Rhythm disturbances in hypertrophic cardiomyopathy: Prevalence,relation to symptoms and management

The prevalence of arrhythmias, associated symptoms and the effect of antiarrhythmic therapy were studied in 33 patients with hypertrophic obstructive cardiomyopathy (mean follow-up period 4.7 years). Arrhythmias were found in 29 patients (88 percent) and were potentially life-threatening in 13 (39 percent). Most patients had more than one type of arrhythmia. All patients were symptomatic at Initial evaluation: A history of syncope was noted in 12 patients, of presyncope in 27 and of palpitations in 23. All patients received large doses of propranolol (more than 240 mg/day or more than 3.5 mg/kg per day; average 460 mg/day or 6.7 mg/kg per day) for treatment of hypertrophic obstructive cardiomyopathy. In addition, pacemaker insertion or additional antiarrhythmic therapy was required in 10 patients; these patients underwent repeated Holter monitoring until arrhythmia control was documented, and at least at yearly intervals thereafter.Although some patients had arrhythmias, including short runs of ventricular tachycardia, in the absence of symptoms during ambulatory monitoring and others had symptoms in the absence of rhythm disturbances, the relation between suppression of potentially life-threatening arrhythmias and symptomatic improvement was striking: potentially life-threatening arrhythmias were suppressed in all but one patient, palpitations and episodes of presyncope have decreased in most, syncope has been eliminated in all and there have been no deaths. In addition, atrial fibrillation appears to have been prevented. Symptomatic improvement was independent of the severity of left ventricular outflow tract obstruction.It is concluded that Holter monitoring and stress testing should be a routine part of the evaluation of all patients with hypertrophic cardiomyopathy and that aggressive therapy of potentially life-threatening arrhythmias results in a lessening of palpitations and episodes of presyncope and syncope and appears to prevent sudden death in these patients when combined with large doses of propranolol.     

Ventricular arrhythmias: medical therapy, device treatment, and indications for electrophysiologic study

Sustained ventricular arrhythmias occur most frequently during the first several months following MI, although the risk of arrhythmia development continues for many years. The mechanism responsible for most of these arrhythmias is a re-entrant circuit located in the border zone between the normal and scarred subendocardium. Clinical factors that identify patients at greatest risk for developing sustained ventricular arrhythmias after MI include depressed left ventricular function, acute left ventricular aneurysm formation, electrical instability, new bundle branch blocks, and residual ischemia. Attempts to lower the arrhythmic risk of these patients is a major area of clinical investigation. Although frequent asymptomatic ventricular ectopy and nonsustained ventricular tachycardia are risk factors for sudden death after infarction, it has not been demonstrated that empiric treatment of these arrhythmias with antiarrhythmic agents improves survival. Electrophysiologic studies have significantly contributed to understanding the mechanisms responsible for sustained ventricular arrhythmias. Although the role of electrophysiologic studies in guiding therapy in patients with sustained ventricular tachycardia or sudden death after infarction has been well established, their utility to identify high risk subgroups after infarction has not been conclusively determined. New treatment modalities have resulted in an improved outcome in patients with malignant ventricular arrhythmias (Table 2). These strategies include new pharmacologic therapies, arrhythmia surgery, use of automatic implantable cardioverter defibrillators or antitachycardia pacemakers, and percutaneous catheter ablation of the re-entrant circuit responsible for these arrhythmias.     

Utility of mobile cardiac outpatient telemetry for the diagnosis of palpitations, presyncope, syncope, and the assessment of therapy efficacy

