A case report of undetected cardiac arrest in a patient with an insertable cardiac monitor.

Insertable cardiac monitors (ICMs) are small electrocardiographs implanted subcutaneously to automatically record electrocardiograms when arrhythmia is detected in patients with syncope. If the ICM misses a significant arrhythmia, it may delay the diagnosis of arrhythmogenic syncope and put the patient at risk. Herein, we describe a case of undetected cardiac arrest in a patient with ICM. An 87-year-old man with syncope was admitted to the hospital. After 8 days of monitoring, the cause could not be determined, and an ICM was implanted. Nine hours after implantation, the patient experienced cardiopulmonary arrest. Despite a body surface electrocardiogram showing ventricular flatline and fibrillation, the ICM failed to record. The cause of failure to record was considered to be the fluctuation in the R-wave amplitude of the ICM and noise oversensing. In conclusion, albeit infrequently, ICMs might overlook life-threatening arrhythmias. Even in cases where the ICM fails to detect an arrhythmia matching the symptoms, it may not be feasible to entirely rule out the presence of arrhythmias. Learning objective: Insertable cardiac monitors (ICMs) are used to diagnose arrhythmogenic syncope. However, extremely infrequently, ICM may fail to record life-threatening arrhythmias. Failure to capture arrhythmias can happen due to an unfortunate combination of factors such as a low amplitude of the recorded R wave and noise. Even in cases where the ICM does not detect an arrhythmia that matches the symptoms, it may not be feasible to completely exclude the presence of arrhythmias.

Semi-urgent pulmonary vein isolation using cryoballoon for haemodynamically unstable atrial fibrillation storm in a patient with low cardiac output syndrome: a case report.

BACKGROUND: Atrial fibrillation and heart failure are common coexisting conditions requiring hospitalisation for heart failure and death. Pulmonary vein isolation is a well-established option for symptomatic atrial fibrillation and for atrial fibrillation concomitant with heart failure with reduced left ventricular ejection fraction. Recently, pulmonary vein isolation using cryoballoon showed non-inferiority to radiofrequency ablation with respect to the treatment of patients with drug-refractory paroxysmal atrial fibrillation. However, the effectiveness of acute-phase rhythm control by semi-urgent pulmonary vein isolation using cryoballoon in patients with haemodynamically unstable atrial fibrillation storm accompanied with low cardiac output syndrome is unclear. Herein, we present a case in which semi-urgent pulmonary vein isolation using cryoballoon was effective for acute-phase rhythm control against drug-resistant and haemodynamically unstable repetitive atrial fibrillation tachycardia accompanied with low cardiac output syndrome. CASE PRESENTATION: A 57-year-old man was hospitalised for New York Heart Association functional class 4 heart failure with atrial fibrillation tachycardia and reduced left ventricular ejection fraction of 20% accompanied with low cardiac output syndrome-induced liver damage. The haemodynamics collapsed during atrial fibrillation tachycardia, which had become resistant to intravenous amiodarone and repeated electrical cardioversions. In addition to atrial fibrillation, atrial tachycardia and common-type atrial flutter appeared on day 3. Multiple organ failure progressed gradually due to haemodynamically unstable atrial fibrillation tachycardia storm accompanied with low cardiac output syndrome. On day 4, to focus on treatment of heart failure and multiple organ failure, semi-urgent rescue pulmonary vein isolation using cryoballoon to atrial fibrillation and cavotricuspid isthmus ablation to common-type atrial flutter were performed for acute-phase rhythm control. Soon after the ablation procedure, atrial fibrillation and common-type atrial flutter were lessened, and sinus rhythm was restored. A stable haemodynamics was successfully achieved with the improvement of hepatorenal function. The patient was discharged on day 77 without complications. CONCLUSIONS: This case demonstrates that acute-phase rhythm control by semi-urgent pulmonary vein isolation using cryoballoon could be a treatment option in patients with haemodynamically unstable atrial fibrillation tachycardia storm accompanied with low cardiac output syndrome, which is refractory to cardioversion and drug therapy.

B-type natriuretic peptide and risk of sudden death in patients with hypertrophic cardiomyopathy.

