J. Anthony Gomes

A new noninvasive index to predict sustained ventricular tachycardia and sudden death in the first year after myocardial infarction: Based on signal-averaged electrocardiogram, radionuclide ejection fraction and holter monitoring

A prospective study of the prognostic significance of the signal-averaged electrocardiogram (ECG), left ventricular function and 24 hour Holter ECG monitoring was performed in 102 patients (age 63 +/- 11 years) after myocardial infarction. The signal-averaged ECG (40 Hz high pass bidirectional filtering) was obtained 10 +/- 6 days after the acute myocardial infarction and all three tests were performed within 72 hours of each other. Ejection fraction was determined by radionuclide ventriculography. An abnormal signal-averaged ECG was seen in 44% of patients; abnormal ejection fraction (less than 40%) in 52% and high grade ectopic activity (greater than or equal to 10 ventricular premature depolarizations/h or couplets, or nonsustained ventricular tachycardia, or a combination of these) in 62%. During a 12 +/- 6 month follow-up period, 15 patients (14.7%) had an arrhythmic event defined as sustained ventricular tachycardia or sudden cardiac death, or both. The event rates were higher in patients with an abnormal versus a normal signal-averaged ECG (29 versus 3.5%, p = 0.003), an abnormal versus a normal ejection fraction (24 versus 6%, p = 0.001) and the presence versus the absence of high grade ectopic activity (23 versus 9%, p = 0.09). Patients with an abnormal signal-averaged ECG and an abnormal ejection fraction had a significantly higher (p = 0.0007) event rate than did patients in whom both the tests were normal (36 versus 0%; odds ratio 30.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Risk stratification of individuals with the Brugada electrocardiogram: a meta-analysis.

Objectives: We performed a meta‐analysis of prognostic studies of patients with a Brugada ECG to assess predictors of events.

The prognostic significance of quantitative signal-averaged variables relative to clinical variables, site of myocardial infarction, ejection fraction and ventricular premature beats: A prospective study☆

A prospective study was undertaken of the prognostic significance of quantitative signal-averaged electrocardiographic (ECG) variables relative to clinical variables, site of myocardial infarction, left ventricular ejection fraction and characteristics of ventricular premature beats in 115 patients (mean age 62 +/- 12 years) studied 10 +/- 6 days after myocardial infarction. Signal-averaged variables included the root mean square voltage of the terminal 40 ms, the duration of the filtered signal-averaged QRS complex and low amplitude signals less than 40 microV determined at 25 and 40 Hz high pass filtering in all patients. Of the 115 patients, 51 (44%) had an abnormal signal-averaged ECG (one or more abnormal signal-averaged variables), 51 (44%) at 25 Hz and 48 (42%) at 40 Hz high pass filtering. A higher proportion of patients with an inferior wall infarction had an abnormal signal-averaged ECG as compared with patients with anterior wall infarction (58% versus 31%). Over a 14 +/- 8 month follow-up period 16 patients (14%) had an arrhythmic event. An abnormal signal-averaged ECG at 40 Hz high pass filtering had a higher sensitivity (81% versus 75%) and specificity (65% versus 61%) than at 25 Hz high pass filtering. The predictive value of the signal-averaged ECG was superior to that of the ejection fraction (40% versus 20%) in anterior wall myocardial infarction, whereas in patients with inferior wall infarction, the predictive values of the two tests were equivalent. The prognostic power of 27 clinical and noninvasive variables was determined with the Cox proportional hazards regression model.(ABSTRACT TRUNCATED AT 250 WORDS)

Sustained ventricular tachycardia associated with sarcoidosis: Assessment of the underlying cardiac anatomy and the prospective utility of programmed ventricular stimulation, drug therapy and an implantable antitachycardia device

The presentation, cardiac anatomy and utility of programmed ventricular stimulation in seven patients with sustained ventricular tachycardia associated with sarcoidosis are described. The mean patient age was 38 +/- 8 years. Pulmonary involvement was apparent in three patients and no systemic manifestations of sarcoidosis were present in one patient. All patients had electrocardiographic abnormalities at rest and six had a left ventricular ejection fraction less than 45%. All seven patients had left ventricular wall motion abnormalities and five had mitral valve dysfunction. Sustained ventricular tachycardia was easily induced in all patients. Spontaneous sustained ventricular tachycardia was not prevented with corticosteroid administration. Despite antiarrhythmic drug therapy, two patients had sudden cardiac death and an additional four had recurrence of ventricular tachycardia. Four patients had an automatic cardioverter-defibrillator implanted and received drug therapy; all four received appropriate shocks. This report represents the largest descriptive series of consecutive patients with sustained ventricular tachycardia associated with sarcoidosis. Antiarrhythmic drug therapy of ventricular tachycardia in patients with sarcoidosis, even when guided with programmed ventricular stimulation, is associated with a high rate of arrhythmia recurrence or sudden death, or both. Thus, implantation of an automatic antitachycardia device (cardioverter-defibrillator) should be considered as primary therapy in such patients. Furthermore, sarcoidosis should be excluded, with Kveim skin testing if necessary, in any patient with sustained ventricular tachycardia of unknown origin.