Introduction: Continuous mobile cardiac outpatient telemetry (MCOT) may have several advantages over traditional ambulatory monitoring systems in the diagnostic evaluation of symptoms such as palpitations, dizziness, and syncope. However, only limited published data are available showing its advantages.
Methods and Results: We reviewed the records of 122 consecutive patients evaluated using MCOT for palpitations, presyncope/syncope, or to monitor the efficacy of a specific antiarrhythmic therapy. Ten of 17 patients (59%) studied for presyncope/syncope had a diagnosis made with MCOT. Eight of these 17 patients had a previous negative evaluation for presyncope/syncope and five had an event correlated with the heart rhythm during the monitoring period. Nineteen patients monitored for palpitations or presyncope/syncope were asymptomatic during monitoring but had a prespecified arrhythmia detected. When MCOT was used as the first ambulatory monitoring system to evaluate palpitations (n = 18), 73% of patients correlated their symptoms with the underlying cardiac rhythm. Seven of 21 patients monitored for medication titration had dosage adjustments during outpatient monitoring.
Conclusions: MCOT can detect asymptomatic clinically significant arrhythmias, and was especially useful to identify the cause of presyncope/syncope, even in patients with a previous negative workup. This outpatient monitoring system allows patients to undergo daily medication dose titration in the outpatient setting, thus avoiding hospitalization.     

Prognostic significance of exercise induced arrhythmias and echocardiographic variables in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HC) often presents with exercise-induced symptoms, including arrhythmias and sudden death. The investigators prospectively studied whether exercise testing is associated with immediate complications and if stress-induced arrhythmias and echocardiographic variables are associated with long-term adverse outcomes. Exercise echocardiography with 6-channel continuous monitoring for arrhythmias was performed in consecutive patients with HC clinically referred for the test. End points included death, myocardial infarction, revascularization, stroke, atrial fibrillation, ventricular tachycardia, and myectomy. Of 86 patients with HC (mean age 56.6 +/- 16.1 years) who underwent exercise echocardiography, arrhythmias occurred in 39 (45%), including 23 (27%) with premature atrial contractions, 2 (2%) with atrial fibrillation, 28 (33%) with premature ventricular contractions (16 also had atrial arrhythmias), and 1 (1.2%) with nonsustained ventricular tachycardia (hemodynamically stable). During a follow-up of 2.6 +/- 2.8 years, major events occurred in 11 patients (3 deaths, 5 revascularizations, 3 strokes). In addition, 12 patients developed atrial fibrillation, 6 developed nonsustained ventricular tachycardia, and 13 underwent myectomies. Variables associated with major events included hypertension, male gender, and worsening wall motion score index with exercise; increased exercise duration was associated with fewer events. ST-T changes on baseline electrocardiography and premature ventricular contractions were associated with atrial fibrillation risk. In conclusion, in this cohort of patients with HC, exercise testing was safe. Test results were associated with risk for adverse events.     

The Utility of Holter Monitoring Compared to Loop Recorders in the Evaluation of Syncope and Presyncope

Background: Holter monitoring is frequently used to assess patients with syncope, but rarely provides a diagnosis. Newer loop recorders provide the opportunity for prolonged electrocardiographic monitoring to enhance diagnostic yield. Methods: The results of 232 Holter monitors and 81 loop recordings performed for the investigation of syncope or presyncope were reviewed for indication, patient demographics, and presence and type of symptoms and/or arrhythmias. The results were classified as (1) symptom‐arrhythmia correlation, (2) clinically useful information (group 1 plus those excluding arrhythmic syncope, and those demonstrating asymptomatic serious arrhythmias) and (3) unhelpful (asymptomatic and no serious arrhythmias). Results: Loop recorders provided a symptom‐arrhythmia correlation in 11.1% of patients compared to only 0.4% in the Holter group (P < 0.0001). Clinically useful information was obtained in 54.3% of loop patients compared to 27.6% in the Holter group (P < 0.0001). Technical problems occurred in 0.4% of the Holter patients and in 3.7% of loop patients (P = 0.05). Classification was difficult in seven patients in the Holter group; two experienced symptoms during sinus rhythm but also had a serious asymptomatic arrhythmia, and five patients had 6–10 beats of asymptomatic ventricular tachycardia at a rate < 160 beats/min. Conclusion: Loop recording was well tolerated and superior to Holter monitoring in providing a symptom‐arrhythmia correlation or clinically useful information in patients with syncope and presyncope. An initial approach with a loop‐recording device should be employed in these patients.     

