Classification by type of ventricular arrhythmia predicts frequency of adverse cardiac events from flecainide

Antiarrhythmic therapy is known to be associated with a significant risk of adverse cardiac reactions, including a proarrhythmic response. This study assessed in 1,330 patients followed up for 292 +/- 393 days the predictive value for cardiovascular safety of a system by which patients were classified according to ventricular arrhythmias on entry, presence or absence of organic heart disease and drug dose for flecainide acetate. Baseline arrhythmia subgroups included patients with premature ventricular complexes only, nonsustained ventricular tachycardia, and sustained ventricular tachycardia. Proarrhythmic events occurred in 6.8% of patients overall and were serious in 2.3% and lethal in 1.0%. However, proarrhythmia was highly dependent on arrhythmia class on entry: serious nonlethal proarrhythmic events occurred in 6.6% of patients with sustained ventricular tachycardia, only 0.9% with nonsustained ventricular tachycardia and 0% with premature ventricular complexes (p less than 0.01). Proarrhythmic death occurred in 3.1% of patients with sustained ventricular tachycardia, 0.2% with nonsustained ventricular tachycardia and 0% with premature ventricular complexes only (p less than 0.01). Proarrhythmia was also influenced by the presence of structural heart disease: serious nonlethal proarrhythmia occurred in 2.6% of patients with versus 0.4% of those without organic heart disease, and death occurred in 1.2 versus 0%, respectively. These adverse events were also dependent on dosing regimen. Flecainide caused premature discontinuation due to new or worsened heart failure in 1.4% of patients, all with underlying organic heart disease; however, heart failure was not clearly related to dose or type of arrhythmia. Symptomatic conduction disturbances occurred in 2.2%, and were predicted by preexistent sinus node disease but not by other baseline features.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevalence of arrhythmias during 24-hour electrocardiographic monitoring and exercise testing in patients with obstructive and nonobstructive hypertrophic cardiomyopathy.

Many patients with hypertrophic cardiomyopathy die suddenly and unexpectedly, a significant number perhaps due to arrhythmia. Of 100 patients initially evaluated for signs or symptoms suggestive of heart disease or a family history of hypertrophic cardiomyopathy, 51 were selected solely because they met the echocardiographic criteria for the disease, and 49 patients were selected primarily because they had: 1) normal sinus rhythm despite left atrial enlargement, 2) a history of syncope, 3) a family history of premature death, or 4) a history of paroxysmal atrial fibrillation. All 100 patients were studied by 24-hour ambulatory electrocardiographic monitoring and 74 of them also underwent treadmill exercise testing. More than 50% of patients in repetitive ventricular premature depolarizations, including 19% who had ventricular tachycardia. Monitoring was superior to exercise testing for exposing these arrhythmias. Two patients experienced cardiac arrest within 2 months of monitoring; in each, monitoring had revealed ventricular tachycardia. Two patients with paroxysms of supraventricular tachycardia during monitoring developed fixed atrial fibrillation within 1 year. These preliminary observations suggest that monitoring may help identify patients at increased risk for significant arrhythmic events.     

Continuous Arrhythmia Monitoring in Pediatric and Adult Patients With Left Ventricular Noncompaction

Patients with left ventricular noncompaction (LVNC) are at risk of clinically significant arrhythmias and sudden death. We evaluated whether implantable loop recorders could detect significant arrhythmias that might be missed in these patients during annual Holter monitoring.Selected pediatric and adult patients with LVNC who consented to implantable loop recorder placement were monitored for 3 years (study duration, 10 April 2014–9 December 2019). Fourteen subjects were included (age range, 6.5–36.4 yr; 8 males). Of 13 patients who remained after one device extrusion, one underwent implantable cardioverter-defibrillator placement. Four patients (31%) had significant arrhythmias: atrial tachycardia (n=2), nonsustained ventricular tachycardia (n=1), and atrial fibrillation (n=1). All 4 events were clinically asymptomatic and not associated with left ventricular ejection fraction. In addition, a high frequency of benign arrhythmic patterns was detected.Implantable loop recorders enable continuous, long-term detection of important subclinical arrhythmias in selected patients who have LVNC. These devices may prove to be most valuable in patients who have LVNC and moderate or greater ventricular dysfunction.     

