Differences in mechanisms and outcomes of syncope in patients with coronary disease or idiopathic left ventricular dysfunction as assessed by electrophysiologic testing

Assessing the Predictive Value of Combining Risk Scoring Systems and Ultrasonography for Short-Term Adverse Outcomes in Syncope: A Prospective Observational Study

BACKGROUND

In the emergency department (ED), the role of ultrasonography (USG) in risk stratification and predicting adverse events in syncope patients is a current research area. However, it is still unclear how ultrasound can be combined with existing risk scores.

OBJECTIVES

In this study, it was aimed to examine the contribution of the use of bedside USG to current risk scores in the evaluation of patients presenting to the ED with syncope. The predictive values of the combined use of USG and risk scores for adverse outcomes at 7 and 30 days were examined.

METHODS

The Canadian Syncope Risk Score (CSRS), San Francisco syncope rules (SFSR), USG findings of carotid and deep venous structures, and echocardiography results were recorded for patients presenting with syncope. Parameters showing significance in the 7-day and 30-day adverse outcome groups were utilized to create new scores termed CSRS-USG and SFSR-USG. Predictive values were evaluated using receiver operating characteristic (ROC) analysis. The difference between the predictive values was evaluated with the DeLong test.

RESULTS

The study was carried out with 137 participants. Adverse outcomes were observed in 45 participants (32.8%) within 30 days. 32 (71.7%) of the adverse outcomes were in the first 7 days. For 30-day adverse outcomes, the SFSR-USG (p = 0.001) and CSRS-USG (p = 0.038) scores had better predictive accuracy compared to SFSR and CSRS, respectively. However, there was no significant improvement in sensitivity and specificity values.

CONCLUSION

The use of USG in the evaluation of syncope patients did not result in significant improvement in sensitivity and specificity values for predicting adverse events. However, larger sample-sized studies are needed to understand its potential contributions better.

Prognosis of programmed ventricular stimulation in adult patients with syncope of unexplained origin: A historical cohort

Background

Programmed ventricular stimulation (PVS) during electrophysiological study (EPS), is a globally accepted tool for risk stratification of sudden cardiac death (SCD) in some specific clinical situations. The aim of this study was to evaluate the prognosis of ventricular arrhythmia induction in a cohort of patients with syncope of undetermined origin (SUO).

Methods

This is a historical cohort study in a population of patients with SUO referred for EPS between the years 2008-2021. In this interval, 575 patients underwent the procedure.

Results

Patients with induced ventricular arrhythmias had a higher occurrence of structural heart disease (36.7% vs. 76.5%), ischemic heart disease (28.2 vs. 57.1%), heart failure (15.5% vs. 34.4%), and lower left ventricular ejection fraction (59.16% vs. 47.51%), when compared to the outcome with a negative study. PVS triggered ventricular arrhythmias in 98 patients, 62 monomorphic and 36 polymorphic. During a median follow-up of 37.6 months, 100 deaths occurred. Only the induction of sustained ventricular arrhythmias showed a significant association with the primary outcome (all-cause mortality) with a p value <.001. After the performance of EPS, 142 patients underwent cardioverter-defibrillator (ICD) implantation. At study follow-up, 30 patients had therapies by the device. Only the induction of sustained monomorphic ventricular arrhythmia showed statistically significant association with appropriate therapies by the device (p = .012).

Conclusion

In patients with SUO, the induction of sustained monomorphic ventricular arrhythmia after programmed ventricular pacing is related to a worse prognosis, with a higher incidence of mortality and appropriate therapies by the ICD.