Diagnostic utility of memory equipped transtelephonic monitors

The diagnostic utility of memory-equipped transtelephonic electrocardiographic monitors was evaluated in a series of 31 patients referred for evaluation of unexplained syncope (16), presyncope (8), or palpitations (7). Previous nondiagnostic workups included 4 +/- 1 days (mean +/- standard error of the mean) of 24-hour Holter and/or in-hospital telemetric monitoring per patient. The duration of monitoring averaged 31 +/- 2 days per patient. Electrocardiographic recordings were made during a typical symptom episode in 9 of 31 (29%) patients, including 0 of 16 with syncope, 3 of 8 (37%) with presyncope, and 6 of 7 (86%) with palpitations (p less than .001). The probability of recording typical symptoms was strongly influenced by their previous frequency. Potentially causal arrhythmias were documented in 5 of 7 (71%) patients with palpitations, but in none of the other symptom subgroups (p less than .001). Monitoring led to changes in therapy in only two patients. During followup of 9 +/- 1 months, symptoms continued in 4 of 16 (25%) with syncope, 7 of 8 (87%) with presyncope, and 7 of 7 (100%) with palpitations (p = .001). The diagnostic utility of these devices thus appears to be low in patients with previously unexplained syncope or presyncope. The yield was high in those monitored for palpitations, which may be in part attributable to the greater frequency of symptoms observed in this group.     

Haemorrhagic cystitis: incidence and risk factors in a transplant population using hyperhydration

Haemorrhagic cystitis (HC) is the syndrome of haematuria and symptoms of lower urinary tract irritability in the absence of bacterial infection. We report a low incidence of HC (18.2%) in 681 haemopoietic stem cell transplant patients, using a prophylactic regimen of hyperhydration and forced diuresis. The incidence of grade 3-4 disease is 3.4%. There was a marked difference in incidence between allogeneic and autologous transplant populations, 24.2% vs. 3.5% (P<0.0005). Busulphan conditioning, acute GVHD, interstitial pneumonitis and use of methotrexate and cyclosporin immune suppression were associated with significantly increased incidence of HC in the allogeneic population. This may reflect the numerous factors that contribute to the greater immunosuppression and consequent increased risk for HC in allogeneic transplantation.     

Ischemic sudden death: critical analysis of risk markers. Part VIII

Coronary artery disease is responsible for approximately 75-80% of sudden cardiac deaths in most industrialized countries. Risk factors can be divided in those which suggest structural heart disease and those reflecting abnormal physiological markers. Therapeutic strategies for primary prevention of sudden cardiac death require careful scrutiny. The systematic use of risk markers to identify and stratify high risk groups may be of help to establish primary prevention measures in daily practice. Different methods to stratify risk factors using ejection fraction, ventricular arrhythmias, heart rate variability, baroreflex sensitivity, and dispersion of repolarization are discussed in this article.     

The diagnosis of cardiac arrhythmias: a prospective multi-center randomized study comparing mobile cardiac outpatient telemetry versus standard loop event monitoring

Introduction: Ambulatory electrocardiographic monitoring systems are frequently used in the outpatient evaluation of symptoms suggestive of a cardiac arrhythmia; however, they have a low yield in the identification of clinically significant but infrequent, brief, and/or intermittently symptomatic arrhythmias. The purpose of this study was to compare the relative value of a mobile cardiac outpatient telemetry system (MCOT) with a patient-activated external looping event monitor (LOOP) for symptoms thought to be due to an arrhythmia.
Methods and Results: The study was a 17-center prospective clinical trial with patients randomized to either LOOP or MCOT for up to 30 days. Subjects with symptoms of syncope, presyncope, or severe palpitations who had a nondiagnostic 24-hour Holter monitor were randomized. The primary endpoint was the confirmation or exclusion of a probable arrhythmic cause of their symptoms. A total of 266 patients who completed the monitoring period were analyzed. A diagnosis was made in 88% of MCOT subjects compared with 75% of LOOP subjects (P = 0.008). In a subgroup of patients presenting with syncope or presyncope, a diagnosis was made in 89% of MCOT subjects versus 69% of LOOP subjects (P = 0.008). MCOT was superior in confirming the diagnosis of clinical significant arrhythmias, detecting such events in 55 of 134 patients (41%) compared with 19 of 132 patients (15%) in the LOOP group (P < 0.001).
Conclusions: MCOT provided a significantly higher yield than standard cardiac loop recorders in patients with symptoms suggestive of a significant cardiac arrhythmia.     

