Case Report: Left bundle branch pacing in an amyloid light-chain cardiac amyloidosis patient with atrioventricular block.

Introduction: Amyloid light-chain cardiac amyloidosis is a progressive infiltrative disease characterized by the deposition of amyloid fibrils in the cardiac tissue, which can cause serious atrioventricular block requiring pacemaker implantation. Left bundle branch pacing has emerged as an alternative method for delivering physiological pacing to achieve electrical synchrony of the left ventricle. However, left bundle branch pacing in patients with amyloid light-chain cardiac amyloidosis has not been studied in detail. Therefore, in this study, we present a case of left bundle branch pacing in a patient with amyloid light-chain cardiac amyloidosis. Case summary: A 66-year-old male patient with amyloid light-chain cardiac amyloidosis presented with syncope for 1 month. Holter monitoring revealed intermittent third-degree atrioventricular block. Left bundle branch pacing was performed successfully. During the 1-year follow-up, it was observed that the left bundle branch capture threshold remained stable without any pacemaker-related complications or left ventricle systolic dysfunction, and there was no recurrence of syncope. Conclusion: Left bundle branch pacing appears to be a safe and feasible option for patients with amyloid light-chain cardiac amyloidosis experiencing atrioventricular block.

Noninvasive electrocardiography monitoring for very early recurrence predicts long-term outcome in patients after atrial fibrillation ablation.

BACKGROUND: Atrial fibrillation (AF) is the most common sustained arrhythmia, and catheter ablation has been shown to be a highly effective treatment for patients with symptomatic AF. Very early recurrence (VER) of AF within 7 days after catheter ablation is common, but the clinical significance of VER remains unclear. We have examined the usefulness of the noninvasive electrocardiography monitor for the detection of VER and the relationship between VER and late recurrence (LR). METHODS: Eighty-eight patients with paroxysmal or persistent atrial fibrillation were retrospectively included. All patients underwent primary catheter ablation at a large general hospital between March 2016 and August 2018. All patients were followed up in atrial fibrillation clinic at an interval of every 3 months for late recurrence of AF. VER was evaluated by one-lead continuous noninvasive electrocardiography monitoring device for 7 days after ablation. The association between VER and LR was analyzed by univariate and multivariate Cox regression model. RESULTS: Mean age was 62.9 ± 9.7 years, and 39.8% were female. Thirty-two patients (36.4%) experienced VER. After a mean follow-up of 539.36 ± 211.66 days, 17 patients (19.3%) experienced LR. Multivariate Cox regression analysis revealed VER was an independent predictor of LR: HR 3.6 (95% CI, 1.2-10.8), p = .020. In addition, diabetes was also associated with LR of atrial fibrillation. CONCLUSIONS: Noninvasive electrocardiography monitoring was a useful tool for detecting VER and VER after catheter ablation was associated with LR.

Effects of the short-term exposure to ambient air pollution on atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is an important arrhythmia associated with cardiovascular morbidity and mortality. This study is focused on exploring the potential relationship between short-term air pollution exposure and occurrence of AF. METHODS: A case-crossover design was used to investigate the effect of pollutants on AF occurrence among 100 patients from 2013 to 2014. The air pollutants included ambient particulate matter less than 2.5 µm in aerodynamic diameter (PM2.5 ), particulate matter less than 10 µm in aerodynamic diameter (PM10 ), nitrogen dioxide (NO2 ), sulfur dioxide (SO2 ), carbon monoxide (CO), and ozone (O3 ). Participants with cardiac implantable electronic devices implanted were followed-up to December 31, 2014. RESULTS: A 10 µg/m3 increase of PM2.5 and PM10 was associated with 3.8% (95% confidence interval [CI]: 1.4-6.2) and 2.7% (95% CI: 0.6-4.8) increase in the risk of AF occurrence, respectively. No statistically significant association was noted with SO2 , NO2 , CO, and O3 . CONCLUSIONS: Short-term exposure to particular matter, both PM2.5 and PM10 , is associated with an increased risk of AF. This further demonstrates the urgency for air quality monitoring and control in geographical area with intense pollution.

Distribution and predictors of hospital charges for haemorrhagic stroke patients in Beijing, China, March 2012 to February 2015: a retrospective study.

