Occurrence Of Malignant Ventricular Arrhythmias Research Articles

Lack of temporal correlations between COVID pandemic waves and the occurrence of malignant ventricular arrhythmias

Lack of temporal correlations between COVID pandemic waves and the occurrence of malignant ventricular arrhythmias

AIEgen-Based Covalent Organic Frameworks for Preventing Malignant Ventricular Arrhythmias Via Local Hyperthermia Therapy.

The engineering of aggregation-induced emission luminogens (AIEgen) based covalent organic frameworks (COFs), TDTA-COF, BTDTA-COF, and BTDBETA-COF are reported, as hyperthermia agents for inhibiting the occurrence of malignant ventricular arrhythmias (VAs). These AIE COFs exhibit dual functionality, as they not only directly modulate the function and neural activity of stellate ganglion (SG) through local hyperthermia therapy (LHT) but also induce the browning of white fat and improve the neuroinflammation peri-SG microenvironment, which is favorable for inhibiting ischemia-induced VAs. In vivo studies have confirmed that BTDBETA-COF-mediated LHT enhances thermogenesis and browning-related gene expression, thereby serving a synergistic role in combating VAs. Transcriptome analysis of peri-SG adipose tissue reveals a substantial downregulation of inflammatory cytokines, highlighting the potency of BTDBETA-COF-mediated LHT in ameliorating the neuroinflammation peri-SG microenvironment and offering myocardial and arrhythmia protection. The work on AIE COF-based hyperthermia agent for VAs inhibition provides a new avenue for mitigating cardiac sympathetic nerve hyperactivity.

Late gadolinium enhancement role in arrhythmic risk stratification of patients with LMNA cardiomyopathy: results from a long-term follow-up multicentre study

We aimed at addressing the role of late gadolinium enhancement (LGE) in arrhythmic risk stratification of LMNA-associated cardiomyopathy (CMP). We present data from a multicentre national cohort of patients with LMNA mutations. Of 164 screened cases, we finally enrolled patients with baseline cardiac magnetic resonance (CMR) including LGE sequences [n = 41, age 35 ± 17 years, 51% males, mean left ventricular ejection fraction (LVEF) by echocardiogram 56%]. The primary endpoint of the study was follow-up (FU) occurrence of malignant ventricular arrhythmias [MVA, including sustained ventricular tachycardia (VT), ventricular fibrillation, and appropriate implantable cardioverter-defibrillator (ICD) therapy]. At baseline CMR, 25 subjects (61%) had LGE, with non-ischaemic pattern in all of the cases. Overall, 23 patients (56%) underwent ICD implant. By 10 ± 3 years FU, eight patients (20%) experienced MVA, consisting of appropriate ICD shocks in all of the cases. In particular, the occurrence of MVA in LGE+ vs. LGE- groups was 8/25 vs. 0/16 (P = 0.014). Of note, no significant differences between LGE+ and LGE- patients were found in currently recognized risk factors for sudden cardiac death (male gender, non-missense mutations, baseline LVEF <45% and non-sustained VT), all P-value >0.05. In LMNA-CMP patients, LGE at baseline CMR is significantly associated with MVA. In particular, as suggested by this preliminary experience, the absence of LGE allowed to rule-out MVA at 10 years mean FU.

Diagnosis of arrhythmogenic cardiomyopathy: The Padua criteria

The original designation of “Arrhythmogenic right ventricular (dysplasia/) cardiomyopathy”(ARVC) was used by the scientists who first discovered the disease, in the pre-genetic and pre-cardiac magnetic resonance era, to describe a new heart muscle disease predominantly affecting the right ventricle, whose cardinal clinical manifestation was the occurrence of malignant ventricular arrhythmias. Subsequently, autopsy investigations, genotype-phenotype correlations studies and the increasing use of contrast-enhancement cardiac magnetic resonance showed that the fibro-fatty replacement of the myocardium represents the distinctive phenotypic feature of the disease that affects the myocardium of both ventricles, with left ventricular involvement which may parallel or exceed the severity of right ventricular involvement. This has led to the new designation of “Arrhythmogenic Cardiomyopathy” (ACM), that represents the evolution of the original term of ARVC. The present International Expert Consensus document proposes an upgrade of the criteria for diagnosis of the entire spectrum of the phenotypic variants of ACM. The proposed “Padua criteria” derive from the diagnostic approach to ACM, which has been developed over 30 years by the multidisciplinary team of basic researchers and clinical cardiologists of the Medical School of the University of Padua. The Padua criteria are a working framework to improve the diagnosis of ACM by introducing new diagnostic criteria regarding tissue characterization findings by contrast-enhanced cardiac magnetic resonance, depolarization/repolarization ECG abnormalities and ventricular arrhythmia features for diagnosis of the left ventricular phenotype. The proposed diagnostic criteria need to be further validated by future clinical studies in large cohorts of patients.