Brugada综合征患者心律失常及临床特点分析

目的通过动态心电图(Holter)检查、置入式心脏复律除颤器(ICD)分析并综合患者临床情况,研究Brugada综合征(Brs)患者心律失常事件发生特征及临床特点。方法对我院近5年诊断的12例Brs住院患者的临床情况进行随访观察;均行Holter检查分析心律失常事件发生特征;根据ICD的随访资料,分析室颤发作的时间特征。结果 Holter显示,其中8例患者室性期前收缩总数为0～80个/d,另外4例以夜间至清晨为主的频发室性期前收缩及短阵室性心动过速(其中1例伴有阵发性心房颤动;1例伴有频发房性期前收缩及房性心动过速,并且夜间心率缓慢29次/min伴交界性逸搏心律)。9例患者置入ICD后随访6～50个月,70次室颤发作中92.8%集中在22:00～07:00。12例患者均有晕厥病史,9例在住院期间发生室速/室颤,2例有猝死家族史,随访期间2例猝死。结论 Brs患者的室速/室颤发作多集中在夜间和凌晨;伴有房性心律失常和缓慢心律失常的Brs患者室速/室颤发生率更高。确诊的Brs患者发生心悸等不适时,应全面了解心律失常发生的情况,并酌情给予相应的治疗。     

Ventricular arrhythmias in congestive heart failure

Despite advances in the treatment of congestive heart failure (CHF), the mortality rate continues to be high. A large number of the deaths are sudden, presumably due to ventricular arrhythmias. Complex ventricular arrhythmias are recorded in as many as 80% of patients with CHF, with nonsustained ventricular tachycardia occurring in 40%. The latter appears to be an independent predictor of mortality. Chronic structural abnormalities responsible for CHF may be the basis for the capability of a ventricle to support life-threatening arrhythmias, which are triggered by premature ventricular contractions. The pathogenesis of arrhythmias is multifactorial. Electrolyte abnormalities, ischemia, catecholamines, inotropic and antiarrhythmic drugs may worsen arrhythmias and increase susceptibility of a ventricle to sustained arrhythmias. Beta-adrenergic blockers and angiotensin-converting enzyme inhibitors have a beneficial effect. The role of various drugs in the pathogenesis and treatment of ventricular arrhythmias is discussed. The efficacy of antiarrhythmic therapy targeted to asymptomatic nonsustained ventricular tachycardia, in order to prevent sudden death, is controversial. Pharmacotherapy guided by electrophysiologic testing is the treatment of choice for patients who have manifest sustained ventricular tachycardia, but patients resuscitated from ventricular fibrillation may require automatic implantable cardioverter defibrillator.     

Determinants of prognosis in idiopathic dilated cardiomyopathy as determined by programmed electrical stimulation

The incidence and prognostic significance of electrically induced ventricular arrhythmias were prospectively assessed in 42 patients with idiopathic dilated cardiomyopathy. All patients underwent 24-hour, long-term electrocardiographic (Holter) monitoring and 30 were analyzed by a signal-averaging vectorcardiographic procedure at entry into the study. Their response to programmed electrical stimulation during basic right ventricular pacing was investigated using 1 and 2 ventricular extrastimuli. A monomorphic tachycardia was not induced in any patient. In 36 patients (86%) polymorphic ventricular arrhythmias were initiated. Three or more induced consecutive ventricular premature complexes occurred in 9 patients (21%), nonsustained polymorphic ventricular tachycardia in 2 (4.8%) and ventricular fibrillation in 1 patient (2.4%). There was no association between electrically induced polymorphic ventricular arrhythmias and the degree of impairment of left ventricular function. Furthermore, the incidence of induced ventricular arrhythmias was not related to the Lown grade or to the total number of ventricular premature complexes during Holter monitoring. A late potential was detected by the averaged vectorcardiogram in only 1 of the 30 patients. During follow-up (mean 16 +/- 7 months) 7 patients died, 5 from chronic congestive heart failure and 2 from sudden cardiac death. No patient had an electrically induced arrhythmia of 3 or more ventricular premature complexes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevention of life-threatening arrhythmias by pharmacologic stimulation of the muscarinic receptors with oxotremorine.

