Electrophysiologic testing in patients at high risk for sudden cardiac death. I. Nonsustained ventricular tachycardia and abnormal ventricular function

Nonsustained ventricular tachycardia, although usually asymptomatic, is associated with a high risk of sudden cardiac death in patients with depressed left ventricular function. To test the vulnerability of such patients to symptomatic and potentially life-threatening arrhythmias, complete electrophysiologic studies were performed in 58 patients with clinically documented nonsustained ventricular tachycardia (greater than or equal to three complexes but less than 15 seconds of self-terminating ventricular tachycardia by 24 hour ambulatory electrocardiographic [Holter] or telemetric monitoring) and abnormal left ventricular function (ejection fraction less than 50% by radionuclide angiography). All patients had nonsustained ventricular tachycardia in the absence of antiarrhythmic drugs, acute ischemia, long QT syndrome, recent infarction or electrolyte abnormalities. The stimulation protocol for each patient included the introduction of single, double and triple ventricular extrastimuli at three cycle lengths (sinus, 600 and 450 ms) and two right ventricular sites (apex and outflow tract). A sustained ventricular tachyarrhythmia was induced in 23 patients (40%) and a nonsustained ventricular tachycardia in 14 patients (24%). Induction of sustained tachycardia correlated with the presence of akinesia or aneurysm, or both, by radionuclide angiography, but not with ejection fraction or presence or absence of coronary artery disease. These results indicate that: 1) patients with clinical nonsustained ventricular tachycardia and chronic left ventricular dysfunction have a high incidence of inducible sustained ventricular tachycardia or ventricular fibrillation; and 2) electrophysiologic testing may allow further substratification of risk of sudden cardiac death in high risk patients with nonsustained ventricular tachycardia.     

Left main coronary artery disease in a 19-year-old woman. Treatment by saphenous vein grafting

Syncope, palpitations, ventricular tachycardia, and electrocardiographic changes of acute myocardial ischemia in a 19-year-old woman resulted from significant narrowing of the left main coronary artery and its ostium, producing high-grade obstruction to flow as documented by selective coronary arteriography. Because of these findings and markedly positive results of cardiovascular stress testing, surgical treatment by aortocoronary artery saphenous vein bypass grafting to the left anterior descending artery was carried out. Four years postoperatively, the patient was asymptomatic, and there are no abnormal findings on cardiovascular stress testing.     

Left main coronary artery stenosis: factors predicting cardiac events in patients awaiting coronary surgery

Although most patients with left main coronary artery stenosis undergo urgent coronary artery bypass grafting, limited information is available regarding the risk factors that might lead to cardiac events between angiographic diagnosis and surgery. We retrospectively reviewed 1,731 cases of coronary artery bypass grafting at our institution, 97 of which were performed in patients with significant (> or = 50%) left main coronary artery stenosis. These patients were placed in 1 of 2 groups: eventful waiting or uneventful waiting. We analyzed multiple preoperative variables, and the incidence of serious cardiac events (death, myocardial infarction, unstable angina, left ventricular failure, and life-threatening ventricular arrhythmias) during the waiting period between angiography and surgery Four patients (4.1%) experienced serious cardiac events while awaiting surgery (1 had non-ST-elevation myocardial infarction; 3 had life-threatening ventricular arrhythmias); none died. All the events occurred more than 24 hours after cardiac catheterization. Of the preoperative variables analyzed (acute coronary syndrome, age, history of diabetes, hypertension, hyperlipidemia, smoking, renal failure, severity of left main stenosis, right coronary artery involvement, ejection fraction, and use of intra-aortic balloon pump), only acute coronary syndrome predicted the incidence of preoperative cardiac events (P=0.001). The occurrence of severe cardiac events while patients await coronary artery bypass grafting is rare. Carefully selected patients with severe left main coronary artery stenosis can safely await surgery. Concomitant acute coronary syndrome and severe left main coronary artery stenosis indicate a high risk for cardiac events. Therefore, in patients with these conditions, emergency coronary artery bypass may be preferable.     