Urolithin B improves cardiac function and reduces susceptibility to ventricular arrhythmias in rats after myocardial infarction

Cardiac fibrosis and inflammation play critical roles in ventricular remodelling after myocardial infarction (MI). Urolithin B (UB), a metabolite of ellagitannin-rich foods, has various biological activities, but its effect on ventricular remodelling after MI has not been determined. The present study evaluated whether UB inhibited ventricular structural remodelling and decreased the occurrence of ventricular arrhythmias after MI. Sprague-Dawley (SD) rats underwent ligation of the left anterior descending coronary artery before randomization to receive phosphate-buffered saline (PBS) or UB at doses of 2.5 mg/kg/day and 5 mg/kg/day via intraperitoneal administration or sham ligation. Cardiac function was assessed using echocardiography, haemodynamic detection and brain natriuretic peptide (BNP) levels 2 weeks post-MI. Hearts were used for electrophysiological testing and molecular and histological analyses. UB (5 mg/kg/day) significantly protected against post-MI cardiac dysfunction. UB markedly reduced infarct areas and myocyte size and attenuated cardiac fibrosis and inflammation post-MI. UB decreased the incidence of ventricular tachycardia and ventricular fibrillation compared to the MI group. We determined that UB inhibited the phosphorylation of JAK2/STAT3 and Smad2/3 signalling molecules. Our data suggest that UB reduces the occurrence of malignant ventricular arrhythmias after MI, which is likely associated with attenuation of ventricular structural remodelling via inactivation of the JAK2/STAT3 and Smad2/3 signalling pathway.

Predicting Ventricular Arrhythmias and In-Hospital Mortality in Acute Coronary Syndrome Patients Presenting to the Emergency Department

Background: Ventricular arrhythmias (VA) after acute coronary syndrome (ACS) is associated with a higher risk of mortality. This study sought to examine the incidence, predictors and outcome of VA in ACS patients. Material and methods: A prospective cross-sectional study was conducted at the emergency department (ED), Universiti Kebangsaan Malaysia Medical Centre (UKMMC) in Kuala Lumpur, Malaysia. Patients with acute coronary syndrome (ST-segment elevation myocardial infarction [STEMI] and non-ST-segment elevation acute coronary syndrome [NSTEACS]) were continuously monitored for the occurrence of VA. Results: A total of 144 patients were recruited (67 STEMI and 77 NSTE-ACS). The total rate of VA was 18.8% (n = 27) and 14.6% (n = 21) experienced malignant ventricular arrhythmias (MVA) (8 ventricular fibrillation, 11 sustained ventricular tachycardia and 2 torsades de pointes). In-hospital mortality was reported in 11.1% of the subjects (n = 16). Factors predicted the occurrence of VA was Killip class IV (OR 8.67, 95% confidence interval [CI] 2.08-36.70, p &lt; 0.05). Meanwhile, occurrence of MVA (OR 86.37, 95% CI 4.16 - 1792.70, p &lt; 0.05) and blood sugar level (OR 1.30, 95% CI 1.01 - 1.67, p &lt; 0.05) independently predicted in-hospital mortality. Conclusion: Incidence of VA was higher than the global estimate and the development of malignant forms of VA during hospitalization for ACS was associated with higher in-hospital mortalities.

Septal Late Gadolinium Enhancement and Arrhythmic Risk in Genetic and Acquired Non-Ischaemic Cardiomyopathies

