Prognostic benefits of His-Purkinje capture in physiological pacemakers for bradycardia.

INTRODUCTION: Clinical outcomes of long-term ventricular septal pacing (VSP) without His-Purkinje capture remain unknown. This study evaluated the differences in clinical outcomes between conduction system pacing (CSP), VSP, and right ventricular pacing (RVP). METHODS: Consecutive patients with bradycardia indicated for pacing from 2016 to 2022 were prospectively followed for the clinical endpoints of heart failure (HF)-hospitalizations and all-cause mortality at 2 years. VSP was defined as septal pacing due to unsuccessful CSP implant or successful CSP followed by loss of His-Purkinje capture within 90 days. RESULTS: Among 1016 patients (age 73.9 ± 11.2 years, 47% female, 48% atrioventricular block), 612 received RVP, 335 received CSP and 69 received VSP. Paced QRS duration was similar between VSP and RVP, but both significantly longer than CSP (p < .05). HF-hospitalizations occurred in 130 (13%) patients (CSP 7% vs. RVP 16% vs. VSP 13%, p = .001), and all-cause mortality in 143 (14%) patients (CSP 7% vs. RVP 19% vs. VSP 9%, p < .001). The association of pacing modality with clinical events was limited to those with ventricular pacing (Vp) > 20% (pinteraction < .05). Adjusting for clinical risk factors among patients with Vp > 20%, VSP (adjusted hazard ratio [AHR]: 4.74, 95% confidence interval [CI]: 1.57-14.36) and RVP (AHR: 3.08, 95% CI: 1.44-6.60) were associated with increased hazard of HF-hospitalizations, and RVP (2.52, 95% CI: 1.19-5.35) with increased mortality, compared to CSP. Clinical endpoints did not differ between VSP and RVP with Vp > 20%, or amongst groups with Vp < 20%. CONCLUSION: Conduction system capture is associated with improved clinical outcomes. CSP should be preferred over VSP or RVP during pacing for bradycardia.

Conduction system versus biventricular pacing in heart failure with non-left bundle branch block.

INTRODUCTION: The benefits of cardiac resynchronization therapy (CRT) with biventricular pacing (BiV) is significantly lower when applied to heart failure (HF) patients with non-left bundle branch block (LBBB) conduction delay. We investigated clinical outcomes of conduction system pacing (CSP) for CRT in non-LBBB HF. METHODS: Consecutive HF patients with non-LBBB conduction delay undergoing CSP were propensity matched for age, sex, HF-etiology, and atrial fibrillation (AF) in a 1:1 ratio to BiV from a prospective registry of CRT recipients. Echocardiographic response was defined as an increase in left ventricular ejection fraction (LVEF) by ≥10%. The primary outcome was the composite of HF-hospitalizations or all-cause mortality. RESULTS: A total of 96 patients were recruited (mean age 70 ± 11years, 22% female, 68% ischemic HF and 49% AF). Significant reductions in QRS duration and LV dimensions were seen only after CSP, while LVEF improved significantly in both groups (p < 0.05). Echocardiographic response occurred more frequently in CSP than BiV (51% vs. 21%, p < 0.01), with CSP independently associated with four-fold increased odds (adjusted odds ratio 4.08, 95% confidence interval [CI] 1.34-12.41). The primary outcome occurred more frequently in BiV than CSP (69% vs. 27%, p < 0.001), with CSP independently associated with 58% risk reduction (adjusted hazard ratio [AHR] 0.42, 95% CI 0.21-0.84, p = 0.01), driven by reduced all-cause mortality (AHR 0.22, 95% CI 0.07-0.68, p < 0.01), and a trend toward reduced HF-hospitalization (AHR 0.51, 95% CI 0.21-1.21, p = 0.12). CONCLUSIONS: CSP provided greater electrical synchrony, reverse remodeling, improved cardiac function and survival compared to BiV in non-LBBB, and may be the preferred CRT strategy for non-LBBB HF.

Successful Ablation of Sustained Monomorphic Ventricular Tachycardia in a Patient With Mitral Annular Disjunction.

