for the composite occurrence of myocardial infarction, stent implantation, repeat urgent or emergency percutaneous intervention or coronary bypass surgery, or death. Pharmacodynamic data were obtained in a subset of 31 patients. Administration of a 90-micrograms/kg bolus of Integrelin achieved an 86% inhibition of platelet aggregation, and this inhibition was maintained by a 1.0-microgram.kg-1.min-1 infusion. There was a trend toward reduction in end-point events from 12.2% (placebo) to 9.6% (4-hour infusion) to 4.1% (12-hour infusion), although these differences were not statistically significant (P = .13 for the 12-hour group compared with placebo). Major bleeding occurred in 8%, 8%, and 2% of patients, while minor bleeding was observed in 14%, 33%, and 47% of patients, respectively. There was no difference in bleeding index among groups (1.5, 1.7, and 1.3, respectively), defined as [(change in hematocrit/3)+red blood cell units transfused].

CONCLUSIONS

This first clinical investigation of Integrelin during routine, elective, low- and high-risk coronary intervention supports the potential efficacy of Integrelin in routine coronary interventions. Pharmacodynamic analyses demonstrate that profound and sustained inhibition of platelet function is achieved, although a higher bolus dose may be required. Definitive assessment of efficacy and safety will need to await a large-scale study powered to achieve statistical significance.

Noninvasive detection of reperfusion after thrombolysis based on serum creatine kinase MB changes and clinical variables. TAMI 7 Study Group. Thrombolysis and Angioplasty in Myocardial Infarction

Coronary artery patency after thrombolytic therapy has important prognostic implications for survival after acute myocardial infarction. The ability to noninvasively identify patients early after thrombolysis may therefore allow other strategies, such as adjunctive therapy or rescue angioplasty, to be used to restore patency of the infarct-related artery. This study examined the use of a rapid creatine kinase (CK)-MB assay in conjunction with selected clinical variables for noninvasive detection of reperfusion after thrombolysis. Patients were enrolled in a study evaluating accelerated plasminogen activator dose regimens with patency assessments by first angiographic injection during acute angiography at a median and interquartile range (25th and 75th percentiles) 142 (96,195) minutes after starting thrombolytic therapy. Serum CK-MB samples measured by a rapid dual monoclonal antibody assay were obtained in 207 patients before (baseline) and 30 minutes, 90 minutes, and 3 hours after starting thrombolytic therapy. In 109 patients a CK-MB sample was obtained within 10 minutes of acute angiography (angio sample). At acute angiography the infarct-related artery was patent (Thrombolysis in Myocardial Infarction trial grade 2 to 3 flow) in 71%. Baseline CK-MB values were similar in patients with and without later reperfusion at acute angiography: 3 (0,8) ng/ml and 0 (0,4) ng/ml, respectively. At acute angiography, patients with successful reperfusion had higher CK-MB values [46 (20,138) ng/ml] compared with patients with persistent occlusion of the infarct-related artery [8 (3,63) ng/ml; p = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Cox/maze procedure for atrial septal defect with atrial fibrillation: management strategies

Atrial fibrillation is found at late follow-up in approximately half of all adults who have had correction of atrial septal defect, even if it was not present preoperatively. These patients are thus exposed to the risks of stroke and chronic drug therapy even after a successful operation. Simultaneous surgical correction of atrial septal defect and atrial fibrillation was accomplished in a 52-year-old man by means of the Cox/maze procedure. The small added risk and the substantial benefit of eliminating atrial fibrillation suggest that this approach is warranted in selected adults with atrial septal defect.

Mechanism of benefit of combination thrombolytic therapy for acute myocardial infarction: a quantitative angiographic and hematologic study

OBJECTIVES

The goal of this study was to lend insight into the mechanisms responsible for the beneficial effects of combination thrombolytic therapy.

BACKGROUND

Combination thrombolytic therapy for acute myocardial infarction has been associated with less reocclusion and fewer in-hospital clinical events than has monotherapy.

METHODS

Infarct-related quantitative coronary dimensions and hemostatic protein levels were evaluated in 287 patients with acute myocardial infarction during the early (90-min) and convalescent (7-day) phases after administration of recombinant tissue-type plasminogen activator (rt-PA), urokinase or combination rt-PA and urokinase.