The potential antiarrhythmic efficacy of pharmacologic parasympathetic activation is still controversial. This study assessed the antiarrhythmic effect of saline solution (n = 9) and of the muscarinic agonist oxotremorine (1.5 micrograms/kg administered intravenously) (n = 17) in a feline animal model in which malignant arrhythmias were reproducibly elicited by the combination of acute myocardial ischemia and left stellate ganglion stimulation. Although saline solution had no effect, oxotremorine significantly decreased heart rate, blood pressure, the incidence of ventricular fibrillation from 47% to 0% (p = 0.004), and the incidence of malignant arrhythmias (either ventricular tachycardia or ventricular fibrillation) from 88% to 12% (p less than 0.001). When reduction in heart rate was prevented by means of atrial pacing (n = 15), the incidence of malignant arrhythmias was still significantly reduced from 87% to 27% (p = 0.001). Arrhythmias were also graded as follows: 0 = no premature ventricular contractions; 1 = 1 to 10 premature ventricular contractions; 2 = 11 to 50 premature ventricular contractions; 3 = ventricular tachycardia; 4 = ventricular fibrillation. Arrhythmia severity was 3.29 +/- 0.16 (SEM) in the control trials and was reduced to 0.76 +/- 0.26 (p less than 0.001) by oxotremorine and to 1.53 +/- 0.34 by oxotremorine and pacing (p = 0.002). Therefore a muscarinic agonist can significantly reduce malignant arrhythmias during acute myocardial ischemia and may represent a novel approach to the prevention of sudden cardiac death.     

Effect of lithium on cardiovascular performance: Report on extended ambulatory monitoring and exercise testing before and during lithium therapy

To assess the effect of long-term lithium therapy on cardiac arrhythmias and cardiovascular performance, extended ambulatory electrocardiographic monitoring was performed in 12 patients, and rest and exercise electrocardiograms in 10 of 12, before and during lithium therapy. Lithium increased the frequency of premature ventricular contractions in three patients, decreased it in one, and produced no change in eight. Three of four patients with atrial arrhythmias showed improvement during lithium therapy. Exercise performance was unchanged. Although 7 of the 12 patients manifested T wave flattening in the resting electrocardiogram, none had S-T segment displacement at rest or on treadmill exercise. Before lithium therapy, arrhythmias on exercise included premature atrial contractions in four patients, ventricular arrhythmias in four (premature ventricular contractions in four, with couplets in two and with ventricular tachycardia in one). During lithium therapy, exercise did not provoke premature atrial contractions or ventricular tachycardia in any of the patients, but three patients had premature ventricular contractions (with couplets in one case).We conclude that lithium at therapeutic levels may precipitate or aggravate ventricular arrhythmias. When administered to patients with heart disease, factors that interfere with renal clearance of lithium (heart failure, salt restriction, long-term diuretic therapy) must be recognized and doses must be adjusted accordingly. Careful follow-up and electrocardiographic monitoring are advisable if lithium is to be used in the presence of ventricular arrhythmias. Cardiovascular performance as assessed by treadmill exercise testing was not affected by long-term lithium therapy.     

平板运动试验诱发冠心病患者心律失常分析

目的：分析平板运动试验诱发冠心病和非冠心病患者心律失常的情况。方法选取234例经冠状动脉造影的患者行平板运动试验,根据冠脉造影结果将其分为冠心病组（141例）和非冠心病组（93例）,比较两组平板运动试验诱发心律失常的类型及特点。结果冠心病组心律失常发生率为42．55％（60／141）,明显高于非冠心病组的15．05％（14／93）,差异有统计学意义（P ＜0．05）。冠心病组心律失常构成类型：室性早搏26．95％、房性早搏5．67％、阵发性室速2．13％、阵发性房颤1．42％、右束支阻滞2．84％和短阵室速3．55％。结论平板运动试验既可诱发冠心病组发生心律失常,又可诱发非冠心病组发生心律失常,可用于冠心病的辅助诊断。     

