Sergio L. Pinski

Electrocardiographic Diagnosis of Evolving Acute Myocardial Infarction in the Presence of Left Bundle-Branch Block

BACKGROUND The presence of left bundle-branch block on the electrocardiogram may conceal the changes of acute myocardial infarction, which can delay both its recognition and treatment. We tested electrocardiographic criteria for the diagnosis of acute infarction in the presence of left bundle-branch block. METHODS The base-line electrocardiograms of patients enrolled in the GUSTO-1 (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) trial who had left bundle-branch block and acute myocardial infarction confirmed by enzyme studies were blindly compared with the electrocardiograms of control patients who had chronic coronary artery disease and left bundle-branch block. The electrocardiographic criteria for the diagnosis of infarction were then tested in an independent sample of patients presenting with acute chest pain and left bundle-branch block. RESULTS Of 26,003 North American patients, 131 (0.5 percent) with acute myocardial infarction had left bundle-branch block. The three electrocardiographic criteria with independent value in the diagnosis of acute infarction in these patients were an ST-segment elevation of 1 mm or more that was concordant with (in the same direction as) the QRS complex; ST-segment depression of 1 mm or more in lead V1, V2, or V3; and ST-segment elevation of 5 mm or more that was disconcordant with (in the opposite direction from) the QRS complex. We used these three criteria in a multivariate model to develop a scoring system (0 to 10), which allowed a highly specific diagnosis of acute myocardial infarction to be made. CONCLUSIONS We developed and validated a clinical prediction rule based on a set of electrocardiographic criteria for the diagnosis of acute myocardial infarction in patients with chest pain and left bundle-branch block. The use of these criteria, which are based on simple ST-segment changes, may help identify patients with acute myocardial infarction, who can then receive appropriate treatment.

Electrical Storm Presages Nonsudden Death

Background—Electrical storm, multiple temporally related episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF), is a frequent problem among recipients of implantable cardioverter defibrillators (ICDs). However, insufficient data exist regarding its prognostic significance. Methods and Results—This analysis includes 457 patients who received an ICD in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial and who were followed for 31±13 months. Electrical storm was defined as ≥3 separate episodes of VT/VF within 24 hours. Characteristics and survival of patients surviving electrical storm (n=90), those with VT/VF unrelated to electrical storm (n=184), and the remaining patients (n=183) were compared. The 3 groups differed in terms of ejection fraction, index arrhythmia, revascularization status, and baseline medication use. Survival was evaluated using time-dependent Cox modeling. Electrical storm occurred 9.2±11.5 months after ICD implantation, and most episodes (86%) were ...

Natural history of isolated bundle branch block

The purpose of this study was to determine the long-term outcome of patients with bundle branch block (BBB) who have no clinical evidence of cardiovascular disease. Among 110,000 participants in a screening program, 310 subjects with BBB without apparent of suspected heart disease were identified. Their outcome after a mean follow-up of 9.5 years was compared with that of 310 similarly screened age- and sex-matched controls. Among the screened population, isolated right BBB was more prevalent than isolated left BBB (0.18% vs 0.1%, respectively; p<0.001), and the prevalence of each abnormality increased with age (p<0.001). Total actuarial survival was no different for those with left BBB or right BBB and their respective controls. Cardiac mortality, however, was increased in the left BBB group when compared with their controls (p=0.01, log rank test). Left BBB, but not right BBB, was associated with an increased prevalence of cardiovascular disease at the follow-up (21% vs 11%; p=0.04). In the absence of clinically overt cardiac disease, the presence of left BBB or right BB is not associated with increased overall mortality. Isolated left BBB is associated with an increased risk of developing overt cardiovascular disease and increased cardiac mortality.

