Case Of Complete Heart Block Research Articles

Lithium Toxicity: A Case Report of Toxicity Resulting in a Third-degree Heart Block.

Lithium is a medication used to treat bipolar disorder. It has a narrow therapeutic index, which frequently causes toxicity in patients. We present an unusual case of a 66-year-old female with a history of bipolar disorder on chronic lithium, who developed a third-degree heart block, encephalopathy, and acute renal failure because of lithium toxicity. This case highlights a rare but life-threatening case of complete heart block in the setting of lithium toxicity. The patient was treated with hemodialysis and pacemaker placement.

SPONTANEOUS THIRD-DEGREE ATRIOVENTRICULAR BLOCK IN A DIABETIC PATIENT PRESENTING AS RECURRENT SYNCOPE

Chronic, uncontrolled hyperglycemia is associated with an increased incidence of coronary artery disease, cardiac failure, diabetic nephropathy, diabetic retinopathy, and associated mortality. A 72-year-old female presented to the OPD with multiple episodes of loss of consciousness for the past 1 month. The patient also had other comorbidities such as hypertension, diabetes mellitus (DM), and hypothyroidism. On systemic examination, her blood pressure was 124/77 mmHg (supine) and 116/72 mmHg (standing), and her pulse rate was 56 beats/min. She had a loss of vibration sense in both lower limbs up to the ankle. Fundus examination showed non-proliferative diabetic retinopathy. The rest of the systemic examination was clinically normal. Her HbA1C was 8.1%, and other routine investigations were within normal limits. Electrocardiography (ECG) showed sinus bradycardia. Echocardiography showed normal ventricular function with no evidence of ischemic heart disease (IHD). 24-h Holter ECG revealed sinus bradycardia with an intraventricular conduction defect, a third-degree AV block with junctional beats, and rare supraventricular ectopics. This is a case of Type 2 DM with complete heart block (CHB) of spontaneous onset. Other causes of AV block have been ruled out, and it seems that this case of CHB is possibly due to cardiac autonomic neuropathy (CAN). Multiple factors, such as the duration of diabetes, poor glycemic control, metabolic derangements, and genetic factors, determine CAN. This case emphasizes that patients with type 2 diabetes without IHD can develop CHB spontaneously.

Abstract 14249: COVID-19 and Complete Heart Block in a Vaccinated Adult

Introduction: Complete heart block (CHB) in association with Covid-19 is uncommon and has been described primarily in the pre-vaccine time period. In the setting of acute Covid-19 infection, decision to treat CHB with permanent pacemaker (PPM) is often uncertain as the CHB may resolve or persist. We present a case of reversible CHB and Covid-19 infection in a vaccinated healthy 28-year-old. Case: A healthy 28-year-old female presented after syncope. She had been vaccinated three times against Covid-19 with Pfizer-BioNTech mRNA vaccine with her third dose four months prior. She had known Covid-19 exposure and developed sore throat three days prior to presenting with syncope. She had no other symptoms. Physical exam was remarkable only for bradycardia. Labs showed positive Covid-19 PCR test and elevated troponin of 0.396 ng/mL. Complete blood counts, metabolic panel, ESR and CRP were normal. Lyme IgM and IgG were negative by Western blot. ECG showed CHB with a rate of 35 beats per minute (Figure 1A). Echocardiogram showed no abnormalities. The patient remained in CHB for 24 hours, at which point PPM was implanted after shared-decision making. Post-PPM ECG showed AV-paced rhythm (Figure 1B). At follow up, PPM interrogation showed that she transitioned to sinus rhythm with right bundle branch block (RBBB) followed by a return to normal sinus rhythm without RBBB 5 days after implantation (Figure 1C). Cardiac MRI two months after PPM implantation showed no abnormalities. Discussion: This was a case of Covid-19 associated myocardial injury with CHB in a fully-vaccinated, healthy adult treated with PPM. Despite vaccination, this patient experienced myocardial and conduction system involvement during acute Covid-19 infection. Myocardial injury along with this ECG progression suggested that there was transient inflammation of the myocardial septum resulting in CHB. It may be reasonable to delay PPM implantation in cases of CHB and Covid-19 infection as the CHB may be transient.

