The incidence and clinical features of anticancer therapy induced atrial fibrillation in patients with breast cancer without previously established cardiac disorder

Background/Introduction

Anthracyclines (ATC), alkylating (AAg) and anti-microtubule (AMA) agents are established chemotherapeutics in management of breast cancer. Both agents might reveal cardiotoxicity, as well as cancer treatment–induced-arrhythmias at varying established rates and by complex mechanisms. Atrial fibrillation (AF) is one of the debilitating dysrhythmias encountered throughout the cancer treatment with a significant impact on mortality and morbidity.

Purpose

To reveal the incidence and clinical features of new onset AF episodes detected in breast cancer patients using different conventional chemotherapeutic regiments.

Methods

All consecutive adult women diagnosed with breast-carcinoma and getting the first chemotherapy treatment with either ATC+AMA or AAg+AMA were prospectively evaluated for 6 months. Clinical, echocardiographic and ECG parameters (QTc by Bazett's-formula) were obtained and evaluated on baseline, first month and 6th month. Patients with Structural/coronary-heart-disease, complete-bundle-branch-block, non-sinus-rhythms and acute-coronary-syndrome in follow-up were excluded. “AF” is diagnosed on 12-lead-ECG or at least 30s of AF on Rhythm/Holter monitoring indicated by palpitation symptoms.

Results

Of 192 cases, 140 women ([mean±SD] age, 64±12, [range] 36–86 years) were enrolled for analysis. 76 patients received the AAg (cyclophosphamide) and 64 received ATC (daunorubicin) in addition to AMA (docetaxel). Mean follow up time was 4.2±2 months (Min–Max 1–6 months). Incident AF was diagnosed in 38 patients (27.1%) at the end of the 6 month follow up. The clinical findings are presented in picture-1. In patients receiving ATC treatment, incident AF was significantly more common (35.9% vs 19.7, p=0,032) and mostly observed in the first month of ATC-chemotherapy compared with AAg-regiments respectively (69% vs 33% of AF events occurred in first month, P<0,001). Incident AF patients were significantly older, and ATC-receiving patients demonstrated significantly greater heart-rate and PR-interval changes from baseline. Age, ATC use, Delta-PR >10 ms, Delta-QTC >50 ms and Delta HR >10 ms from baseline significantly predicted incident AF in the 6 month follow up in univariate-regression-analysis. However, only age and more significantly Anthracyclin use was found to predict Incident AF in multivariate regression analyses (picture 2) [(OR 3.7 (95% CI 1.2–10) (p=0.02)].

Conclusion(s)

Compared with alkylating-agents, anthracycline-regimens seem to induce significantly more incident-AF-events and profound ECG changes on the acute phase of chemotherapy for breast-cancer in women. They seem to exert their effects irrespective of conventional AF risk-factors apart from advanced-age. Affected ECG-parameters of delayed-conduction and repolarization-heterogeneity might be suggested as a surrogate for multiple-ion-channel-interactions and a possible mechanism underlying higher incident-AF.

Funding Acknowledgement

Type of funding sources: None.

The prevalence of concealed Brugada Syndrome in patients with paroxysmal atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Background

Brugada Syndrome (BS) is an inherited rhythm-disorder with risk of sudden-cardiac-death defined by a specific ST-segment elevation pattern in precordial ECG-leads either spontaneous or provoked by Na-channel-blocker-drug-provocation-test with Ajmaline and/or higher-precordial-intercostal-space (HICS)-ECGs. Scarce data denote that the prevalence of atrial fibrillation (AF) is higher in BS and most of the antiarrhythmic-drugs used in AF are contraindicated in BS.

Purpose

Our aim was to elucidate the frequency of BS in paroxysmal-AF (PAF) patients without heart-disease and reveal possible clinical/genetic relations.

Methods

Adult patients with an history of PAF less than 55-years-old were prospectively and consecutively evaluated with resting and HICS-ECGs, cardiac-examination and routine Ajmaline-drug-provocation-test (if not contraindicated). After the exclusion of subjects with any cardiac-disease, anti-arrhythmic-use, bundle-branch-blocks, pre-excitations and ventricular hypertrophies; 96 subjects ([mean±SD] age, 37.3±18, [range]18-55 years) were enrolled in the study (male n [%overall]:55 [57.2%]). All ECGs were interpreted manually by two experienced cardiologists for BS and Brugada-type-ECG-patterns (BTEPs). In 32 patients SCNA5A genetic tests were done (n: 15 BS(+) 17 BS(-) patients). In BS(+) patients, electrophysiological-study (EPS) with programmed-ventricular-stimulation (PVS) was also done and compared with the EPS parameters of BS(-) PAF patients that undergone AF-catheter-ablation-strategy (n: 30).

Results

Overall frequency of concealed-BS was 22,9% (n: 22 [male n: 14]). No spontaneous type-1 BTEP was found with HICS-ECGs and all BS diagnosis were Ajmaline-induced. The clinical characteristics of PAF patients with and without BS and statistical findings are presented in Table-1 and Figure-1. BS(+) patients were predominantly male, younger, slimmer, significantly more suffering from situational syncopal episodes and revealing more BTEPs by baseline HICS-ECGs. The SCN5A-mutation positivity was non-significant between BS(+) and (-) PAF patients (p= 0,80). Baseline heart-rates were lower and PR-intervals, P-wave-duration and Sinus-node-recovery-times were significantly higher in BS(+) patients. Only one BS(+) PAF patient with an history of syncope developed VF with 2 extra-beats in PVS and received an ICD.

Conclusions

Concealed-BS is found to be highly prevalent in middle-aged-subjects and especially males with PAF without an apparent cardiac-disorder. Knowing this considerably lethal condition might protect a vulnerable sub-group of patients from the deleterious effects of antiarrhythmics and risk stratification might confer an increased risk. Non-invasive/invasive indices regarding the delayed conduction features in atrial electrophysiological characteristics of BS(+) patients and a higher vagal state might be suggested as one of the probable mechanisms underlying the higher prevalence of AF in BS.

Telemedicine-based early rule out and followup ECG algorithm for COVID-19 patients

Funding Acknowledgements

Type of funding sources: None.

Background

Drugs with the potential to prolong QT are used in the treatment of coronavirus 19 (COVID-19) pneumonia. We have developed a telemedicine-based corrected QT (QTc) follow-up algorithm that allows early rule out for follow up.

Aims

In this study, we investigated the availability and safety of the algorithm.

Study design

Retrospective cohort

Methods

Consecutive patients; administered hydroxychloroquine (HCQ) for COVID-19 pneumonia were enrolled into digital ECG recording program which includes QTc follow-up algorithm.

Results

Patients were classified into three groups as those, excluded promptly from the QTc follow-up based on two consecutive ECG findings (early rule out, n = 92) and those, for whom the follow-up was continued (n = 12) and usual care group (n = 68). Of note, 237 ECG tracings were performed in our algorithm population contrary to standard practice of daily recommended ECG monitoring which could have yielded 975 ECG tracings along with accompanied risks of exposure. This way; we ended in 738 (75.7%) fewer ECG tracings. Sustained ventricular arrhythmia or sudden cardiac death was not observed in the entire patient population.

Conclusions

It is safe to rely on telemedicine-based early rule out algorithm in COVID-19 patients, receiving hydroxychloroquine treatment. This algorithm abolished the need for further ECG in majority of patients without increased risk during follow up. These algorithms can significantly reduce the healthcare worker exposures by eliminating the need for ECG follow-up promptly.