Prevention of sudden death in hypertrophic cardiomyopathy: but which defibrillator for which patient?
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Adolescent↗
Biomedical subjects
Win-Kuang Shen
Publications and source records attributed to Win-Kuang Shen.
Age- and sex-related atrial electrophysiologic and structural changes.
Age and gender dependence of the 3 major variables--left atrial (LA) dimension, effective refractory period (ERP), and atrial conduction--that govern the development of atrial fibrillation (AF) were examined in 76 women and 39 men without structural heart disease. A significant positive correlation was found between age and LA dimension, mainly because of a strongly positive correlation in women not taking hormone replacement therapy but not in women on hormone replacement therapy. Men had a significantly greater average LA dimension than women. Neither ERP nor atrial conduction estimated by normalized P-wave duration demonstrated any significant correlation with either age or gender. It was concluded that LA size is greater in the elderly and in men, which may increase their risk for AF.
Adult↗
Atrial fibrillation and ventricular dysfunction: a vicious electromechanical cycle.
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Adult↗
The natural history of lone atrial flutter.
BACKGROUND: The natural history of atrial flutter is not well defined. OBJECTIVE: To report the risk for stroke, conversion to atrial fibrillation, and anticoagulation for lone atrial flutter. DESIGN: Retrospective cohort analysis. SETTING: A clinically based longitudinal study of inpatients and outpatients with atrial flutter. PATIENTS: The authors compared the stroke rate in 59 patients with atrial flutter with rates in a sample in which age- and sex-specific ischemic cerebrovascular event rates were determined and in a sample of nonhypertensive patients with lone atrial fibrillation. The risk for developing atrial fibrillation after presenting with atrial flutter is also reported. MEASUREMENTS: Electrocardiograms and clinical data were collected and reviewed for each study participant. RESULTS: After adjustment for age and sex, patients with atrial flutter had a higher incidence of thromboembolic events than the sample control patients and patients with atrial fibrillation. Atrial fibrillation developed in 56% of patients with atrial flutter. CONCLUSIONS: Lone atrial flutter has a stroke risk at least as high as lone atrial fibrillation and carries a higher risk for subsequent development of atrial fibrillation than in the general population. Anticoagulation should be considered for all patients with atrial flutter who are older than 65 years of age.
Adult↗
Long-term prognosis of inducible ventricular flutter: not an innocent finding.
BACKGROUND: The prognostic significance of ventricular flutter (VFL) induced during programmed electrical stimulation (PES) is currently unknown. METHODS: This study examined patients who had PES-induced VFL and assessed their long-term prognosis compared with patients who had inducible sustained monomorphic ventricular tachycardia (SMVT). RESULTS: Of 3414 patients undergoing PES, 74 (2%) had sustained VFL. They were compared with a group of 71 patients undergoing PES in the same time frame who had inducible SMVT. Patients with inducible VFL had a higher ejection fraction than patients with SMVT (0.39 vs 0.33; P =.05). More aggressive pacing was required for arrhythmia induction in patients with VFL, with more stimuli (2.7 +/- 0.5 vs 2.2 +/- 0.6; P <.01) and tighter S(2), S(3), and S(4) intervals. After a mean follow-up of 30 +/- 31 months, the mortality rate was 34% in patients with VFL and 30% in patients with SMVT (P =.41). No difference in the 2 groups in overall survival or a combined end point of sudden death or appropriate implantable cardioverter defibrillator shock was revealed with Kaplan-Meier analysis. CONCLUSION: The long-term prognosis of patients with inducible VFL is similar to that of patients with inducible SMVT, even when VFL is induced with a relatively aggressive protocol.
Arrhythmias, Cardiac↗
Long-term subjective memory function in ventricular fibrillation out-of-hospital cardiac arrest survivors resuscitated by early defibrillation.
