The cost of non-response to cardiac resynchronization therapy: characterizing heart failure events following cardiac resynchronization therapy.

AIMS: The aim of this study is to quantify healthcare resource utilization among non-responders to cardiac resynchronization therapy (CRT-NR) by heart failure (HF) events and influence of comorbidities. METHODS AND RESULTS: The ADVANCE CRT registry (2013-2015) prospectively identified responders/CRT-NRs 6 months post-implant using the clinical composite score. Heart failure event rates and associated cost, both overall and separated for inpatient hospitalizations, office visits, emergency room visits, and observational stays, were quantified. Costs of events were imputed from payments for similar real-world encounters in subjects with CRT-D/P devices in the MarketScan™ commercial and Medicare Supplemental insurance claims databases. Effects of patient demographics and comorbidities on event rates and cost were evaluated. Of 879 US patients (age 69 ± 11 years, 29% female, ischaemic disease 52%), 310 (35%) were CRT-NR. Among CRT-NRs vs. responders, more patients developed HF (41% vs. 11%, P < 0.001), HF event rate was higher (67.0 ± 21.7 vs. 11.4 ± 3.7/100 pt-year, P < 0.001), and HF readmission within 30 days was more common [hazard ratio 7.06, 95% confidence interval (2.1-43.7)]. Inpatient hospitalization was the most common and most expensive event type in CRT-NR. Comorbid HF was increased by diabetes, hypertension, and pulmonary disorders. Over 2 years, compared to CRT responders, each CRT-NR resulted in excess cost of $6388 ($3859-$10 483) to Medicare (P = 0.015) or $10 197 ($6161-$17 394) to private insurances (P = 0.014). CONCLUSION: Healthcare expenditures associated with contemporary CRT non-response management are among the highest for any HF patient group. This illustrates an unmet need for interventions to improve HF outcomes and reduce costs among some CRT recipients.

Risk of Silent Myocardial Infarction in Prediabetic Patients: A Case-Control Study in a Veteran Population.

OBJECTIVES: In the management of cardiovascular disease, it is important to identify patients at risk early on, to provide interventions to prevent the disease and its complications. The goal of our study was to investigate the association between glucose levels and silent myocardial infarction (SMI) among patients, who consisted of veterans within the Veterans Affairs clinical system. METHODS: Among the group of patients with an initially normal electrocardiogram, a cohort of patients with a subsequent diagnosis of SMI was selected as the case cohort, whereas 4 patients for each study subject, without evidence of coronary artery disease and normal electrocardiogram within the previous 6 months, were identified and constituted the control cohort. We conducted an adjusted logistic regression model using the stepwise function to assess the association between glucose level and SMI. RESULTS: Of the 540 patients included in the study, 108 (20.0%) with an SMI diagnosis made up the case cohort. We observed that as compared with those who had normal levels of glucose, those who were prediabetic were 3.99 times as likely (95% confidence interval 1.48-12.85) to have SMI, whereas the diabetic patients were 3.80 times as likely (95% confidence interval 1.39-12.38) to experience SMI. CONCLUSIONS: SMIs have been shown to be predictive of subsequent cardiovascular events, including another MI and death, and that indicates the importance of identifying a group at high risk for a SMI. As such, our findings could be extremely beneficial for targeted intervention toward prediabetics and to improve health outcomes in the entire population.

Atrio-ventricular junction: Can precision electrocardiology bridge cell and electrocardiogram?

The Atrio Ventricular Junction (AVJ) is a well-defined anatomical region of the heart the physiology of which, despite extensive and numerous observations, it is not fully understood. The aim of this review is to present an up to date summary of old and more recent findings on histology, cellular electrophysiology and intracellular connectivity of this region. We have also attempted to relate our increasing understanding of nodal pathophysiology to the interpretation of the electrocardiographic (ECG) manifestations of AVN behavior. Bridging cellular observations with ECG analysis in a process we call "Precision Electrocardiology" renders this tool far more sensitive and clinically useful than the pattern analysis too often employed in the ECG interpretation.

Reliability of Electronic Health Records in Recording Veterans' Tobacco Use Status.

