Long-term outcome following programmed electrical stimulation in patients with high-grade ventricular ectopy

QT dispersion in nonsustained ventricular tachycardia and coronary artery disease

This study examines the relation between QT dispersion and the inducibility of ventricular tachycardia (VT) in 35 consecutive patients with coronary artery disease who underwent electrophysiologic testing for evaluation of nonsustained VT. The mean age of the patients was 66 +/- 9 years (+/- SD) and the mean left ventricular ejection fraction was 0.36 +/- 0.14. In 6 patients in whom sustained, monomorphic VT was inducible by programmed ventricular stimulation, QT dispersion was significantly greater than in the 29 patients in whom VT was not inducible (126 +/- 35 vs 67 +/- 25 ms, p < 0.001). All patients who had a QT dispersion > 120 ms had inducible sustained monomorphic VT, and no patient who had a QT dispersion < 90 ms had inducible VT. The patients who had inducible VT dis not differ significantly from those who did not with regard to age, gender, ejection fraction, RR interval, or mean QT. In conclusion, in patients with coronary artery disease who have nonsustained VT, inducibility of monomorphic VT is associated with an increase in QT dispersion. QT dispersion may be helpful in predicting which patients with nonsustained VT are and are not likely to have inducible VT by programmed stimulation.

Determinants of induction of ventricular tachycardia in nonsustained ventricular tachycardia after myocardial infarction and the usefulness of the signal-averaged electrocardiogram

Assessment of the implications of clinical and noninvasive variables, including the results of signal-averaged electrocardiography, was performed > or = 3 weeks after myocardial infarction in 57 patients with nonsustained ventricular tachycardia (VT) who underwent programmed ventricular stimulation to guide antiarrhythmic therapy. The clinical and noninvasive parameters assessed included ages, left ventricular ejection fractions, sites of infarction, presence of akinetic or dyskinetic left ventricular segments, history of syncope, history of coronary artery bypass surgery, and presence or absence of late potentials from signal-averaged electrocardiography. Other than the presence of late potentials, no clinical or noninvasive parameters identified such persons with a significantly higher likelihood of inducible VT. When assessed as positive if 1 or more variables were abnormal, 16 of 16 (100%) patients with versus 17 of 41 without inducible VT had late potentials (p < 0.002). With more stringent criteria required (defined as prolongation of the QRS vector complex duration and low root-mean-square voltage of the terminal 40 ms of the vector complex) 8 of 16 patients (50%) with and 4 of 41 (10%) without inducible VT had late potentials recorded (p < 0.002). Thus, the signal-averaged electrocardiogram may enable identification of persons with nonsustained VT after myocardial infarction who are most likely to have VT induced at programmed ventricular stimulation.

Management of nonsustained ventricular tachycardia guided by electrophysiological testing

Two hundred eighty patients with spontaneous nonsustained ventricular tachycardia were treated based on the results of electrophysiological testing. Seventy-nine patients had no evidence of structural heart disease, 134 had coronary artery disease, 43 had idiopathic dilated cardiomyopathy, and 24 patients had miscellaneous types of heart disease. Sustained monomorphic ventricular tachycardia was induced during electrophysiological testing in the drug free state in 52 of 280 patients (19%). Ventricular tachycardia was induced more frequently in patients with coronary artery disease (32%) than in any of the other groups (P < 0.001). The patients with inducible sustained monomorphic ventricular tachycardia underwent a mean of 1.9 +/- 1.3 drug trials. Twenty-five patients had the induction of ventricular tachycardia suppressed by pharmacological therapy and were treated with the drug judged to be effective during electropharmacological testing. Twenty-seven patients continued to have inducible sustained monomorphic ventricular tachycardia despite antiarrhythmic therapy and were discharged on the drug that made induced ventricular tachycardia best tolerated. Forty-five of 280 patients (16.1%) died during a mean follow-up period of 19.6 +/- 14.4 months. There were 15 sudden cardiac deaths, 21 nonsudden cardiac deaths, 6 noncardiac deaths, and 3 deaths that could not be classified. Sudden cardiac death mortality was lowest in the patients without structural heart disease (0% at 2 years), intermediate in the patients with coronary artery disease and miscellaneous heart disease (4% at 2 years), and highest in the patients with idiopathic dilated cardiomyopathy (13% at 2 years; P < 0.01 for pairwise comparisons). No patient treated with a drug that had suppressed the induction of sustained ventricular tachycardia died suddenly during the follow-up period whereas four of 27 patients who were discharged on "ineffective antiarrhythmic drugs" and 11 of 228 patients without inducible sustained ventricular tachycardia experienced sudden cardiac death during the follow-up period. By multivariate analysis, ejection fraction and inducible ventricular tachycardia during the predischarge electrophysiological test were independent predictors of sudden cardiac death. In conclusion, in patients with spontaneous non-sustained ventricular tachycardia: (1) Arrhythmia inducibility varies depending on the underlying heart disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Prospective detection of vulnerability to sustained ventricular tachycardia in patients awaiting cardiac transplantation