Arrhythmic syncope: From diagnosis to management

Syncope is a concerning symptom that affects a large proportion of patients. It can be related to a heterogeneous group of pathologies ranging from trivial causes to diseases with a high risk of sudden death. However, benign causes are the most frequent, and identifying high-risk patients with potentially severe etiologies is crucial to establish an accurate diagnosis, initiate effective therapy, and alter the prognosis. The term cardiac syncope refers to those episodes where the cause of the cerebral hypoperfusion is directly related to a cardiac disorder, while arrhythmic syncope is cardiac syncope specifically due to rhythm disorders. Indeed, arrhythmias are the most common cause of cardiac syncope. Both bradyarrhythmia and tachyarrhythmia can cause a sudden decrease in cardiac output and produce syncope. In this review, we summarized the main guidelines in the management of patients with syncope of presumed arrhythmic origin. Therefore, we presented a thorough approach to syncope work-up through different tests depending on the clinical characteristics of the patients, risk stratification, and the management of syncope in different scenarios such as structural heart disease and channelopathies.

Electrophysiological study as a predictor of mortality in unexplained syncope

Background

Electrophysiological study can help in the diagnosis of arrhythmic syncope. According to the electrophysiological study finding, the prognosis of patients with syncope is still a matter of study.

Objective

The aim of this study was to assess the survival of patients undergoing electrophysiological study according to their findings and to identify clinical and electrophysiological independent predictors of all-cause mortality.

Methods

A retrospective cohort study included patients with syncope who underwent electrophysiological study from 2009 to 2018. A Cox logistic regression analysis was performed to identify independent prognostic factors for all-cause mortality.

Results

We included 383 patients in our study. During a mean follow-up of 59 months, 84 (21.9%) patients died. The split His group had the worst survival compared with the control group, followed by sustained ventricular tachycardia and HV interval ≥ 70 ms, respectively (p = .001; p < .001; p = .03). The supraventricular tachycardia group showed no differences compared with the control group (p = .87). In the multivariate analysis, independent predictors of all-cause mortality were Age (OR 1.06; 1.03-1.07; p < .001); congestive heart failure (OR 1.82; 1.05-3.15; p = .033); split His (OR 3.7; 1.27-10.80; p = .016); and sustained ventricular tachycardia (OR 1.84; 1.02-3.32; p = .04).

Conclusion

Split His, sustained ventricular tachycardia, and HV interval ≥ 70 ms groups had worse survivals when compared to the control group. Age, congestive heart failure, split His, and sustained ventricular tachycardia were independent predictors for all-cause mortality.

ACR Appropriateness Criteria® Syncope

Syncope and presyncope lead to well over one million emergency room visits in the United States each year. Elucidating the cause of syncope or presyncope, which are grouped together given similar etiologies and outcomes, can be exceedingly difficult given the diverse etiologies. This becomes more challenging as some causes, such as vasovagal syncope, are relatively innocuous while others, such as cardiac-related syncope, carry a significant increased risk of death. While the mainstay of syncope and presyncope assessment is a detailed history and physical examination, imaging can play a role in certain situations. In patients where a cardiovascular etiology is suspected based on the appropriate history, physical examination, and ECG findings, resting transthoracic echocardiography is usually considered appropriate for the initial imaging. While no imaging studies are considered usually appropriate when there is a low probability of cardiac or neurologic pathology, chest radiography may be appropriate in certain clinical situations. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Presence and extent of cardiac computed tomography angiography defined coronary artery disease in patients presenting with syncope

Background

In syncope patients, presence of coronary artery disease (CAD) is associated with poor prognosis. However, data concerning CAD prevalence in syncope patients without known cardiovascular disease are lacking. Therefore, the aim of this study was to investigate presence and extent of CAD in syncope patients.

Methods

We included 142 consecutive patients presenting with syncope at the outpatient cardiology clinic who underwent coronary computed tomography (CT) angiography. Syncope type was ascertained by two reviewers, blinded for coronary CT angiography results. Of the patients, 49 had cardiac syncope (arrhythmia or structural cardiopulmonary disease) and 93 had non-cardiac syncope (reflex [neurally-mediated], orthostatic or of unknown cause). Cardiac syncope patients were compared with matched stable chest pain patients regarding age, gender, smoking status, diabetes mellitus type 2 and systolic blood pressure.

