Ki-Woon Kang

Electromechanical cardioplasty using a wrapped elasto-conductive epicardial mesh

A mesh made of a conductive nanowire composite can be wrapped around the heart to improve hemodynamics in experimental heart failure in rodents. An electromechanical hug for the heart Heart failure can be treated by pacemakers to keep the beats in rhythm, but pacemakers apply electrical stimulation at specific points and do not provide comprehensive coverage of the entire organ. Park and colleagues therefore devised an electric mesh that wraps around the heart to deliver electrical impulses to the whole ventricular myocardium. The heart wrap was made from silver nanowires embedded in a rubber polymer that could conform to the unique three-dimensional anatomy of different hearts. In rats that had a heart attack, the mesh integrated structurally and electrically with the myocardium and exerted beneficial effects, including preserved diastolic relaxation, reduced wall stress, and improved cardiac contractile function. The mesh also terminated induced ventricular arrhythmia, acting as an epicardial defibrillator. Such epicardial meshes have been tested in clinical trials before and were effective in preventing ventricular remodeling but showed controversial results in long-term survival. The authors hope that their device, which is designed to integrate more faithfully with the heart’s structure and electrical conduction system, is more consistent in people. Heart failure remains a major public health concern with a 5-year mortality rate higher than that of most cancers. Myocardial disease in heart failure is frequently accompanied by impairment of the specialized electrical conduction system and myocardium. We introduce an epicardial mesh made of electrically conductive and mechanically elastic material, to resemble the innate cardiac tissue and confer cardiac conduction system function, to enable electromechanical cardioplasty. Our epicardium-like substrate mechanically integrated with the heart and acted as a structural element of cardiac chambers. The epicardial device was designed with elastic properties nearly identical to the epicardial tissue itself and was able to detect electrical signals reliably on the moving rat heart without impeding diastolic function 8 weeks after induced myocardial infarction. Synchronized electrical stimulation over the ventricles by the epicardial mesh with the high conductivity of 11,210 S/cm shortened total ventricular activation time, reduced inherent wall stress, and improved several measures of systolic function including increases of 51% in fractional shortening, ~90% in radial strain, and 42% in contractility. The epicardial mesh was also capable of delivering an electrical shock to terminate a ventricular tachyarrhythmia in rodents. Electromechanical cardioplasty using an epicardial mesh is a new pathway toward reconstruction of the cardiac tissue and its specialized functions.

Fragmented QRS as a candidate marker for high-risk assessment in hypertrophic cardiomyopathy

BACKGROUND The relationship between a fragmented QRS complex (fQRS) on 12-lead ECG and fatal arrhythmic events in hypertrophic cardiomyopathy (HCM) remains unclear. OBJECTIVE The purpose of this study was to investigate whether fQRS is associated with ventricular arrhythmic events (VAEs) in HCM patients. METHODS Of an initial cohort of 273 patients (57% male, mean age 55 years) diagnosed with HCM, 167 patients were included and divided into 2 groups: those with fQRS (n = 67) and those without fQRS (n = 100). fQRS was defined as notching of the R or S wave in 2 contiguous leads. VAEs were defined as nonsustained or sustained ventricular tachycardia (VT) or sudden cardiac death (SCD). Major arrhythmic events (MAEs) were sustained VT or SCD. RESULTS During mean follow-up of 6.3 years, univariate analysis showed that fQRS was significantly associated with increased VAEs (unadjusted hazard ratio [HR] 6.17, 95% confidence interval [CI] 2.46-15.49, P < .001) and MAEs (unadjusted HR 5.12, 95% CI 1.38-19.01, P = .014). Multivariate analysis revealed that fQRS was a strong independent predictor of VAEs (adjusted HR 6.28, 95% CI 2.49-15.84, P < .001) and MAEs (adjusted HR 6.04, 95% CI 1.49-24.39, P = .011). fQRS in the inferior leads was most closely related to MAEs compared to fQRS in other myocardial territories, and its inclusion in a risk calculator for mortality in HCM patients increased the positive predictive value from 8% to 25% in low-risk patients. CONCLUSION Presence of an fQRS may be a good candidate marker for prediction of VAE in patients with HCM.