In many genetic and acquired non-ischaemic cardiomyopathies (NICM) there have been frequent reports of involvement of the interventricular septum (IVS) by late gadolinium enhancement (LGE) at cardiac magnetic resonance (CMR). However, no studies have investigated the relationship between septal LGE and arrhythmias in different NICM subtypes. This study enrolled 103 patients with septal LGE at baseline CMR and different NICM: hypertrophic (n=29) or lamin A/C gene (LMNA)-associated (n=23) cardiomyopathy, and acute (n=30) or previous (n=21) myocarditis. During follow-up, the occurrences of malignant ventricular arrhythmias (MVA) and major bradyarrhythmias (BA) were evaluated. At 4.9±0.7 years of follow-up, the occurrence of MVA and major BA in genetic vs acquired NICM were 10 of 52 vs 12 of 51, and 10 of 52 vs 4 of 51, respectively (both p=n.s.). However, MVA occurred more frequently in LMNA-NICM (eight of 23 vs two of 29 hypertrophic, p=0.015) and in previous myocarditis (nine of 21 vs three of 30 acute, p=0.016), while major BAs were particularly common in LMNA-NICM patients only (nine of 23 vs one of 29 hypertrophic, p=0.003). Different patterns of septal LGE were consistently retrospectively identified at baseline CMR: junctional and limited to the base in 79.3% of uneventful hypertrophic NICM; extended and focally transmural in LMNA-NICM with follow-up arrhythmias (both p<0.05); transitory in patients with acute myocarditis, who, differently from the post-myocarditis ones, showed follow-up arrhythmias only in the presence of unmodified LGE at follow-up CMR (five of 13, p=0.009). Septal LGE was significantly associated with MVA at the 5-year follow-up in LMNA-NICM or previous myocarditis, and with major BA in LMNA-NICM only. These differences correlated with heterogeneous patterns of IVS LGE in different NICM.

Global Identification of FitzHugh-Nagumo Equation via Deterministic Learning and Interpolation

Spiral wave is closely related to the occurrence of malignant ventricular arrhythmia. It is important and necessary to study the spiral wave dynamics to better analyze and control spiral waves. In this paper, the dynamics of FitzHugh-Nagumo(FHN) model is identified by using a novel method based on deterministic learning and interpolation method. The FHN model, which has been studied extensively in physical and mathematical science, is often used to study spiral waves. It is a distributed parameter (DPS) described by two coupled partial differential equations (PDEs). To identify the underlying system dynamics of the FHN model globally, we first transform the FHN model into a set of ordinary differential equations (ODEs) by applying the method of lines. Then, we identify the dynamics of the approximation system by employing deterministic learning. That is, the FHN dynamics on a set of spatial grid nodes is accurately identified. To achieve the global identification of the FHN model, the underlying system dynamics of the FHN model on any other spatial point is approximated via an algorithm based on the interpolation method. The effectiveness and feasibility of the proposed method are demonstrated theoretically and numerically.

Structural assessment of myocardial infarction scars and left ventricular function with cardiac magnetic resonance imaging in patients at high risk of sudden cardiac death.

Results of qualitative and quantitative analyses of scars and LV (left ventricle) function acquired by means of cardiac magnetic resonance (CMR) were correlated with a subsequent occurrence of malignant ventricular arrhythmias in patients at high risk of sudden cardiac death (SCD). We have prospectively followed 47 patients (mean age 60 ± 11 years) who were hospitalized for an implantable cardioverter-defibrillator (ICD) implantation to prevent SCD. All post-MI patients had severe residual LV dysfunction (LVEF 33±14%). Patients were examined with CMR. Based on CMR analysis, we evaluated the basic functional parameters of LV as well as mass, volume, transmurality and heterogeneity of the post-MI scar. The patients with malignant arrhythmias were characterized by smaller LV end-diastolic diameters (LVED 192 ± 79 vs 254 ± 47 mm, p = 0.003) and end-systolic diameters (LVES 131 ± 80 vs 181 ± 45 mm, p = 0.01). As for the other observed functional and morphological CMR parameters, no significant differences between the two groups were detected. These results indicate that post-MI patients with severe residual left ventricular dysfunction and dilatation are in the long term characterized by a lower incidence of malignant arrhythmias compared to the patients with less dilated LV with a comparably severe LV dysfunction (Tab. 2, Fig. 3, Ref. 26). Text in PDF www.elis.sk.

Association between Microvolt T-Wave Alternans and Malignant Ventricular Arrhythmias in Chagas Disease.