Mitral valve prolapse: etiology, clinical presentation and neuroendocrine function.

Based on our experience and the experience of others, the following classification of patients with mitral valve prolapse has been proposed. Mitral valve prolapse - Anatomic includes patients with a wide spectrum of mitral valve abnormalities from mild to severe. Symptoms, physical findings and laboratory abnormalities in these patients are directly related to mitral valve dysfunction and progressive mitral regurgitation. Complications related to abnormal mitral valve include infective endocarditis, thromboembolic events, cardiac arrhythmias, progressive mitral regurgitation, rupture of chordae tendineae and congestive heart failure. Individuals with thick mitral leaflets and mitral systolic murmur are at higher risk of developing complications. The term mitral valve prolapse syndrome refers to the occurrence of symptoms such as palpitation, chest pain, fatigue, poor exercise tolerance, dyspnea, orthostatic phenomena and syncope or presyncope in patients with mitral valve prolapse which cannot be explained on the basis of mitral valve abnormality alone. The pathogenesis of these symptoms in patients with mitral valve prolapse syndrome appears to be related to metabolic neuroendocrine abnormalities. Preventing infective endocarditis is a major consideration in patients with mitral valve prolapse. Significant mitral regurgitation with the development of congestive heart failure often requires mitral valve surgery. The most important therapeutic approach in patients with mitral valve prolapse syndrome is to explain the mechanisms of symptoms and to reassure the patient.     

Cognitive decline is associated with nutritional risk in subjects with small head circumference (HC)

Nutrition has been found to be associated with cognitive impairment, but it has not been established whether these associations are present solely in later life or whether they are present in younger age as well. HC is a good indicator of brain development and the most sensitive anthropometric indicator of prolonged malnutrition during early life. This study examined the interaction between early HC and later (nutrition screening initiative) nutritional factors on the risk of cognitive decline in the elderly. The longitudinal factorial design had the mini-mental state examination (MMSE) score as the dependent variable, with HC as one factor and nutritional risk as another. We studied a sample of 495 not cognitively impaired Korean participants with 2 years follow-up data. After multivariable adjustment, interactive effect between HC and nutritional risk was significantly associated with cognitive decline (F = 2.449, p = 0.045). Simple main effect analysis showed that compared with highest HC, lowest HC was associated with a cognitive decline. Nutritional risk was associated with cognitive function decline only in individuals with small HC. Therefore, the prevention for cognitive impairment and dementia should involve nutritional strategies throughout life.     

Cardiac involvement in patients with sarcoidosis: diagnostic and prognostic value of outpatient testing

BACKGROUND: Cardiac sarcoidosis (CS) causes substantial morbidity and sudden death. Early diagnosis and risk stratification are warranted. METHODS: Ambulatory patients with sarcoidosis were interviewed to determine whether they experienced palpitations, syncope, or presyncope, and were evaluated with ECG, Holter monitoring, and echocardiography (transthoracic echocardiogram [TTE]). Those with symptoms or abnormal results were studied with cardiac MRI (CMRI) or positron emission tomography (PET) scanning. The diagnosis of CS was based on abnormalities detected by these imaging studies. Patients with CS were referred for risk stratification by electrophysiology study (EPS). RESULTS: Among the 62 patients evaluated, the prevalence of CS was 39%. Patients with CS had more cardiac symptoms than those without CS (46% vs 5%, respectively; p < 0.001), and were more likely to have abnormal Holter monitoring findings (50% vs 3%, respectively; p < 0.001) and TTE findings (25% vs 5%, respectively; p = 0.02). The degree of pulmonary impairment did not predict CS. Two of the 17 patients who underwent EPS had abnormal test findings and received implantable cardioverter-defibrillators. No patients died, had ventricular arrhythmias that triggered defibrillator therapy, or had heart failure develop during almost 2 years of follow-up. This diagnostic approach was more sensitive than the established criteria for identifying CS. CONCLUSION: CS is common among patients with sarcoidosis. A structured clinical assessment incorporating advanced cardiac imaging with PET scanning or CMRI is more sensitive than the established criteria for the identification of CS. Sarcoidal lesions seen on CMRI or PET scanning do not predict arrhythmias in ambulatory patients with preserved cardiac function, who appear to be at low risk for short-term mortality.     