Feasibility of an automatic computer-assisted algorithm for the detection of significant coronary artery disease in patients presenting with acute chest pain

Automatic computer-assisted detection (auto-CAD) of significant coronary artery disease (CAD) in coronary computed tomography angiography (cCTA) has been shown to have relatively high accuracy. However, to date, scarce data are available regarding the performance of auto-CAD in the setting of acute chest pain. This study sought to demonstrate the feasibility of an auto-CAD algorithm for cCTA in patients presenting with acute chest pain. We retrospectively investigated 398 consecutive patients (229 male, mean age 50±21 years) who had acute chest pain and underwent cCTA between Apr 2007 and Jan 2011 in the emergency department (ED). All cCTA data were analyzed using an auto-CAD algorithm for the detection of >50% CAD on cCTA. The accuracy of auto-CAD was compared with the formal radiology report. In 380 of 398 patients (18 were excluded due to failure of data processing), per-patient analysis of auto-CAD revealed the following: sensitivity 94%, specificity 63%, positive predictive value (PPV) 76%, and negative predictive value (NPV) 89%. After the exclusion of 37 cases that were interpreted as invalid by the auto-CAD algorithm, the NPV was further increased up to 97%, considering the false-negative cases in the formal radiology report, and was confirmed by subsequent invasive angiogram during the index visit. We successfully demonstrated the high accuracy of an auto-CAD algorithm, compared with the formal radiology report, for the detection of >50% CAD on cCTA in the setting of acute chest pain. The auto-CAD algorithm can be used to facilitate the decision-making process in the ED.

Additional linear ablation from the superior vena cava to right atrial septum after pulmonary vein isolation improves the clinical outcome in patients with paroxysmal atrial fibrillation: prospective randomized study

AIMS Although circumferential pulmonary vein isolation (CPVI) has been considered as the cornerstone for paroxysmal atrial fibrillation (PAF) ablation, there has been a substantial recurrence rate. We conducted a prospectively randomized study to evaluate whether additional linear ablation from the superior vena cava (SVC) to the right atrial (RA) septum (SVC-L) improves the clinical outcome. METHODS AND RESULTS This study enroled 200 patients with PAF (male 74.5%, 56.8 ± 11.7 years old) randomly assigned to either the CPVI (n = 100) or CPVI + SVC-L (n = 100) groups. An RA isthmus ablation was performed in all patients. The CPVI + SVC-L group required a longer ablation procedure time (82.7 ± 17.9 min) than the CPVI group (63.6 ± 16.8 min, P < 0.001). The complication rates were 5% in CPVI + SVC-L group and 2% in CPVI group, respectively (P = 0.445). Two CPVI + SVC-L group patients had post-procedural sinus node dysfunction, which recovered within 24 h. During 12.2 ± 5.3 months of follow-up, the recurrence rate was significantly lower in the CPVI + SVC-L group (6%) than the CPVI group (27%, P < 0.001). The post-procedural 3-month follow-up heart rate variability in the CPVI + SVC-L group showed a significantly greater reduction in the rMSSD (25.2 ± 13.7 vs. 13.7 ± 8.5 ms, P < 0.001), HF (10.2 ± 7.1 vs. 5.5 ± 5.8 ms(2), P < 0.001), and LF/HF (1.6 ± 0.5 vs. 0.9 ± 0.3, P < 0.001) than in the CPVI group. CONCLUSION In spite of a longer procedure time and risk of transient sinus node dysfunction, an SVC-L in addition to CPVI improved the clinical outcome of catheter ablation, and was associated with post-procedural autonomic neural remodelling in patients with PAF.

Paced QT interval is a better predictor of mortality than the intrinsic QT interval: Long-term follow-up study

BACKGROUND Prolongation of the corrected QT (QTc) interval on 12-lead electrocardiogram is related to total mortality and sudden cardiac death. The value of the paced QTc interval in predicting mortality has not been investigated. OBJECTIVE To evaluate the relationship between the paced QTc interval and mortality. METHODS Of 1440 patients who underwent pacemaker implantation from January 1990 to March 2010, 766 had a recorded intrinsic and ventricular paced rhythm and were included in this study. The intrinsic and paced QTc intervals were measured on 12-lead electrocardiogram before and 1-month after implantation. RESULTS During a mean follow-up period of 7 ± 5 years, 189 (24.4%) patients died, of which 63 (8.1%) were cardiac deaths. Compared with patients in the first tertile of the paced QTc interval (<484 ms), patients in the third tertile (>511 ms) were significantly more likely to die (19% vs 29%; P < .05). A comparison of the third and first tertiles of the QTc interval showed that a prolonged paced QTc interval was a significant independent predictor of all-cause mortality (adjusted hazard ratio 2.08; 95% confidence interval 1.44-3.01; P < .001) and cardiac mortality (adjusted hazard ratio 2.53; 95% confidence interval 1.29-4.95; P = .007) and a better predictor than was a prolonged intrinsic QTc interval. When treated as a continuous variable, a prolonged paced QTc interval predicted increased total mortality and cardiac mortality. CONCLUSION The paced QTc interval appears to be a more useful marker in predicting bad prognosis than does the intrinsic QTc interval in patients with indications for a permanent pacemaker.