Complete Heart Block in a Case of Rheumatoid Arthritis: Uncommon Presentation of a Common Disease

We report a case of complete heart block (CHB) in a patient with rheumatoid arthritis (RA) because of its atypical presentation, negative Anti CCP and one of the uncommon causes of CHB. It occurs mainly in patients with established erosive nodular RA. It is usually sudden and permanent. It has several mechanisms, but the most common cause is infiltration in or near the AV node or bundle of His. If CHB develop the best option of treatment is the insertion of a permanent pacemaker. The prognosis is usually good provided no other cardiac lesions exist.
 University Heart Journal 2022; 18(2): 132-134

0854 A case of complete heart block in a patient with severe obstructive sleep apnea

Abstract Introduction Obstructive sleep apnea (OSA) has been associated with bradycardic arrythmias and cases of transient heart block. Heart block occurring during sleep has been described in up to 10% of patients with obstructive sleep apnea, most commonly during stage R sleep and through a mechanism known as vagal activation. Stage R sleep is associated with desynchronization of respiratory and cardiovascular functions, and the excessive autonomic response (vagal activation) occurs due to the stronger stimulation of chemoreceptors and baroreceptors induced by hypoxemia, intrathoracic pressure swings, and hemodynamic alterations. Treatment of the underlying sleep-disordered breathing will typically treat the bradycardic arrythmia as well. Report of Cases: A 49-year-old male with a BMI of 30 kg/m , neck circumference of 16 inches, and obstructive sleep apnea presented to the sleep center to establish care for management of his preexisting OSA. He was previously diagnosed with moderate OSA in 2007 but had discontinued therapy shortly after due to Continuous Positive Airway Pressure (CPAP) intolerance. The patient complained of snoring, nocturia, and excessive daytime sleepiness (18/24 on Epworth Sleepiness Scale). During the split night study, the patient was noted to have 2:1 second degree heart block followed by a transient episode of complete heart block, manifested by 4 non-conducted p-waves. The patient remained asymptomatic throughout the night. Upon study completion, the patient denied any prior chest pain, presyncope, syncope, or medications that might cause heart block. Conclusion Bradyarrythmias can be seen in severe obstructive sleep apnea in the setting of excessive vagal stimulation through increased stimulation of chemoreceptors and baroreceptors. Treatment with PAP therapy can lead to prevention of heart block in 80-90% of these patients. Support (If Any)

Complete heart block ensuing from a metastatic small cell carcinoma: a case report

IntroductionNotwithstanding the diagnostic and therapeutic advancements, the incidence of cardiac metastases has increased in recent decades. Lung cancers are the most common primary malignant neoplasms with cardiac metastasis potential. The clinical presentation of cardiac metastases is either silent or vague, and largely depends on the infiltrated location and tumor burden. Although arrhythmias are not uncommon in metastatic cardiac tumors, complete heart block is relatively a rare manifestation. We present a case of complete heart block due to a metastatic small cell carcinoma in a 67-year-old male of African origin.Case presentationA 67-year-old male of African origin from rural Tanzania was referred to us for expert management. He is a retired agromechanic with over 30 years exposure to asbestos-containing brake linings. His past medical history was unremarkable, but the family-social history was evident for a heavy alcohol intake and chronic cigarette smoking. He presented with a 24-week history of progressive shortness of breath and an 8-week history of recurrent syncopal attacks coupled with a significant weight loss. He had normal echocardiographic findings, however, the electrocardiogram showed features of complete heart block. Chest X-ray showed a homogeneous opacification on the right side and computed tomography scan revealed a solid right lung mass with metastases to the liver, heart, bowels, and bone. He underwent bronchoscopy, which revealed an endobronchial mass obstructing the bronchus intermedius. Histological examination of a section of lung biopsy taken during bronchoscopy confirmed the diagnosis of a small cell carcinoma. The patient underwent dual chamber pacemaker implantation with successful sinus rhythm restoration. He made an informed refusal of chemotherapy and inevitably died 18 months post pacing.ConclusionsDespite the advancements in medical diagnostics and management, lung cancers are often diagnosed in advanced stages, with an inevitable grave prognosis. Small cell carcinoma has the potential to metastasize to the heart, resulting in complete heart block.

