Inappropriate Sinus Tachycardia Research Articles

Intracardiac echocardiography guided anatomical ablation of the arcuate ridge for drug refractory inappropriate sinus tachycardia.

Inappropriate sinus tachycardia (IST) is a common condition with frequently not tolerated beta-blockers or ivabradine and a high rate of complication in ablation strategy; we describe an alternative anatomical approach of sinus node (SN) modulation. This retrospective study describes a case series of 6 patients from two centers diagnosed with symptomatic IST undergoing SN ablation. The mean age was 40.6 ± 13.9 years; five of the six patients were female, 100% of patients reported heart palpitations, and 66% reported dizziness, the average heart rate(HR) on a 24-h Holter was 93.2 ± 7.9 bpm. HR during the first stage of a stress test using a standard Bruce protocol was 150 ± 70 bpm, The average HR on 24-h Holter postablation was 75 ± 5.6 bpm, the sinus rate HR during stage 1 of a Bruce protocol exercise stress test was 120 ± 10 bpm. This is the first case series reporting the acute and long-term results of a novel anatomical approach for SN modulation to treat IST targeting the arcuate ridge(AR) under intracardiac echography(ICE) guidance. The novel anatomic ICE-guided catheter ablation approach aimed to identify the earliest activation at the AR with an extension of RF lesions towardits septal region seems effective and safe to modulate the SN in symptomatic patients with IST refractory to medical treatment.

Does dysautonomia contribute to inappropriate sinus tachycardia in patients with post-COVID-19 syndrome?

Abstract Funding Acknowledgements None. Introduction Post-COVID-19 syndrome (PCS) refers to a wide spectrum of health issues experienced by individuals who have previously had COVID-19, starting three months after acute COVID-19 and enduring for a minimum of two months. Approximately 20% of PCS patients encounter inappropriate sinus tachycardia (IST), defined as the mean 24-hour heart rate greater than 90 bpm. IST is often accompanied by symptoms including palpitations and breathlessness that hinder patients in their daily tasks. Previous research has suggested that dysautonomia, a dysfunction in the autonomic nervous system, might underlie most PCS symptoms. Yet, its role in the development of IST within the context of PCS has not been fully investigated. Purpose This retrospective study examines IST prevalence and cardiovascular symptoms in PCS patients. It also assesses cardiac autonomic function through analysing the time and frequency fluctuations between successive heart rates, termed heart rate variability, to investigate the role of dysautonomia in the development of IST in PCS. Methods Patients who continued to experience PCS symptoms 12 weeks after their initial SARS-CoV-2 infection were referred to a multidisciplinary PCS unit at our hospital. Using our electronic patient record system, we identified 685 eligible patients who underwent 24-hour Holter monitoring between March 2020 and February 2023. After excluding patients with various conditions that could affect heart rate, we performed a comparative sub-analysis on 524 patients, dividing them into two age- and gender-matched groups of IST (n=100) and non-IST (n=424). The ECG data extracted from the 24-hour Holter records of these patients were entered into the KUBIOS software for HRV analysis and assessment of sympathetic and parasympathetic activity which could indicate cardiac dysautonomia. Demographic data was analysed using basic descriptive statistics and a chi-square test between the two groups. The normality of each parameter was tested using the Shapiro-Wilk test. Using Mann-Whitney and unpaired t-tests, we statistically analysed the differences between the IST and non-IST groups on the GraphPad Prism software. Results The LF/HF ratio was significantly higher in the IST group (2.78 ± 1.89) compared to the non-IST group (2.15 ± 1.93, p<0.001). The sympathetic nervous system (SNS) index was significantly higher in the IST group (1.50 ± 0.77 versus -0.13 ±0.70, p<0.001), whilst the parasympathetic nervous system (PNS) index was significantly lower in the IST group (-1.75 ± 0.65 versus -0.16 ± 1.61, p<0.001). Conclusions In PCS patients with IST, cardiac dysautonomia leads to a shift in the cardiac sympathovagal balance towards PNS and subsequently increased SNS activity, with a more pronounced effect on the parasympathetic side. Addressing dysautonomia and promoting parasympathetic activity could thereby improve PCS diagnostic and treatment strategies to restore a balanced autonomic regulation of the heart.