BACKGROUND: The association between B-type natriuretic peptide (BNP) levels and sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM) remains unclear. OBJECTIVE: This study evaluated the effect of elevated BNP levels on sudden death risk in a cohort of patients with HCM. METHODS: This study included 346 patients with HCM. Plasma BNP levels were measured at the initial evaluation. RESULTS: The median (interquartile range) BNP level in the study patients was 197.2 (84.4-353.3) pg/mL. During a median (interquartile range) follow-up period of 8.4 (4.2-12.5) years, 37 patients (10.7%) experienced the combined end point of sudden death or potentially lethal arrhythmic events, including 11 patients with sudden death (3.2%), 8 resuscitated after cardiac arrest, and 18 with appropriate implantable defibrillator shocks. Time-dependent receiver operating characteristic curve analysis of the prognostic value of BNP for the combined end point showed that the Harrell's concordance index was 0.748 and the optimal BNP cutoff point was 312 pg/mL. Patients with high BNP levels (>312 pg/mL) were at a significantly higher risk of sudden death (Gray test, P = .001) and the combined end point (Gray test, P < .001) than were patients with low BNP levels (≤312 pg/mL). Multivariable analysis that included BNP levels and established risk factors for sudden death showed that high BNP levels were an independent determinant of the combined end point (adjusted hazard ratio 5.71; 95% confidence interval 2.86-11.4; P < .001). CONCLUSION: Elevated BNP levels may be associated with sudden death and the combination of sudden death or potentially lethal arrhythmic events in patients with HCM.

Association of elevated pulmonary artery systolic pressure with stroke and systemic embolic events in patients with hypertrophic cardiomyopathy.

BACKGROUND: Echocardiographically estimated pulmonary artery systolic pressure (PASP) is a non-invasive widely available method that is used to estimate pulmonary arterial pressure. Although elevated PASP predicts mortality in patients with hypertrophic cardiomyopathy (HCM), the relationship between PASP and embolic events is unclear. This study aimed to determine whether elevated PASP is associated with stroke and systemic embolic events in a tertiary referral HCM cohort. METHODS: This study included 374 clinically diagnosed patients with HCM. PASP was estimated from tricuspid regurgitant jet velocity using the modified Bernoulli equation. RESULTS: The median (interquartile range) PASP was 33 (28-37) mm Hg, and elevated PASP (>40mmHg) was observed in 66 (17.6%) patients. Seventeen of the 66 (25.8%) patients with elevated PASP and 24 of the 308 (7.8%) patients without elevated PASP experienced stroke and systemic embolic events during the 10.3±7.4years of follow-up (log-rank P<0.001). Multivariable analysis showed that age at diagnosis, atrial fibrillation, and PASP >40mmHg (adjusted hazard ratio, 2.59; 95% confidence interval, 1.31-5.12; P=0.006) were independently associated with embolic events. CONCLUSIONS: In addition to age and atrial fibrillation, PASP estimated by Doppler echocardiography could help embolic risk stratification in patients with HCM.

Implantable cardioverter defibrillator therapy and sudden death risk stratification in hypertrophic cardiomyopathy patients with midventricular obstruction: A single-center experience.

BACKGROUND: Previous studies reported that the presence of midventricular obstruction (MVO) was an independent determinant of sudden death and potentially lethal arrhythmic events in patients with hypertrophic cardiomyopathy (HCM). However, it remains unclear whether implantable cardioverter defibrillator (ICD) improves survival in HCM patients with MVO. In addition, the risk factors for lethal arrhythmic events in MVO-HCM patients are not fully understood. The aim of this study was to provide an overview of the ICD therapy on sudden death prevention, and to determine the risk factors for lethal arrhythmic events in MVO-HCM patients. METHODS: This study included 593 HCM patients. Left ventricular MVO was diagnosed when the peak midventricular gradient was estimated as ≥30mmHg. RESULTS: MVO was identified in 56 patients (9.4%), and 15 of the 56 MVO-HCM patients (26.8%) received an ICD. Six of 15 ICD-implanted patients (40.0%) had appropriate ICD interventions over the follow-up period of 6.5±5.1years after ICD implantation. Although two of 42 patients without an ICD died suddenly, no patients experienced sudden death after ICD implantation in patients with an ICD throughout the follow-up period of 9.0±8.0years after referral to our hospital. By multivariate analysis, maximal wall thickness was an independent determinant of lethal arrhythmic events in MVO-HCM patients. CONCLUSIONS: A quarter of MVO-HCM patients received an ICD, and the incidence of appropriate ICD intervention was about 6.2%/year. It may be necessary to give careful consideration to the prevention of lethal arrhythmic events in MVO-HCM patients, especially those with severe left ventricular hypertrophy.