室性心律失常对老年心力衰竭患者预后的影响

目的　探讨室性心律失常对心力衰竭老年患者预后的影响。方法　 180例心力衰竭老年患者行 2 4h动态心电图检查 ,随访 3个月。观察猝死与各种室性心律失常的关系。结果　 16 9例(93 9% )患者有室性心律失常。 2 4h >10 0 0个室性早搏 (PVCs)者 6 9例 (38 3% ) ,多形PVCs 34例(18 9% ) ,成对PVCs 6 6例 (36 7% )。非持续性室性心动过速 81例 (45 0 % ) ,随访 3个月 7例发生猝死 ,无心动过速的患者猝死 1例。结论　非持续性室性心动过速是心力衰竭老年患者猝死的危险因素     

Patients with supraventricular tachycardia presenting with aborted sudden death: incidence, mechanism and long-term follow-up

A total of 13 (4.5%) of 290 patients with aborted sudden death had either documented (7; 54%) or strong presumptive evidence of supraventricular tachycardia that deteriorated into ventricular fibrillation. Six (46%) of the 13 had an accessory conduction pathway and either atrial fibrillation (5 patients) or paroxysmal atrioventricular (AV) reentrant tachycardia (1 patient) that deteriorated into ventricular fibrillation. Three patients with AV node reentrant tachycardia and four with atrial fibrillation and enhanced AV node conduction presented with supraventricular arrhythmias that deteriorated into ventricular fibrillation. Patients were treated with medical, surgical or catheter ablative procedures designed to prevent recurrences of supraventricular arrhythmias. Four patients received an implanted automatic defibrillator, but none had an appropriate device discharge. Over a follow-up period of 41.6 +/- 33.6 months, 12 patients are alive without symptomatic arrhythmias. One patient died because of severe chronic lung disease and heart failure. Supraventricular tachycardia was the cause of aborted sudden death in approximately 5% of patients referred for evaluation of sudden cardiac death. Treatment directed at prevention of supraventricular tachycardia was associated with an excellent prognosis. Current treatment techniques appear to obviate the need for automatic defibrillator therapy in these patients.     

Significance and control of cardiac arrhythmias in patients with congestive cardiac failure

A wide spectrum of ventricular and supraventricular tachyarrhythmias occurs in the setting of congestive cardiac failure. However, the two most clinically significant are atrial fibrillation and ventricular tachycardia and fibrillation.In the past there has been much emphasis on premature ventricular contractions and more recently, on nonsustained ventricular tachycardia. For the most part, these arrhythmias are asymptomatic in heart failure. They are markers of sudden arrhythmic death but their suppression by antiarrhythmic drugs have not resulted in a reduction of total mortality. Two approaches have been used to this end. The first is the use of beta-adrenergic blocking drugs and antiarrhythmic agents such as amiodarone. Beta-blockers have been shown to significantly reduce sudden death as well as total mortality, while the effects of amiodarone have been less decisive. The prospective role of the implantable cardioverter defibrillator (ICD) is undergoing critical evaluation in patients with cardiac failure at high risk for sudden death. The elective role of the ICD is well established as first-line therapy in patients with heart failure resuscitated from sudden death and in those with sustained ventricular tachycardia in conjunction with conventional therapies for cardiac decompensation.The prevalence of atrial fibrillation rises as a function of severity of cardiac failure, but it is also in known that persistent atrial fibrillation with an uncontrolled ventricular response may induce heart failure. Controlled ventricular response may prevent congestive heart failure and improve left ventricular function. The two most common causes of atrial fibrillation in cardiac failure in Europe and America are ischemic heart disease and hypertension, while mitral valve disease remains the prevalent cause elsewhere. The choice of antiarrhythmic drugs for maintaining sinus rhythm is critical in the prevention of heart failure aggravation and proarrhythmic reactions of antiarrhythmic drugs. Amiodarone and dofetilide are most widely used in this context.     