Mitral annular disjunction (MAD) with or without mitral valve prolapse is associated with sudden death. Observed arrhythmias are usually ventricular ectopic beats originating from the papillary muscles. We describe a successful ablation of sustained monomorphic ventricular tachycardia from an epicardial focus in a patient with MAD. (Level of Difficulty: Intermediate.).

Use of extendable helix leads for conduction system pacing: Differences in lead handling and performance lead design impacts conduction system pacing.

INTRODUCTION: Pacing leads with extendable-retractable helix (EHL) are alternatives to fixed-helix leads (FHL) for conduction system pacing (CSP), but data on handling characteristics are limited. This study evaluated a dual-center experience of lead handling and performance during CSP. METHODS AND RESULTS: Consecutive patients with His-bundle pacing (HBP) or left bundle branch pacing (LBBP) were evaluated for the primary outcome of lead failure, defined as structural damage to the lead necessitating lead replacement. Differences in pacing characteristics were compared. Among 280 patients (mean age 74 ± 11 years, 44% male, 50% LBBP), 246 (88%) received FHL and 34 (12%) received EHL. Of 299 leads used, lead failure occurred more frequently among patients with EHL than FHL (29% vs. 2%, p < .001), regardless of CSP modality. Majority of damaged leads (89%) in the form of helix deformation were successfully removed, with failure occurring in only two patients, both EHL, leading to helix fracture and retention within the septal myocardium. EHL, compared to FHL, was associated with 25-fold increased odds of lead failure (odds ratio: 25.21, 95% confidence interval: 7.35-86.51), and persisted after adjustment in turn for age, pacing modality and indication. CSP implant success rates did not differ by lead design (FHL 80% vs. EHL 71%, p = .18), with similar pacing thresholds at implant and follow-up. CONCLUSION: Helix deformation and fracture were more frequent with EHL in CSP despite similar implant success. These findings have significant implications for lead selection during CSP and raises concerns about the long-term extractability of EHL in CSP.

Magnetic resonance imaging of dilated cardiomyopathy: prognostic benefit of identifying late gadolinium enhancement in Asian patients.

INTRODUCTION: Risk stratification in dilated cardiomyopathy (DCM) is imprecise, relying largely on echocardiographic left ventricular ejection fraction (LVEF) and severity of heart failure symptoms. Adverse cardiovascular events are increased by the presence of myocardial scarring. Late gadolinium enhancement (LGE) on cardiovascular magnetic resonance (CMR) imaging is the gold standard for identifying myocardial scars. We examined the association between LGE on CMR imaging and adverse clinical outcomes during long-term follow-up of Asian patients with DCM. METHODS: Consecutive patients with DCM undergoing CMR imaging at a single Asian academic medical centre between 2005 and 2015 were recruited. Clinical outcomes were tracked using comprehensive electronic medical records and mortality was determined by cross-linkages with national registries. Presence and distribution of LGE on CMR imaging were determined by investigators blinded to patient outcomes. Primary endpoint was a composite of heart failure hospitalisations, appropriate implantable cardioverter-defibrillator shocks and cardiovascular mortality. RESULTS: Of 86 patients, 64.0% had LGE (80.2% male; mean LVEF 30.1% ± 12.7%). Mid-wall fibrosis (71.7%) was the most common pattern of LGE distribution. Over a mean follow-up period of 4.9 ± 3.2 years, 19 (34.5%) patients with LGE reached the composite endpoint compared to 4 (12.9%) patients without LGE (p = 0.01). Presence of LGE, but not echocardiographic LVEF, independently predicted the primary endpoint (hazard ratio 4.15 [95% confidence interval 1.28-13.50]; p = 0.02). CONCLUSION: LGE presence independently predicted adverse clinical events in Asian patients with DCM. Routine use of CMR imaging to characterise the myocardial substrate is recommended for enhanced risk stratification and should strongly influence clinical management.

Causes and prognosis of symptomatic pericardial effusions treated by pericardiocentesis in an Asian academic medical centre.