Oral d,lsotalol reduces the incidence of postoperative atrial fibrillation in coronary artery bypass surgery patients: a randomized, double-blind, placebo-controlled study

Abstract OBJECTIVES The purpose of this prospective, randomized, double-blind, placebo-controlled study was to assess the efficacy of preoperatively and postoperatively administered oral d,lsotalol in preventing the occurrence of postoperative atrial fibrillation (AF). BACKGROUND Atrial fibrillation is the most common arrhythmia following coronary artery bypass surgery (CABG). Its etiology, prevention and treatment remain highly controversial. Furthermore, its associated morbidity results in a prolongation of the length of hospital stay post-CABG. METHODS A total of 85 patients, of which 73 were to undergo CABG and 12 CABG plus valvular surgery (ejection fraction ≥28% and absence of clinical heart failure), were randomized to receive either sotalol (40 patients; mean dose = 190 ± 43 mg/day) started 24 to 48 h before open heart surgery and continued for four days postoperatively, or placebo (45 patients, mean dose = 176 ± 32 mg/day). RESULTS Atrial fibrillation occurred in a total of 22/85 (26%) patients. The incidence of postoperative AF was significantly (p = 0.008) lower in patients on sotalol (12.5%) as compared with placebo (38%). Significant bradycardia/hypotension, necessitating drug withdrawal, occurred in 2 of 40 (5%) patients on sotalol and none in the placebo group (p = 0.2). None of the patients on sotalol developed Torsade de pointes or sustained ventricular arrhythmias. Postoperative mortality was not significantly different in sotalol versus placebo (0% vs. 2%, p = 1.0). Patients in the sotalol group had a nonsignificantly shorter length of hospital stay as compared with placebo (7 ± 2 days vs. 8 ± 4 days; p = 0.24). CONCLUSIONS The administration of sotalol, in dosages ranging from 80 to 120 mg, was associated with a significant decrease (67%) in postoperative AF in patients undergoing CABG without appreciable side effects. Sotalol should be considered for the prevention of postoperative AF in patients undergoing CABG in the absence of heart failure and significant left ventricular dysfunction.

Sudden Death in Coronary Artery Disease Acute Ischemia Versus Myocardial Substrate

Sudden cardiac death accounts for ≈50% of the estimated 500 000 cardiovascular deaths that occur annually in the United States, and a vast majority are the result of coronary artery disease.1-4 Although in some subjects there is a history of angina pectoris, myocardial infarction, or previous cardiac arrest, a significant proportion of events occur in subjects without any history of cardiac disease.1,5 Advanced therapies such as thrombolytic agents and implantable cardioverter/defibrillators are of no value to the thousands of victims who do not survive to receive medical attention. Because so many instances of sudden cardiac death cannot be predicted, any intervention directed toward the general community would have to be applied to an estimated 1000 persons for every 1 person in whom sudden death might be prevented.6 Ventricular tachyarrhythmias are responsible for most cases of sudden cardiac death, although there is more than one mechanism for these arrhythmias. Some victims die from ventricular fibrillation, which can result from acute coronary ischemic thrombosis in an otherwise normal heart,7-9 whereas others die from tachyarrhythmias arising from chronic scar.9 The relative incidence of the two mechanisms is uncertain due to (1) the lack of a consistent definition of sudden cardiac death, especially in terms of the timing between the onset of symptoms and death, and (2) the frequent overlap of the two mechanisms. Most authors define sudden death as that which occurs within 1 hour of the onset or abrupt change of symptoms.1 Some earlier series used more liberal criteria and included subjects who died up to 24 hours after symptom onset.10 However, there are important pathophysiological differences between deaths that occur instantaneously and those that occur hours after the onset of symptoms, as noted by Friedman et al11 more than 2 decades ago. Most …

Optimal Bandpass Filters for Time-Domain Analysis of the Signal-Averaged Electrocardiogram

The optimal bandpass filter for signal averaging of the surface QRS complex to detect late potentials is undefined. A study was conducted in 87 patients; 25 (mean age 34 +/- 10 years) were normal (group I), 29 (60 +/- 20 years) had organic heart disease without ventricular tachycardia (group II) and 33 (62 +/- 15 years) had sustained ventricular tachycardia (group III). In all patients signal-averaged electrocardiography (200 beats) was performed using a sharp, bidirectional filter and data analyzed using the following 7 high-pass filter settings: 10, 15, 20, 25, 40, 80 and 100 Hz. For each filter the duration of the signal-averaged QRS complex, the low-amplitude signals of less than 40 microV and the root-mean-square voltage of the terminal 40 ms (RMS-40) were determined. Normal values for each filter were determined from group I patients. In all 3 groups, quantitative signal-averaged variables were filter dependent. There was a progressive and marked decrease in RMS-40 and a progressive and marked increase in low-amplitude signal duration as the high-pass filtering was increased from 10 to 100 Hz. In contrast, high-pass, filter-dependent changes in signal-averaged QRS duration were less marked. The sensitivity and specificity for each filter using RMS-40 as the index of late potentials in separating group III patients from group II patients were: 10 Hz-64% and 52%; 15 Hz-57% and 72%; 20 Hz-57% and 76%; 25 Hz-42% and 90%; 40 Hz-61% and 83%; 80 Hz-88% and 69%; and 100 Hz-79% and 62%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Signal averaging of the surface QRS complex predicts inducibility of ventricular tachycardia in patients with syncope of unknown origin: A prospective study