Triglicerydes/high-density lipoprotein ratio as a risk factor of post-Covid-19 sinus tachycardia: A retrospective study.

Inappropriate sinus tachycardia (IST) is one of the manifestations of the post-COVID-19 syndrome (PCS), which pathogenesis remains largely unknown. This study aimed to identify potential risk factors for IST in individuals with PCS. The 1349 patients with PCS were included into the study. Clinical examination, 24H Holter ECG, 24H ambulatory blood pressure monitoring and biochemical tests were performed 12-16 weeks after the COVID-19 in all participants. IST was found in 69 (3.5%) individuals. In the clinical assessment IST patients were characterized by a higher age (p < 0.001) and lower prevalence of the diagnosed hypertension (p = 0.012), compared to remaining patients. Biochemical testing showed higher serum triglycerides (1.66 vs. 1.31 pmol/L, p = 0.007) and higher prevalence of a low high-density lipoprotein (HDL) cholesterol (24.6% vs. 15.2%, p = 0.035) in the IST group. Subsequently, the triglicerydes (TG)/HDL ratio, an indicator of insulin resistance, was significantly higher in the IST individuals (3.2 vs. 2.4, p = 0.005). 24H monitoring revealed a significantly higher minimum diastolic, maximum systolic and mean arterial blood pressure values in the IST group (p < 0.001 for all), suggesting a high prevalence of undiagnosed hypertension. A multivariate analysis confirmed the predictive value TG/HDL ratio >3 (OR 2.67, p < 0.001) as predictors of IST development. A receiver operating characteristic curve analysis of the relationship between the TG/HDL ratio and the IST risk showed that the predictive cut-off point for this parameter was 2.46 (area under the ROC curve = 0.600, p = 0.004). Based on these findings, one can conclude that insulin resistance seems to be a risk factor of IST, a common component of PCS.

A novel sinus node-sparing hybrid ablation approach for inappropriate sinus tachycardia

A novel sinus node-sparing hybrid ablation approach for inappropriate sinus tachycardia

How to establish a successful and sustainable surgical atrial fibrillation program: key considerations on the arrhythmia, training and treatment strategies.

Establishing a successful and sustaining atrial fibrillation (AF) program should be current standard of care in cardiac surgery by providing not only sinus rhythm restoration but improving survival significantly. Recognition of AF as a serious cardiac disease impacting a considerable number of patients in terms of stroke, heart failure development and mortality is key when implementing a protocol to identify patients suitable for surgical ablation and a treatment standard according to the underlying pathology. The ablation strategy resulting in the best potential rhythm outcome should be chosen, and the applied access should follow this decision in a way that the optimal lesion set can be executed completely. A thorough follow-up is required to confirm results or make necessary adjustments to the implemented treatment protocol. This should be done in close collaboration with other treatment specialists such as cardiologists, electrophysiologists, primary care physicians, or neurologists. This collaboration might also facilitate an expansion of the program towards stand-alone ablation, ventricular tachycardia ablation, and inappropriate sinus tachycardia ablation.

Extended Use of Ivabradine in Heart Failure with Preserved Ejection Fraction and Inappropriate Sinus Tachycardia

Ivabradine has been used for over a decade in managing chronic coronary syndromes and heart failure (HF) with reducedejection fraction (HFrEF). HF with preserved ejection fraction (HFpEF) accounts for 50% of the total HF cases carrying equalmortality and morbidity risk as HFrEF. Increased heart rate (HR) in such cases has been shown to be associated with poorclinical outcomes. Clinical conditions like inappropriate sinus tachycardia (IST) manifest with elevated HR without anyspecific triggers. Beta-blockers have been the preferred treatment of choice for both HFpEF and IST but are often ineffective orpresent with side effects due to their negative ionotropic effects. Ivabradine, through its inhibitory action on funny current(Ifc), reduces HR without altering the inotropic mechanism. Few case reports and small case series have documented itsextended use and efficacy in reducing HR in these cardiac conditions. In this article, we present two cases who needed HRcontrol, one with HFpEF and another case of IST syndrome. Ivabradine was successfully used in both these cases to controlthe elevated HR.