INTRODUCTION: This study aimed to investigate the causes, clinical management and outcomes of clinically significant pericardial effusions, and evaluate the practice of pericardiocentesis within an academic medical centre in Singapore, a multiethnic country in Southeast Asia. METHODS: Consecutive patients undergoing pericardiocentesis at a single Asian academic medical centre were identified. Patient demographics, echocardiographic findings, investigations, pericardiocentesis procedural details and clinical progress were tracked using a comprehensive electronic medical records system. RESULTS: Of 149 patients who underwent pericardiocentesis, malignancy (46.3%) was the most common cause of pericardial effusions, followed by iatrogenic postsurgical complications (17.4%). 77.3% of effusions were large and 69.8% demonstrated tamponade physiology. Pericardiocentesis guided by echocardiography and fluoroscopy was successful in 99.3% of patients and had a complication rate of 2.0%. Likelihood of effusion recurrence and survival to discharge was determined by the aetiology of the pericardial effusion. 24.6% of malignant effusions recurred, and the survival rate 12 months after drainage of a malignant pericardial effusion was 45.0%. Short-term mortality was highest among patients presenting with tamponade due to acute aortic syndromes and those with myocardial rupture due to ischaemic heart disease. CONCLUSION: Cancer and iatrogenic complications were the most common causes of pericardial effusion in this large cohort of Singapore patients. Pericardiocentesis has a high success rate and relatively low complication rate. Prognosis and clinical course after pericardiocentesis are determined by the underlying cause of the pericardial effusion.

Coronary venoplasty during cardiac resynchronization therapy device implantations: Acute results and clinical outcomes.

BACKGROUND: Optimal left ventricular (LV) lead placement improves response to cardiac resynchronization therapy (CRT) but can be hindered by unfavorable venous anatomy. Interventional procedures in the coronary veins have been described with promising short-term outcomes. OBJECTIVE: The purpose of this study was to establish the safety and efficacy of percutaneous coronary venoplasty (PCV) during CRT implantation and assess medium-term lead performances and clinical outcomes against matched controls not requiring PCV. METHODS: Each consecutive PCV case was matched according to age, gender, and bundle branch morphology to 2 controls from a large prospective registry of CRT recipients. Demographics, procedural success, lead performance, and response to CRT were tracked using a comprehensive electronic medical records system. RESULTS: Of 422 consecutive CRT recipients treated between 2012 to 2018, 29 patients (6.9%; mean age 65.7 ± 10.7 years; 7 female; 17 ischemic cardiomyopathy; 22 left bundle branch block) required PCV, which was successful in 21 cases (72%). Target veins measuring 1.1 ± 0.6 mm were dilated by noncompliant balloons with mean diameter 2.8 ± 0.5 mm. No complications occurred. Fluoroscopic and procedural durations were longer in the PCV group (P <.01) Over mean follow-up of 33.0 ± 25.0 months, no differences in lead performance, CRT response, or 2-year survival were observed compared to the control group. CONCLUSION: PCV during CRT device implant is typically successful, safe and associated with long-term clinical outcomes comparable to patients who did not need PCV. This is an important technique to optimize LV lead placement and maximize CRT response.

Left ventricular pacing in patients with preexisting tricuspid valve disease.

BACKGROUND: Conventional right ventricular (RV) pacing is increasingly recognised to cause tricuspid valve (TV) injury or dysfunction, in part due to the need to pass the lead through the valve. This may be especially problematic in patients with preexisting TV disease or prior TV surgery. An alternative in this situation is to implant a left ventricular (LV) lead instead of ventricular pacing. METHODS: We performed a single-center retrospective analysis of 26 patients with tricuspid valve surgery/disease who received a LV pacing lead in the coronary veins to avoid crossing the tricuspid valve, with or without a right atrial lead. A matched control population was obtained from patients receiving conventional right ventricular pacing and outcomes were compared. Main outcomes of interest were lead stability, electrical lead parameters and change in echocardiographic parameters such as left ventricular ejection fraction (LVEF) during long-term follow-up. RESULTS: Successful left ventricular pacing was established in 25 out of the 26 cases with one case converted to a RV lead due to lead dislodgement. During the 2.96 ± 1.0 year follow-up, 24 of 25 (96.0%) leads were functional with stable pacing and sensing parameters, and 1 of 25 (4.0%) was extracted for due to device infection following an episode of thrombophlebitis. CONCLUSION: We conclude that in patients with existing tricuspid valve disease or surgery, ventricular pacing via the coronary veins is a feasible, safe, and reliable alternative to right ventricular pacing.