OBJECTIVES: The purpose of this study is to analyse hospital charges for patients with haemorrhagic stroke in China and investigate potential factors associated with inpatient charges. METHODS: The study participants were in-hospital patients with a primary diagnosis of haemorrhagic stroke from all the secondary and tertiary hospitals in Beijing during the period from 1 March 2012 to 28 February 2015. Distribution characteristics of detailed hospital charges were analysed. The influence of potential factors on hospital charges was researched using a stepwise multiple regression model. RESULTS: A total of 34 890 patients with haemorrhagic stroke of mean age 61.19±14.37 years were included in the study, of which 37.2% were female. Median length of hospital stay (LOHS) was 15 days (IQR 9-23) and median hospital cost was 18 577 Chinese yuan (CNY) (IQR 10 442-39 784). The hospital costs for patients in Western medicine hospitals (median 19 651 CNY) were significantly higher (P<0.01) than those in traditional Chinese medicine hospitals (median 14 560 CNY), and were significantly higher (P<0.01) for Level 3 hospitals (median 20 029 CNY) than for Level 2 hospitals (median 16 095 CNY). The proportion of medicine fees and bed fees within total hospital charges showed a decreasing trend during the study period. With stepwise multiple regression, the major factors associated with hospital charges were LOHS, surgery, pulmonary infection, ventilator usage, hospital level, occupation, hyperlipidaemia, hospital type, in-hospital death, sex and age. CONCLUSION: We conclude that medicines form the largest part of hospital charges but are showing a decreasing trend, and LOHS is strongly associated with patient charges for haemorrhagic stroke in China. This implies that the cost structure is very unreasonable in China and medical technology costs fail to be fully manifested. A reasonable decrease in medicine charges and shortening LOHS may be effective ways to reduce hospital charges.

The importance of Purkinje activation in long duration ventricular fibrillation.

BACKGROUND: The mechanisms that maintain long duration ventricular fibrillation (LDVF) are unclear. The difference in distribution of the Purkinje system in dogs and pigs was explored to determine if Purkinje activation propagates to stimulate working myocardium (WM) during LDVF and WM pacing. METHODS AND RESULTS: In-vivo extracellular recordings were made from 1044 intramural plunge and epicardial plaque electrodes in 6 pig and 6 dog hearts. Sinus activation propagated sequentially from the endocardium to the epicardium in dogs but not pigs. During epicardial pacing, activation propagated along the endocardium and traversed the LV wall almost parallel to the epicardium in dogs, but in pigs propagated away from the pacing site approximately perpendicular to the epicardium. After 1 minute of VF, activation rate near the endocardium was significantly faster than near the epicardium in dogs (P<0.01) but not pigs (P>0.05). From 2 to 10 minutes of LDVF, recordings exhibiting Purkinje activations were near the endocardium in dogs (P<0.01) but were scattered transmurally in pigs, and the WM activation rate in recordings in which Purkinje activations were present was significantly faster than the WM activation rate in recordings in which Purkinje activations were absent (P<0.01). In 10 isolated perfused dog hearts, the LV endocardium was exposed and 2 microelectrodes were inserted into Purkinje and adjacent myocardial cells. After 5 minutes of LDVF, mean Purkinje activation rate was significantly faster than mean WM activation rate (P<0.01). CONCLUSION: These extracellular and intracellular findings about activation support the hypothesis that Purkinje activation propagates to stimulate WM during sinus rhythm, pacing, and LDVF.

[Causes of insufficient anticoagulation in Chinese patients with non-valvlar atrial fibrillation].

OBJECTIVE: To evaluate the factors responsible for the insufficient application of oral anticoagulation (OAC) in Chinese patients with non-valvular atrial fibrillation. METHODS: The research is a single center registration study in a tertiary referral hospital in Beijing. The general characteristics, history of atrial fibrillation, comorbidities and anticoagulation treatment were obtained from all patients.Factors affecting the oral Walfarin use were evaluated by univariable and multivariable regression analysis. RESULTS: OAC therapy with Walfarin was applied on Only 214(39.4%) out of 576 consecutive patients with non-valvular atrial fibrillation. The OAC rate was 30.3% among non-ablation patients. Patients with persistent atrial fibrillation, diabetes, chronic heart failure, history of ischemic stroke/TIA and higher CHA2DS2-VASc score were more likely prescribed with Walfarin. Multivariable regression analysis showed that persistent fibrillation, history of chronic heart failure, ischemic stroke/TIA and non-coronary heart disease predicted the treatment with Walfarin. CONCLUSIONS: OAC use is extremely low in Chinese patients with non-valvular atrial fibrillation. More efforts are warranted to improve OAC use in these patients.