Interference in Implanted Cardiac Devices, Part I

Sensing intrinsic cardiac electrical activity is essential for the function of pacemakers and implantable cardioverter defibrillators (ICDs). Examples of undesired triggering or inhibition of pacemaker output by extraneous signals were identified early after the introduction of noncompetitive, “ demand” pacemakers. Hermetic shielding in metal cases, filtering, and interference rejection circuits, together with a preference (much more marked in the United States 1 than in Europe 2 ) for bipolar sensing, made contemporary pacemakers and ICDs relatively immune to electromagnetic energy sources in homes and workplaces. Sources of electromagnetic interference (EMI) remained ubiquitous in the medical environment. However, they were predictable and avoidable. New technologies that use more of the electromagnetic spectrum (i.e., wireless telephones, electronic article surveillance [EAS] devices) have rekindled interest in EMI risks for patients with implanted cardiac devices. Although these technologies do not constitute a major public health threat, adverse interactions can occur. The counterpart to EMI is electromagnetic compatibility, a science aimed at avoiding interference potential by adding shielding or redesigning circuits against specific EMI sources. There are three essential elements to any electromagnetic compatibility problem. There must be an electromagnetic source, a receptor or victim (in our case the implanted cardiac device) that cannot function properly due to the electromagnetic phenomenon, and a path between them that allows the source to interfere with the receptor. Each of these three elements must be present, although they may not be readily identified in every situation. Identifying at least two of these elements and eliminating (or attenuating) one of them generally solves electromagnetic compatibility problems. Collaboration among industry, physicians, regulatory agencies, and consumer groups will hopefully achieve full compatibility between implanted devices and other technologies. This will require adoption of international standards establishing the upper limit of permissible field intensities for the whole electromagnetic spectrum. Implanted devices should not react to fields below this limit; more intense fields will be prohibited. This two-part review discusses EMI with implanted cardiac devices. The first part of the review addresses general concepts and specific sources of EMI in everyday life and the workplace. The second part focuses on medical sources of EMI, highlighting preventive measures.

Chronic atrial fibrillation and stroke in paced patients with sick sinus syndrome. Relevance of clinical characteristics and pacing modalities.

BACKGROUND The goal of the report was to study the long-term incidence and the independent predictors for chronic atrial fibrillation and stroke in 507 paced patients with sick sinus syndrome, adjusting for differences in baseline clinical variables with multivariate analysis. METHODS AND RESULTS From 1980 to 1989, we implanted 376 dual-chamber, 19 atrial, and 112 ventricular pacemakers to treat patients with sick sinus syndrome. After a maximum follow-up of 134 months (mean: 59 +/- 38 months for chronic atrial fibrillation, 65 +/- 37 months for stroke), actuarial incidence of chronic atrial fibrillation was 7% at 1 year, 16% at 5 years, and 28% at 10 years. Independent predictors for this event, from Coxs proportional hazards model, were history of paroxysmal atrial fibrillation (P < .001; hazard ratio [HR] = 16.84), use of antiarrhythmic drugs before pacemaker implant (P < .001; HR = 2.25), ventricular pacing mode (P = .003; HR = 1.98), age (P = .005; HR = 1.03), and valvular heart disease (P = .008; HR = 2.05). For patients with preimplant history of paroxysmal atrial fibrillation, independent predictors were prolonged episodes of paroxysmal atrial fibrillation (P < .001; HR = 2.56), long history of paroxysmal atrial fibrillation (P = .004; HR = 2.05), ventricular pacing mode (P = .025; HR = 1.69), use of antiarrhythmic drugs before pacemaker implant (P = .024; HR = 1.71), and age (P = .04; HR = 1.02). Actuarial incidence of stroke was 3% at 1 year, 5% at 5 years, and 13% at 10 years. Independent predictors for stroke were history of cerebrovascular disease (P < .001; HR = 5.22), ventricular pacing mode (P = .008; HR = 2.61), and history of paroxysmal atrial fibrillation (P = .037; HR = 2.81). CONCLUSIONS Development of chronic atrial fibrillation and stroke in paced patients with sick sinus syndrome are strongly determined by clinical variables and secondarily by the pacing modality. Ventricular pacing mode predicts chronic atrial fibrillation in patients with preimplant paroxysmal atrial fibrillation but not in those without it.

