Cardiac complications of COVID-19: Incidence and outcomes.

BACKGROUND: Coronavirus disease-2019 (COVID-19) has been associated with pre-existing cardiac conditions as well as cardiovascular complications. The incidence rates of cardiac complications, age, and gender differences in this population are unknown. OBJECTIVES: We wanted to study the incidence of cardiac complications and mortality in patients with COVID-19. METHODS: Data from the TriNetX COVID-19 global research network platform was used to identify COVID-19 patients. We compared patients with and without cardiac complications in patients with COVID-19 and obtained survival data. RESULTS: The final cohort was composed of 81,844 patients with COVID-19. Cardiac complications occurred in 9.3% of patients as follows: acute coronary syndromes in 1.3%, heart failure in 4.4%, atrial fibrillation in 4.5%, sinus bradycardia 1.9%, ventricular tachycardia in 0.5% and complete heart block in 0.01%. Mortality was significantly higher in patients with the cardiac complications mentioned (20%) than in those without them (2.9%) (odds ratio 7.2, 95% CI, 6.7-7.7; p < 0.0001). Older males seem to have higher incidence of cardiac complications and mortality. CONCLUSIONS: Patients with COVID-19 who have cardiac complications have a higher risk of mortality when compared to those without cardiac complications.

A Tragic Case of Wearable Cardioverter-Defibrillator Failure.

The American College of Cardiology/American Heart Association guidelines recommend a wearable cardioverter defibrillator (WCD) for certain conditions or scenarios. WCD is felt to provide adequate protection against ventricular arrhythmias. This case highlights failure of a WCD to detect and deliver life-saving therapy and the need for improved detection algorithms. (Level of Difficulty: Beginner.).

Design and implementation of an ultra-low energy FFT ASIC for processing ECG in Cardiac Pacemakers.

In embedded biomedical applications, spectrum analysis algorithms such as Fast Fourier Transform (FFT) are crucial for pattern detection and has been the focus of continued research. In deeply embedded systems such as cardiac pacemakers, FFT based signal processing is typically computed by Application Specific Integrated Circuits (ASIC) to achieve low power operation. This research proposes a data driven design approach for an FFT ASIC solution which exploits the limited range of data encountered by these embedded systems. The optimizations proposed in this paper uses the simple concept of Hashing and Look-Up Tables (LUT) to effectively reduce the number of arithmetic operations required to perform the FFT of an electrocardiogram (ECG) signal. By reducing the dynamic power consumption and overall energy footprint of FFT computation, the proposed design aims to achieve longer battery life for a Cardiac Pacemaker. The design is synthesized using a 90nm standard cell library, and gate level switching activity is simulated to obtain accurate power consumption results. The proposed optimizations achieved a low energy consumption of 27.72nJ per FFT, which is 14.22% lower than a standard 128-point radix-2 FFT when tested with actual ECG data collected from PhysioNet.

Admittance to detect alterations in left ventricular stroke volume.

BACKGROUND: Implantable cardioverter-defibrillators monitor intracardiac electrograms (EGMs) to discriminate between ventricular and supraventricular tachycardias. The incidence of inappropriate shocks remains high because of misclassification of the tachycardia in an otherwise hemodynamically stable individual. Coupling EGMs with an assessment of left ventricular (LV) stroke volume (SV) could help in gauging hemodynamics during an arrhythmia and reducing inappropriate shocks. OBJECTIVE: The purpose of this study was to use the admittance method to accurately derive LV SV. METHODS: Ultrasonic flow probe and LV endocardial crystals were used in canines (n = 12) as the standard for LV SV. Biventricular pacing leads were inserted to obtain admittance measurements. A tetrapolar, complex impedance measurement was made between the Bi-V leads. The real and imaginary components of impedance were used to discard the myocardial component from the blood component to derive instantaneous blood conductance (Gb). Alterations in SV were measured during right ventricular pacing, dopamine infusion, and inferior vena cava occlusion. RESULTS: Gb tracks steady-state changes in SV more accurately than traditional magnitude (ie, |Y|, without removal of the muscle signal) during right ventricular pacing and dopamine infusion (P = .004). Instantaneous LV volume also was tracked more accurately by Gb than ∣Y∣ in the subset of subjects that underwent inferior vena cava occlusions (n = 5, P = .025). Finite element modeling demonstrates that admittance shifts more sensitivity of the measurement to the LV blood chamber as the mechanism for improvement (see Online Appendix). CONCLUSION: Monitoring LV SV is possible using the admittance method with biventricular pacing leads. The technique could be piggybacked to complement EGMs to determine if arrhythmias are hemodynamically unstable.