The Impact of Long COVID-19 on the Cardiovascular System.

Long coronavirus disease (COVID) is the development or persistence of symptoms after an acute SARS-CoV-2 (COVID-19) infection. Fewer patients are developing acute COVID-19 infections, but patients with long COVID continue to have alarming long-term sequelae. Many cardiac magnetic resonance imaging studies show significant changes in cardiac structure after a COVID-19 infection, suggestive of an increased burden of many cardiovascular diseases, notably myocarditis. The pathophysiology of COVID-19 requires viral binding to angiotensin-converting enzyme 2 protein receptors throughout the body, which are upregulated by inflammation. Consequently, the numerous preexisting conditions that worsen or prolong inflammation enhance this binding and have differing effects on patients based on their unique immune systems. These pathophysiological changes drive long COVID cardiac sequelae such as inappropriate sinus tachycardia, postural orthostatic tachycardia, and other types of orthostatic intolerance. Increased screening for long COVID and low-risk interventions such as exercise regimens could alleviate the suffering endured by patients with long COVID. Many studies such as the Researching COVID to Enhance Recovery Initiative (RECOVER) trials at the National Institutes of Health are exploring potential treatments for long COVID patients.

Surgery for Cardiac Arrhythmias: Past, Present, Future.

There is a rich history of surgery for cardiac arrhythmias, spanning from atrial fibrillation and Wolff-Parkinson-White syndrome to inappropriate sinus tachycardia and ventricular tachycardia. This review describes the history of these operations, their evolution over time, and the current state of practice. We devote considerable time to the discussion of atrial fibrillation, the most common cardiac arrhythmia addressed by surgeons. We discuss ablation of atrial fibrillation as a stand-alone operation and as a concomitant operation performed at the time of cardiac surgery. We also discuss the emergence of newer procedures to address atrial fibrillation in the past decade, such as the convergent procedure and totally thoracoscopic ablation, and their outcomes relative to historic approaches such as the Cox maze procedure.

Pericarditis prophylactic therapy after sinus node–sparing hybrid ablation for inappropriate sinus tachycardia/postural orthostatic sinus tachycardia

Pericarditis is the most common complication following hybrid sinus node-sparing ablation for inappropriate sinus tachycardia (IST)/postural orthostatic tachycardia syndrome (POTS). The study sought to evaluate the association of prophylaxis therapy on the risk of symptomatic pericarditis following hybrid IST/POTS ablation. All consecutive patients undergoing to hybrid ablation of symptomatic IST/POTS refractory or intolerant to drugs were retrospectively analyzed. Pharmacological prophylaxis therapy was based on acetylsalicylic acid and colchicine started on the day of the ablation and continued for at least 3 months. The primary endpoint was occurrence of symptomatic pericarditis. The secondary endpoint was occurrence of pericarditis-related complications, including the following: duration of pericarditis >3 months, hospitalization for pericarditis, postpericardiectomy pleuro-pericarditis, and pericardiectomy. A total of 220 patients undergone to hybrid IST/POTS ablation were included and 44 (20%) underwent prophylaxis therapy. Pericarditis occurred in 101 (45.9%) patients, with 97 (96%) in the first 5 days. At survival analysis, prophylaxis was associated with higher rate of freedom from pericarditis (81.9% vs 47.2%, log-rank P < .001). Pericarditis-related complications were low, occurring in 7 (3.2%) patients. There was no difference in pericarditis-related complications between the patients who underwent prophylaxis therapy and patients who did not. At Cox multivariate analysis, predictors of pericarditis were IST (vs POTS) (hazard ratio 0.61, 95% confidence interval0.39-0.99, P = .04) and prophylaxis therapy (hazard ratio 0.27, 95% confidence interval 0.13-0.55, P < .001). In a large cohort of patients undergoing hybrid ablation for IST/POTS, a prophylaxis therapy with acetylsalicylic acid and colchicine was associated with a lower rate of symptomatic pericarditis.