BackgroundSudden cardiac death is the most frequent death mechanism in Chagas disease, responsible for 55% to 65% of the deaths of patients with chronic Chagas cardiomyopathy (CCC). The most often involved electrophysiological mechanisms are ventricular tachycardia and ventricular fibrillation. The implantable cardioverter defibrillator (ICD) has a beneficial role in preventing sudden death due to malignant ventricular arrhythmias, and, thus the correct identification of patients at risk is required. The association of microvolt T-wave alternans (MTWA) with the appearance of ventricular arrhythmias has been assessed in different heart diseases. The role of MTWA is mostly unknown in patients with CCC.ObjectivesTo evaluate the association between MTWA and the occurrence of malignant ventricular arrhythmias in patients with CCC. MethodThis is a case-control study including patients with CCC and ICD, with history of malignant ventricular arrhythmias (case group), and patients with CCC and no history of those arrhythmias (control group). The MTWA test results were classified as negative and non-negative (positive and indeterminate). The significance level adopted was a = 0.05.ResultsWe recruited 96 patients, 45 cases (46.8%) and 51 controls (53.1%). The MTWA test was non-negative in 36/45 cases (80%) and 15/51 controls (29.4%) [OR = 9.60 (95%CI: 3.41 - 27.93)]. After adjustment for known confounding factors in a logistic regression model, the non-negative result continued to be associated with malignant ventricular arrhythmias [OR = 5.17 (95%CI: 1.05 - 25.51)].ConclusionPatients with CCC and history of malignant ventricular arrhythmias more often have a non-negative MTWA test as compared to patients with no history of arrhythmia.

Clinical value of ECG in diagnosis of low blood potassium

Objective To investigate the clinical diagnostic value of electrocardiogram(ECG) in patients with low blood potassium. Methods From January 2015 to October 2015, patients with low blood potassium were given ECG examination in Yueqing Maternal And Child Health Care Hospital.The relationship between low blood potassium and ECG changes was analyzed. Results The concentration of serum potassium in patients with 0.9-2.5mmol/L electrocardiogram U wave change, T wave change, ST segment changes, Q-T prolongation, arrhythmia were significantly higher than that of serum potassium concentration in 2.6-3.4mmol/L patients, and the difference was statistically significant (χ2=4.63, 4.10, 4.47, 5.01, 4.92, all P<0.05). Of patients with hypokalemic ECG showed characteristics of U wave amplitude increased, ST segment depression, T wave amplitude decreased, QT interval prolongation, arrhythmia, of which the most common was premature ventricular contractions, severe low blood potassium could also be occurrence of malignant ventricular arrhythmia. Conclusion Low blood potassium has characteristic changes of ECG, ECG as a noninvasive, simple and quick examination, which is helpful for the rapid diagnosis of low blood potassium. Key words: Electrocardiogram; Diagnosis; Low blood potassium

Sudden unexplained nocturnal death syndrome (SUNDS), czyli zespół Brugadów

Brugada syndrome (BS) is a genetically determined illness which is a result of disfunctions of ion channels that regulate currents taking part in the formation of the action potential. It manifests itself in the occurrence of malignant ventricular arrhythmias leading to fainting, and they might be the cause of a sudden cardiac death. Nowadays, the only effective treatment and primary prevention of a sudden cardio-respiratory arrest is the implementation of a cardioverter-defibrillator. The main aim of the thesis was to present an ill person who was diagnosed with BS.

Schlafbezogene Atmungsstörungen und ventrikuläre Arrhythmien

Sleep-disordered breathing (SDB) is an important comorbidity in patients with cardiac arrhythmias. Previous studies confirmed associations between supraventricular and ventricular arrhythmias and SDB. In heart failure patients, SDB was also found independently associated with a shorter event-free survival to the occurrence of malignant ventricular arrhythmias requiring appropriate cardioverter-defibrillator therapy. In obstructive sleep apnea, repetitive hypoxemia, mechanical stress (wall tension), arousals from sleep, and activation of the sympathetic nervous system promote cardiac arrhythmias. Pathophysiological concepts for the link between Cheyne-Stokes respiration and malignant arrhythmias are not fully understood and require further research. In addition, large-scale, randomized, controlled trials are awaited to prove whether adequate treatment of SDB is associated with a risk reduction for the occurrence of arrhythmias, in general, and malignant ventricular arrhythmias, in particular, in these patients.

Sodium Current and Potassium Transient Outward Current Genes in Brugada Syndrome: Screening and Bioinformatics