Electrocardiography findings and clinical presentation in Ebstein's anomaly.

Ebstein's anomaly is a congenital malformation characterised by tricuspid valve pathology with right heart enlargement. Cases of Ebstein's anomaly can vary widely in severity, anatomy and presentation. In this article, we presented three cases of Ebstein's anomaly and discussed the presentation as well as electrocardiographic (ECG) changes. Patients may first present to their primary care physicians with cardiac symptoms such as reduced effort tolerance together with an abnormal ECG. ECG changes suggestive of right heart enlargement are important in the initial consideration and eventual formal diagnosis of the condition.

Effect of Diabetes Mellitus on Cardiac Resynchronization Therapy and to Prognosis in Heart Failure (from the Prospective Evaluation of Asian With Cardiac Resynchronization Therapy for Heart Failure Study).

The association of diabetes mellitus (DM) with cardiac resynchronization therapy (CRT) response and cardiovascular outcomes in Asian patients with heart failure (HF) is unclear. This study aims to investigate the effects of DM on CRT response and cardiovascular outcomes in Asian HF patients. Consecutive Asian HF patients receiving CRT were enrolled in the Prospective Evaluation of Asian with CRT for Heart Failure (PEACH) study from 2011 to 2017. CRT response and super-response were defined as decrease in end-systolic volume index ≥15% and ≥30%, respectively. Primary endpoint was time to composite of HF-hospitalization and all-cause mortality. Among 161 patients followed for 3.3 ± 1.5 years (age 66.7 ± 11.2 years, 22% females, mean QRS duration 154.3 ± 22.4 ms, 83% left bundle branch block), 84 (52%) were CRT responders and 57 (35%) were super-responders. Of 82 (51%) patients with DM (100% type 2, mean HbA1c 7.3 ± 1.9%), 35 (43%) were responders. DM attenuated reverse remodeling (CRT response: AOR 0.44, 95% confidence interval [CI] 0.20 to 0.98, p < 0.05; super-response: AOR 0.42, 95% CI 0.18 to 0.97, p <0.05), and DM increased HF-hospitalization and all-cause mortality (AHR 1.68, 95% CI 1.00 to 2.82, p = 0.05). The extent of CRT-response correlates with higher event-free survival (CRT response: AHR 0.5, 95% CI 0.30 to 0.81, p = 0.005; super-response: AHR 0.27, 95% CI 0.14 to 0.52, p < 0.001). In conclusion, the extent of reverse remodeling post-CRT is the strongest predictor of event free survival. However, DM is detrimental to the CRT recipient by attenuating reverse remodeling, inducing end organ dysfunction and is independently associated with worsened clinical outcomes among Asian HF patients.

Optimal duration and predictors of diagnostic utility of patient-activated ambulatory ECG monitoring.

OBJECTIVE: We studied the optimal duration of ambulatory event monitors for symptomatic patients and the predictors of detected events. METHODS: Patients with palpitations or dizziness received a patient-activated handheld event monitor which records 30 s single-lead ECG strips. Patients were monitored in an ambulatory setting for a range of 1-4 weeks and ECG strips interpreted by five independent electrophysiologists. Event pick-up rates and clinical covariates were analysed. RESULTS: Of 335 consecutive adults (age 50±16 years, 58% female) with palpitations (94%) and dizziness (25%) monitored, 286 patients (85%) reported events, and clinically significant events were detected in 86 (26%) patients. Of these 86 patients, 26% had ≥2 significant events, and 73% had events detected in the first 3 days. No significant events were detected after 12 days. The most common ECG abnormalities detected were premature ventricular ectopy (38%), premature atrial ectopy (37%) and atrial fibrillation (AF)/atrial flutter (34%). A history of AF (adjusted OR (AOR) 4.2, 95% CI 1.1 to 15.8), previous arrhythmia (AOR 2.8, 95% CI 2.3 to 5.9) and previous abnormal ambulatory monitoring (AOR 3.4, 95% CI 1.0 to 9.4) were associated with detection of clinically significant events. Patients older than 50 years were 82% more likely to have a clinically significant event (OR 1.8, 95% CI 1.3 to 3.6). CONCLUSION: Patient-activated ambulatory event monitoring for 7 days may be sufficient in the diagnosis of symptomatic patients as significant events first detected beyond 10 days were rare. Patients with a history of AF, arrhythmia or previous abnormal ambulatory monitoring may require even shorter monitoring periods.