Results

Distribution of CAD presence and extent in cardiac and non-cardiac syncope patients was as follows: 72% versus 48% any CAD; 31% versus 26% mild, 8% versus 14% moderate and 33% versus 7% severe CAD.

Compared with non-cardiac syncope, patients with cardiac syncope had a significantly higher CAD presence and extent (p = 0.001). Coronary calcium score, segment involvement and stenosis score were also higher in cardiac syncope patients (p-values ≤0.004). Compared to the chest pain control group, patients with cardiac syncope showed a higher, however, non-significant, prevalence of any CAD (72% versus 63%) and severe CAD (33% versus 19%).

Conclusion

Patients with cardiac syncope show a high presence and extent of CAD in contrast to non-cardiac syncope patients. These results suggest that CAD may play an important role in the occurrence of cardiac syncope.

Electronic supplementary material

The online version of this article (doi: 10.1007/s12471-017-0970-7) contains supplementary material, which is available to authorized users.

Implications of a History of Syncope in Patients Hospitalized With Heart Failure

We assessed the frequency and implications of a history of syncope of up to 1 year prior to hospitalization with acute heart failure (AHF) between February and November 2012. Data were collected for 5005 patients hospitalized with AHF and analyzed and compared according to the absence/presence of a history of syncope (group 1 vs group 2). Prior syncope among patients with heart failure was 5.3%. Age, gender, hypertension, atrial fibrillation, bundle branch block, left ventricular ejection fraction (LVEF), and obstructed coronary vessels were comparable in the 2 groups. Group 2 patients were more likely to smoke or have diabetes mellitus, stroke, and cardiac arrest. Group 2 patients frequently required aggressive treatment and had more worse in-hospital and 1-year outcomes compared to group 1. After adjustment for age, sex, ethnicity, and LVEF, multivariate regression analysis showed that history of syncope predicted in-hospital mortality (odds ratio: 2.61; 95% confidence interval: 1.707-4.002). History of syncope during the year prior to the index admission with AHF is a marker of worse outcomes regardless of patient age and LVEF. Further studies are required to confirm this observation and its clinical implications.

Characteristics of syncope in patients with dilated cardiomyopathy

BACKGROUND

Syncope carries a poor prognosis among patients with dilated cardiomyopathy (DCM).

OBJECTIVES

To assess the prevalence, describe the underlying mechanisms and to identify risk factors for syncope in patients with DCM.

METHODS

One thousand six hundred and ten medical files of 897 patients with a diagnosis of DCM were reviewed. Patients with syncope were identified and their clinical and paraclinical profiles were compared to an equal number of age- and sex-matched patients with DCM without syncope.

RESULTS

Thirty patients (27 males) with an average age of 62.5 years were identified, corresponding to a prevalence of syncope of 3.3%. A cardiac origin of syncope was identified in 56% of patients (n=17): ventricular arrhythmias in 33% (n=10), and conduction disorders in 23% (n=7). Other mechanisms of syncope were neurally mediated in 7% (n=2) and orthostatic hypotension in 7% (n=2). In 30% of cases (n=9), the etiology was unidentified. There were no significant differences regarding the etiology of DCM, ejection fraction (35.3% vs 35.3%, p=1.0), NYHA class (mild or advanced, p=0.79) and associated conditions (hypertension, p=0.36; diabetes, p=0.75; atrial fibrillation, p=0.43; and dyslipidemia, p=0.33) between the two groups. However, among patients with syncope, patients with a noncardiac cause were more likely to have hypertension (61.53% vs 23.52%, p=0.08) and diabetes (46.15% vs 5.88%, p=0.03).

CONCLUSION

In patients with DCM, syncope is a relatively rare finding. Cardiac causes (arrhythmias and conduction disorders) are responsible for the majority of cases. Risk factors for syncope in these patients remain to be determined.

What is The Utility of Electrophysiological Study in Elderly Patients with Syncope and Heart Disease?