Abstract 13727: Prediction of Pacemaker Implantation in Patients With Postoperative Heart Block: A Data Analytics Approach

Introduction: Current guidelines recommend observation for AV node recovery until postoperative days (POD) 7 to 10 for patients with complete heart block (CHB) after congenital cardiac surgery prior to permanent pacemaker (PPM) placement. We created a predictive tool to identify patients at high risk of requiring PPM before POD 7 to aid in surgical decision making. Methods: Postoperative CHB cases from August 2009 to January 2019 were identified. We collected demographic, anatomic, and surgical details. Random forest, logistic regression, and decision tree models were trained and evaluated using 5-fold cross validation, then prospectively validated on data from January 2019 to April 2021. Separate models were developed for all patients on POD 0 and those without recovery on POD 4. Results: Of 101 cases of CHB (22 in validation cohort), 60 (59%) required PPM. Median days [IQR] to AVN recovery was 3 [1-7] and PPM was 10 [7-13]. A decision tree model was used for its performance and interpretability, and included: (1) aortic valve replacement, subaortic stenosis repair, or Konno incision; (2) ventricular L-loop; (3) atrioventricular valve replacement; (4) use of preoperative antiarrhythmic agent (in POD 0 model only; figure 1). The POD 4 model (table 1) had a positive predictive value (PPV) of 0.94 [95% CI 0.81-0.98], which was stable in prospective validation (PPV 1.0). Conclusions: Our decision tool identified patients requiring PPM with high specificity and PPV. On POD 4, patients with left ventricular outflow tract repair, AV valve replacement, or ventricular L-Looping could be considered for PPM placement before POD 7 to reduce risks of temporary pacing and improve care efficiency.

Complete Heart Block as a Clinical Feature in Critically Ill Coronavirus Disease 2019 (COVID-19) Patients: A Case Series of Three Cases

Background. Novel coronavirus-19 disease (COVID-19) is associated with significant cardiovascular morbidity and mortality. However, there have been very few reports on complete heart block (CHB) associated with COVID-19. This case series describes clinical characteristics, potential mechanisms, and short-term outcomes of critically ill COVID-19 patients complicated by CHB. Case Summary. We present three cases of new-onset CHB in critically ill COVID-19 patients. Patient 1 is a 41-year-old male with well-documented history of Familial Mediterranean Fever (FMF) who required mechanical ventilator support for acute hypoxic respiratory failure from severe COVID-19 pneumonia. He developed new-onset CHB without a hemodynamic derangement but subsequently had acute coronary syndrome complicated by cardiogenic shock. Patient 2 is a 77-year-old male with no past medical history who required intubation for severe COVID-19 pneumonia acute hypoxic respiratory failure. He developed CHB with sinus pause requiring temporary pacing but subsequently developed multiorgan failure. Patient 3 is 36-year-old lady 38 + 2 weeks pregnant, gravida 2 para 1 with no other medical history, who had an emergency Lower Section Caesarean Section (LSCS) as she required intubation for acute hypoxic respiratory failure. She exhibited new-onset CHB without hemodynamic compromise. The CHB resolved spontaneously after 24 hours. Discussion. COVID-19-associated CHB is a very rare clinical manifestation. The potential mechanisms for CHB in patients with COVID-19 include myocardial inflammation or direct viral infiltration as well as other causes such as metabolic derangements or use of sedatives. Patients diagnosed with COVID-19 should be monitored closely for the development of bradyarrhythmia and hemodynamic instability.

A case of complete heart block with a therapeutic dilemma

A case of complete heart block with a therapeutic dilemma

Late Complete Heart Block after Surgical Repair of an Atrial Septal Defect

ABSTRACT Atrial septal defects (ASD) are among the most common forms of congenital heart disease. Although surgical correction was the only available therapy for decades, its long-term complications remain unknown and many patients do not have structured medical follow-up in later life. However, increasing evidences suggest that late-onset cardiac problems, such as complete heart block (CHB), can arise after surgery and therefore, long-term follow-up should be advised in these patients. We hereby present an interesting case of CHB occurring in a 30-year-old patient who had undergone surgical secundum ASD closure approximately 21 years prior to this event and now presented with episodes of dizziness and pre-syncope. Seven-day Holter reported seven episodes of CHB, corresponding to the presenting complaints. The patient was successfully managed with conduction system pacing and he remained asymptomatic on further follow-up. The case description is followed by a brief overview of the available literature.