BackgroundBrugada syndrome (BrS) is a primary arrhythmia syndrome characterized by the occurrence of malignant ventricular arrhythmias. Previously, the genes SCN1B, SCN3B, MOG1, and KCND3 have been associated with BrS. Recent data from exome screening efforts permit better discrimination between low-frequency genetic variants and true monogenetic disease-causing variants. We aimed to screen the genes SCN1B through SCN4B, MOG1, CAV3, and KCND3 for variations in a population of SCN5A negative Danish and Iranian BrS patients, as well as research prior associations using newly released exome data. MethodsScreening of all exons and splice sites was performed using Sanger sequencing. Bioinformatic searches were performed in the Single-nucleotide polymorphism database (build 132) and in the National Heart, Lung, and Blood Institute Grand Opportunity Exome Sequencing Project (ESP) for both previously published variant-BrS associations and newly uncovered variations within the noted genes. ResultsA total of 42 BrS patients were screened, and 2 different nonsynonymous mutations in SCN1Bb (H162P and R214Q) were found in 2 different Danish patients. The variants were not found in 216 Danish controls, but R214Q was present in ESP data (5 of 841 alleles). No other mutations were found. Previously BrS-associated mutations in KNCD3 and SCN3B were also present in ESP data. This was not the case for MOG1, but a nonsense polymorphism was present in 0.5% of alleles. ConclusionsOur study supports the association of SCN1Bb with BrS. However, recently released exome data make some of the prior associations of BrS with genes SCN3B, MOG1, and KCND3 less likely.

ORAL PRESENTATION

ORAL PRESENTATION

Serum Markers of Collagen Turnover Predict Future Shocks in Implantable Cardioverter-Defibrillator Recipients With Dilated Cardiomyopathy on Optimal Treatment

We investigated prospectively whether serum markers of collagen turnover could be used as predictors for the occurrence of malignant ventricular arrhythmias in patients with nonischemic dilated cardiomyopathy (NIDC) who had received an implantable cardioverter-defibrillator (ICD) for primary prevention. Extracellular matrix alterations in NIDC might provide electrical heterogeneity, thus potentially contributing to the occurrence of ventricular arrhythmia and subsequent sudden cardiac death (SCD). Serum C-terminal propeptide of collagen type-I, C-terminal telopeptide of collagen type-I, matrix metalloproteinase (MMP)-1, and tissue inhibitor of MMP-1 were measured as markers of collagen synthesis and degradation in 70 patients with mild to moderate symptomatic heart failure due to NIDC with left ventricular ejection fraction <35%, who received an ICD for primary prevention of SCD. Patients were evaluated for any appropriate ICD delivered therapy, whether shock or antitachycardia pacing, during a 1-year follow-up period. Appropriate device therapies were delivered in 14 of the 70 patients during the follow-up period, with antitachycardia pacing in 2, antitachycardia pacing with shocks in 4, and shocks in 8. Pre-implantation serum concentrations of C-terminal telopeptide of collagen type-I levels were significantly higher in patients who had appropriate ICD-delivered therapy than in those who did not have any therapy (0.46 +/- 0.19 ng/ml vs. 0.19 +/- 0.07 ng/ml, p < 0.001, respectively). The same was true for baseline MMP-1 and tissue inhibitor of MMP-1 (27.7 +/- 1.6 ng/ml vs. 24.1 +/- 2.5 ng/ml, p < 0.001, and 89 +/- 14 ng/ml vs. 58 +/- 18 ng/ml, p = 0.008, respectively). If the maximum benefit is to be achieved from ICD therapy in NIDC patients for the primary prevention of SCD, a more precise risk stratification is required. As extracellular matrix alterations affect the arrhythmogenic substrate in NIDC, we observed that serum markers of collagen turnover could predict arrhythmic events in ICD recipients.

A clinical study of T-wave alternans in pediatric patients

Objective To investigate the cause of T-wave altemans in pediatric patients, and prevent malignant ventricular arrhythmia and sudden cardiac death. Methods We retrospectively analyzed the treating process of 6 pediatric patients with T-wave alternans. Case 1 was a child with acute serious myocarditis. Case 2 was a child with idiopathic left ventricular tachycardia, and had acquired long-QT syndrome after treated with large dose of amiodarone for a long time by unclear diagnosis. Case 3 had congenital long-QT syndrome. Case 4 was a child with myocardial infarction after correction of coarctation of aorta for 5 months. Case 5 and case 6 were children who hade increasing heart rate with severe congenital stenosis of aortic valve. Results All of 6 cases occurred T-wave altemans, and 5 of them occurred malignant ventricular arrhythmia instantly or after several hours. In 2 cases, T-wave altemans disappeared and malignant ventricular arrhythmia did not occurred through prevention and treatment. The other 4 cases died without active prevention for malignant ventricular arrhythmia. Conclusion T-wave alternans is presymptom of malignant ventricular arrhythmia and sudden cardiac death. We should take notice of occurrence of malignant ventricular arrhythmia in pediatric patients with T-wave altemans and diagnosing and treating correctly for primary disease. It is of great importance to prevent occurrence of T-wave altemans. Key words: Pediatric T-wave altemans; Sudden death; Malignant ventricular arrhythmia