Cardiovascular autonomic dysfunction in post-COVID-19 syndrome: a major health-care burden.

Cardiovascular autonomic dysfunction (CVAD) is a malfunction of the cardiovascular system caused by deranged autonomic control of circulatory homeostasis. CVAD is an important component of post-COVID-19 syndrome, also termed long COVID, and might affect one-third of highly symptomatic patients with COVID-19. The effects of CVAD can be seen at both the whole-body level, with impairment of heart rate and blood pressure control, and in specific body regions, typically manifesting as microvascular dysfunction. Many severely affected patients with long COVID meet the diagnostic criteria for two common presentations of CVAD: postural orthostatic tachycardia syndrome and inappropriate sinus tachycardia. CVAD can also manifest as disorders associated with hypotension, such as orthostatic or postprandial hypotension, and recurrent reflex syncope. Advances in research, accelerated by the COVID-19 pandemic, have identified new potential pathophysiological mechanisms, diagnostic methods and therapeutic targets in CVAD. For clinicians who daily see patients with CVAD, knowledge of its symptomatology, detection and appropriate management is more important than ever. In this Review, we define CVAD and its major forms that are encountered in post-COVID-19 syndrome, describe possible CVAD aetiologies, and discuss how CVAD, as a component of post-COVID-19 syndrome, can be diagnosed and managed. Moreover, we outline directions for future research to discover more efficient ways to cope with this prevalent and long-lasting condition.

Successful Three-Dimensional Mapping-Guided Sinus Node Modification for Drug-Refractory Inappropriate Sinus Tachycardia after Circumferential Pulmonary Vein Isolation.

Successful Three-Dimensional Mapping-Guided Sinus Node Modification for Drug-Refractory Inappropriate Sinus Tachycardia after Circumferential Pulmonary Vein Isolation.

A gain-of-function HCN4 mutant in the HCN domain is responsible for inappropriate sinus tachycardia in a Spanish family.

In a family with inappropriate sinus tachycardia (IST), we identified a mutation (p.V240M) of the hyperpolarization-activated cyclic nucleotide-gated type 4 (HCN4) channel, which contributes to the pacemaker current (If) in human sinoatrial node cells. Here, we clinically study fifteen family members and functionally analyze the p.V240M variant. Macroscopic (IHCN4) and single-channel currents were recorded using patch-clamp in cells expressing human native (WT) and/or p.V240M HCN4 channels. All p.V240M mutation carriers exhibited IST that was accompanied by cardiomyopathy in adults. IHCN4 generated by p.V240M channels either alone or in combination with WT was significantly greater than that generated by WT channels alone. The variant, which lies in the N-terminal HCN domain, increased the single-channel conductance and opening frequency and probability of HCN4 channels. Conversely, it did not modify the channel sensitivity for cAMP and ivabradine or the level of expression at the membrane. Treatment with ivabradine based on functional data reversed the IST and the cardiomyopathy of the carriers. In computer simulations, the p.V240M gain-of-function variant increases If and beating rate and thus explains the IST of the carriers. The results demonstrate the importance of the unique HCN domain in HCN4, which stabilizes the channels in the closed state.

Cardioneuroablation for reflex asystolic syncope: Mid-term safety, efficacy, and patient’s acceptance