MANAGEMENT OF SEVERE PREECLAMPSIA IN COMPLETE HEART BLOCK: A RARE COMBINATION

Complete heart block is rare during pregnancy. It may be congenital or acquired. There are no proper guidelines regarding its management, posing a great challenge for obstetricians .It is further compounded, if it is associated with severe preeclampsia. Normal physiological hemodynamics and cardiac changes pose challenges in the setting of cardiac lesions like congenital heart block .When it is associated with preeclampsia it has profound effects over the cardiac function. Pregnancy with rare combination of complete heart block and severe preeclampsia warrants cautious use of antihypertensive drugs and pacemaker implantation. Commonly used antihypertensives drugs like labetalol used as the rst line of treatment in preeclampsia is contraindicated in case of complete heart block. Here we present challenges faced and its management by a multidisciplinary team when a case of complete heart block associated with severe preeclampsia reported in emergency at term gestation

Cardiac Pacing Using A Guidewire In Emergency Situation

We were describing an interesting case of complete heart block (CHB) received in the emergency department (ED) with the cardiogenic shock in the life-threatening situation, who was successfully manage by cardiac pacing, initially using a J Tip guidewire (JTG) due to non-availability of temporary transvenous pacing catheter (TVPC) and later on using TVPC once available . TVPC placement is a potentially life-saving procedure that involves placing a catheter-based electrode within the right ventricle via central venous access, and then stimulating that electrode and the heart with an external pacing generator to optimize cardiac output. In the ED, the procedure can be performed either blindly or with ECG guidance and recently with USG guidance. After placement, CXR perform to verify position of TVPC as well as any procedural complication.

Complete heart block in a 40-year-old man with anti-SSA/Ro autoantibodies

Atrio-ventricular dissociation (AVD), including complete heart block (CHB), are far more common in the elderly. We report a rare case of CHB in a 40-year-old man, who tested positive for anti-Ro autoantibodies without systemic features. He had been suffering for giddiness over the previous two months. On arrival, his electrocardiogram revealed high-degree AVD. Upon further history, he mentioned that his 68-year-old mother with systemic lupus erythematosus (SLE) had suffered from similar episodes, requiring a permanent pacemaker implantation. On further investigation, he tested positive for antinuclear antibodies (ANA), anti-SSA/Ro and anti-RNP antibodies. However, from history and clinical examination, he had not manifested any articular, extra-articular or extra-glandular features suspicious of rheumatological conditions. Following a failed trial of intravenous hydrocortisone, he subsequently had a permanent pacemaker implanted himself. Although difficult to ascertain whether our patient suffered from a congenital form of anti-SSA/Ro-related CHB, there is evidence to suggest delayed presentation of CHB in those with anti-SSA/Ro and neonatal lupus syndrome. Anti-SSA/Ro antibodies without systemic features can be present in 3% of the population, although this occurs more commonly in the presence of a confirm diagnosis of SLE, Sjögren’s syndrome or poly- and dermatomyositis. Despite the scarcity of evidence, a trial of steroid-based treatment was attempted prior to subjecting the young patient to a permanent pacemaker and its associated complications. To our knowledge, this is only the second case of isolated anti-SSA/Ro syndrome presenting with CHB reported in the literature.

Asymptomatic complete heart block in labor: A case report of none response to atropine therapy

Introduction: A complete heart block is a cardiac electrical conduction disorder with a very rare occurrence in pregnancy, which may be asymptomatic. There are no specific guidelines for the management of asymptomatic complete heart block in labor, vaginal delivery, and cesarean with only a few reports of cesarean management of patients with complete heart block. Case report: A 30-year-old woman, Gravida 4, abortion 3, gestational age of 41 weeks without any specific problems, was referred to our maternity hospital. The pulse rate and blood pressure were 68 and 60/110, respectively. Labor was induced with oxytocin and, after three hours, was discontinued due to late decelerations of fetal heart rate. Electrocardiography confirmed a maternal pulse rate of 42. Cardiac consultation led to the diagnosis of a complete heart block. Due to the frequent late decelerations of fetal heart rate and no response to atropine therapy, the patient was a candidate for a cesarean. Before cesarean, the pacemaker was installed. Cesarean was performed with general anesthesia, and the infant was delivered in good condition. In Postpartum, the pacemaker was removed (PR=55, BP=125/80), and the mother was discharged the next day. Due to the lack of specific guidelines, fetal indication for an emergency cesarean, mother poor obstetrics history, and none response to atropine therapy, we chose to incorporate pacemakers and remove it after cesarean safely. Conclusion: Vital signs assessment during pregnancy and childbirth is recommended to detect cases of complete heart block and provide optimal care.