Complications of stress echocardiography

BACKGROUND: Stress echocardiography is an established clinical testing method and is accurate for the detection of coronary artery disease. Despite its widespread use, the safety of stress echocardiography has not been sufficiently documented in Japanese laboratories. OBJECTIVES: The feasibility, safety, complications and side effects of stress echocardiography were assessed for detecting myocardial ischemia in patients with suspected coronary artery disease. METHODS: 1,866 patients who underwent dobutamine echocardiography(n = 897), exercise echocardiography(n = 722), and dipyridamole echocardiography(n = 247) were prospectively studied from November 1990 to April 2000. Dobutamine was administered intravenously at 5, 10, 20, 30, 40 micrograms/kg/min in 3-minute intervals. Exercise echocardiography used the supine ergometer, starting at 50 W and increasing gradually by 25 W at 3-minute intervals to the maximum of 150 W. Dipyridamole was administered intravenously at 0.14 mg/kg/min for 4 min. After a 4-minute observation period, the drug was re-administered at the same dose for 2 min. RESULTS: The most common side effects under each stress were ventricular premature beats in 34.1% (dobutamine echocardiography), ventricular premature beats in 14.4%(exercise), and headache in 24.3% (dipyridamole). Serious side effects occurred in one patient(0.05%). The case of acute myocardial infarction was caused by dipyridamole echocardiography, and the patient needed emergency coronary angioplasty. Seven patients needed other drug therapy for nonsustained ventricular tachycardia(one), paroxysmal supraventricular tachycardia(two), sinus bradycardia(three), and bronchial asthma(one). There was no incidence of death, shock, or ventricular fibrillation, sustained ventricular tachycardia or other conditions requiring inpatient observation during stress echocardiography. CONCLUSIONS: Stress echocardiography is a reasonable, safe method for determining myocardial ischemia, but may be associated with minor, self-limiting side effects.     

Clinical characteristics of cardiomyopathy with mild dilatation

The clinical features of 20 patients with mildly dilated cardiomyopathy (MDCM) were investigated by electrocardiography and echocardiography. MDCM was defined as conditions with: 1) left ventricular end-diastolic dimension between 55 and 65 mm and 2) left ventricular fractional shortening between 10 and 25%. Nine patients (45%) had no histories of congestive heart failure. Eight patients had atrial fibrillation, and the other 12 patients were in regular sinus rhythm. Two patients had supraventricular premature contractions and five patients had ventricular premature contractions. One patient had paroxysmal atrial tachycardia. During the 40-months' span of this echocardiographic study, left ventricular end-diastolic dimension (60.8 +/- 3.8 mm to 57.3 +/- 4.6 mm) and left ventricular fractional shortening (17.2 +/- 4.6% to 22.7 +/- 7.1%) did not change significantly. One patient died suddenly. These results suggest that 1) some patients with MDCM have neither definite histories nor symptoms to suggest heart failure; 2) the hemodynamic conditions of patients with MDCM do not always deteriorate, but rather stabilize, and even improve during follow-up periods; 3) several types of arrhythmias can be observed, even in standard resting electrocardiograms; and 4) patients with MDCM may die suddenly.     