BACKGROUND: Brain injury after a cardiac arrest remains a major cause of morbidity. Programs focusing on early defibrillation have yielded improved survival of patients after hospital discharge following ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA). Early defibrillation that promptly restores a circulating rhythm should decrease the hypoxic period and subsequent organ injury. Therefore this study was designed to determine if long-term memory complaints persist in VF OHCA survivors resuscitated in an early defibrillation program when compared with a healthy control population not experiencing cardiac arrest. METHODS: All patients with an OHCA between November 1990 and January 2001 who received defibrillation by emergency medical services personnel in Olmsted County, MN, USA, were included. The memory function questionnaire (MFQ), a 64-item, 7-point Likert-scaled instrument to evaluate the perception of everyday memory functioning was sent to all survivors. The MFQ comprises four scales: general frequency of forgetting (rates general forgetting), retrospective functioning (compares current memory with past ability), seriousness of forgetting (rates how memory impairment impacts daily life), and mnemonics usage (measures adaptation). The MFQ is scaled so that high scores reflect less severe memory complaints. The comparison population comprised members of the Mayo Older Americans Normative Studies (MOANS) cohort. Quality of life was ascertained with a short form (SF)-36 survey. RESULTS: Seventy-nine of the 200 VF OHCA patients (40%) were discharged. Twenty-two patients have died since dismissal, with an overall average length of follow-up of 4.9+/-3.0 years. Thirty-eight (67%) of the survivors completed the MFQ. Compared with the normal, there was a significant decrease in the general frequency of forgetting score of 144.2+/-37.4 versus 168.1+/-27.3 ( P<0.001) and the seriousness of forgetting score of 84.8 +/-26.7 versus 95.2+/-19.7 (P=0.004). The retrospective function-scale scores were not significantly different ( 18.4+/-6.8 versus 18.7+/- 5.0 (P=0.74). Younger patients (lesser than 65 years of age) reported an increase in general forgetting and the seriousness of forgetting compared with older survivors. A comparison with SF-36 scores suggested an association between general forgetting and decreased vitality (P=0.03) and the seriousness of forgetting with a decreased general health (P=0.005), mental health (P=0.009), physical functioning ( P=0.02 ), and vitality ( P=0.05). CONCLUSION: In a cohort of VF OHCA patients, survivors report more memory complaints in comparison with a general healthy older population. There were more long-term-memory complaints in younger patients. Patients with higher long-term quality-of-life score have fewer memory complaints.
Adult↗
Prediction of short- and long-term outcomes by electrocardiography in survivors of out-of-hospital cardiac arrest.
BACKGROUND: Programs focusing on early defibrillation have improved both short- and long-term survival of patients with VF out-of-hospital cardiac arrest (OHCA). Subsequent long-term management of survivors would be facilitated by a straight-forward, non-invasive method of identifying those at highest risk for recurrence. Therefore, we assessed the predictive value of the standard ECG to determine both short- and long-term outcomes in survivors of VF OHCA to assist in risk stratification of those patients at highest risk of sudden death. METHODS: All patients with an OHCA between November 1990 and December 2000 who received early defibrillation for VF in Olmsted County Minnesota (MN) were included. Cox proportional hazards modeling was used to examine ECG variables and subsequent ICD deployment and death. RESULTS: Two hundred patients presented in VF OHCA; of these 138 (69%) survived to hospital admission (seven died in the emergency department prior to admission) and 79 (40%) were discharged. The QRS duration (141 +/- 41ms in nonsurvivors, 123 +/- 35 in survivors, P = 0.004) was predictive of short-term mortality in patients who did not survive to hospital discharge. The ventricular rate, PR interval, presence of right or left bundle branch block, QTc, ST elevation myocardial infarction, and atrial fibrillation/flutter were nonpredictive. The average length of follow up for hospital dismissal survivors was 4.8 +/- 3.0 years. In univariate analysis, each 30 ms interval increase in the QRS width and PR interval was associated with increased mortality and ICD deployment hazard ratio of 1.6 (CI 1.1-2.5, P = 0.02) and 1.12 (CI 1.0-1.2, P = 0.05), respectively. In multivariate analysis accounting for admission ejection fraction, a PR > 200 ms [HR 4.5 (CI 1.7-11.8, P = 0.022)], QRS width increase greater than 30 ms [HR 1.9 (CI 1.3-2.8, P < 0.001)], and a QRS > 120 ms [HR 2.4 (CI 1.1-5.4, P = 0.032)] were predictive of long-term mortality and ICD shocks. CONCLUSION: Careful evaluation of the admitting and discharge ECG provides prognostic information for in-hospital and long-term outcomes, respectively in this cohort of out-of-hospital cardiac arrest survivors. The QRS duration on the dismissal ECG following VF OHCA provides prognostic information which might be useful to identify those at highest risk long-term, and who would benefit from more aggressive antiarrhythmic therapy and cardiac stabilization.