RESULTS

Minimal lumen diameter was similar in the 90-min and 7-day phases after treatment with rt-PA, urokinase and combination rt-PA and urokinase (0.72 +/- 0.45 mm, 0.62 +/- 0.53 mm and 0.75 +/- 0.58 mm, respectively, at 90 min, p = 0.16; and 1.05 +/- 0.56 mm, 1.12 +/- 0.72 mm and 0.94 +/- 0.54 mm, respectively, at 7 days, p = 0.22). In-hospital clinical event and reocclusion rates were less frequent in patients receiving combination therapy than in those receiving monotherapy (25% vs. 38% and 32% for rt-PA and urokinase, respectively, p = 0.084; and 3% vs. 13% and 9% for rt-PA and urokinase, respectively, p = 0.03), but these events were unrelated to early or late coronary dimensions. Patients receiving combination therapy or urokinase monotherapy had significantly higher peak fibrin degradation products (1,307 +/- 860 and 1,285 +/- 898 micrograms/ml vs. 435 +/- 717 micrograms/ml, respectively, p < 0.0001) and lower nadir fibrinogen levels (0.85 +/- 1.00 and 0.75 +/- 0.53 g/liter vs. 1.90 +/- 0.86 g/liter, respectively, p < 0.0001) than did those receiving rt-PA monotherapy. Peak fibrinogen degradation products indirectly correlated (p = 0.004) and baseline (p = 0.026) and nadir (p = 0.089) fibrinogen levels directly correlated with reocclusion.

CONCLUSIONS

Lower in-hospital clinical event and reocclusion rates observed with combination thrombolytic therapy may relate to systemic hematologic factors rather than to the residual lumen obstruction after thrombolysis.

Accelerated plasminogen activator dose regimens for coronary thrombolysis. The TAMI-7 Study Group

To determine the clinical profile and efficacy of accelerated recombinant tissue-type plasminogen activator (rt-PA) dose regimens, five different strategies of thrombolytic therapy in a total of 232 patients were systematically evaluated in the setting of acute myocardial infarction. The fifth strategy involved a combination of accelerated rt-PA and intravenous urokinase (regimen E). A weight-adjusted dose of 1.25 mg/kg body weight of tissue plasminogen activator over 90 min (regimen C) yielded the highest coronary patency rate (83%) at acute angiography. The associated in-hospital reocclusion rate for this regimen was low (4%). An exaggerated (60-min) dosage regimen yielded an inferior coronary patency rate (63%). Combination therapy (regimen E) was associated with a 72% patency rate and 3% reocclusion rate. Marginal improvement in global ejection fraction and regional wall function was demonstrated with all strategies by predischarge catheterization. Bleeding complications were most common at the periaccess site and were not different from those in previous experiences reported with conventional 3-h dosing regimens. Measurements of baseline, 30-min and 3-h levels of tissue plasminogen activator, fibrinogen and fibrin(ogen) degradation products were obtained. At 3 h, fibrinogen levels of less than 1 g/liter were demonstrated with combination therapy (regimen E) as well as with regimen C. Major clinical outcomes including death, reocclusion and reinfarction also showed a tendency to be less common with regimen C. Therefore, although accelerated dose regimens of rt-PA do not reliably yield acute coronary patency rates greater than 85%, an acute coronary patency rate of approximately 85% can be approached.(ABSTRACT TRUNCATED AT 250 WORDS)

Determinants of the need for early acute intervention in patients treated conservatively after thrombolytic therapy for acute myocardial infarction. TAMI-5 Study Group

This study sought to determine whether clinical variables can be used to identify patients at high risk of recurrent spontaneous myocardial ischemia or hemodynamic compromise during the 1st 4 days after intravenous thrombolysis for acute myocardial infarction. Of 288 patients randomly assigned to a conservative postthrombolysis strategy, 54 (19%) required urgent cardiac catheterization within 24 h; 75 (26%) underwent urgent cardiac catheterization within 4 days of admission. Of the clinical variables examined by multiple logistic regression analysis, only patient age and anterior wall myocardial infarction correlated with the need for urgent cardiac catheterization (p = 0.0016 and p = 0.017, respectively). Compared with recombinant tissue-type plasminogen activator or urokinase monotherapy, combination therapy with these agents was associated with a lower need for acute intervention during the 1st 24 h after admission, but the difference did not reach statistical significance (14% for combination therapy vs. 21% for each agent alone, p = 0.30). Of the 75 patients undergoing urgent coronary angiography, only 39% had an occluded infarct-related artery. Emergency coronary angioplasty was performed in 49% of the patients and coronary artery bypass graft surgery was performed urgently in 3%. Despite these interventions, the need for urgent cardiac catheterization was associated with an in-hospital mortality rate of 7% (vs. 3% in the group not requiring urgent angiography, p = 0.36); mean left ventricular ejection fraction was 50.5 +/- 11% (vs. 54.3 +/- 10.8%, p = 0.12) and regional infarct zone wall motion was -2.68 +/- 1.07 SD/chord (vs. -2.46 +/- 1.19 SD/chord; p = 0.44).(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of combination thrombolytic therapy and timing of cardiac catheterization in acute myocardial infarction. Results of thrombolysis and angioplasty in myocardial infarction--phase 5 randomized trial. TAMI Study Group