Genotype-guided versus traditional clinical dosing of warfarin in patients of Asian ancestry: a randomized controlled trial.

BACKGROUND: Genotype-guided warfarin dosing has been shown in some randomized trials to improve anticoagulation outcomes in individuals of European ancestry, yet its utility in Asian patients remains unresolved. METHODS: An open-label, non-inferiority, 1:1 randomized trial was conducted at three academic hospitals in South East Asia, involving 322 ethnically diverse patients newly indicated for warfarin (NCT00700895). Clinical follow-up was 90 days. The primary efficacy measure was the number of dose titrations within the first 2 weeks of therapy, with a mean non-inferiority margin of 0.5 over the first 14 days of therapy. RESULTS: Among 322 randomized patients, 269 were evaluable for the primary endpoint. Compared with traditional dosing, the genotype-guided group required fewer dose titrations during the first 2 weeks (1.77 vs. 2.93, difference -1.16, 90% CI -1.48 to -0.84, P < 0.001 for both non-inferiority and superiority). The percentage of time within the therapeutic range over 3 months and median time to stable international normalized ratio (INR) did not differ between the genotype-guided and traditional dosing groups. The frequency of dose titrations (incidence rate ratio 0.76, 95% CI 0.67 to 0.86, P = 0.001), but not frequency of INR measurements, was lower at 1, 2, and 3 months in the genotype-guided group. The proportions of patients who experienced minor or major bleeding, recurrent venous thromboembolism, or out-of-range INR did not differ between both arms. For predicting maintenance doses, the pharmacogenetic algorithm achieved an R2 = 42.4% (P < 0.001) and mean percentage error of -7.4%. CONCLUSIONS: Among Asian adults commencing warfarin therapy, a pharmacogenetic algorithm meets criteria for both non-inferiority and superiority in reducing dose titrations compared with a traditional dosing approach, and performs well in prediction of actual maintenance doses. These findings imply that clinicians may consider applying a pharmacogenetic algorithm to personalize initial warfarin dosages in Asian patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT00700895 . Registered on June 19, 2008.

High Incidence of Occult Atrial Fibrillation in Asian Patients with Cryptogenic Stroke.

BACKGROUND: Occult atrial fibrillation (AF) is not uncommon in patients with stroke. In western cohorts, insertable loop recorders (ILRs) have been shown to be the gold-standard and are cost-effective for AF detection. Anticoagulation for secondary stroke prevention is indicated if AF is detected. The incidence of occult AF among Asian patients with cryptogenic stroke is unclear. METHODS: Patients with cryptogenic stroke referred between August 2014 and February 2017 had ILRs implanted. Episodes of AF >2 minutes duration were recorded using proprietary algorithms within the ILRs, whereupon clinicians and patients were alerted via remote monitoring. All AF episodes were adjudicated using recorded electrograms. Once AF was detected, patients were counseled for anticoagulation. RESULTS: Seventy-one patients with cryptogenic stroke, (age 61.9 ± 13.5 years, 77.5% male, mean CHA2DS2VASc score of 4.2 ± 1.3) had ILRs implanted. Time from stroke to the ILR implant was a median of 66 days. Duration of ILR monitoring was 345 ± 229 days. The primary endpoint of AF detection at 6 months was 12.9%; and at 12 months it was 15.2%. Median time to detection of AF was 50 days. The AF episodes were all asymptomatic and lasted a mean of 77 minutes (± 118.9). Anticoagulation was initiated in all but 1 patient found to have AF. CONCLUSIONS: The incidence of occult AF is high in Asian patients with cryptogenic stroke and comparable to western cohorts. The combination of ILR and remote monitoring is a highly automated, technologically driven, and clinically effective technique to screen for AF.

Mapping clinical journeys of Asian patients presenting to the Emergency Department with syncope: Strict adoption of international guidelines does not reduce hospitalisations.