The prognostic significance of exercise-induced atrial arrhythmias

OBJECTIVES: The purpose of the study was to determine if atrial ectopy (AE) or atrial arrhythmias during exercise are predictive of an increased risk of cardiac events and death. BACKGROUND: Although stress-induced atrial arrhythmias are common during exercise testing, there is a paucity of data regarding the correlation with underlying heart disease and cardiovascular outcomes. Atrial arrhythmias may reflect underlying left atrial enlargement and diastolic dysfunction, which are prognostic of mortality. We hypothesized that these stress-induced arrhythmias are associated with long-term adverse cardiac events. METHODS: Exercise echocardiography was performed in 5,375 patients (age 61 +/- 12 years) with known or suspected coronary artery disease. An abnormal result was defined as exercise-induced atrial fibrillation (AF)/atrial flutter, supraventricular tachycardia (SVT), or AE. RESULTS: A total of 311 (5.8%) patients died (132 [2.5%] from cardiac causes) over a period of 3.1 +/- 1.7 years. In addition, 193 (3.6%) patients experienced a myocardial infarction (MI) and 531 (9.9%) patients required revascularization. During exercise testing, 1,272 (24%) patients developed AE, 185 (3.4%) developed SVT, and 43 (0.8%) developed AF. The five-year cardiac death rate was not statistically different between groups (none [3.8%], AE [4.3%], SVT [3.7%], AF [0%], p = 0.43). The five-year rate of MI was significantly different between groups (none [5.7%], AE [8.3%], SVT [0%], AF [9.0%], p = 0.005). The five-year rate of revascularization between groups was not significantly different (none [14.2%], AE [17.0%], SVT [11.8%], AF [14.8%], p = 0.50). A composite of all five-year adverse end points was similar between groups (none [22.7%], AE [27.8%], SVT [17.7%], AF [25.7%], p = 0.10). In stepwise multivariate analysis, AE was not predictive of myocardial infarction when taking into account traditional clinical variables and exercise test results. CONCLUSIONS: In this large cohort of patients, the occurrence of AE was predictive of an increased risk of MI. However, the association did not persist after adjustment for clinical and exercise variables known to predict adverse long-term cardiovascular outcomes. The rate of long-term cardiac death or revascularization was not influenced by the development of stress-induced atrial arrhythmias.     

Holter detection of cardiac arrhythmias in intracranial subarachnoid hemorrhage

To determine the frequency and severity of cardiac arrhythmias in intracranial subarachnoid hemorrhage, 120 nonselected patients were prospectively studied by 24-hour Holter monitoring. Arrhythmias were found in 96 of 107 patients (90%) with adequate Holter recording: ventricular premature complexes in 49, nonsustained ventricular tachycardia in 5, supraventricular premature complexes in 29, paroxysmal supraventricular tachycardia or atrial fibrillation in 9, sinoatrial block and arrest in 29, second-degree atrioventricular block in 1, atrioventricular dissociation in 4 and idioventricular rhythm in 2. Life-threatening ventricular arrhythmias (torsades de pointes-type ventricular tachycardia) occurred in 4 patients, degenerating into either ventricular flutter or fibrillation in 2. ST-segment changes suggestive of acute transitory myocardial ischemia were found in 8 patients (1.5 mm or more of ST depression in 7 patients and 1.5 mm or more of ST elevation in 1 patient). The frequency and severity of arrhythmias were significantly higher in patients studied within 48 hours of subarachnoid hemorrhage; serious ventricular arrhythmias were associated with QTc prolongation more than 550 ms and with hypokalemia less than 3.5 mEq/liter. No correlation was found between age, clinical condition, site and extent of subarachnoid hemorrhage and either the occurrence or severity of arrhythmias. The results of our study indicate an extremely high incidence of arrhythmias, sometimes serious, in subarachnoid hemorrhage, especially in the first 48 hours after hemorrhage. Continuous electrocardiographic monitoring is therefore mandatory.     

Prognostic significance of programmed ventricular stimulation in patients surviving complicated acute myocardial infarction: a prospective study.

In survivors of complicated myocardial infarction, the inducibility of sustained ventricular tachycardia may help identify a subset that is at increased risk for subsequent sudden cardiac death or spontaneous sustained ventricular tachycardia. We performed prehospital discharge programmed ventricular stimulation in 86 survivors of acute myocardial infarction complicated by heart failure, angina pectoris, or nonsustained ventricular tachycardia. These patients also underwent cardiac catheterization with coronary angiography and 24-hour ambulatory ECG recording. Programmed ventricular stimulation induced sustained ventricular tachycardia in 19 patients (22%) and ventricular fibrillation in six (7%) and did not induce these arrhythmias in 61 patients (71%). During an average follow-up of 18 +/- 13 months, 11 patients had arrhythmic events (seven sudden death and four nonfatal spontaneous sustained ventricular tachycardia) and 10 patients had nonsudden cardiac death. The total cardiac mortality rate was 20%. Arrhythmic events occurred in 32% of the 19 patients with inducible sustained ventricular tachycardia compared with 7% of the remaining 67 patients (p less than 0.003). By multivariate analysis the occurrence of arrhythmic events was independently predicted by both inducible sustained ventricular tachycardia and Killip class III or IV heart failure. The risk of arrhythmic events was 4.4% in the absence of both variables versus 38.4% (p less than 0.001) when both variables were present. The total cardiac mortality rate was best predicted by low left ventricular ejection fraction (less than 30%). Thus programmed ventricular stimulation is useful in risk stratification of survivors of complicated acute myocardial infarction. The prognostic utility appears to be particularly high in patients with infarction complicated by Killip class III or IV heart failure.     