Recent trials of myocardial reperfusion using single-agent thrombolytic therapy and sequential cardiac catheterization have supported a conservative approach to the patient with acute myocardial infarction. To evaluate combination thrombolytic therapy and the role of a previously untested strategy for the aggressive use of cardiac catheterization, we performed a multicenter clinical trial with a 3 x 2 factorial design in which 575 patients were randomly allocated to one of three drug regimens--tissue-type plasminogen activator (t-PA) (n = 191), urokinase (n = 190), or both (n = 194) - and one of two catheterization strategies--immediate catheterization with angioplasty for failed thrombolysis (n = 287) or deferred predischarge catheterization on days 5-10 (n = 288). Patients with contraindications to thrombolytic therapy, cardiogenic shock, or age of more than 75 years were excluded. Global left ventricular ejection fraction was well preserved and almost identical at predischarge catheterization (54%), regardless of the catheterization or thrombolytic strategy used (p = 0.98). Combination thrombolytic therapy was associated with a less complicated clinical course, most clearly documented by a lower rate of reocclusion (2%) compared with urokinase (7%) and t-PA (12%) (p = 0.04) and a lower rate of recurrent ischemia (25%) compared with urokinase (35%) and t-PA (31%). When a composite clinical end point (e.g., death, stroke, reinfarction, reocclusion, heart failure, or recurrent ischemia) was examined, combination thrombolytic therapy was associated with greater freedom from any adverse event (68%) compared with either single agent (urokinase, 55%; t-PA, 60%) (p = 0.04) and with a less complicated clinical course when the composite clinical end points were ranked according to clinical severity (p = 0.024). Early patency rates were greater with combination therapy, although predischarge patency rates after considering interventions to maintain patency were similar among drug regimens. No difference in bleeding complication rates was observed with any thrombolytic regimen. The aggressive catheterization strategy led to an overall early patency rate of 96% and a predischarge patency rate of 94% compared with a 90% predischarge patency in the conservative strategy (p = 0.065). The aggressive strategy improved regional wall motion in the infarct region (-2.16 SDs/chord) compared with deferred catheterization (-2.49 SDs/chord) (p = 0.004). More patients treated with the aggressive strategy were free from adverse outcomes (67% versus 55% in the conservative strategy, p = 0.004), and the clinical course was less complicated when the adverse outcomes were ranked according to severity (p = 0.016). No significant increase in use of blood products resulted from the aggressive strategy.(ABSTRACT TRUNCATED AT 400 WORDS)

Electrohydraulic shock wave decalcification of stenotic aortic valves: postmortem and intraoperative studies

Decalcification of stenotic aortic valves is limited by the difficulty in removing sufficient calcium to restore valve function without cusp perforation. The present study demonstrates that electrohydraulic shock waves generated by a hand-held lithotriptor fragmented the calcifications contained within the cusps of four necropsy specimens of stenotic aortic valves. The electrohydraulic shock waves appeared to create a cleavage plane between the valve tissue and the fragmented calcific deposits, allowing the fragmented calcified masses to be removed without cusp perforation. Five patients with severe aortic stenosis also underwent successful aortic valve decalcification augmented by electrohydraulic shock waves generated with the hand-held lithotriptor, without significant complication. The shock waves permitted removal, from the aortic valve, of calcium that had not been removed by mechanical means. These results indicate that the addition of electrohydraulic shock waves to mechanical aortic valve decalcification may facilitate successful decalcification in patients undergoing operative treatment for aortic stenosis and may allow patients to avoid the need for aortic valve replacement.

Comparison of time domain and frequency domain variables from the signal-averaged electrocardiogram: a multivariable analysis

The relative values of the unprocessed signal-averaged electrocardiogram (ECG) and time domain analysis and frequency domain analysis of the signal-averaged ECG were compared in 36 patients with sustained monomorphic ventricular tachycardia and a remote myocardial infarction, in 29 asymptomatic patients with a remote myocardial infarction and in 23 normal subjects. Area ratios of the energy spectra derived from fast Fourier transform analysis were calculated using six separate 140 ms intervals starting at 0, 40, 50 and 60 ms after QRS onset; 40 and 50 ms before QRS end and a variable length interval starting 40 ms before QRS end and extending to the T wave. Total filtered QRS duration, late potential duration and root mean square voltage of the terminal QRS complex were measured from the filtered vector magnitude signal-averaged ECG. The total QRS duration was also measured from the X, Y, Z leads of the unfiltered signal-averaged ECG. Seven variables were significantly different in univariate tests between myocardial infarction patients with and without ventricular tachycardia: three fast Fourier transform area ratios with the sampling interval starting at 1) QRS onset (p = 0.007), 2) 40 ms after QRS onset (p = 0.02), and 3) 60 ms after QRS onset (p less than 0.0001); and all four time domain variables at 1) total filtered QRS duration (p less than 0.0001), 2) late potential duration (p = 0.0001), 3) root mean square terminal QRS voltage (p = 0.0001), and 4) QRS duration from the unprocessed signal-averaged ECG (p less than 0.0001). Of these seven variables, only the fast Fourier transform area ratio starting at QRS onset was significantly different between patients with myocardial infarction without ventricular tachycardia and normal subjects. In multi-variable analysis, the total filtered vector magnitude QRS duration, a time domain variable that includes the late potential, was the only independent factor that separated patients with myocardial infarction with and without associated ventricular tachycardia.