Role of myocardial ischemia during programmed stimulation in survivors of cardiac arrest with coronary artery disease

The role of ischemia in the induction of ventricular tachycardia during programmed stimulation was studied in 19 patients who survived a cardiac arrest and were found to have a significant stenosis in at least one branch of the left coronary artery. The arterial-coronary sinus lactate difference was measured during electrophysiologic testing, before the induction of ventricular tachycardia. Ventricular tachycardia was induced in 15 patients; it was sustained and unimorphic in 6 patients and polymorphic in 9. Myocardial ischemia, as reflected by net myocardial lactate production, was present within 60 seconds before the induction of ventricular tachycardia in 8 of the 15 patients with inducible ventricular tachycardia. In 9 of the 15 patients, programmed stimulation was repeated after a 15 minute rest period, with the same coupling intervals that had induced ventricular tachycardia previously. Net myocardial lactate production was not present in any patient during this repeat attempt. In three patients without evidence of ischemia during the first induction of ventricular tachycardia, the arrhythmia was induced again by the specific coupling intervals that had induced it previously. However, in five of six patients with net myocardial lactate production during the first induction of ventricular tachycardia, the same coupling intervals that had induced the arrhythmia in the presence of ischemia no longer induced it in the absence of ischemia. The results of this study suggest that myocardial ischemia may be a requirement for the induction of ventricular tachycardia in some patients with coronary artery disease who survive a cardiac arrest.     

Determinants of survival in patients with malignant ventricular arrhythmia associated with coronary artery disease

The long-term survival data in patients with coronary artery disease and a history of malignant ventricular arrhythmia, defined as noninfarction ventricular fibrillation (VF) or hemodynamically compromising ventricular tachycardia (VT) followed for up to 9 years, were analyzed. In this group of 161 patients there was a total of 57 deaths, of which 35 (63%) were sudden. Life-table analysis demonstrated a 10% sudden death rate for all patients in the first year and a 7% annual rate in the subsequent 4 years. In patients managed noninvasively, the overall mortality rate was 27% over 9 years, or 3% per year. Suppression of ventricular tachycardia on both ambulatory monitoring and exercise testing was associated with improved survival. In patients evaluated by electrophysiologic testing the sudden death rate was 1.4% per year over an average of 5 years. This survival rate was not different compared with the noninvasive group (p = 0.09). Measures of left ventricular dysfunction and the frequency of ventricular arrhythmia before and after drug therapy were associated with a risk of sudden cardiac death by univariate analysis. Multivariate regression analysis identified 4 variables as independent predictors of sudden cardiac death: rales (p = 0.009), the number of runs of VT during exercise testing while receiving antiarrhythmic drug therapy (p = 0.0003), a history of congestive heart failure (p = 0.0009) and the number of premature beats on Holter monitoring (p = 0.01). These findings support the concept that suppression of repetitive arrhythmia on Holter monitor and exercise testing is a marker for improved survival among patients with malignant ventricular arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Predictors of inducible sustained ventricular tachyarrhythmias in patients with coronary artery disease

To determine predictors of inducible sustained ventricular tachycardia or fibrillation by programmed electrical stimulation in patients with coronary artery disease and ventricular tachyarrhythmias, 14 clinical and angiographic variables were analyzed in 60 consecutive patients. All patients had angiographically documented coronary artery disease and symptomatic ventricular arrhythmias (sustained ventricular tachycardia in 21, ventricular fibrillation in 21 and nonsustained ventricular tachycardia in 18). Baseline programmed electrical stimulation while the patient was not taking antiarrhythmic drugs was performed with use of single, double and triple extrastimuli and burst pacing from two right ventricular sites. The variables analyzed were presenting arrhythmia; presence, frequency and complexity of ventricular ectopic activity on baseline 24 h electrocardiographic (Holter) monitoring; greater than or equal to 70% narrowing in either the left anterior descending, proximal left anterior descending, right coronary or circumflex coronary artery (independently assessed); single, double or triple vessel coronary disease; anterior, apical or inferior wall motion abnormalities; segmental dyskinesia and ejection fraction. Thirty-seven patients (62%) had inducible sustained ventricular tachycardia (rate greater than 100 beats/min, duration greater than 30 s or requiring cardioversion) and two patients (3%) had ventricular fibrillation induced. Eleven patients (18%) had nonsustained ventricular tachycardia (duration greater than or equal to 3 beats, less than 30 s) induced and 10 patients (17%) had no inducible arrhythmia (duration less than 3 beats). Multivariate stepwise logistic regression analysis identified three independent variables predictive of inducible sustained ventricular arrhythmias: sustained ventricular tachycardia as the presenting arrhythmia (p = 0.004), proximal left anterior descending artery lesion (p = 0.002) and anterior wall motion abnormality (p = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)     