CARDIAC AA AMYLOIDOSIS SECONDARY TO FAMILIAL MEDITERRANEAN FEVER PRESENTING AS INTERMITENT COMPLETE HEART BLOCK: A RARE CASE WITH LITERATURE REVIEW

SESSION TITLE: Medical Student/Resident Cardiovascular Disease Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Cardiac amyloidosis is rare but relatively more frequently seen with ATTR and AL types of amyloidosis. AA amyloidosis related cardiomyopathy or conduction abnormalities are rare owing to less frequent involvement of the myocardium in AA amyloidosis. We present a case of complete heart block in the setting of AA amyloidosis secondary to familial mediterranean fever. CASE PRESENTATION: A 50-year-old female with history of familial mediterranean fever (FMF) presented with syncopal episode. On presentation patient's vitals were stable, labs including TSH were within normal limits. Orthostatic vitals were positive. High-sensitivity troponins were negative with a normal EKG on presentation. Laterally displaced apical beat was noticed on examination. During hospitalization patient was noticed to have complete heart block that was not responsive to atropine and transcutaneous pacing however a response was noticed with epinephrine drip. TTE revealed heart failure with reduced ejection fraction of 41% with severe concentric left ventricular thickening typical for amyloid cardiomyopathy with a well-preserved E/A-wave, which is not usually seen in as thickened ventricle as patients. CRP and SAA were elevated. Patient had endomyocardial biopsy that confirmed amyloid deposition staining positive for amyloid AA and negative for TTR, kappa and lambda and a technetium pyrophosphate scan was also negative. A biventricular pacemaker was placed for complete heart block without adequate escape rhythm, which resulted in resolution of episodes of dizziness associated with bradycardia. Patient's FMF was managed with colchicine and anakinra with the help of rheumatology. Patient was started on diuresis during hospitalization and continued on discharge. Patient followed up with amyloidosis clinic after discharge. DISCUSSION: Systemic amyloidosis is rare and results from deposition of amyloid deposits in various organs and hence a wide range of effects. Prognosis may be vary with the type and extent of amyloidosis. More than 95% of cardiac amyloidosis is secondary to light chain/AL amyloidosis or transthyretin amyloidosis (ATTR), both genetic/hereditary and wild type.[1] Cardiac involvement from AA amyloidosis is very rare. Cardiac amyloidosis usually manifests with syncope or postural hypotension, which may be related with bradyarrhythmias.[2] Like the involvement of cardiovascular system, developments of arrhythmias are also common with ATTR type of amyloidosis as compared to other types and may require pacemaker placement. AA cardiac amyloidosis is rare and bradyarrhythmias or conduction system involvement has also been rarely reported. We report a rare case of complete heart block secondary to AA amyloidosis from familial Mediterranean fever requiring pacemaker placement. CONCLUSIONS: We present cardiac AA amyloidosis as a rare cause of syncope and orthostatic hypotension. Reference #1: Sipe, J.D., et al., Amyloid fibril proteins and amyloidosis: chemical identification and clinical classification International Society of Amyloidosis 2016 Nomenclature Guidelines. Amyloid, 2016. 23(4): p. 209-213. Reference #2: Chamarthi, B., et al., Features and prognosis of exertional syncope in light-chain associated AL cardiac amyloidosis. Am J Cardiol, 1997. 80(9): p. 1242-5 DISCLOSURES: No relevant relationships by Usama Talib, source=Web Response

Ticagrelor-Induced Paroxysmal Complete Heart Block

Complete heart block is an uncommon condition that can be fatal if unidentified, as it affects the conduction system of the heart. The phenomenon may be caused by a drug or underlying medical condition requiring a temporary or permanent pacemaker to stabilize the condition. We report a case of complete heart block precipitated by ticagrelor which was reversed with the cessation of ticagrelor therapy.