The amplitude of fibrillatory waves on leads aVF and V1 predicting the recurrence of persistent atrial fibrillation patients who underwent catheter ablation.

OBJECTIVE: To evaluate whether the amplitude of fibrillatory wave (F wave) on electrocardiography could predict the recurrence in persistent atrial fibrillation (AF) patients who underwent catheter ablation. METHODS: All consecutive persistent AF patients who underwent catheter ablation at Peking Union Medical College Hospital between November 2006 and February 2012, were enrolled. The amplitude of F wave was measured on three orthogonal leads (leads I, V1 and aVF) on the Prucka CardioLab recording system. The primary end point was the recurrence after catheter ablation. RESULTS: A total of 54 persistent AF patients were enrolled. Fifty patients (age: 58 ± 11years, 72% male) constituted the study population after excluding four patients lost of follow-up. The duration of AF was 9 ± 7 (2-18) months. Twenty-four patients (48%) recurred during the follow-up of 25 ± 19 months, constituted recurrence group. The remaining 26 patients constituted control group. The F-wave amplitude in recurrence group was significantly lower than control group (lead aVF, 0.085 ± 0.018 vs. 0.111 ± 0.036mV, P = 0.002; lead V1 , 0.116 ± 0.031 vs. 0.148 ± 0.047mV, P = 0.008). The amplitudes of leads aVF (P = 0.023) and V1 (P = 0.031) were the independent predictors of AF recurrence. The sensitivity and specificity of F-wave amplitude of lead aVF < 0.093mV or V1 < 0.123mV to predict the recurrence were 75% and 73%, 68% and 64%, respectively. CONCLUSION: The low amplitudes of F wave in leads aVF and V1 could predict the recurrence of patients with persistent AF who underwent catheter ablation.

The R-wave deflection interval in lead V3 combining with R-wave amplitude index in lead V1: a new surface ECG algorithm for distinguishing left from right ventricular outflow tract tachycardia origin in patients with transitional lead at V3.

BACKGROUND: To distinguish left ventricular outflow tract (LVOT) from right ventricular outflow tract (RVOT) origin in idiopathic premature ventricular contractions or ventricular tachycardia (PVCs/VT) patients with transitional lead at V3 is still a challenge. We sought to develop a new electrocardiography (ECG) algorithm for distinguishing LVOT from RVOT origin in patients with idiopathic outflow tract PVCs/VT with precordial transitional lead at V3. METHODS: We analyzed the surface ECG characteristics in a retrospective cohort of idiopathic PVCs/VT patients with transitional lead at V3 who underwent successful radiofrequency catheter ablation and developed a new surface ECG algorithm, then validated it in a prospective cohort. RESULTS: A total of 82 consecutive patients (47 ± 17 years, 39% male) underwent radiofrequency catheter ablation of idiopathic outflow tract PVCs/VT between January 2006 and August 2010. Among them, 31 patients (38%) with transitional lead at V3 constituted the retrospective cohort. Based on the areas under the receiver operating characteristic curves, R-wave deflection interval in lead V3>80 ms and R-wave amplitude index in lead V1>0.30 were selected to develop the new surface ECG algorithm. It correctly identified the origin sites of eleven from 12 patients in the prospective cohort, yielding the accuracy of 91.7%. CONCLUSIONS: We presented a new simple surface ECG algorithm, R-wave deflection interval in lead V3>80 ms combining with R-wave amplitude index in lead V1>0.30 which can reliably distinguish LVOT from RVOT origin in idiopathic outflow tract PVCs/VT in patients with transitional lead at V3.

Elimination of fatal arrhythmias through ablation of triggering premature ventricular contraction in type 3 long QT syndrome.

Congenital long QT syndrome (LQTS) is the most common inherited arrhythmia, fatal arrhythmias are the main causes of sudden death, and often induced by the premature ventricular contractions (PVCs). Ablation of the triggering PVCs may eliminate the fatal arrhythmias and prevent the sudden death in patients with LQTS. We report a 19-year-old boy diagnosed with type 3 LQTS, frequent fatal arrhythmias induced by PVCs with the identical QRS morphology. Successful ablation of the triggering PVCs was done and a single-chamber implantable cardioverter defibrillator (ICD) was implanted. There was no fatal arrhythmia events recorded by ICD during 29-month follow-up. Catheter ablation was the effective method to eliminate the fatal arrhythmias through ablation of the triggering PVCs in the present LQT3 patient.