Evaluation Of Two Thromboembolism (TE) Risk Methods And Oral Anticoagulation Use Among Cardiac Device Patients With Atrial Tachyarrhythmias (AT).

BACKGROUND: In the implantable cardiac device (CD) population, not only can clinically silent atrial tachyarrythmias (AT) be detected, but an associated AT burden can be documented. There are two methods of determining stroke risk: CHADS2 and CHA2DS2-VASc. Recommendations for initiating anticoagulation based on stroke risk profiles and/or AT burden remain unclear for device-detected AT. OBJECTIVE: Aims of this study were to reveal the AT burden among CD patients, determine CHADS2 and CHA2DS2-VASc scores among patients with an AT burden, and evaluate current practices for anticoagulation. METHODS: Records were reviewed from patients undergoing a new CD implant within the last three years from two device clinics. Continuous variables were expressed as mean with standard deviation (SD) and categorical variables were stated as numbers and percentages. The categorical variables were compared using the Chi2 Square test and the continuous variables were compared using the independent 2-sided t-test. RESULTS: There were 275 CD patients enrolled. Eighty-seven had an AT burden and 188 patients did not have an AT burden. CD patients with AT burden were older than those without AT burden [69 (11), p=0.007]. Patients with AT burden had more hypertension and previous history of stroke (p=0.038, p=0.005) compared to those without AT burden. Both the CHADS2 and CHA2DS2-VASc mean scores were higher in patients with an AT burden (p=0.018 and p=0.041). Thirty patients with a previous history of AT were on anticoagulation (p=<0.001) prior to implant. Forty-eight patients had a new diagnosis of AT (NDAT) and 46% (n=22) were started on anticoagulation. CONCLUSIONS: An AT burden was detected in 32% of patients with at least 75% falling within a high-risk category using both scores. However, less than half of NDAT patients were started on anticoagulation. The use of oral anticoagulation in practice remains inconsistent and further randomized trials are recommended.

Cardiac sarcoidosis mimicking arrhythmogenic right ventricular dysplasia with high defibrillation threshold requiring subcutaneous shocking coil implantation.

Cardiac involvement in patients with sarcoidosis has been reported in up to 25-39% of patients and is responsible for up to 85% of deaths attributed to the disease, often due to sudden cardiac death. An established diagnosis of cardiac sarcoidosis (CS) portends an ominous prognosis, with an estimated five year-survival of 44%. We report a case that was initially diagnosed as arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), but extra-cardiac biopsies later on were consistent with sarcoidosis and a final diagnosis of CS was made. The patient received an implantable cardioverter defibrillator (ICD) with a subcutaneous lead array implant for high defibrillation threshold (DFT). Exclusive right ventricular (RV) involvement is atypical for CS. The predominant RV involvement based on echocardiogram, cardiac magnetic resonance imaging (MRI) and right precordial electrocardiogram changes can lead to misdiagnosis as ARVD/C based on the modified task force criteria. Cardiac sarcoidosis is an under-diagnosed disease and the delay in its diagnosis and appropriate therapy can lead to a fatal outcome. High defibrillation thresholds have not been previously reported in patients with CS, but given the natural progression of the disease and the limitations in current pharmacotherapy, implanters who diagnose and treat such patients must be prepared to deal with this issue.

Down to the wire: tricuspid stenosis in the setting of multiple pacing leads.

Tricuspid stenosis in the setting of endocardial pacing leads is a rare entity, attributed to infection or lead malposition. We report the case of a 37-year-old man without these risk factors, who presented with new onset severe tricuspid stenosis in the setting of multiple chronic pacing leads.