Profound myocardial ischemia associated to occlusion of the right coronary artery

A 75-year-old man with hypertension, hypercholesterolemia and history of coronary artery disease was admitted to the hospital because of sudden loss of consciousness. The patient suffered an acute myocardial infarction seven years before this admission, which was treated with percutaneous transluminal coronary angioplasty and stent implantation in the right coronary artery. The initial electrocardiogram showed a complete atrioventricular block, with narrow ventricular complexes at a rate of 40 bpm. The next electrocardiogram, obtained after the administration of atropine, showed a sinus rhythm at 84 bpm with first-degree atrioventricular block, obvious ST-segment elevation on leads II, III, aVF, V3 to V6, and electrical alternation of the ST-segment. Subsequently, he suffered three episodes of ventricular fibrillation which were successfully defibrillated. The ST-segment elevation improved after sublingual nitroglycerine and the patient underwent urgent coronary angiography, which showed a critical stenosis in the middle part of the right coronary artery with a lot of thrombus material in the site of the previous stent. The rest of the coronary arteries did not reveal significant lesions. Thrombus aspiration and balloon angioplasty were successfully performed without residual stenosis. The ST-elevation alternans is a rare phenomenon which was initially described in the setting of coronary artery spasm. It is believed to be associated to profound myocardial ischemia, particularly in relation with occlusions of the left anterior descending coronary artery, and to the occurrence of malignant ventricular arrhythmia and sudden cardiac death.

B‐type Natruiretic Peptide Levels Stratify the Risk for Arrhythmia Among Implantable Cardioverter Defibrillator Patients

We sought to study the association between brain natriuretic peptide (BNP) levels and the occurrence of ventricular arrhythmias in patients with left ventricular dysfunction (LVD) and an implantable cardioverter defibrillator (ICD). This was a prospective study of consecutive, stable, ambulatory patients with moderate and severe ischemic LVD and an ICD. A plasma BNP level was obtained at recruitment. Patients were evaluated every 3-6 mo for a minimum of 1 y. The primary end point was the occurrence of malignant ventricular arrhythmia or sudden cardiac death (SCD). The cohort consisted of 94 subjects (6 women) with a mean +/- standard deviation (SD) age of 69 +/- 10 y. The ICD implantation indication was primary and secondary prevention of SCD in 49% and 51% of subjects, respectively. A primary end point occurred in 27 patients (29%), and was more frequent in symptomatic heart failure patients and those implanted for secondary prevention of SCD. The median BNP level was significantly higher among patients who experienced an end point (191 pg/ml versus 142 pg/ml, p = 0.03). After controlling for New York Heart Association heart failure class and ICD implantation indication, the odds ratio (OR) for experiencing an adverse outcome among the upper BNP quartile versus all others was 3.5 (95% confidence interval [CI]: 1.2-10.2). Among patients implanted for primary prevention of SCD, none of the patients in the lower BNP quartile (BNP < 91 pg/ml) experienced an adverse outcome. These results suggest that abnormally high BNP levels not only predict cardiac death, but also arrhythmic death in this patient population, and a low BNP level can serve to identify low risk patients. (c)

Stress Testing in Patients With Implantable Cardioverter‐Defibrillators: A Preliminary Report

This retrospective study was undertaken to assess the responses to, and complications associated with, stress testing in patients with implantable cardioverter-defibrillators (ICDs). Primary end points were occurrence of malignant ventricular arrhythmias, onset of burst pacing or ICD firing, cardiopulmonary resuscitation, or death during or soon after stress testing. Secondary end points were urgent coronary revascularization and/or hospital readmission for cardiovascular complications. During a 4-year period, 1734 patients underwent ICD implantation or generator replacement at our institution; 84 patients (mean age +/- SD, 67+/-12 years; 76% men) subsequently underwent 107 stress tests, including 44 exercise and 63 pharmacologic (22 dobutamine, 41 dipyridamole) evaluations. None of the ICDs were inactivated before testing. All tests were supervised by specially trained paramedical personnel, with a physician immediately available. Four patients had self-terminating, nonsustained ventricular tachycardia at peak stress. None had sustained ventricular tachycardia requiring emergent therapy. There were no deaths or hospital readmissions for ventricular arrhythmias. These findings suggest that stress testing is feasible in patients with ICDs and that it can be performed without pretest inactivation.