This prospective study tested the hypothesis that abnormal signal-averaged electrocardiograms (ECGs) and inducible ventricular arrhythmias identify patients awaiting cardiac transplantation who are prone to sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). Thirty-seven patients with advanced symptoms of heart failure and a mean left ventricular ejection fraction of 20 +/- 7 were studied. In response to programmed ventricular stimulation using up to 3 extrastimuli, sustained monomorphic VT was induced in 8 (22%) and polymorphic VT or VF was induced in 5 patients (13%). Patients with inducible arrhythmias underwent drug therapy guided by results of programmed ventricular stimulation or implantation of a defibrillator. Patients in whom ventricular arrhythmias could not be induced were not treated for arrhythmias. The signal-averaged ECG was abnormal and sustained VT or VF was induced in 10 patients (27%). Follow-up ranged from 1 to 33 months (mean 12). Four patients (11%) died suddenly and 4 (11%) had nonfatal sustained VT or VF. The positive predictive value for sudden death or nonfatal VT/VF was 27% for the signal-averaged ECG, 38% for programmed ventricular stimulation, and 50% if both tests were abnormal. The negative predictive values for these tests were 87, 88 and 88%, respectively. The actuarial incidence of arrhythmic events was significantly higher in patients with inducible ventricular arrhythmias (p = 0.017) and in patients in whom both the results of signal-averaged electrocardiographic analysis and the response to programmed ventricular stimulation were abnormal (p = 0.002). This study demonstrates that results of signal-averaged electrocardiographic analysis and the response to programmed ventricular stimulation improve risk stratification for sudden cardiac death in patients awaiting cardiac transplantation.

Does programmed stimulation really help in the evaluation of patients with nonsustained ventricular tachycardia? Results of a meta-analysis

There has been considerable debate regarding the value of programmed electrical stimulation in patients who present with asymptomatic, or minimally symptomatic, nonsustained VT. Unfortunately, there has never been a sufficiently large study of an untreated group of patients to make any sense of the issue. We culled the literature for reports published between 1986 and 1990 that met certain minimum requirements, the most important of which were adequate patient profiling and outcome data. The survey identified 12 studies of 926 patients, mean age 61 years, with a 5:1 male preponderance. Underlying heart disease was coronary in 818 patients, including 665 who had experienced previous but not recent myocardial infarctions. Of these, 302 (33%) had inducible sustained ventricular arrhythmias (monomorphic VTs in 264). Eighty-three percent of these patients were treated with antiarrhythmic drugs compared to only 13% of the noninducible group (p less than 0.0001). Sudden death or a sustained arrhythmic event occurred in 54 (18%) of the 302 patients in the inducible group compared with 46 (7%) of the 624 in the noninducible group (p less than 0.001). The sensitivity, specificity, and positive and negative predictive accuracies of the test were 54%, 70%, 18%, and 93%, respectively. Thus a patient with an inducible sustained arrhythmia who manifests nonsustained VT is two and a half times as likely to have a major arrhythmic event, but a negative result bodes well for the patient. However, widespread application of the technique cannot be recommended until these results are confirmed in a large, prospective study in which antiarrhythmic therapy is controlled.

Prospective comparison of a conventional and an accelerated protocol for programmed ventricular stimulation in patients with coronary artery disease

BACKGROUND

This study compared the sensitivity, specificity, and efficiency of a "conventional" and "accelerated" programmed stimulation protocol in 293 patients with coronary artery disease who had a history of sustained or nonsustained monomorphic ventricular tachycardia (VT).