Sudden cardiac death: management of high-risk patients

Sudden cardiac death remains a leading cause of death in the United States, accounting for more than 350,000 deaths each year, and the survival rate of victims remains low. Most survivors face a significant risk for recurrence. The typical substrate is chronic--abnormal myocardium with fibrosis (often from previous myocardial infarction) and left ventricular dysfunction. Acute triggers for sudden cardiac death are primarily electrical, ischemic, metabolic, neurohormonal, and pharmacologic. In most electrocardiographically documented cases of sudden cardiac death, the trigger-substrate interaction appears to result in ventricular tachycardia and fibrillation. After initial resuscitation, survivors need a thorough cardiovascular evaluation, including definition of coronary anatomy, left ventricular function, and wall-motion abnormalities, as well as an electrophysiologic evaluation. An attempt must be made to determine what each survivor's correctable triggers are. Management should address all reversible triggers, such as acute ischemia and electrolyte abnormalities, and should include modifying or correcting the arrhythmogenic substrate. Empiric antiarrhythmic therapy offers no advantage in such modification. Pharmacologic therapy with antiarrhythmic drugs should be guided by an objective therapeutic endpoint, which is best accomplished through the use of programmed ventricular stimulation and serial electrophysiologic studies. Other therapeutic options include surgical suppression of ventricular tachycardia and implantation of a cardioverter defibrillator.     

Ventricular arrhythmias after coronary artery bypass graft surgery: incidence, risk factors and long-term prognosis

The incidence, risk factors and long-term prognosis of complex ventricular arrhythmias after coronary artery bypass graft surgery are not known. Complex ventricular arrhythmias are defined as Lown grades 4a (couplets), 4b (ventricular tachycardia) and 5 (R on T phenomenon). Ninety-two patients with normal left ventricular function who underwent elective coronary artery bypass graft surgery were prospectively evaluated. Ventricular arrhythmias were documented by predischarge 24 hour ambulatory electrocardiographic monitoring; 43% of patients had no or simple ventricular arrhythmias (Lown grades 1 to 3) and 57% had complex ventricular arrhythmias. Risk factors analyzed included age, sex, diabetes, hypertension, smoking, preoperative digoxin or propranolol therapy, cardiopulmonary bypass time, aortic cross-clamp time, number of vessels bypassed, peak creatine kinase (CK) elevation and pericarditis. No risk factor identified patients at higher risk for complex ventricular arrhythmias. Patients were followed up for 6 to 24 months (mean 16). Patients with complex ventricular arrhythmias did not have a higher incidence of sudden death, cardiac death, syncope, angina, myocardial infarction or cerebrovascular accident. It was concluded that: Complex ventricular arrhythmias are common after coronary artery bypass graft surgery. None of the risk factors considered identify high risk patients. Complex ventricular arrhythmias after coronary artery bypass graft surgery do not indicate a poor prognosis in patients with normal left ventricular function.     

Iatrogenic left main coronary artery stenosis

Iatrogenic left main coronary artery stenosis is a potentially life-threatening complication of cardiac valve replacement surgery due to injury by perfusion cannulas. This requires prompt clinical recognition and diagnosis by repeat coronary angiography, and treatment by early coronary artery bypass grafting. We present 3 patients who had normal coronary arteries prior to valve replacement surgery, and who developed severe left main coronary artery stenosis after surgery. Accelerating angina and refractory ventricular arrhythmia were presenting clinical manifestations. Coronary artery bypass grafting was successfully performed in all 3 patients.     