Identifying high risk in adults with congenital heart disease and atrial arrhythmias

Atrial arrhythmias are associated with an increased mortality risk in adults with congenital heart disease (CHD). However, little is known about risk stratification in the specific group of adult patients with CHD and atrial arrhythmias. We sought to identify predictors of mortality in adult with CHD and atrial arrhythmias and to establish a risk score. The study involved 378 adult patients with CHD (mean age 39 ± 13 years) and atrial arrhythmias who had serial follow-up in a tertiary referral center from 1999 through 2009. During a median follow-up of 5.2 years, there were 40 deaths (11%). Overall mortality rate was 2.0% per patient-year. Common modes of death included heart failure-related death (35%), sudden cardiac death (20%), and perioperative death (18%). Independent predictors of mortality were poor functional class (hazard ratio 3.69, 95% confidence interval [CI] 1.69 to 8.03, p = 0.001), single-ventricle physiology (hazard ratio 3.33, 95% CI 1.51 to 7.35, p = 0.003), pulmonary hypertension (hazard ratio 2.96, 95% CI 1.41 to 6.19, p = 0.004), and valvular heart disease (hazard ratio 2.73, 95% CI 1.33 to 5.59, p = 0.006). A risk score was constructed using these predictors in which patients were assigned 1 point for the presence of each risk factor. Mortality rates in the low-risk (no risk factor), moderate-risk (1 risk factor), and high-risk (>1 risk factor) groups were 0.5%, 1.9%, and 6.5% per patient-year, respectively (log-rank p <0.001). In conclusion, in adult with CHD and atrial arrhythmias specific clinical variables identify patients at high risk for death. Importantly, the absence of any of these risk factors is associated with an excellent survival despite the presence of atrial arrhythmias.     

Long-term outcome of patients with syncope associated with coronary artery disease and a nondiagnostic electrophysiologic evaluation

Syncope in the patient with structural heart disease and a nondiagnostic noninvasive workup is a generally accepted indication for an invasive electrophysiologic study. However, if the electrophysiologic evaluation is not highly sensitive, arrhythmic causes of syncope may not be discovered. In these patients, recurrent syncope and even sudden death may be observed at follow-up. Thus, we evaluated long-term follow-up in 68 consecutive patients who presented with syncope, coronary artery disease, and who had a negative invasive electrophysiologic evaluation. At a mean follow-up of 30 +/- 18 months (range 1 to 65), there have been 2 sudden deaths and 1 episode each of ventricular fibrillation and ventricular tachycardia in patients treated with an implantable cardioverter-defibrillator. All 4 arrhythmias occurred in patients with left ventricular fractions < or = 25%. Seventeen patients had recurrent presyncope or syncope. Bradycardia causing syncope was found in 8 of these patients. A bundle branch block at the initial evaluation predicted for the occurrence of bradycardia at follow-up. We conclude that in patients with coronary artery disease and syncope, noninducibility at electrophysiologic study predicts a lower risk of sudden death and ventricular arrhythmias. However, in patients with a reduced ejection fraction, the risk of sudden death and ventricular arrhythmias remains up to 10%/year and these patients may warrant treatment with implantable cardioverter-defibrillators. Recurrent syncope is common, and frequently a bradyarrhythmia is found to be the cause. Treatment of selected patients (especially those with bundle branch blocks) with permanent pacemakers may be justified.     