BACKGROUND

Syncope in elderly patients with heart disease is a growing problem. Its aetiological diagnosis is often difficult. We intended to investigate the value of the electrophysiological study (EPS) in old patients with syncope and heart disease.

METHODS

EPS was performed in 182 consecutive patients with syncope and heart disease, among whom 62 patients were ≥75 years old and 120 patients <75.

RESULTS

Left ventricular ejection fraction was 43.9±11.7% in patients ≥75 and 41.1±12.6% in patients <75. During EPS, induced sustained ventricular arrhythmias were as frequent in both groups (27.4% in patients ≥75 versus 27.5% in patients <75, p=0.99) whereas AV conduction abnormalities were more frequent in older patients (37.1% in patients ≥75 versus 18.3% in patients <75, p<0.005). Syncope remained unexplained in 35.5% of patients ≥75 and in 51.7% of patients <75 (p>0.04). ICD was more likely to be implanted in younger patients than in patients ≥75 years (37.5% vs 21% respectively, p<0.009). During a mean follow-up period of 3.3±3 years, the 4-year-survival rate was 66.9±6.8 % in patients ≥75 and 75.9±6.2 % in patients <75 years. The main cause of death was heart failure in both groups. The factors related to a worse outcome in a multivariate analysis were low LVEF and higher age.

CONCLUSION

Complete EPS allows the identification of treatable causes in a high proportion of elderly patients with syncope and heart disease. Yet, the prognosis of these patients is mainly related to LVEF and age.

Atrial flutter or fibrillation is the most frequent and life-threatening arrhythmia in myotonic dystrophy

BACKGROUND

Several arrhythmias were reported in myotonic dystrophy (MD).

OBJECTIVES

To evaluate the prevalence of atrial fibrillation (AF) and atrial flutter (AFL) in MD and the clinical consequences.

METHODS

One hundred sixty-one patients, mean age 41 ± 14 years, were referred for a type 1 MD. All patients were asymptomatic except four patients and followed during 5 ± 4 years. Electrocardiogram (ECG), echocardiography assessing left ventricular ejection fraction, and Holter monitoring were obtained and repeated.

RESULTS

Twenty-seven patients (17%) presented sustained (>1 hour) AF (n = 15) or AFL (n = 12); two of them presented syncope-related 1/1 AFL. In one of them, 16 years of age, cardiac defibrillator was implanted for a diagnosis of ventricular tachycardia, but the true diagnosis was established after inappropriate shocks. AFL ablation was performed in five patients, but four developed AF. The other seven patients with AFL developed AF. During the follow-up, 22 patients died (14%) from cardiac and respiratory failure; eight patients with AF/AFL died (30%) while only 14 without AF/AFL died (10%; P < 0.01). Univariate analysis indicated that age >40 years (death: 48 ± 14 vs 40 ± 8 in alive patients), abnormal ECG, and occurrence of AF/AFL were significant factors of death. At multivariate analysis, AF at ECG (odds ratio: 3.12) and age >40 (odds ratio: 3.14) were the sole independent variables predicting death.

CONCLUSIONS

AF and AFL were frequent in MD and increased mortality. AFL could present as 1/1 AFL with a poor tolerance and a risk of misdiagnosis despite frequent conduction disturbances. This arrhythmia could explain wide QRS tachycardia occurring in MD and interpreted as VT.

Nonischemic dilated cardiomyopathy: results of noninvasive and invasive evaluation in 310 patients and clinical significance of bundle branch block

BACKGROUND

The survival of patients with idiopathic dilated cardiomyopathy (IDCM) at III and IV stages of New York Heart Association (NYHA) is decreased in those with a bundle branch block (BBB) compared to those without BBB. Less is known on the prognosis of patients at earlier stages of NYHA and who had a left BBB (LBBB) or right BBB (RBBB). We sought to evaluate the prevalence and the clinical significance of LBBB or RBBB in patients with IDCM and classes I and II of NYHA.