INTRODUCTION: The prevalence of tobacco use in the Veteran population and among Veterans Health Administration patients remains high, resulting in significant health and economic consequences. This problem has generated many tobacco research studies and clinical interventions, which often rely upon tobacco use status data previously recorded in electronic health records (EHR). Therefore, the consistency and reliability of these data are critical. The Veterans Health Administration uses an extensive EHR system where tobacco use status can be documented either as free text (FT) or as health factors (HF). The current literature assessing the reliability of HF and FT data is limited. This analysis evaluated the agreement between HF and FT tobacco use status data. MATERIALS AND METHODS: This retrospective study included Veterans who underwent coronary revascularization and had tobacco use statuses recorded as both HF and FT. These statuses were categorized as "Current," "Former," or "Never." The closest recorded status to the index date (date of revascularization procedure) for each subject in both datasets was chosen, and Cohen's kappa statistic was calculated to measure the agreement between HF and FT. Implausible tobacco use status changes within each dataset were quantified to assess trustworthiness. Agreement between HF and FT data was first measured for all subjects (n = 1,095), which included those who had implausible status changes in either dataset and then measured again for subjects (n = 770) without any implausible status changes in either dataset. This study was exempt from institutional review board review. RESULTS: Overall, 14.3% and 17.7% of all subjects had implausible tobacco use status changes in HF and FT data, respectively. For all subjects (n = 1,095), including those with implausible data, there was "moderate" agreement between HF and FT data (kappa = 0.49; 95% CI, 0.44-0.53). For subjects without implausible data (n = 770), the strength of agreement between HF and FT data was "good" (kappa = 0.64; 95% CI, 0.59-0.69). CONCLUSIONS: Agreement between HF and FT data that document the tobacco use statuses of Veterans varied because of implausible data. HF data had fewer implausible tobacco use statuses, but FT data were recorded more frequently. Although HF and FT data can be reasonably relied upon to determine the tobacco use statuses of Veterans, researchers and clinicians must be aware of implausible data and consider methods to overcome this limitation. Future studies should investigate the ways of improving the consistency of EHR documentation by health care providers and benchmark HF and FT data against a gold standard like biochemical verification to determine accuracy.

Ventricular Fibrillation in an Afebrile COVID-19 Patient Presenting With Transient Type-I Brugada Pattern.

COVID-19 has been associated with an increased risk of both atrial and ventricular arrhythmias. Brugada syndrome (BrS), an inherited sodium channelopathy presenting with a characteristic ECG morphology, confers a baseline risk of ventricular arrhythmias such as ventricular fibrillation (VF), especially during febrile illnesses. However, mimics of BrS, termed Brugada phenocopies (BrP), have been noted in association with fever, electrolyte abnormalities, and toxidromes outside of viral illness. Such presentations manifest the same ECG pattern, the type-I Brugada pattern (type-I BP). Thus, the acute stage of an illness such as COVID-19, when accompanied by a first-time presentation of type-I BP, may not result in a certain diagnosis of BrS versus BrP. Thus, expert recommendations are to anticipate arrhythmia regardless of the presumed diagnosis. Here we demonstrate the importance of these guidelines and a novel report of VF in the setting of a transient type-I BP in afebrile COVID-19. We discuss the potential factors which may have triggered VF, the presentation of isolated "coved" ST elevation in V1, and the difficulty of BrS versus BrP diagnosis in acute illness. In summary, a SARS-CoV-2 positive 65-year-old male without significant cardiac history for BrS presented with type-I BP after two days of shortness of breath. Hypoxemia, hyperkalemia, hyperglycemia, elevated inflammatory markers, and acute kidney injury were present. After treatment, his ECG normalized; however, aborted VF occurred days later while afebrile and normokalemic. Follow-up ECG again revealed a type-I BP, which also became more apparent during an episode of bradycardia, a classic finding in BrS. This case suggests that there is room for larger studies to determine the prevalence and outcomes when type-I BP presents in acute COVID-19. When possible, genetic data should be obtained to confirm BrS, a notable limitation in our case. Regardless, it corroborates guideline-directed clinical management, with heightened vigilance for arrhythmia in such patients until full recovery.

Unknown QRS Morphology Change at Peak Exercise: To Stop or to Continue?

Electrocardiogram changes during stress tests are well standardized and understood. We present and explain a reversible QRS morphology change at peak exercise previously unreported. (Level of Difficulty: Intermediate.).