Poor prognosis in chronic heart failure patients with reduced ejection fraction in China.

Most Chinese cardiologists are challenged by the high mortality rate of heart failure (HF) in patients with reduced ejection fraction in China. This study was designed as a single-center, retrospective study. All consecutive HF patients with left ventricular ejection fraction (LVEF) ≤ 45% from January 1, 2007, to December 31, 2009, were enrolled. The primary outcome was all-cause mortality. The secondary outcome was all-cause mortality or the first cardiovascular readmission event. A total of 187 patients comprised the study population, classified into two groups: LVEF ≤ 35% (n=83) and LVEF 36% to 45% (n=104). The median follow-up was 18 months (2-41 months). All-cause mortality was 27% among patients with LVEF ≤ 35%, as compared with 14% among those with LVEF 36% to 45% (P=.025). All-cause mortality or first cardiovascular readmission rates were 53% and 32% among patients with LVEF ≤ 35% and 36% to 45% (P=.003), respectively. The predictors of all-cause mortality were advanced age and New York Heart Association functional class, chronic kidney disease, oral ß-blockers, and statins at discharge. The prognosis of chronic HF patients with LVEF ≤ 45% was poor in China, especially for patients with LVEF ≤ 35%. Cardiologists should provide further efforts to improve the prognosis of HF in Chinese patients.

Evolution of activation patterns during long-duration ventricular fibrillation in pigs.

Quantitative analysis has demonstrated five temporal stages of activation during the first 10 min of ventricular fibrillation (VF) in dogs. To determine whether these stages exist in another species, we applied the same analysis to the first 10 min of VF recorded in vivo from two 504-electrode arrays, one each on left anterior and posterior ventricular epicardium in six anesthetized pigs. The following descriptors were continuously quantified: 1) number of wavefronts, 2) wavefront fractionations, 3) wavefront collisions, 4) repeatability, 5) multiplicity index, 6) wavefront conduction velocity, 7) activation rate, 8) mean area activated by the wavefronts, 9) negative peak rate of voltage change, 10) incidence of breakthrough/foci, 11) incidence of block, and 12) incidence of reentry. Cluster analysis of these descriptors divided VF into four stages (stages i-iv). The values of most descriptors increased during stage i (1-22 s after VF induction), changed quickly to values indicating greater organization during stage ii (23-39 s), decreased steadily during stage iii (40-187 s), and remained relatively unchanged during stage iv (188-600 s). The epicardium still activated during stage iv instead of becoming silent as in dogs. In conclusion, during the first 10 min, VF activation can be divided into four stages in pigs instead of five stages as in dogs. Following a 16-s period during the first minute of VF when activation became more organized, all parameters exhibited progressive decreased organization. Further studies are warranted to determine whether these changes, particularly the increased organization of stage ii, have clinical consequences, such as alteration in defibrillation efficacy.

[Deviation of ST-segment and detection of infarction related artery in patients with acute inferior wall infarction].

OBJECTIVE: To explore the characteristics of ST-segment deviation in patients with acute ST elevation myocardial infarction(STEMI)having only one vessel lesion in either left circumflex artery (LCX) or right coronary artery (RCA). METHODS: All AMI (acute myocardial infarction) patients were admitted into Peking Union Medical College Hospital from January 1996 to March 2009. They underwent coronary angiography (CAG). And the IRA (infarction-related artery) was either LCX or RCA without other coronary artery stenosis. Their ST-segments deviations on electrocardiogram (ECG) were analyzed quantitatively. RESULTS: Among 2503 AMI cases undergoing CAG during hospitalization, 75 cases had LCX (n = 16) or RCA (n = 59)-related STEMI. The RCA group was further divided into the proximal subgroup (n = 21) and the distal subgroup (n = 38). RCA as IRA was diagnosed when ST I depression < 0, ST V(1) elevation ≥ 0 or ST I and aVL depression < 0 with the sensitivities of 55.9%, 74.6% and 54.2% and the specificities of 81.3%, 62.5% and 81.3% respectively. LCX as IRA was diagnosed when ST aVR depression ≥ 0.1 mv, ST I elevation ≥ 0 or ST V(5) and V(6) elevation ≥ 0 with the sensitivities of 68.8%, 81.3% and 31.3% and the specificities of 76.3%, 59.3% and 91.5% respectively. Proximal occlusion of RCA was diagnosed when there was no ST depression in V(1) and depression in V(2), Max precordial ST depression in V(1)-V(3) with the sensitivities of 47.6% and 52.4% and the specificities of 78.9% and 84.2%. CONCLUSION: While discriminating IRA in STEMI patients with single LCX or RCA lesion, it is necessary to assess all ST-segments deviations on ECG.