Favourable association of leg fat with cardiovascular risk factors

OBJECTIVES: To assess the association of trunk and leg fat mass (FM) and leg lean tissue mass (LTM) with conventional cardiovascular risk factors. DESIGN: Cross-sectional study. SETTING AND SUBJECTS: We studied 1249 men and 3007 women (age 20-79 years) who attended a research institute for a health checkup between October 1995 and February 2004. MAIN OUTCOME MEASURES: Body mass index, waist circumference (WC), hip circumference (HC), systolic and diastolic blood pressure, total cholesterol, HDL cholesterol, triglycerides, glucose and haemoglobin A(1C) were measured. Trunk FM, leg FM and leg LTM were obtained by dual-energy X-ray absorptiometry. We evaluated the associations between the indices for regional body composition and cardiovascular risk factors, which included hypertension, hypercholesterolaemia, hypo-HDL cholesterolaemia, hypertriglyceridaemia, dyslipidaemia and diabetes mellitus. RESULTS: Increase in WC and HC respectively showed increase and decrease in odds ratios of cardiovascular risk factors. Increase in trunk FM by 1 kg significantly increased the risk of the cardiovascular risk factors with the odds ratios ranging between 1.11 and 1.45. Increase in leg FM by 1 kg significantly decreased the risk with the odds ratios ranging between 0.52 and 0.90, except for the nonsignificant results for hypercholesterolaemia and hypo-HDL cholesterolaemia in men. Odds ratios of 1 kg increase in leg LTM were only significant for dyslipidaemia in men and hypercholesterolaemia in women (both 0.93). CONCLUSIONS: WC and HC showed opposite and independent associations with cardiovascular risk factors. The favourable association of HC was mainly attributable to that of leg FM.     

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.     

Value of the implantable loop recorder for the management of patients with unexplained syncope.

AIM: Recurrent syncope often remains unexplained despite extensive multidisciplinary screening. The implantable loop recorder (ILR) may be a tool to define the cardiac arrhythmias underlying syncope. METHODS AND RESULTS: The study population consisted of 43 consecutive patients with unexplained syncope who underwent extensive cardiological screening and were followed with an ILR. During follow-up, 5 patients had only presyncope, 4 had palpitations, and 15 had a true recurrence of syncope. In all patients with palpitations, 3 with presyncope, and 7 with a recurrence of syncope, the ILR excluded arrhythmias. In the patients with a true recurrence, 1 had symptomatic paroxysmal atrial fibrillation (PAF) treated with drugs, 1 had polymorphic ventricular tachycardia (VT) and received an implantable cardioverter defibrillator (ICD), and 7 had asystole and received a pacemaker. Two patients with presyncope received a pacemaker for Mobitz II block and PAF with brady-tachycardia syndrome. One asymptomatic patient received a pacemaker for significant nocturnal asystole recorded by ILR. Abnormalities in the cardiac screening were observed both in patients with and without syncope, but none of these had a predictive value. CONCLUSION: The ILR is a valuable and effective tool to establish an arrhythmic cause for unexplained syncope. The results of head-up tilt testing (HUTT) and electrophysiological study (EPS) are neither sufficiently sensitive nor specific enough in this patient group.     

Sudden cardiac death--an approach to management of the patient at risk

Sudden cardiac death due to ventricular fibrillation is the most common cause of death in industrialized countries. Patients with an increased risk of sudden cardiac death may be found to have, in addition to high-grade ventricular arrhythmias, impaired left ventricular function. Mechanisms responsible for precipitation of ventricular fibrillation include risk factors such as increased sympathetic nervous system activity, electrolyte disturbances, coronary artery spasm and transient, thrombotic coronary artery occlusion. For detection of high-grade arrhythmias as well as for assessment of treatment, continuous 24-hour EKG monitoring and exercise EKG should be employed. The indication for antiarrhythmic therapy should be regarded as established in patients successfully resuscitated after unexpected ventricular fibrillation as well as in patients status-post myocardial infarction, with angina pectoris, cardiomyopathies, QT-prolongation, mitral valve prolapse, congenital or other markedly symptomatic heart disease and high-grade ventricular arrhythmias. The treatment initiated, after discontinuation of all antiarrhythmic drugs for at least four half lives and ambulatory EKG monitoring for 48 hours as well as maximal symptom-limited exercise testing, should be evaluated after acute drug administration and after 72 hours of maintained therapy with the aid of continuous EKG monitoring and exercise EKG. In patients with a history of malignant arrhythmias in whom no evidence of high-grade ventricular arrhythmias can be found in either the continuous EKG recording or in the exercise EKG, initiation of drug treatment should be based on the results of programmed electrical stimulation. Effective treatment can be assumed on documentation of complete suppression of arrhythmias grade IVb and V or prevention of precipitation of ventricular tachycardias, respectively, as well as 90% reduction of grade IVa and 50% reduction of premature ventricular beats. During acute testing, aggravation of arrhythmias after administration of antiarrhythmic drugs was seen in 11.1%. While the yearly mortality of successfully controlled patients ranged between 2.3 and 2.8%, the yearly mortality rate in those in whom the arrhythmias were inadequately controlled ranged from 43.6 to 56%.     