Aged↗
Heart rate dependence of the QT interval duration: differences among congenital long QT syndrome subtypes.
INTRODUCTION: The heart rate dependence of QT interval duration is abnormal in patients with congenital long QT syndrome. Patients with LQT1 have a defective I(Ks) current, a major determinant of QT response to heart rate. METHODS AND RESULTS: We studied the heart rate dependence of QT interval duration in different long QT syndrome genotypes and control subjects using computerized QT measurements obtained from Holter recordings. The dependence of QT duration on heart rate is steeper in long QT syndrome than in control subjects (0.347 +/- 0.263 vs 0.162 +/- 0.083 at heart rate 100 beats/min; P < 0.05). In addition, QT interval is significantly longer in LQT2 and LQT3 than in LQT1 patients at slow (533 +/- 23 ms vs 468 +/- 30 ms at heart rate 60 beats/min; P < 0.0001) but not at rapid heart rate. The heart rate dependence of QT interval is steeper in LQT2 and LQT3 than in LQT1 (0.623 +/- 0.245 vs 0.19 +/- 0.079 at heart rate 100 beats/min; P < 0.05). For a given heart rate, the QT intervals vary more in LQT2 and LQT3 than in LQT1 patients (25.98 +/- 11.18 ms vs 14.39 +/- 1.55 ms; P < 0.01). CONCLUSION: Individual long QT syndrome genotypes differ with respect to QT interval dependence on heart rate. These differences may relate to the propensity of LQT2 and LQT3 patients to develop arrhythmias during bradycardia.
Adult↗
Outcomes and in-hospital treatment of out-of-hospital cardiac arrest patients resuscitated from ventricular fibrillation by early defibrillation.
OBJECTIVE: To describe and evaluate the in-hospital treatment of ventricular arrhythmias and underlying structural heart disease in patients who survive ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA) in a region with a high survival rate after hospital discharge. PATIENTS AND METHODS: The study included all patients presenting in Olmsted County, Minnesota, who had experienced OHCA between November 1990 and December 2000 and who underwent defibrillation of VF by an emergency medical service system. RESULTS: Of 200 patients who experienced VF arrest, 138 (69%) survived to hospital admission (7 died in the emergency department before admission), and 79 (40%) were discharged. Of patients who were discharged, 37 (47%) had a reversible cause of the arrest (perimyocardial infarction) and received treatment of the primary process. The other 42 patients who were discharged had ischemic coronary heart disease (CHD) (n=25), nonischemic CHD (n=10), or idiopathic VF (n=7). Four of the patients with CHD but no left ventricular dysfunction were treated with coronary artery bypass grafting or percutaneous coronary intervention alone. A total of 52 patients (66%) were candidates for electrophysiologic testing. Of these patients, 48 (92%) underwent electrophysiologic testing; of these patients, 10 received amiodarone alone, and 35 received an implantable cardioverter-defibrillator (ICD) (of whom 3 also received amiodarone). Patients who did not receive ICD therapy typically presented before 1998 with CHD and underwent coronary artery bypass grafting or percutaneous coronary intervention only. Of 79 patients who were discharged, 14 (18%) with an ICD have received subsequent shocks. Nineteen (24%) of 79 patients have died, 5 of a primary cardiac etiology (including 2 with repeated OHCA). CONCLUSIONS: The VF OHCA survival rate is high in the setting of rapid defibrillation, with 40% of patients being discharged from the hospital. By the end of the 10-year study, more patients were receiving antiarrhythmic therapy, in particular ICD implantation, after hospital admission. Overall, the long-term survival in patients with VF OHCA is favorable.