BackgroundCardioneuroablation (CNA) is a promising therapy for reflex asystolic syncope; however, convincing data on the mid-term safety and efficacy of this procedure are lacking. ObjectiveThe purpose of this study was to assess the mid-term safety, efficacy, and patient acceptance of CNA. MethodsThis prospective observational single-center study included 115 consecutive patients (mean age 39 ± 13 years; 58% female) treated between 2016 and 2022 who completed at least 1-year follow-up. ResultsNo significant procedure-related acute complications occurred. During median follow-up of 28 months (range 12–75), 95 (83%) remained free from syncope. Of the 20 patients (17%) with syncope recurrence, syncope burden decreased from a mean 17 (median 6.5) to 3.75 (median 2.5) episodes (P = .015). In 9 of 10 patients, pacing system removal was possible. Repeated CNA was needed in 3 patients (3%), whereas pacemaker implantation was performed in 5 (4%). The most frequent mid-term complication of CNA was sinus rhythm acceleration (from 60 ± 14 bpm to 90 ± 16 bpm; P <.0001), which was symptomatic in 31 patients (27%); 8 patients (7%) required chronic beta-blocker and/or ivabradine. Sinus node modification was necessary in 1 patient. Other complaints included dyspnea, chronic chest pain, and decreased exercise capacity, which were mild and reported by 16 patients (14%). Patient acceptance of CNA was very high: 96% stated that it was worth undergoing the procedure. ConclusionsMid-term efficacy of CNA exceeds 80%, and acute complications are absent. The most frequent mid-term chronic complication is inappropriate sinus tachycardia, which in 7% required chronic treatment. The procedure is well accepted by patients.

Abstract 14607: Management of Inappropriate Sinus Tachycardia: A Promising Breakthrough

Introduction: Inappropriate Sinus Tachycardia (IST) is a cardiac dysautonomia with limited treatment options. This case highlights the effectiveness of a novel sinus node-sparing hybrid surgical ablation (SNSHA) for IST. Objective: To describe a novel hybrid surgical approach for management of IST. Case Description: A 43 y/o female presented with history of palpitations/tachycardia for 5 years. A comprehensive evaluation directed towards the diagnosis of IST with resting heart rates (HR) above 100 bpm and HR changes greater than 30% with minimal exertion. A trial of ivabradine &amp; beta blockers along with lifestyle modifications offered limited relief. Patient was offered the novel SNSHA after a shared decision-making process. Methods: The SNSHA is a minimally invasive procedure performed by a CT surgeon in conjunction with an electrophysiologist involving thoracoscopic epicardial ablation of the sympathetic connections from the SVC to the IVC. The thoracoscopic approach allows for safeguarding of the phrenic nerve and sinus node followed by endocardial ablation along the lateral wall. Results: Intraprocedural pre and post ablation electroanatomic map (EAM) and electrogram (EGM) demonstrated an immediate drop in HR as shown in the Figure 1(a-d). An ILR was implanted during the procedure. On 45-day post-op visit, the patient experienced significant symptom relief and improvement in her HR as well as HR variability on ILR as shown in Figure 1(e). Conclusion: SNSHA offers a reasonable treatment option for patients with drug resistant IST. This procedure provided symptom alleviation and improvement in HR without increasing the risk of complications in comparison to sinus node modification ablation, which has previously been shown to be associated with higher incidence of pacemaker implantation.

Abstract 19064: Sex Specific Gene Profile in Canine Sinoatrial Node

Introduction: Biological sex plays an important role in cardiac function and occurrence of cardiac arrhythmias. Clinical reports show that adult females have faster resting and intrinsic heart rate (HR) while males have faster HR peak and larger HR reserve. Furthermore, inappropriate sinus tachycardia primarily occurs in females, suggesting sex-specific function and/or structure of the sinoatrial node (SAN). The aim of the study is to define sex-specific molecular features of the SAN complex. Methods: mRNA was isolated from SAN pacemaker tissue of healthy adult canines (male=4, female=4). Differential RNA expression patterns of &gt;400 genes, including fibrosis, inflammation, and metabolism markers were quantified with nCounter Nanostring fibrosis panel. Quantitative PCR was used to compare mRNAs of key ion channels related to SAN pacemaker function. Results: Nanostring panel revealed sex-specific and SAN-specific gene profiles of inflammation and fibrotic markers with multiple mRNAs higher in male (e.g. NLRP3, CD86, COL3A1, TGFB1) and several higher in females (e.g. MARCOL, IL20RB). mRNAs responsible for SAN pacemaking e.g. HCN1, HCN4, Cav1.3, and GIRK4 are higher expressed in female SAN. Sex-specific retrospective analysis of published gene profiles from non-failing human hearts showed a similar pattern to canine with HCN1, HCN4, Cav1.3 expression higher in female SAN. Conclusions: The study revealed significantly different gene expressions of fibrosis, inflammation, and pacemaking in male vs female SAN. The higher expression of HCN1/4 and Cav1.3 may explain the faster intrinsic sinus rhythm and susceptibility to SAN arrhythmias in females. The elevated fibrosis and inflammation genes in male SAN may suggest higher vulnerability to fibrotic remodeling during cardiac disease.