Interpretation of Typical and Atypical Atrial Flutters by Precision Electrocardiology Based on Intracardiac Recording.

Atrial flutter is a term encompassing multiple clinical entities. Clinical manifestations of these arrhythmias range from typical isthmus-dependent flutter to post-ablation microreentries. Twelve-lead electrocardiogram (ECG) is a diagnostic tool in typical flutter, but it is often unable to clearly localize atrial flutters maintained by more complex reentrant circuits. Electrophysiology study and mapping are able to characterize in fine details all the components of the circuit and determine their electrophysiological properties. Combining these 2 techniques can greatly help in understanding the vectors determining the ECG morphology of the flutter waveforms, increasing the diagnostic usefulness of this tool.

Relationships Between Atrial Flutter and Fibrillation: The Border Zone.

Atrial flutter and fibrillation have been inextricably linked in the study of electrophysiology. With astute clinical observation, advanced diagnostic equipment in the Electrophysiology Laboratory, and thoughtful study of animal models, the mechanism and inter-relationship between the 2 conditions have been elucidated and will be reviewed in this article. Though diagnosis and management of these conditions have many similarities, the mechanisms by which they develop and persist are quite unique.

Typical Atrial Flutter Mapping and Ablation.

Isthmus-dependent flutter represents a defeated arrhythmia. Possibly one of the most outstanding successes in terms of understanding the mechanism behind it has led to an effective, relatively simple, and safe targeted therapy. Technology, fulfilling a number of the clinical electrophysiologist's dreams, has linked diagnosis and therapy in computerized systems showing real-time imagines of the right atrium, the arrhythmia circuit, and the ablation target. The entire history of clinical electrophysiology is contained in its path and atrial flutter needs to be regarded with immense respect for a large amount of knowledge that its study always engenders."

The History of Atrial Flutter Electrophysiology, from Entrainment to Ablation: A 100-Year Experience in the Precision Electrocardiology.

Atrial flutter (AFL) is a regular supraventricular reentrant tachycardia generating a continuous fluttering of the baseline electrocardiography (ECG) at a rate of 250 to 300 beats per minute. AFL is classified based on the involvement of the cavo-tricuspid isthmus in the circuit. The "isthmic" (or type 1) AFL develops entirely in the right atrium; this circuit is commonly activated in a counter-clockwise direction, generating the common sawtooth ECG morphology in the inferior leads (slow descendent-fast ascendent). AFL can be nonisthmus dependent (type 2), often presenting with faster atrial rate and most commonly a left atrial location.

Electrocardiographic Approach to Atrial Flutter: Classifications and Differential Diagnosis.

Atrial flutter (AFL) is a macro-reentrant arrhythmia characterized, in a 12 lead ECG, by the continuous oscillation of the isoelectric line in at least one lead. In the typical form of AFL, the oscillation is most obvious in the inferior leads, due to a macro-reentrant circuit localized in the right atrium, with the cavo-tricuspid isthmus as a critical zone.: This circuit can be activated in a counterclockwise or clockwise direction generating in II, III, and aVF leads, respectively, a slow descending/fast ascending F wave pattern (common form of typical AFL) or a balanced ascending/descending waveform (uncommon form of typical AFL). Atypical AFLs (scar-related) do not include the CTI in the circuit and show an extremely variable circuit location and ECG morphology.

Pathophysiology of Atypical Atrial Flutters.

Atypical atrial flutters are complex supraventricular arrhythmias that share different pathophysiological aspects in common. In most cases, the arrhythmogenic substrate is essentially embodied by slow-conducting areas eliciting re-entrant circuits. Although atrial scarring seems to promote slow conduction, these arrhythmias may occur even in the absence of structural heart disease. To set out the ablation strategy in this setting, three-dimensional mapping systems have proved invaluable over the last decades, helping the cardiac electrophysiologist understand the electrophysiological complexity of these circuits and easily identify critical areas amenable to effective catheter ablation.

Mapping and Ablation of Atypical Atrial Flutters.

Atypical atrial flutters are complex, hard-to-manage atrial arrhythmias. Catheter ablation has progressively emerged as a successful treatment option with a remarkable role played by irrigated-tip catheters and 3D electroanatomic mapping systems. However, despite the improvement of these technologies, the ablation results may be still suboptimal due to the progressive atrial substrate modification occurring in diseased hearts. Hence, a patient-tailored approach is required to improve the long-term success rate in this scenario, aiming at achieving specific procedure end points and detecting any potential arrhythmogenic substrate in each patient.