Aged↗
Significant effects of atrioventricular node ablation and pacemaker implantation on left ventricular function and long-term survival in patients with atrial fibrillation and left ventricular dysfunction.
Control of ventricular rate by atrioventricular node ablation and pacemaker implantation in patients with drug-refractory atrial fibrillation (AF) is associated with improved left ventricular (LV) function. The objective of this study was to determine the effect of atrioventricular node ablation on long-term survival in patients with AF and LV dysfunction. Survival was determined by the Kaplan-Meier method for 56 study patients with LV ejection fraction (EF) < or =40% who underwent atrioventricular node ablation and pacemaker implantation and 56 age- and gender-matched control patients with AF and LVEF >40%, and age- and gender-matched control subjects from Minnesota. Groups were compared using the log-rank test. In study patients (age 69 +/- 10 years; 45 men), LVEF was 26% +/- 8% and 34% +/- 13% (p <0.001) before and after ablation, respectively. During follow-up (40 +/- 23 months), 23 patients died. Observed survival was worse than that of normal subjects (p <0.001) and control patients (p = 0.005). After ablation, LVEF nearly normalized (> or =45%) in 16 study patients (29%), in whom observed survival was comparable to that of normal subjects (p = 0.37). Coronary artery disease, hyperlipidemia, chronic renal failure, previous myocardial infarction, and coronary artery operation were independent predictors for mortality. Near normalization of LVEF occurred in 29% of study patients, suggesting that AF-induced EF reduction is reversible in many patients. Normal survival in patients with reversible LV dysfunction highlights potential survival benefits of rate control. Poor survival in patients with persistent LV dysfunction confirms the importance of optimal medical therapy.
Aged↗
Comparison of frequency of recurrent syncope after beta-blocker therapy versus conservative management for patients with vasovagal syncope.
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Adrenergic beta-Antagonists↗
Long-term outcomes of out-of-hospital cardiac arrest after successful early defibrillation.
BACKGROUND: Mortality after out-of-hospital cardiac arrest from ventricular fibrillation is high. Programs focusing on early defibrillation have improved the rate of survival to hospital discharge. We conducted a population-based analysis of the long-term outcome and quality of life of survivors. METHODS: All patients who had an out-of-hospital cardiac arrest between November 1990 and January 2001 who received early defibrillation for ventricular fibrillation in Olmsted County, Minnesota, were included. The survival rate was compared with that of an age-, sex-, and disease-matched (2:1) control population of residents who had not had an out-of-hospital cardiac arrest and with that of age- and sex-matched controls from the general U.S. population. The quality of life was assessed with use of the Medical Outcomes Study 36-item Short-Form General Health Survey (SF-36) and compared with U.S. population norms. RESULTS: Of 200 patients who presented with an out-of-hospital cardiac arrest with ventricular fibrillation, 145 (72 percent) survived to hospital admission (7 died in the emergency department) and 79 (40 percent) were neurologically intact (good overall capability or moderate overall disability) at discharge. The mean (+/-SD) length of follow-up was 4.8+/-3.0 years. Nineteen patients died after discharge from the hospital. The expected five-year survival rate (79 percent) was identical to that among age-, sex-, and disease-matched controls (P=0.68) but lower than that among the age- and sex-matched U.S. population (86 percent, P=0.02). Fifty patients completed SF-36 surveys at the end of follow-up, and the majority had a nearly normal quality of life, with the exception of reduced vitality. CONCLUSIONS: Long-term survival among patients who have undergone rapid defibrillation after out-of-hospital cardiac arrest is similar to that among age-, sex-, and disease-matched patients who did not have out-of-hospital cardiac arrest. The quality of life among the majority of survivors is similar to that of the general population.