BACKGROUND: Limited data exists about management of syncope in Asia. The American College of Emergency Physicians (ACEP) and European Society of Cardiology (ESC) guidelines have defined the high-risk syncope patient. This study aims to determine the effectiveness of managing syncope in an Asian healthcare system and whether strict adherence of international guidelines would reduce hospitalizations. METHODS: Patients attending the Emergency Department of a Singaporean tertiary hospital with syncope were identified. Clinical journeys of all patients were meticulously mapped by interrogation of a comprehensive electronic medical record system and linkages with national datasets. Primary endpoint was hospitalization. Secondary endpoints were recurrent syncope within 1year and all-cause mortality. Expected admission rates based on application of ACEP/ESC guidelines were calculated. RESULTS: 638 patients (43.8±22.4years, 49.0% male) presented with syncope. 48.9% were hospitalized for 2.9±3.2days. Yields of common investigations ranged from 0 to 11.5% and no diagnosis was reached in 51.5% of patients. Diuretics use (HR 5.1, p=0.01) and prior hospitalization for syncope (HR 6.9, p<0.01) predicted recurrent syncope. Over 2.8 SD 0.3years of follow-up, 40 deaths occurred. 24 patients who died within 12months of presentation were admitted or had a firm diagnosis upon discharge. Application of guidelines did not significantly reduce hospitalisations, with limited agreement which patients warrant admission. (Actual 376, ACEP 354, ESC 391 admissions, p=NS). CONCLUSIONS: Unstructured management of syncope results in nearly half of patients being admitted and substantial healthcare expenditures, yet with limited diagnostic yield. Strict adoption of ACEP or ESC guidelines does not reduce admissions.

Ischemic ventricular tachycardia presenting as a narrow complex tachycardia.

This report describes a patient presenting with a narrow complex tachycardia in the context of prior myocardial infarction and impaired ventricular function. Electrophysiological studies confirmed ventricular tachycardia and activation and entrainment mapping demonstrated a critical isthmus within an area of scar involving the His-Purkinje system accounting for the narrow QRS morphology. This very rare case shares some similarities with upper septal ventricular tachycardia seen in patients with structurally normal hearts, but to our knowledge has not been seen previously in patients with ischemic heart disease.

Adverse impact of chronic subpulmonary left ventricular pacing on systemic right ventricular function in patients with congenitally corrected transposition of the great arteries.

BACKGROUND: Patients with congenitally corrected transposition of the great arteries (ccTGA) are at high risk of heart block requiring subpulmonary left ventricular (LV) pacing. Long-term right ventricular (RV) pacing in congenitally normal hearts is associated with LV dysfunction. We examined the effects of univentricular subpulmonary LV pacing on the systemic RV in a ccTGA cohort. METHODS: ccTGA patients with two echocardiographic studies at least 6 months apart were included. Records of 52 patients, 22 with pacing, were retrospectively reviewed. Seven patients with biventricular pacing were included for comparison. RESULTS: The LV-Paced Group experienced deterioration in the RV fractional area change (RVFAC) (28.7 ± 10.0 vs. 21.9 ± 9.1%; P=0.003), systemic atrioventricular valve regurgitation (P=0.019) and RV dilatation (end-diastolic area 32.7 ± 8.7 vs. 37.2 ± 9.0 cm(2); P=0.004). There was a corresponding deterioration in NYHA class (P=0.013). Multivariate Cox regression analysis showed that pacing was an independent predictor of deteriorating RV function and RV dilation (hazard ratio 2.7(10-7.0) and 4.7(1.1-20.6) respectively). None of these parameters changed significantly in the Un-paced Group. The CRT Group showed improvement in RVFAC (22.0% to 30.7% (P=0.030) and NYHA class (P=0.030), despite having lower baseline RVFAC (22.0±5.7 vs. 31 ± 9.7%; P=0.025) and greater dyssynchrony (RV total isovolumic time 13.4 ± 2.1 vs. 9.3 ± 4.2s/min; P=0.016) when compared to the Un-Paced Group. CONCLUSIONS: Univentricular subpulmonary LV pacing in patients with ccTGA predicted deterioration in RV function and RV dilatation over time associated with deteriorating NYHA class. Alternative primary pacing strategies such as biventricular pacing may need consideration in this vulnerable group already highly prone to mortality from systemic RV failure.