Angina and vasospasm at rest in a patient with an anomalous left coronary system

An anomalous left main coronary artery with passage between the right ventricular infundibulum and aortic root has been incriminated as the causation of sudden death in a small number of individuals, many of whom are quite young. Mechanical features such as angulation and compression are most often incriminated. A 59-year-old man with such a coronary anomaly who had chest pain at rest, ST segment elevation, and ventricular tachycardia, but who had no evidence of effort-related myocardial ischemia, is reported. Improvement in the degree of coronary tone in the anomalous left main coronary with intracoronary nitroglycerin administration was demonstrated. This represents the first report of an individual with an anomalous left main coronary system with ventricular tachycardia/ventricular fibrillation and documented vasospasm in the anomalous artery.     

Ventricular Fibrillation and Polymorphic Ventricular Tachycardia with Critical Coronary Artery Stenosis:

ICD Therapy and CABG for Sudden Death. Introduction: Previous studies have suggested that coronary artery bypass surgery is sufficient to prevent recurrence of sudden death in patients with critical coronary artery stenosis presenting with ventricular fibrillation or polymorphic ventricular tachycardia. We present our experience in patients with one or more episodes of sudden death associated with documented ventricular fibrillation or polymorphic ventricular tachycardia and severe operable coronary artery disease who underwent defibrillator implant at the time of bypass surgery. Methods and Results: Fifty-eight consecutive patients (age 63 ± 8 years) were included in this study. Eighteen of the 58 patients had no evidence of previous myocardial infarction. The mean ejection fraction was 37 ± 13%. All patients underwent electrophysiologic study before and after revascularization. At the time of first defibrillator discharge, each patient was reevaluated to exclude the presence of ischemia. The benefits of defibrillator implant were estimated comparing the projected survival based upon defibrillator discharge preceded by syncope or presyncope with survival curves generated including total death and sudden plus cardiac death. After a mean follow-up of 4.6 ± 2 years, 22 patients received appropriate shocks preceded by syncope or presyncope, and an additional 19 patients received asymptomatic shocks. At 4 years, survival free of total death was 71.2%, and the projected survival was 58.8% (P < 0.05). Multivariate analysis showed that ejection fraction lower than 30% and induction of arrhythmia with one or two extrastimuii (S2, S3) were independent predictors for defibrillator discharge. None of the remaining variables including age, gender, number of bypasses, history of myocardial infarction, and type of arrhythmias induced were predictive for death and occurrence of shocks. Conclusions: In patients with ventricular fibrillation and polymorphic ventricular tachycardia, bypass surgery does not protect from recurrence of life-threatening arrhythmias, and, as in our population, defibrillator implant may have significant impact on survival.     

Clinical, angiographic, and electrophysiologic findings in patients with aborted sudden death as compared with patients with sustained ventricular tachycardia after myocardial infarction

After the acute phase of myocardial infarction, patients who develop sustained ventricular arrhythmias present with either sudden death or ventricular tachycardia (VT). Although current evidence suggests that VT frequently precedes ventricular fibrillation (VF) in patients presenting with sudden death, the factors resulting in rapid deterioration of VT to VF have not been delineated in humans. To determine whether left ventricular function, coronary anatomy, or electrophysiologic characteristics could differentiate patients with sudden death from those with VT without sudden death, we compared results of cardiac angiography and programmed electrical stimulation in 42 patients referred for evaluation of sustained VT or surviving "aborted" sudden death for more than 9 days after myocardial infarction. By univariate analysis there were no differences between patients with sudden death and those with VT in age, time from myocardial infarction to VT or sudden death, ejection fraction (0.31 +/- 0.12 vs 0.29 +/- 0.09), or the number of patients with a major area of contracting myocardium supplied by an artery with a 50% or greater or a 70% or greater stenosis (84% vs 64% and 68% vs 41%). Thirty-six percent of patients with sudden death but no patient with VT had two separate areas of infarction. During programmed electrical stimulation, a sustained ventricular arrhythmia was initiated in 100% of patients with VT and 73% of patients with sudden death and rapidly produced syncope in 67% of patients with sudden death but in only 5% of those with VT. This difference was due to the more frequent initiation of rapid polymorphic VT or VF (27% of patients) and to the shorter VT cycle length (242 +/- 31 vs 319 +/- 69 msec) when monomorphic VT was induced in the group with sudden death. No difference was found in the number of extrastimuli required for initiation of a sustained ventricular arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Myocardial bridging of the left anterior descending coronary artery and right coronary artery in a patient with mitral valve stenosis