METHODS

Clinical data, noninvasive, and invasive studies were consecutively collected in 310 patients, with IDCM, followed up to 4.8+/-3.7 years.

RESULTS

Seventy-six patients (25%) had LBBB, 21 (7%) had RBBB, and 212 had no BBB. Patients with BBB were older than other patients (P < 0.009). Left ventricular ejection fraction (LVEF) was lower in LBBB than in RBBB and other patients (P < 0.05). Syncope was more frequent in BBB than in absence (P < 0.05). Incidence of spontaneous ventricular tachycardia (VT) and atrial fibrillation, VT induction, total cardiac events, and sudden death were similar in the presence or absence of BBB. Deaths by heart failure and heart transplantations tended to be more frequent in BBB than in absence.

CONCLUSIONS

LBBB was present in 25% of patients with IDCM; RBBB was rare. Patients with BBB were older and had more frequent syncope than patients without BBB; LVEF was lower in LBBB than in RBBB or in absence of BBB. BBB did not increase the risk of spontaneous VT, VT induction, or sudden death, and tended to increase deaths by heart failure and the indications of heart transplantation.

Neurocardiogenic mechanisms of unexplained syncope in idiopathic dilated cardiomyopathy

Syncope in patients with advanced heart failure is a sign of poor prognosis. The cause of syncope in patients with dilated cardiomyopathy (DC) is not fully recognized and may remain elusive even after standardized evaluation. The purpose of the present study was to examine the implication of neurally mediated mechanisms in the pathophysiology of syncopal episodes in patients with DC. Twenty-six patients (21 men, 5 women; mean age 59 +/- 2 years, range 38 to 79) with DC and left ventricular ejection fractions <or=40% were included in the study. Thirteen patients with unexplained syncope or presyncope and a control group of 13 patients without unexplained syncope underwent head-up tilt tests with clomipramine challenge. The 2 groups were matched with regard to age, gender, and left ventricular ejection fractions, and there were no major differences in terms of medication. Heart rate variability analysis and plethysmography of forearm flow were performed during the tilt tests. Blood samples were also drawn for catecholamine measurements. In the group with histories of unexplained syncope, the head-up tilt test results were positive in 11 patients (84.6%). Sympathetic and parasympathetic heart rate indexes were markedly stimulated, while catecholamine concentrations and blood flow changes indicated sympathetic withdrawal during tilting. In the control group, the head-up tilt test results were negative in 12 patients (92.3%). In conclusion, neurally mediated mechanisms seem to be implicated in the pathophysiology of syncope in patients with DC and should therefore be considered in the differential diagnosis of syncopal episodes of unexplained origin.

Current management of syncope : focus on drug therapy

Syncope is defined as transient loss of consciousness as a result of inadequate cerebral perfusion. The causes of syncope fall into five broad categories: neurally mediated, orthostatic (the most frequent causes), cardiac arrhythmias, structural cardiovascular (relatively uncommon cause), and cerebrovascular (very rare). The initial evaluation of the syncope patient includes a detailed medical history and physical exam, and usually an ECG and echocardiogram. Thereafter, selected additional testing (e.g. ambulatory ECG recording, autonomic function testing, electrophysiologic study) may be needed on a case-by-case basis. Neurally mediated and orthostatic syncope should first be treated by conservative therapies including hydration/volume expanders and physical counter-maneuvers. Various drugs may play a role as second-line of treatment. However, apart from midodrine, randomized studies of drug therapy are largely lacking, and most agents have not proved to be predictably effective. For syncope due to cardiac arrhythmias, treatment options (depending on the specific circumstance) include ablation of the arrhythmia origin, antiarrhythmic drugs, and/or implantable devices (pacemakers and defibrillators). In the case of syncope due to structural cardiovascular defects (e.g. acute myocardial ischemia, pulmonary hypertension, obstructive cardiomyopathy), treatment is aimed at ameliorating the underlying structural defect. In brief, establishing a specific cause(s) for syncope is crucial. Only then can a potentially effective treatment strategy be contemplated.