Aged↗
Catecholamine-provoked microvoltage T wave alternans in genotyped long QT syndrome.
Macrovoltage T wave alternans (TWA) has been described in congenital long QT syndrome (LQTS). Microvoltage T wave alternans (microV-TWA) at low heart rate (HR) is a marker of arrhythmogenic risk in many conditions, but its significance in LQTS has not been established. Twenty-three genotypically heterogeneous patients with LQTS and 16 control subjects were studied at rest and during phenylephrine and dobutamine provocation. Genotyping was established by PCR amplification and DNA sequencing of the three most common LQTS genes; KCNQ1/KVLQT1 (LQT1), KCNH2/HERG (LQT2), and SCN5A (LQT3). microV-TWA was determined using Fast Fourier transform. Precluded by ectopy, microV-TWA could not be assessed in 8 of 23 patients with LQTS. In the remaining 15 patients with LQTS, microV-TWA occurred at lower HR in LQTS than in controls (117 +/- 49 vs 153 +/- 37 beats/min; P < 0.05). Patients with LQTS developed microV-TWA at HR < 150 beats/min more often than controls (10/15 vs 2/16; P = 0.003). However, microV-TWA was not detected in the 3 individuals with a history of out-of-hospital cardiac arrest including a 14-year-old male with an F339del-KVLQT1 mutation (LQT1) who had dobutamine-provoked polymorphic ventricular tachycardia requiring external defibrillation. Catecholamine-provoked microV-TWA occurs at lower HR in patients with LQTS than in healthy people but does not identify high risk subjects.
Adolescent↗
Antiarrhythmic drugs: new agents and evolving concepts.
Properties of several new antiarrhythmic drugs are summarised in this review article. Recent concepts concerning their safety and efficacy of antiarrhythmics are discussed. A brief perspective on possible future strategies for pharmacotherapy of arrhythmias is provided.
Angiotensin Receptor Antagonists↗
Catecholamine-induced T-wave lability in congenital long QT syndrome: a novel phenomenon associated with syncope and cardiac arrest.
OBJECTIVE: To determine the effects of phenylephrine and dobutamine on repolarization lability in patients with genotyped long QT syndrome (LQTS). PATIENTS AND METHODS: Between December 1998 and August 2000, 23 patients with genotyped LQTS (13 LQT1, 7 LQT2, and 3 LQT3) and 16 controls underwent electrocardiographic stress testing at the Mayo Clinic in Rochester, Minn. Aperiodic repolarization lability was quantified from digitized electrocardiograms recorded during catecholamine stress testing with phenylephrine and dobutamine. T-wave lability was quantified as a root-mean-square of the differences between corresponding signal values of subsequent beats. The magnitude of aperiodic T-wave lability was quantified by using a newly derived T-wave lability index (TWLI). RESULTS: The TWLI was significantly greater in patients with LQTS than in controls (0.0945 +/- 0.0517 vs 0.0445 +/- 0.0123; P < .003). Marked T-wave lability (TWLI > or = 0.095) was detected in all 3 LQTS genotypes (10/23) but in no controls (P < .003). There was no correlation between the TWLI and the baseline corrected QT interval. All high-risk patients having either a history of out-of-hospital cardiac arrest or syncope had a TWLI of 0.095 or greater. CONCLUSIONS: Beat-to-beat nonalternating T-wave lability occurs in LQT1, LQT2, and LQT3 patients during catecholamine provocation and is associated with a history of prior cardiac events. The quantification of this novel phenomenon may assist in identifying LQTS patients with increased risk of sudden cardiac death.