Abstract 12838: Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-Like Episodes (MELAS) and m.3243A&gt;G Mutations Have Higher Prevalence of Wolff-Parkinson-White Syndrome

Background: Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is one of the most common mitochondrial disorders. Cardiovascular involvement has been reported in up to 30% of MELAS patients with varying clinical presentations from non-specific cardiogenic abnormalities to conduction abnormalities, cardiomyopathies, heart failure, fatal arrhythmias and cardiac death. Although conduction defects are a known complication, the frequency of Wolff-Parkinson-White (WPW) Syndrome among MELAS patients and mutations associated with MELAS is uncertain, and their association with cardiomyopathy and treatment outcomes have rarely been reported. Methods: A retrospective chart review of 50 MELAS patients from January 2007 to December 2022 from the Neuroscience Institute at University of Texas Houston was conducted. Medical histories, genetic testing, electrocardiograms, echocardiograms, and electrophysiology studies were reviewed. Results: 43 patients were included (mean age 23.8, median age 18.5, range 2-58). Eight of 43 patients with MELAS (20 %), inclusive of one of 3 patients with m.4317A&gt;G (33.3%) and seven of 40 patients with m.3243A&gt;G variants had electrocardiographic findings consistent with WPW. Other conduction abnormalities were noted in ten of 20 patients (50%) with m.3243A&gt;G with neurological involvement and six of 20 patients (30%) with m.3243A&gt;G mutation without strokes. Four patients required electrophysiology studies with ablation (mean age 8.5, range 7-10), one for inappropriate sinus tachycardia resistant to several medications, and three patients with WPW syndrome all of whom required repeat ablations. Conduction abnormalities had a positive correlation with higher heteroplasmy levels (mean 35 % vs 51%, 95% CI -30.2 to -2.88, p=0.019). Six patients with MELAS had cardiomyopathy of varying severity which were all associated with conduction abnormalities, including two patients with WPW syndrome (p=0.014). Conclusion: The prevalence of WPW in patients with MELAS syndrome and the m.3243A&gt;G variant appears much higher than in the normal population and may require multiple electrophysiology studies ablations to treat. Routine cardiology screening is recommended for early detection.

ECG changes and post-COVID arrhythmia incidence in patients with acute COVID-19 infection

Objective: During the COVID-19 pandemic, many patients have experienced cardiovascular complications, including a variety of arrhythmias. The aim of our study was to evaluate the acute electrocardiography (ECG) changes and post-COVID arrhythmia incidence in patients with acute COVID-19 infection. Patients and Methods: One hundred hospitalized COVID-19 patients were consecutively included. Patients were divided into two groups according to their troponin levels. Thirty subjects were included as controls. All patients underwent daily 12-lead ECG during hospitalization and were followed up for at least 12 months, by performing ECG and ambulatory ECG monitoring and questioning their symptoms at 3-month intervals. Results: Thirty-one patients had elevated high sensitive cardiac troponin I (hs-cTnI). These patients had significantly longer QT dispersion compared to COVID-19 patients with normal troponin levels and controls. Regardless of troponin elevation, COVID-19 patients had significantly longer Tp-e intervals and P wave (PW) durations compared to controls. During the follow-up period; palpitation, beta-blocker usage, and inappropriate sinus tachycardia were more common in the COVID-19 group with hs-cTnI than control group. Conclusion: Our study did not find any relation between serum fibroblast growth factor-21 levels and carotid intima-media thickness. Further researches with wider study population are needed.