Reproducibility of isoproterenol tilt-table tests in patients with syncope.

To assess the reproducibility of head-up tilt-table testing 46 patients each underwent 2 isoproterenol tilt-table tests 1 to 6 weeks apart. Of 20 patients with an initially asymptomatic negative test result, 17 (85%) had a second negative test result. Of 20 patients whose initial test ended in syncope, 18 had a second test ending in syncope (n = 12) or presyncope (n = 6). Five of 6 patients whose first test ended in presyncope had a second test that ended in presyncope, and 1 had a second test that was asymptomatic. Finally, a total of 14 patients had at least 1 test (either the first or second) ending in presyncope, and 11 of these (79%) had another test ending in presyncope or syncope. The dose-dependence of isoproterenol was irreproducible. The reproducibility of the duration of head-up tilt necessary to elicit symptoms of presyncope or syncope was determined in the 23 patients who had these symptoms on both tests. Symptoms developed monoexponentially with duration of head-up tilt with half-times of 1.4 to 2.6 minutes, but these times did not correlate significantly between tests. In a selected subgroup of 12 patients who developed syncope in the first test and either presyncope or syncope in the second test during administration of isoproterenol (5 micrograms/min), the time of onset of presyncope correlated well (r = 0.73, p = 0.007) as did that of syncope (r = 0.86, p = 0.012). Finally, hemodynamic changes during symptoms were compared between the 2 tests.(ABSTRACT TRUNCATED AT 250 WORDS)     

Tpeak-Tend and Tpeak-Tend dispersion as risk factors for ventricular tachycardia/ventricular fibrillation in patients with the Brugada syndrome.

OBJECTIVES: Our objective in this study was to evaluate Tpeak-Tend interval (Tp-e) and other electrocardiographic parameters as risk factors for recurrence of life-threatening cardiac events in patients with the Brugada syndrome (BS). BACKGROUND: The Tp-e interval in the electrocardiogram (ECG) has been reported to predict life-threatening arrhythmias in the long QT syndrome. METHODS: Twenty-nine patients with the ECG pattern of BS and 29 healthy age- and gender-matched controls were studied. The follow-up period was 42.65 +/- 24.42 months (range 11 to 108 months). RESULTS: Upon presentation, five patients had suffered aborted sudden death, five syncope, and two presyncope. Eleven patients with the ECG pattern of BS had a prolonged (>460 ms) QTc in V2 but usually not in inferior or left leads. No patient had abnormally prolonged QT dispersion. Programmed electrical stimulation induced ventricular tachycardia/fibrillation in 5 out of 26 patients. Inducibility did not predict recurrence of events. Cardioverter-defibrillators were implanted in 14 patients (all symptomatic and two asymptomatic). During follow-up, nine symptomatic patients experienced recurrences. Previous cardiac events and a QTc >460 ms in V2 were significant risk factors (p = 0.00002 and p = 0.03, respectively). Tp-e and Tp-e dispersion were significantly prolonged in patients with recurrences versus patients without events (104.4 and 35.6 ms vs. 87.4 and 23.2 ms; p = 0.006 and p = 0.03, respectively) or controls (90.7 and 17.9 ms; p = 0.02 and p = 0.001, respectively). CONCLUSIONS: Our study demonstrates significant correlation between previous events, QTc >460 ms in V2, Tp-e, and Tp-e dispersion and occurrence of life-threatening arrhythmic events, suggesting that these parameters may be useful in risk stratification of patients with the Brugada syndrome.