Myocardial bridging is defined as the intramural course of a major epicardial coronary artery, and is mostly confined to the left ventricle and the left anterior descending coronary artery (LAD). Although it is considered to be a benign anomaly, it can lead to such complications as acute myocardial infarction, ventricular tachycardia, syncope, atrioventricular block and sudden cardiac death. Isolated myocardial bridging of the right coronary artery (RCA) and left circumflex artery have been reported in the literature In our case, myocardial bridging was observed in both the LAD and the RCA in a patient with mitral valve stenosis.     

Value of programmed ventricular stimulation in the evaluation and management of patients with nonsustained ventricular tachycardia associated with coronary artery disease

Programmed ventricular stimulation with up to 3 extrastimuli at the right ventricular apex was performed in 52 patients with spontaneous nonsustained ventricular tachycardia (VT) associated with coronary artery disease. There were 44 men and 8 women, aged 66 +/- 9 years (range 45 to 86). The mean left ventricular ejection fraction was 41 +/- 14%. Nonsustained VT was asymptomatic in 10 patients (19%), while the arrhythmia was detected during evaluation of palpitations in 5 patients (10%), presyncope in 11 (21%) and syncope in 26 patients (50%). All patients were tested in the drug-free state and were classified as having no inducible arrhythmia (31 patients, group I), or an inducible arrhythmia (21 patients, group II). The age, gender, type of heart disease, symptoms and left ventricular ejection fraction were similar in both groups. Group I patients had a higher overall incidence of syncope. Group I patients received no therapy, while group II patients received antiarrhythmic therapy guided by electropharmacologic testing. At 21 +/- 17 months there was no sustained VT in either group. There were 3 deaths in group I patients, including 1 sudden, 1 nonsudden cardiac and 1 noncardiac death. In group II patients 6 deaths occurred including 4 nonsudden cardiac and 2 noncardiac deaths. In patients with nonsustained VT and coronary artery disease undergoing programmed ventricular stimulation, the incidence of significant arrhythmic events is low in those without therapy with no inducible arrhythmia, and in those with an inducible arrhythmia with therapy guided by electrophysiologic testing.     

Fatal left main coronary artery embolism from aortic valve endocarditis following cardiac catheterization.

Coronary artery embolization has been associated with sudden cardiac death. It is more commonly seen with aortic valve endocarditis. It manifests as acute myocardial ischemia or infarction, causing instability of the cardiac rhythm, which may be fatal. We report a patient with aortic valve endocarditis who had sudden cardiac death following coronary angiography. Autopsy revealed embolic occlusion of the left main coronary artery.     

Influence of left ventricular function on signal averaged late potentials in patients with coronary artery disease with and without ventricular tachycardia

Left ventricular dysfunction has been suggested as a cause of late potentials on the signal averaged ECG of patients with coronary artery disease. We compared the averaged surface ECG with angiographic findings in 57 patients with coronary artery disease and left ventricular dysfunction. Sixteen patients had sustained ventricular tachycardia and 41 had no documented arrhythmia. These two patient groups were comparable with respect to age, mean ejection fraction, and wall motion score. Late potentials, defined as voltage less than 25 microV in the last 40 msec of the filtered QRS complex, were found in 10 of 16 patients with ventricular tachycardia and in 6 of 41 patients without arrhythmia (p less than 0.005). However, late potentials were independent of ejection fraction, wall motion score, or presence of dyskinesis in both groups. There was no correlation between the total filtered QRS duration and ejection fraction or wall motion score in either patient group. In patients with coronary artery disease, late potentials are associated with ventricular tachycardia but are independent of global or regional left ventricular function. This finding has important implications for studies of the prognostic value of late potentials following myocardial infarction.     