METHODS AND RESULTS

In the conventional protocol, one and two extrastimuli were introduced during sinus rhythm and during basic drive trains at cycle lengths of 600 and 400 msec at the right ventricular apex and then at the outflow tract or septum. In the accelerated protocol, one, two, and then three extrastimuli were introduced at each of three basic drive train cycle lengths (350, 400, and 600 msec) at the right ventricular apex; the procedure was repeated at a second right ventricular site. Six hundred thirty-four electrophysiological tests were performed using one of these two protocols either in the baseline state (293 tests) or during drug testing (341 tests). The yield of sustained, monomorphic VT was 89% with the conventional protocol and 92% with the accelerated protocol during baseline tests in patients who had a history of sustained VT (p = 0.05); 20% and 34%, respectively, during baseline tests in patients with a history of nonsustained VT (p = 0.06); and 70% and 77%, respectively, during drug testing (p = 0.2). To induce sustained, monomorphic VT, 10.1 +/- 5.0 (mean +/- SD) protocol steps and 14.4 +/- 8.7 minutes were required with the conventional protocol, compared with 4.0 +/- 3.7 steps and 5.6 +/- 6.1 minutes with the accelerated protocol (p less than 0.001 for each comparison). Among the tests in which sustained, monomorphic VT was induced, sustained polymorphic VT or ventricular fibrillation was induced more often with the conventional protocol (3.6%) than with the accelerated protocol (0.9%, p = 0.05).

CONCLUSIONS

The efficiency of programmed stimulation can be improved by the early use of a basic drive train cycle length of 350 msec and three extrastimuli. Compared with a conventional stimulation protocol, the accelerated protocol used in this study reduces the number of protocol steps and duration of time required to induce monomorphic VT by an average of more than 50% and improves the specificity of programmed stimulation without impairing the yield of monomorphic VT.

The signal averaged electrocardiogram and programmed stimulation in patients with complex ventricular arrhythmias

The signal averaged electrocardiogram (SA-ECG), programmed electrical stimulation (PES), and left ventricular ejection fraction (EF) studies were utilized for risk stratification and management of patients with complex ventricular arrhythmias and nonsustained ventricular tachycardia (VT). The study population included 90 patients (63 with coronary artery disease and 27 with dilated cardiomyopathy). Sustained monomorphic VT was induced in 22 cases (24%), ventricular fibrillation (VF) in 10 (11%), and no sustained VT/VF in 58 (64%). An abnormal SA-ECG was recorded in 23 patients (26%) and was more common in patients with than in those without induced sustained VT (68% vs 12%, P less than 0.0001). None of 33 patients with normal SA-ECG and EF greater than or equal to 40% had induced VT. Patients were followed-up for 2.5 +/- 0.8 years off antiarrhythmic therapy, unless they had induced sustained VT. The 3-year sudden death rate was 19% in the group with induced sustained VT, 0 in that with induced VF, and 9% in that without induced VT/VF (P = NS). The 3-year total cardiac mortality was higher in patients with than in those without EF less than 40% (27% vs 7%, P less than 0.05). It is concluded that patients with organic heart disease and spontaneous nonsustained VT may not need PES or antiarrhythmic therapy if SA-ECG is normal and EF is greater than or equal to 40%, since their risk of induced VT and sudden death is low. On the other hand, patients with abnormal SA-ECG and/or EF less than 40% may require PES, since their risk for induced VT is high. Antiarrhythmic therapy may also be considered in these patients.

Value of electrophysiologic testing in patients with previous myocardial infarction and nonsustained ventricular tachycardia. Philadelphia Arrhythmia Group

Previous studies of the value of electrophysiologic studies in patients with nonsustained ventricular tachycardia (VT) have been hampered by the inclusion of a small number of patients with various types of heart disease. This retrospective study was designed to assess the value of programmed stimulation in 205 asymptomatic patients who had had an acute myocardial infarction greater than 1 month before study. Inclusion was based on 24-hour Holter monitoring during which patients had to manifest greater than or equal to 3 consecutive ventricular beats at a rate greater than 135 beats/min. Forty-seven (23%) patients had normal, 70 (34%) mildly impaired and 88 (43%) severely impaired left ventricular function. Programmed stimulation, using up to 3 extrastimuli, was used in each. Seventy-five patients (36%) were noninducible, 59 (29%) had nonsustained VT (less than 30 seconds), 67 (33%) had sustained monomorphic VT and 4 (2%) had either polymorphic VT or ventricular fibrillation. Eighty-two patients were not treated with antiarrhythmic drugs, 57 others were placed on a program selected empirically and 66 had therapy guided by electrophysiologic testing. Satisfactory follow-up information was gathered in 187 of the 205 patients, with a mean follow-up of 18 months. One hundred forty-two patients are alive and well, 39 had sustained VT or sudden death and 6 others had a cardiac death. Only left ventricular function discriminated those who had a sustained arrhythmia or died from those who did not. Thus, programmed stimulation did not have independent predictive value in patients with nonsustained VT. However, definitive conclusions can be reached only with a large prospective study carried out in untreated patients.