Inducible ventricular flutter and fibrillation predict for arrhythmia occurrence in coronary artery disease patients presenting with syncope of unknown origin

INTRODUCTION: Ventricular fibrillation and ventricular flutter (cycle length < or = 230 msec) induced at electrophysiologic studies are thought to be nonspecific findings in patients presenting with syncope of unknown origin. However, there are limited data on the prognosis of these patients in long-term follow-up. METHODS AND RESULTS: We followed 274 consecutive patients with coronary artery disease presenting with syncope or presyncope who underwent electrophysiologic studies from January 1992 to June 1999 and assessed the risk of subsequent arrhythmias stratified by the electrophysiologic result at the time of their presentation with syncope. Ventricular fibrillation was induced in 23 patients (8%); ventricular flutter in 24 (9%), sustained ventricular tachycardia in 41 (15%); and nonsustained ventricular tachycardia 42 (15%). In 37 +/- 25 months of follow-up, there have been ventricular arrhythmias in 34 patients, including 3 (13%) of 23 who had induced ventricular fibrillation, and 7 (30%) of 24 with induced ventricular flutter, compared to 13 (32%) of 41 with sustained ventricular tachycardia, 7 (17%) of 42 with nonsustained ventricular tachycardia, and only 4 (3%) of 144 noninducible patients (P < 0.001 for induced ventricular fibrillation and ventricular flutter vs noninducible patients). The inducibility of ventricular fibrillation and ventricular flutter were independent risk factors for arrhythmia occurrence in follow-up. CONCLUSION: Ventricular fibrillation and ventricular flutter induced at electrophysiologic studies have prognostic significance for arrhythmia occurrence in patients presenting with syncope. These induced arrhythmias may not be as nonspecific as previously thought and treatment should be considered for these patients.     

Electrophysiologic testing and follow-up of patients with aborted sudden death

Clinical, electrophysiologic and follow-up data were analyzed for 108 patients with aborted sudden death. The mean follow-up interval was 2 years. All patients underwent baseline drug-free invasive electrophysiologic studies. Seventy-five patients (group I) had inducible ventricular arrhythmias (including nonsustained and sustained ventricular tachycardia and ventricular fibrillation) and 33 patients (group II) had no inducible arrhythmias. Noninducibility was not predictive of a favorable outcome, because the incidence of both sudden death and recurrent ventricular tachycardia was similar in the two groups. Treatment guided by electrophysiologic testing was used in 17 patients; in 13 (17%) in group I arrhythmias became noninducible, and in 4 (5%) sustained ventricular arrhythmias became nonsustained after administration of conventional drugs. There was a significantly higher incidence of sudden death and recurrent ventricular tachycardia in the 4 patients with inducible arrhythmias (n = 3, 75%) compared with the 13 patients whose arrhythmias were noninducible (n = 2, 15%) (p less than 0.05). For the group as a whole, 11% died suddenly and 15% had recurrence of ventricular tachycardia. Sixty-four patients were treated with amiodarone and, of these, four (6%) died suddenly during the follow-up period and nine (14%) had recurrent ventricular tachycardia. Ventricular arrhythmias could be induced in 69% of patients with aborted sudden death but inducibility could be suppressed in only 20% of them. The role of therapy guided by electrophysiologic testing could therefore not be fully assessed. The findings reveal a significant recurrence rate of symptomatic, potentially life-threatening ventricular arrhythmias in medically treated patients with aborted sudden death.(ABSTRACT TRUNCATED AT 250 WORDS)