[ST segment deviation in acute myocardial infarction with isolated disease of left anterior descending artery].

OBJECTIVE: To analyze the characteristics of the electrocardiogram (ECG) of left anterior descending coronary artery (LAD) occlusion in patients with acute ST elevation myocardial infarction (STEMI). METHODS: Patients included were those diagnosed with STEMI in Peking Union Medical College Hospital from January 1996 to March 2009, and underwent coronary angiography (CAG). The infarction related artery (IRA) was LAD, and there were no significant stenosis in left circumflex artery and right coronary artery. A total of 170 cases were consecutively enrolled. They were divided into 2 groups according to occlusive sites of the LAD: LAD proximal (n = 77), LAD medius distal group (n = 93). Standard 18 leads ECG within 12 hours from the onset of STEMI were recorded and ST segment deviation was analyzed quantitatively. RESULTS: Proximal LAD occlusion as IRA was diagnosed with aVL ≥ 0.1 mV, ST aVL > aVR, sum of II, III and aVF STsegment depression ≥ 0.1 mV, in which sensitivity was 39.0%, 37.7% and 50.6%, specificity was 78.5%, 77.4% and 74.2% respectively. Statisticully significance (P < 0.05). Medius-distal LAD occlusion as IRA was diagnosed with no II ST depression, aVF ST depression and sum of II, III and aVF ST segment depression > 0.1 mV, In which sensitivity were 86.0%, 81.7% and 74.2% and the were 31.2%, 48.1% and 50.6% respectively. Statisticully significance (P < 0.05). CONCLUSION: In STEMI patients with isolated LAD occlusion, ECG can be useful to predict the occlusion site.

Utility of combined indexes of electrocardiography and echocardiography in the diagnosis of biopsy proven primary cardiac amyloidosis.

OBJECTIVE: Primary cardiac amyloidosis (CA) is associated with poor prognosis. However, the noninvasive diagnostic tools are limited. The aim of the study is to assess the utility of combined indexes of electrocardiography (ECG) and echocardiography (ECHO) in the diagnosis of primary CA. METHODS: A total of 20 consecutive patients (7 men, mean age 50 ± 12 years) referred for endomyocardial biopsy (EMB) were included. Eleven of these patients (55%) confirmed primary CA, the rest of 9 patients were EMB negative and used for the control. RESULTS: The voltage of S(V1) + R(V6) < 1.2 mV has a sensitivity of 91% and specificity of 89% for the identification of primary CA, yields the positive and negative predictive values of 91% and 89%, respectively. Among ECHO parameters, there were no significant differences between the 2 groups, except for left ventricular ejection fraction (47 ± 12% in primary CA vs 67 ± 11% in the control, P < 0.001). However, the combined indexes of ECG and ECHO parameters, including the ratio of R(I) /LVPW as well as R(V5) /LVPW and R(V6) /LVPW, were significantly lower in the patients with primary CA than the control. The ratio of R(I) /LVPW < 0.4 has the sensitivity of 91% and specificity of 100%, yields the positive and negative predictive values of 100% and 91%, respectively. The ratios of R(V5(6)) /LVPW < 0.7 have the sensitivity of 91% and specificity of 89%, yield the positive and negative predictive values of 91% and 89%, respectively. CONCLUSION: Patients with clinically suspected primary CA, combined indexes of ECGs and ECHOs could be used as the noninvasive diagnostic tools.

[Clinico-pathological evaluation of restrictive cardiomyopathy].