Supraventricular tachyarrhythmia as a cause of sudden cardiac arrest

INTRODUCTION

Supraventricular tachyarrhythmias (SVTA) are an accepted cause of cardiac arrest in patients with Wolff-Parkinson-White syndrome (WPW) and hypertrophic cardiomyopathy but their participation in other conditions is less well understood. The purpose of the study was to examine the role of SVTA in sudden cardiac arrest (SCA) by comprehensive evaluation of patients successfully resuscitated from SCA.

METHODS

A total of 169 survivors of SCA in the absence of acute myocardial infarction underwent systematic evaluation that included echocardiography, Holter monitoring, coronary angiography and electrophysiological study (EPS) with additional testing in selected cases using provocative drug testing with isoproterenol, ajmaline or ergonovine.

RESULTS

SVTA was found as the only possible cause or as the cause facilitating SCA in 29 patients: (1) 3 had a WPW syndrome related to accessory pathway with short refractory period; (2) for 12 patients, SVTA was the cause of cardiovascular collapse; heart disease (HD) was present in 11 cases, but disappeared in two of four with dilated cardiomyopathy after the restoration of sinus rhythm; (3) in 14 patients, SVTA degenerated either in a VF or ventricular tachycardia (VT); HD was present in 12 cases, but disappeared in one; two had no HD and recurrent similar arrhythmia was documented by cardiac defibrillator in one of them. SVTA induced coronary ischemia was the main cause of SCA.

CONCLUSION

Rapid SVTA was a cause of SCA, either by cardiovascular collapse or by the degeneration in VT or VF. The complication generally occurred in patients with advanced HD or with rapid SVTA-induced cardiomyopathy and rarely in patients without HD. The incidence of SVTA as the only cause or the facilitating cause of SCAs is probably underestimated, because it is difficult to prove.

Sudden death is associated with a widened paced QRS complex in noncoronary cardiac disease

INTRODUCTION

Recent experimental and clinical trials have provided evidence that increased duration of right ventricular electrogram in response to premature extrastimuli correlates with the risk of ventricular fibrillation in noncoronary heart disease. The aim of the present study was to investigate the duration of the surface QRS complex at short coupling intervals of extrastimuli as a new indicator for major arrhythmic events.

METHODS

32 patients all with nonischemic heart diseases and well preserved left ventricular function in sinusrhythm were included into the study. Fifteen had witnessed sudden death due to ventricular fibrillation or polymorphic ventricular tachycardia (VF/VT group). The control group comprised seventeen patients without a history of ventricular arrhythmias (control group). All subjects underwent programmed ventricular stimulation and QRS-durations S1-S2-S3 directly above the ventricular refractory period were analyzed.

RESULTS

Both groups had a comparable basic QRS complex of 85 +/- 9 (VF/VT) vs. 87 +/- 13 ms (control), p = 0.83. The stimulated QRS complex S3 was significantly wider in the VF/VT group compared to the control group at pacing rates of 500 and 430 ms (500 ms: 256 +/- 22 vs. 235 +/- 32 ms, p = 0.04; 430 ms: 258 +/- 23 vs. 226 +/- 27 ms, p = 0.001). No differences with regard to the ventricular effective refractory period and the ventriculoatrial conduction could be observed beween the groups.

CONCLUSIONS

Our results indicate that the duration of the paced QRS complex may be a valuable parameter to predict arrhythmic risk in patients with nonischemic heart disease. Further prospective studies in larger trials are necessary to corroborate this investigation.