Forty patients with syncope of unknown origin underwent quantitative signal averaging of the surface QRS complex before invasive electrophysiologic testing with programmed ventricular stimulation. Of 34 patients without bundle branch block, 12 had inducible ventricular tachycardia (Group I) and 22 did not (Group II). The duration of low amplitude signals, the root mean square voltage of the terminal 40 ms and the signal-averaged QRS vector duration were measured in each case. One or more abnormal signal averaging variables were present in 92% of patients in Group I, but in only 27% of patients in Group II (p less than 0.005). An abnormal root mean square voltage of the terminal 40 ms was the most significant distinguishing variable, being present in 83% of Group I patients and in only 14% of Group II patients (p less than 0.005). The QRS vector duration was prolonged in 58% of Group I patients, but in only 9% of Group II patients (p less than 0.05). Likewise, the duration of low amplitude signals was prolonged in 58% of Group I patients, but in only 19% of Group II patients (p less than 0.05). When compared with 24 hour ambulatory electrocardiographic monitoring, the presence of abnormal signal averaging variables was more predictive of inducible ventricular tachycardia. Seven (32%) Group II patients had greater than or equal to 10 ventricular premature beats/h, couplets or episodes of nonsustained ventricular tachycardia; however, none had abnormal late potentials recorded. In contrast, three patients (25%) in Group I had less than 10 ventricular premature beats/h, although all in that group had one or more abnormal signal-averaged variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation and Entrainment Mapping of Hemodynamically Unstable Ventricular Tachycardia Using a Percutaneous Left Ventricular Assist Device

OBJECTIVES Our goal was to investigate the effects of percutaneous left ventricular assist device (pLVAD) support during catheter ablation of unstable ventricular tachycardia (VT). BACKGROUND Mechanical cardiac support during ablation of unstable VT is being increasingly used, but there is little available information on the potential hemodynamic benefits. METHODS Twenty-three consecutive procedures in 22 patients (ischemic, n = 11) with structural heart disease and hemodynamically unstable VT were performed with either pLVAD support (n = 10) or no pLVAD support (intra-aortic balloon pump counterpulsation, n = 6; no support, n = 7). Procedural monitoring included vital signs, left atrial pressure, arterial blood pressure, cerebral perfusion/oximetry, VT characteristics, and ablation outcomes. RESULTS The pLVAD group was maintained in VT significantly longer than the non-pLVAD group (66.7 min vs. 27.5 min; p = 0.03) and required fewer early terminations of sustained VT for hemodynamic instability (1.0 vs. 4.0; p = 0.001). More patients in the pLVAD group had at least 1 VT termination during ablation than non-pLVAD patients (9 of 10 [90%] vs. 5 of 13 [38%]; p = 0.03). There were no differences between groups in duration of cerebral deoxygenation, hypotension or perioperative changes in left atrial pressure, brain natriuretic peptide levels, lactic acid, or renal function. CONCLUSIONS In patients with scar-related VT undergoing catheter ablation, pLVAD support was able to safely maintain end-organ perfusion despite extended periods of hemodynamically unstable VT. Randomized studies are necessary to determine whether this enhanced ability to perform entrainment and activation mapping will translate into a higher rate of clinical success.

The role of silent ischemia, the arrhythmic substrate and the short-long sequence in the genesis of sudden cardiac death

To study the role of silent ischemia and the arrhythmic substrate in the genesis of sudden cardiac death, 67 patients were studied (mean age 62 +/- 12 years). Of these, 14 patients (Group 1) had an in-hospital episode of ventricular tachycardia or fibrillation while wearing a 24 h Holter ambulatory electrocardiographic (ECG) monitor, 33 (Group II) had a documented episode of sustained ventricular tachycardia or fibrillation, or both, and 20 (Group III) had angina pectoris but no ventricular tachycardia or fibrillation. Eight Group I survivors underwent programmed electrical stimulation or ECG signal averaging, or both. All Group II patients underwent 24 h Holter monitoring and ECG signal averaging to detect late potentials before programmed electrical stimulation. Group III patients underwent both 24 h Holter recording and coronary angiography. The 24 h ECG tapes were analyzed for ST segment changes, prematurity index and characteristics of ventricular premature depolarizations. Any ST depression greater than or equal to 1 mm for greater than 30 s was considered to be a reflection of silent ischemia, and the induction of ventricular tachycardia or fibrillation by programmed electrical stimulation or the presence of late potentials, or both, was considered to be a reflection of the arrhythmia substrate. Silent ischemia preceded ventricular tachycardia in only 2 (14%) of the 14 Group I patients. The prematurity index was less than 1 in only 18% of ventricular tachycardia episodes.(ABSTRACT TRUNCATED AT 250 WORDS)