Radiofrequency catheter ablation for management of symptomatic ventricular ectopic activity

OBJECTIVES This study assessed the useful role of intracardiac mapping and radiofrequency catheter ablation in eliminating drug-refractory monomorphic ventricular ectopic beats in severely symptomatic patients. BACKGROUND Ventricular ectopic activity is commonly encountered in clinical practice. Usually, it is not associated with life-threatening consequences in the absence of significant structural heart disease. However, frequent ventricular ectopic beats can be extremely symptomatic and even incapacitating in some patients. Currently, reassurance and pharmacologic therapy are the mainstays of treatment. There has been little information on the use of catheter ablation in such patients. METHODS Ten patients with frequent and severely symptomatic monomorphic ventricular ectopic beats were selected from three tertiary care centers. The mean frequency +/- SD of ventricular ectopic activity was 1,065 +/- 631 beats/h (range 280 to 2,094) as documented by baseline 24-h ambulatory electrocardiographic (ECG) monitoring. No other spontaneous arrhythmias were documented. These patients had previously been unable to tolerate or had been unsuccessfully treated with a mean of 5 +/- 3 antiarrhythmic drugs. The site of origin of ventricular ectopic activity was accurately mapped by using earliest endocardial activation time during ectopic activity or pace mapping, or both. RESULTS During electrophysiologic study, no patient had inducible ventricular tachycardia. The ectopic focus was located in the right ventricular outflow tract in nine patients and in the left ventricular posteroseptal region in one patient. Frequent ventricular ectopic beats were successfully eliminated by catheter-delivered radiofrequency energy in all 10 patients. The mean number of radiofrequency applications was 2.6 +/- 1.3 (range 1 to 5). No complications were encountered. During a mean follow-up period of 10 +/- 4 months, no patient had a recurrence of symptomatic ectopic activity, and 24-h ambulatory ECG monitoring showed that the frequency of ventricular ectopic activity was 0 beat/h in seven patients, 1 beat/h in two patients and 2 beats/h in one patient. CONCLUSIONS Radiofrequency catheter ablation can be successfully used to eliminate monomorphic ventricular ectopic activity. It may therefore be a reasonable alternative for the treatment of severely symptomatic, drug-resistant monomorphic ventricular ectopic activity in patients without significant structural heart disease.

Cost-Effectiveness of the Implantable Cardioverter-Defibrillator Versus Antiarrhythmic Drugs in Survivors of Serious Ventricular Tachyarrhythmias Results of the Antiarrhythmics Versus Implantable Defibrillators (AVID) Economic Analysis Substudy

Background—The implantable cardioverter-defibrillator (ICD) is an effective but expensive device. We used prospectively collected data from a large randomized clinical trial of secondary prevention of life-threatening ventricular arrhythmias to determine the cost-effectiveness of the ICD compared with antiarrhythmic drug (AAD) therapy, largely with amiodarone. Methods and Results—Charges for initial and repeat hospitalizations, emergency room, and day surgery stays and the costs of antiarrhythmic drugs were collected on 1008 patients. Detailed records of all other medical encounters and expenses were collected on a subgroup of 237 patients. Regression models were then created to attribute these expenses to the rest of the patients. Charges were converted to 1997 costs using standard methods. Costs and life years were discounted at 3% per year. Three-year survival data from the Antiarrhythmics Versus Implantable Defibrillators trail were used to calculate the base-case cost-effectiveness (C/E) ratio. Six-year, twenty-year, and lifetime C/E ratios were also estimated. At 3 years, total costs were

Acute Myocardial Infarction and Complete Bundle Branch Block at Hospital Admission: Clinical Characteristics and Outcome in the Thrombolytic Era

71 421 for a patient taking AADs and

Cardiac pacing: the state of the art

85 522 for a patient using an ICD, and the ICD provided a 0.21-year survival benefit over AAD treatment. The base-case C/E ratio was thus

Is hospital admission for initiation of antiarrhythmic therapy with sotalol for atrial arrhythmias required?: yield of in-hospital monitoring and prediction of risk for significant arrhythmia complications

66 677 per year of life saved by the ICD compared with AAD therapy (95% CI,