High risk of ventricular arrhythmias in patients with nonischemic dilated cardiomyopathy presenting with syncope

It is not entirely clear whether the presentation of syncope in patients with nonischemic dilated cardiomyopathy (NIDC) is an ominous prognostic indicator, because randomized controlled implantable cardioverter-defibrillator (ICD) trials generally exclude such patients. This study compared 108 consecutive patients with NIDC presenting with syncope with 71 consecutive patients with NIDC who presented with sustained ventricular arrhythmias, with regard to freedom from any ventricular arrhythmias or life-threatening arrhythmias and all-cause mortality. There was no significant difference between the groups in the 3 outcomes during the follow-up of 43.5 +/- 32.1 months. Male gender and ICD therapy predicted increased risk for any ventricular arrhythmias. A reduced left ventricular ejection fraction and increased age were predictive of increased mortality. In conclusion, patients with NIDC presenting with syncope are a high-risk group, with event rates similar to patients with NIDC presenting with sustained arrhythmias, and should be considered for ICD therapy.

Increased sensitivity of electrophysiological study by isoproterenol infusion in unexplained syncope

The purpose of the study was to evaluate the interests of electrophysiologic study (EPS) after infusion of isoproterenol in patients with syncope and negative EPS in control state.

METHODS

1350 patients were consecutively admitted for syncope and EPS. Patients were included if they had no history of tachycardia, a normal Holter monitoring, a negative EPS in control state. EPS was repeated after infusion of 2-4 mug/kg of isoproterenol.

RESULTS

256 patients, 35 with exercise-related syncope and 105 with heart disease (HD), were recruited. After isoproterenol, an arrhythmia was identified as the sign associated with syncope in 102 patients (40%): SVT in 32 patients, VT in 36 patients, infrahisian 2nd or 3rd degree AV block in three patients and vasovagal reaction in 31 patients. Arrhythmias were more frequent in patients with HD (50/105) than in those without HD (52/151) (p<0.05); SVT tended to be more frequent in patients without HD (n=23) than in those with HD (n=9) (p<0.1); VT was more frequent in patients with HD (n=26) than in those without HD (n=10) (p<0.001). There was no relationship between a positive isoproterenol testing and occurrence of syncope at exercise (19/35 vs 81/221) (p<0.1).

CONCLUSION

isoproterenol infusion increased the sensitivity of EPS in patients with syncope, related or not to exercise, and with negative study in control state, but principally in those with HD. However, SVT was diagnosed in patients without HD and EPS associated with isoproterenol infusion remained an important and rapid tool to establish this diagnosis.

Significance of Inducible Ventricular Flutter-Fibrillation After Myocardial Infarction

AIM

The purpose of this study was to determine the factors associated with the induction of ventricular flutter/fibrillation (VFl/VF)and its prognostic significance in post-myocardial infarction.

METHODS

Programmed ventricular stimulation was performed after myocardial infarction (MI) for syncope (n = 232) or systematically (n = 755); 230 patients had an induced VFl/VF and were followed during 4 +/- 2 years.

RESULTS

VFl/VF was induced in 49/232 patients (21%) with syncope versus 181/755 asymptomatic patients (24%) (NS) and 94/410 patients (23%) with left ventricular ejection fraction (LVEF) <40% versus 136/577 patients (22.5%) with LVEF >40% (NS). Cardiac mortality was 9%; LVEF was 33 +/- 15% in patients who died, 43 +/- 13% in alive patients (P < 0.004). In patients with LVEF <40%, induced VFl/VF, mortality rate was 31% in those with syncope, 10% in asymptomatic patients (P < 0.001), because of an increase of deaths by heart failure; patients with LVEF >40% with or without syncope had a low mortality (5% and 3%). After linear logistic regression, VFl/VF and LVEF were predictors of total cardiac mortality, but only LVEF <40% predicted sudden death.

CONCLUSION

Syncope and the level of LVEF did not increase the incidence of VFl/VF induction after MI, but modified the cardiac mortality: induced VF increased total cardiac mortality in patients with syncope and LVEF <40%, but did not increase sudden death. In patients with LVEF >40%, induced VFl/VF has no significance neither in asymptomatic patients nor in those with syncope.