OBJECTIVE: restrictive cardiomyopathy (RCM) is characterized by impairment of ventricular filling during diastole with preserved systolic function. The clinical and histopathological profile on endomyocardial biopsy of 25 consecutive patients with RCM was analyzed in this study. METHODS: twenty-five patients with diagnosis of RCM and underwent endomyocardial biopsy (EMB) were enrolled in the study. The clinical characteristics, electrocardiogram, serum chemistry, right heart catheter and cardiac pathology results were obtained. RESULTS: heart failure symptom was present in all 25 patients and left ventricular size and function were normal or near normal while serum brain natriuretic peptide (577 pg/ml) was moderately elevated. Right atrial and ventricular end-diastolic as well as pulmonary capillary wedge pressures derived from right heart catheter examination were increased. Amyloid deposition were evidenced in 16 and eosinophilic myocarditis in 2 patients upon pathological examination of EMB. In the remaining 7 patients, 3 were diagnosed idiopathic RCM, 2 were diagnosed as amyloidosis by biopsy from non-cardiac tissue and etiology remained unknown in 2 patients. Thus, conclusive diagnosis was made on EMB samples in 84% (21/25) patients of RCM. CONCLUSION: RCM may result from various local and systemic disorders. EMB is helpful for identifying the underlying etiology.

[Electrocardiographic and echocardiographic features of patients with primary cardiac amyloidosis].

OBJECTIVE: To summarize the electrocardiography and echocardiography features of patients with cardiac amyloidosis (CA) diagnosed by endo-myocardial biopsy (EMB). METHODS: A total of 20 consecutive patients [7 men, mean age (50 ± 12) years] referred for EMB because of clinical suspicion of CA from September 2006 to October 2009 were included in the study. Primary CA was diagnosed in 11 out of 20 patients (55%) by EMB and biomarkers examination. The electrocardiography and echocardiography features were analyzed. RESULTS: The voltage of all the limb leads were low in the 11 CA patients [mean values of (0.33 - 0.51) mV], the incidence of low voltage and pseudo-infarction patterns were 45% and 45%, respectively. Concentric hypertrophy and normal left ventricular diameters were evidenced in all CA patients on echocardiography, left atrial enlargement (n = 10, 91%), granular/sparking appearance of the myocardium (n = 9, 82%) and moderate to large pericardial effusion (n = 7, 64%) as well as left ventricular systolic dysfunction (n = 8, 73%) were often presented in CA patients. CONCLUSIONS: The diagnosis of primary CA should be considered in patients with unknown origin of heart failure, concentric hypertrophy and normal left ventricular diameters with granular/sparking appearance of the myocardium or pericardial effusion presented on echocardiography and low voltage of limb leads or pseudo-infarction pattern presented on electrocardiography. EMB and serum (urine) biomarkers examinations should be then performed to confirm or exclude the diagnosis of CA.

Primary prevention of sudden cardiac death by implantable cardioverter-defibrillator therapy in Chinese patients with heart failure: a single-center experience.

BACKGROUND: An implantable cardioverter-defibrillator (ICD) has been suggested for heart failure patients for primary prevention of sudden cardiac death. However, few data have been reported on the application of ICD as primary prevention of sudden cardiac death in China. We evaluated the value of primary prevention ICD therapy in Chinese patients with heart failure. METHODS: Thirty-four patients at an average age of (60.2 +/- 13.7) years seen in Peking Union Medical College Hospital were treated with ICD implantation for primary prevention of sudden cardiac death from November 2005 to July 2009. Single-chamber ICDs were implanted in 16 (47.0%) cases, and dual-chamber or cardiac resynchronization therapy defibrillators in 18 (53.0%) cases. The patients had an average left ventricular ejection fraction of (26.9 +/- 5.5)% (11% to 35%), of which 18 (53.0%) patients had ischemic cardiomyopathy and 16 (47.0%) patients had non-ischemic cardiomyopathy. All patients were followed up at three months after the implantation and every six months thereafter or when prompted by an ICD event. RESULTS: There were five (14.7%) deaths, including two of heart failure and three with a non-cardiac course, during an average follow-up of (15.0 +/- 11.9) months. Forty-one ICD therapy events were recorded, including 19 (46.3%) appropriate ICD therapies in six patients and 22 (53.7%) inappropriate ICD therapies in four patients with single chamber leads. Inappropriate ICD therapies were mainly due to supraventricular tachyarrhythmias, especially atrial fibrillation. Patients with ischemic cardiomyopathy and non-ischemic cardiomyopathy did not differ in the incidence of either appropriate or inappropriate therapy. CONCLUSIONS: ICD for primary prevention of sudden cardiac death in China prevents patients from arrhythmia death. Relatively high incidence of inappropriate therapies highlights the importance of an atrial lead.