Adolescent↗
Prevalence and clinical outcomes of patients with multiple potential causes of syncope.
OBJECTIVE: To determine the prevalence, predictors, and prognosis of patients with multiple potential causes of syncope. PATIENTS AND METHODS: This is a retrospective cohort study with prospective follow-up of consecutive patients with syncope of uncertain cause who were referred to the electrophysiology service for syncope evaluation from January 1, 1996, through December 31, 1998. The main outcome measures were prevalence of multiple potential causes of syncope, survival of patients with multiple potential causes of syncope compared with survival of patients with a single cause, and clinical predictors of multiple potential causes of syncope. RESULTS: A total of 987 patients were studied (mean +/- SD age, 58.0 +/- 21.4 years; male, 550 [55.7%]). Multiple potential causes were present in 182 patients (18.4%). Patients with multiple potential causes of syncope had a lower survival rate at 4 years, 73.1% (95% confidence interval, 64.6%-82.8%), vs those with a single cause, 89.3% (95% confidence interval, 86.4%-92.2%) (P < .001). Multivariate predictors of multiple potential causes were older age, atrial fibrillation, use of cardiac medications, and New York Heart Association classification II, III, and IV. CONCLUSION: Of the patients evaluated for syncope, 18.4% had multiple potential causes. The presence of multiple potential causes was an independent predictor of increased mortality among patients with syncope.
Age Factors↗
Sudden death after radiofrequency ablation of the atrioventricular node in patients with atrial fibrillation.
OBJECTIVES: We evaluated the incidence and predictors of sudden death after atrioventricular (AV) node ablation and pacemaker implantation. BACKGROUND: Sudden death may occur after radiofrequency catheter ablation of the AV node and pacemaker implantation in patients with atrial fibrillation (AF). Whether it is related to the procedure or to pre-existing heart disease remains unclear. METHODS: All patients who had radiofrequency catheter ablation of the AV node and pacemaker implantation for rate control of medically refractory AF were identified retrospectively and observed prospectively. All patients with sudden death after ablation were identified. The relationship between the procedure and sudden death was defined on the basis of the time between the two as "likely," "possibly" or "unlikely." RESULTS: Of 334 consecutive patients with AF who underwent AV node ablation, nine had sudden death after the ablation. Four patients (1.2%) had sudden death likely related to the procedure: in 3 patients, arrest occurred within 48 h after the procedure; in one patient, arrest occurred four days after the procedure. In three other patients (0.9%), sudden death was possibly related to the procedure because the event occurred within three months afterward. The remaining two deaths were unrelated to the procedure. Diabetes, New York Heart Association functional class (>or=II), preprocedure ventricular arrhythmia, mitral or aortic stenosis, aortic regurgitation and chronic obstructive pulmonary disease were independent predictors for sudden death. CONCLUSIONS: Sudden death likely or possibly related to catheter ablation occurred in 7 of 334 patients (2.1%). Risk of sudden death is highest within two days after the procedure.
Aged↗
When is intracardiac electrophysiologic evaluation indicated in the older or very elderly patient? Complications rates and data.
The use of invasive EPS and catheter ablation is well established for many cardiac rhythm disorders. Because of the high prevalence of arrhythmias, which often are tolerated poorly in the elderly, and the increased frequency of adverse effects of pharmacologic therapy in this population, the potential for benefit from invasive EPS and catheter ablation is great. The notion that elderly patients are at increased risk of complications from invasive EPS is not borne out by available data. Therefore, the suitability of this form of diagnostic and therapeutic approach should be based on the assessment of the individual patient and the clinical context, while taking into consideration patient-specific risks, goals, and expectations in adopting an invasive strategy.
Aged↗