One-year clinical outcomes in invasive treatment strategies for acute ST-elevation myocardial infarction complicated by cardiogenic shock in elderly patients

Objective To investigate the clinical outcomes of an invasive strategy for elderly (aged ≥ 75 years) patients with acute ST-segment elevation myocardial infarction (STEMI) complicated by cardiogenic shock (CS). Methods Data on 366 of 409 elderly CS patients from a total of 6,132 acute STEMI cases enrolled in the Korea Acute Myocardial Infarction Registry between January 2008 and June 2011, were collected and analyzed. In-hospital deaths and the 1-month and 1-year survival rates free from major adverse cardiac events (MACE; defined as all cause death, myocardial infarction, and target vessel revascularization) were reported for the patients who had undergone invasive (n = 310) and conservative (n = 56) treatment strategies. Results The baseline clinical characteristics were not significantly different between the two groups. There were fewer in-hospital deaths in the invasive treatment strategy group (23.5% vs. 46.4%, P < 0.001). In addition, the 1-year MACE-free survival rate after invasive treatment was significantly lower compared with the conservative treatment (51% vs. 66%, P = 0.001). Conclusions In elderly patients with acute STEMI complicated by CS, the outcomes of invasive strategy are similar to those in younger patients at the 1-year follow-up.

Successful Embolectomy of a Migrated Thrombolytic Free-Floating Massive Thrombus Resulting in a Pulmonary Thromboembolism

The optimal treatment for free-floating massive right heart thrombi remains uncertain. However, they appear to increase the risk of mortality compared to the existence of a solitary pulmonary thromboembolism. Thrombolytic therapy has been shown to be effective in most patients, resulting in complete resolution of the massive thrombus and clinical improvement. We report the echocardiographic disappearance of a free-floating right heart thrombus after thrombolysis, however, the thrombus migrated and resulted in pulmonary thromboembolism. It was successfully removed with surgery.

A Case of Acute Thrombotic Occlusion of an Anomalous Origin of the Right Coronary Artery From the Left Coronary Sinus: Focus on the Importance of Dual-Source Computed Tomography for Failed Emergency Coronary Angiography

Coronary artery anomalies in patients undergoing coronary angiography are often technically challenging for invasive cardiologists and may delay revascularization time. We report a patient who underwent successful bailout revascularization using dual-source computed tomography after failed emergency angiography. This case emphasizes the utility of dual-source computed tomography, especially in an urgent clinical setting, for allowing interventional cardiologists to rapidly identify and effectively treat the aberrant coronary artery.

Comparison of Vascular Remodeling in Patients Treated With Sirolimus-Versus Zotarolimus-Eluting Stent Following Acute Myocardial Infarction

The differences in the vascular response to stent implantation or in the incidence of late acquired stent malapposition among different types of drug‐eluting stents are not well known in patients with acute myocardial infarction (MI).

Concurrent renal dysfunction with ischemic heart disease is an important determinant for cardiac and cerebrovascular mortality in patients on chronic digoxin therapy for atrial fibrillation

Background Major adverse cardiac and cerebrovascular events (MACCEs) are main concerns in patients with atrial fibrillation (AF); however, factors affecting MACCEs remain inconclusive in AF patients chronically treated with digoxin. We investigated the major clinical determinants for fatal MACCEs in AF patients treated with digoxin over a 10-year follow-up period. Methods We analyzed a retrospective cohort of 1,480 AF patients at Eulji University Hospital, Daejeon, South Korea from March 2004 to August 2015. Among this population, 402 consecutive patients receiving chronic digoxin therapy were selected for the study. Data for electrocardiography, medication history, laboratory values including the serum digoxin concentration (SDC) and fatal MACCEs were collected. All data were divided and compared between groups based on the occurrence of MACCEs. Results The overall incidence of fatal MACCEs among the 402 digoxin-treated AF patients (age, 68 ± 11 years; male, 40.3%) was 12.1%. These fatalities resulted from heart failure (46.1%), fatal stroke (26.9%), fatal myocardial infarction (15.3%) and sudden cardiac death (5.7%). A higher prevalence of diabetes, pre-existing ischemic heart disease (IHD), lower estimated glomerular filtration rate (eGFR), higher SDC, and junctional bradycardia were more frequently observed in patients with MACCEs compared to those without MACCEs. Multivariable analysis showed that an eGFR of ≤ 60 mL/min/1.73 m2 and pre-existing IHD had a hazard ratio of 3.35 and a confidence interval of 1.64–6.87 (P < 0.001) for fatal MACCEs. Conclusion Chronic kidney disease stage III–V with pre-existing IHD is significantly associated with increased cardiac and cerebrovascular mortality in AF patients with chronic digoxin use.