Electrolyte Disturbances in Post-Acute Myocardial Infarction Arrhythmias

Introduction: Electrolyte disturbances are an important predictor for the prediction of arrhythmias after acute myocardial infarction (AMI). This study investigated the prevalence and relationship of various electrolyte disorders with common types of arrhythmias after AMI. Material and Methods: This cross-sectional study was performed on 153 patients with arrhythmias after AMI. Patient's demographic variables were collected from patient files and required laboratory findings including serum potassium (K), calcium (Ca), and magnesium (Mg) were measured in the first 12 hours after AMI. Any type of serum electrolyte disturbance was defined as a value above or below the reference values. The incidence of any arrhythmias during hospitalization was determined for each group of electrolyte disturbances using chi-square test and fisher exact test. Logistic regression was used in order to evaluate the risk of any arrhythmias in association with serum electrolyte levels. Results: In this study, the most common arrhythmias after AMI were inappropriate sinus tachycardia (IST) (43.1%), sinus bradycardia (33.3%), and premature ventricular contractions (30.7%), respectively. Majority of subjects had normal levels of serum K and Ca levels (P=0.001). Also, most of the patients with ventricular tachycardia and SB were in the range of normokalemia (P=0.015) and normocalcemia (P=0.035), respectively. The risk of IST increases by 1.911 times for every 0.648 units increase in K (P=0.033). However, no significant relationship was seen between other electrolyte disturbances and any other post-AMI arrhythmias. Conclusion: Occurrence of IST increases with higher levels of K. lack of association between other serum electrolytes levels and arrhythmias indicate the importance of further studies in this regard with consideration of other affecting factors.

Sex Related Differences in Electrocardiography.

Since its implementation into the clinical medicine by Willem Einthoven electrocardiography had become one of crucial diagnostic method in cardiology. In spite of this fact effects of gender differences on parameters of electrocardiographic recordings started to be studied only recently. Sex related differences in physiological ECG are only minimal in childhood but there are developing during adolescence reflecting rapidly evolving differences particularly in hormonal secretion and activity of an autonomic nervous system. The heart rate is approximately 7 % higher in women than in men, PQ and QRS intervals are longer in men while QT interval is longer in women. The ST segment in females is flatter but generally the sex-related differences in ST-T waveform patterns are relatively very small with higher level of ST segment and taller T wave in men. The effects of sex-related differences, including sex hormones, on cardiac cell injury and death and their influence in determining rhythmogenesis and action potential configuration and conduction play an important role in clinics. Women have a higher prevalence of sick sinus syndrome, inappropriate sinus tachycardia, atrioventricular nodal reentry tachycardia, idiopathic right ventricular tachycardia, and arrhythmic events in the long QT syndrome. In contrast, men have a higher prevalence of atrioventricular block, carotid sinus syndrome, atrial fibrillation, supraventricular tachycardia due to accessory pathways, Wolff-Parkinson-White syndrome, reentrant ventricular tachycardia, ventricular fibrillation and sudden death, and the Brugada syndrome.

Cardiovascular Considerations in the Management of People With Suspected Long COVID.

Approximately 15% of adult Canadians with SARS-CoV-2 infection develop lingering symptoms beyond 12 weeks after acute infection, known as post-COVID condition or long COVID. Some of the commonly reported long COVID cardiovascular symptoms include fatigue, shortness of breath, chest pain, and palpitations. Suspected long-term cardiovascular complications of SARS-CoV-2 infection might present as a constellation of symptoms that can be challenging for clinicians to diagnose and treat. When assessing patients with these symptoms, clinicians need to keep in mind myalgic encephalomyelitis/chronic fatigue syndrome, postexertional malaise and postexertional symptom exacerbation, dysautonomia with cardiac manifestations such as inappropriate sinus tachycardia, and postural orthostatic tachycardia syndrome, and occasionally mast cell activation syndrome. In this review we summarize the globally evolving evidence around management of cardiac sequelae of long COVID. In addition, we include a Canadian perspective, consisting of a panel of expert opinions from people with lived experience and experienced clinicians across Canada who have been involved in management of long COVID. The objective of this review is to offer some practical guidance to cardiologists and generalist clinicians regarding diagnostic and treatment approaches for adult patients with suspected long COVID who continue to experience unexplained cardiac symptoms.