Atypical Cases of Typical Atrial Flutter? A Case Study.

Ablation of typical atrial flutter has a high safety and efficacy profile, but hidden pitfalls may be encountered. In some cases, a longer cycle length with isoelectric lines is associated with a different or more complex arrhythmogenic substrate, which may be missed if conduction block of the cavotricuspid isthmus is performed in the absence of the clinical arrhythmia. Prior surgery may have consistently modified the atrial substrate and complex or multiple arrhythmias associated with an isthmus-dependent circuit can be encountered. In these cases, electroanatomic mapping is useful to guide the procedure and plan an appropriate ablation strategy.

Change of Paradigm in the Management of Patients with Accessory Pathways over the Last Forty Years: Wolff-Parkinson-White Syndrome as an Electrophysiological Marvel at Risk of Extinction.

Over the last decades, the approach to the Wolff-Parkinson-White syndrome, as well as its treatment, has substantially changed, leading to improvement in the prognosis and quality of life of these patients. From the first diagnostic electrophysiologic studies to the most recent evaluations, important data on pathophysiologic and clinical aspects have been gathered, and this learning journey is still not concluded. This body of knowledge is a fundamental part of any cardiologists' armamentarium despite the fact that this syndrome is rarely observed in adult patients.

Arrhythmias with Bystander Accessory Pathways.

An accessory pathway (AP) could manifest its presence exclusively during an orthodromic supraventricular tachycardia or with preexcitation during sinus rhythm (SR). The manifestations of the presence of an AP depend on its ability to conduct antegradely from atrium (A) to ventricle (V), retrogradely (V to A), or both. AP retrograde conduction is necessary to establish an atrioventricular reentrant tachycardia circuit. If an AP can only conduct antegradely, it will function as a bystander AV connection during independent arrhythmias. The correct diagnosis of this condition is very important, as it will determine the immediate and long-term management.

Clinical Approach to Symptomatic and Asymptomatic Patients with Ventricular Pre-excitation.

Despite extensive knowledge of the physiopathology of ventricular pre-excitation, management of asymptomatic patients with this condition remains controversial.

Ventricular Preexcitation: An Anomalous Wave Interfering with the Ordered Ventricular Activation.

Ventricular preexcitation is a depolarization of the ventricles that occurs before the conventional sequence, and the electrocardiogram is the specific test for diagnosis. A Kent bundle is the paradigm of ventricular preexcitation, and it is associated with short PR, wide QRS and delta wave. This finding is not always very evident, as it can have different degrees of pre-eccitazione; therefore great diagnostic care must be taken in this field. If not properly identified, the pattern of ventricular preexcitation may lead to an incorrect diagnosis. The methodology of precision electrocardiology is able to confront all these aspects.

Accessory Pathway-Mediated Tachycardias: Precision Electrocardiology Through Standard and Advanced Electrocardiogram Recording Techniques.

An accessory pathway (AP) can be apparent during sinus rhythm if it depolarizes part of the ventricles ahead of the normal wave front from the conduction system. An AP can generate an anatomic circuit able to sustain a macroreentrant atrioventricular reentrant tachycardia. This arrhythmia can engage the normal conducting system in an antegrade direction or retrogradely, generating, respectively, a narrow or a wide complex tachycardia. The combined use of a standard electrocardiogram and an esophageal recording-pacing can be particularly useful in the first approach to patients with Wolff-Parkinson-White syndrome, further stratifying patients requiring electrophysiology study and transcatheter ablation.

Arrhythmias Involving Variants of Accessory Pathways.

In some cases, atrioventricular reentrant arrhythmias are sustained by accessory pathways with peculiar electrophysiologic properties related to their specific anatomy. Most of these fibers, which may be responsible for variants of ventricular preexcitation, show decremental conduction properties due to a nodelike aspect or a peculiar tortuous anatomic route across the atrioventricular groove. Moreover, some fibers do not actively sustain any reentrant circuit and can be only involved as bystander in other arrhythmias. Although rare, these accessory pathway variants should be properly diagnosed using noninvasive and invasive methods to guide catheter ablation procedures when needed.