Sudden cardiac death

Most sudden deaths in industrial nations are the result of underlying coronary artery disease. Longitudinal studies have demonstrated that the percent of all coronary events presenting as sudden death increases with age in both men and women. Relative weight is another important risk factor; the age-adjusted rate of sudden cardiac death for the upper weight tercile in the Framingham study was over 2 times higher for men and 3 times higher for women than the rate for the lower weight tercile. Most patients who die suddenly initially experience ventricular tachycardia that subsequently degenerates into ventricular fibrillation. Patients with a high risk of sudden cardiac death include: survivors of myocardial infarction with left ventricular dysfunction or complex ventricular ectopy, or both; survivors of out-of-hospital cardiac arrest, particularly when the event is not associated with an acute myocardial infarction; patients with recurrent ventricular tachycardia; and patients with dilated congestive cardiomyopathy, particularly when associated with ventricular ectopy. Reducing the risk of sudden death in these patients remains a major challenge.     

Programmed stimulation in patients with malignant ventricular arrhythmias. I: Diagnostic value

Sudden cardiac death is a leading cause of death in industrially developed countries and accounts for approximately 90 000 deaths yearly in the FRG. While the majority of victims have severe coronary heart disease, sudden cardiac death is infrequently caused by acute myocardial infarction (20%) but is predominantly related to malignant ventricular arrhythmias (i.e., ventricular fibrillation or sustained ventricular tachycardia). Patients with a history of such malignant ventricular arrhythmias are at high risk for sudden death. Spontaneous occurrence of sustained ventricular tachycardia and of ventricular fibrillation is critically related to two factors: 1. trigger-arrhythmias consisting usually of complex ventricular extrasystoles (Lown classification IV to V); 2. increased vulnerability of the myocardium representing the target organ for trigger-arrhythmias. While trigger-arrhythmias can be easily recorded by noninvasive techniques including Holter monitoring or exercise and stress ECG, ventricular vulnerability is more difficult to determine and often requires ventricular stimulation with intracardiac electrocatheters. In patients with documented spontaneous malignant ventricular arrhythmias, two aspects of programmed stimulation must be considered: 1. diagnostic, and more importantly, 2. therapeutic purposes of this method. Diagnostic purposes include determination of the mode of initiation and unequivocal ventricular localization of the tachycardia excluding other arrhythmias with broad QRS complex. In patients with spontaneous sustained ventricular tachycardia, programmed stimulation can reproducibly initiate the clinical arrhythmia in 85% (sensitivity and specificity of the method approximately 90%). In patients with cardiac arrest due to ventricular fibrillation, programmed stimulation is less reliable (50%). However, the main purpose of programmed stimulation in patients with documented clinical malignant arrhythmias is not diagnostic or prognostic evaluation but is serial electrophysiological studies for individual optimization of antiarrhythmic therapy.     

植入型心律转复除颤器治疗冠心病伴室性心律失常疗效观察

目的 观察冠心病伴恶性室性心律失常患者植入心律转复除颤器(ICD)治疗后的长期预后.方法 23例冠心病患者,其中男性18例,女性15例,年龄(71.56±10.38)岁.心功能不良16例.22例行血运重建术(经皮冠状动脉介入术20例,冠状动脉搭桥术2例).术后发生晕厥9例,持续性室性心动过速(VT)发作22例,心室颤动(VF)发作5例.植入单腔ICD(VVI)15例,双腔ICD(DDDR)1例,三腔ICD(CRT-D)7例.随访时间平均为(33.37±25.39)个月.结果 (1)死亡2例,因急性心肌梗死和急性左心衰竭死亡各1例.(2)4例患者术后再次住院.原因:1例为心功能不良,3例为ICD多次放电住院.(3)13例(56.5%)发生持续性VT或VF事件.持续性VT发作434次,386次(98.6%)经抗心动过速起搏(ATP)治疗成功.FVT发作25次,ATP治疗FVT总的成功率为84.0%.(4)ICD电风暴3例.(5)ICD误识别及误治疗2例.结论 冠心病伴恶性室性心律失常患者血运重建后用ICD治疗,可防止由于心肌的慢性的瘢痕产生室性心律失常而导致猝死的风险.