Mid-term Results of First Experience in Sutureless Aortic Valve Replacement in Iran

Background: Although the TAVI technique has been widespread in Europe and America, concerns have emerged regarding the associated complications, mainly paravalvular leakage, vascular complications, stroke, post-operative pacemaker implantation due to complete AV block, optimal access sites, long-term valve durability, and economic sustainability, therefore controversy remains about the ideal treatment of high-risk operable patients. Sutureless tissue valves like Perceval S may be a good option for these high risk operable patients. We will present the clinical outcomes of first cases of Perceval S in Iranian patients. Methods: From July 2015 to August 2016, 11 patients (8 male, 3 female) with severe aortic stenosis who were candidates for aortic valve replacement were included in this study. The mean age of patients was 73 ± 8 ranged from 65 to 86 years. The most common presenting symptom was dyspnea and three of the patients had coronary artery disease in need for concomitant revascularization. Preoperative peak gradient across the aortic valve ranged from 72 to 135 mmHg (mean = 97 ± 25). All patients were followed up from 3 to 20 months with a median of 13 months. Results: Dramatic reduction of trans-aortic peak gradients was seen in all patient (mean postoperative gradient = 29 ± 8 mmHg). Small degrees of transvalvular and paravalvular leakage were seen in intraoperative echocardiographies but only one patient had small asymptomatic paravalvular leakage during midterm follow up. Two patients need for transient pace maker; however we had no case of complete heart block. Mean post-operative mediastinal bleeding was 480 ± 150 mL and no patient needed re-exploration for bleeding or tamponade management. ICU stay time was 3 ± 1.54 days, and there was no in-hospital mortality. All patients were discharged in good status and there was no mortality during follow-up period. Conclusions: Preliminary clinical results of the first experience was encouraging; however we need to continue the study with more study volume, more follow up period and more high risk or complicated patients.

COMPLETE HEART BLOCK FROM ANOMALOUS RIGHT CORONARY ARTERY, AN ASSOCIATION OR CAUSATION? A CASE REPORT AND LITERATURE REVIEW

Anomalous coronary arteries can have varied clinical presentations. We present a challenging case of complete heart block (CHB) in a patient with anomalous right coronary artery (RCA) 48-year-old male with no medical history presented for severe fatigue. He denied any other cardiac symptoms. He

A Case of Complete Heart Block Due to Intentional Ingestion of Plant Extracts

AbstractCardiac glycosides are widely available in botanic products and other naturally occurring substances worldwide. Accidental consumption of it leads to digitalis toxicity with varied systemic manifestations. We describe a case of consumption of extract of leaves of the Indian rubber vine plant (Crytostegia grandi flora) which led to gastrointestinal, cardiac, electrolyte, and hematological disturbances.

Doxorubicin Induced Complete Heart Block in a Patient Without Cardiac Lymphoma

Background: Doxorubicin is an anthracycline antineoplastic antibiotic used to treat solid and haematological malignancies. It is associated with several cardiotoxic effects including ventricular arrhythmias and congestive heart failure with a reported incidence of up to 25%. There are only five cases of complete heart block associated with doxorubicin toxicity described in the literature. Case study: A healthy 60 year old male presented to his local medical officer with an incidental left neck mass. He had no significant medical conditions or cardiovascular risk factors. He had not experienced any pre-syncopal or syncopal episodes. An excisional biopsy diagnosed diffuse large B cell lymphoma. A pre chemotherapy gated heart pool scan was normal but electrocardiography (ECG) revealed Mobitz type 1 heart block. He proceeded with R-CHOP chemotherapy that included rituximab 800 mg, cyclophosphamide 1600 mg, hydrocortisone 100 mg, vincristine 2 mg, doxorubicin 108 mg and prednisolone 200 mg. Three days after his first cycle, he presented with dizziness and ECG revealed complete heart block with a rate of 30 beats per minute (Figure 1). He was managed with intravenous isoprenaline with good effect. Transthoracic echocardiography revealed normal left ventricular size and systolic function and cardiac magnetic resonance imaging excluded cardiac lymphoma. A dual chamber pacemaker was inserted prior to continuing further cycles. Conclusion: The exact cardiotoxic mechanism remains unknown but there are suggestions that a subtype of the anthracycline molecular target, topoisomerase II-alpha, is expressed by myocytes. Although rare, anthracycline chemotherapy may worsen underlying atrioventricular node disease in susceptible individuals. Pre-chemotherapy electrocardiography may help to stratify higher risk patients.