nonsustained ventricular tachycardia

T-wave alternans (TWA) is a test that is thought to reflect dispersion of repolarization and has been shown to predict VT inducibility and future arrhythmic events better than SAECG. Polymorphic VT associated with QT prolongation often has a characteristic waxing and waning QRS amplitude referred to as “torsade de pointes (TdP) (Roden, 2008).”. This Doctor Discussion Guide has been sent to {{form.email}}. Some patients develop sustained episodes (>30 seconds) during the recovery phase, and this behavior differentiates repetitive monomorphic VT from the exercise-triggered paroxysmal VT first described by Wilson and others in patients with apparently normal hearts.54–56 It should be noted, however, that repetitive behavior has been documented in various clinical settings, including cardiomyopathy and previous MI, as well as tachycardias originating in the aortic valve cusps.51,57. Grimm However, as it offers cluesto a possible case of some other severe heart disease, physicians give great importance to a diagnosis of NSVT. Judith A. Mackall, Mark D. Carlson, in Cardiac Intensive Care (Second Edition), 2010. Furthermore, in patients treated with thrombolysis or β-blockers, the predictive ability of SAECG is limited.82,99 In patients with DCM, SAECG does not predict SCD, but in arrhythmogenic right ventricular dysplasia, SAECG can identify those with more extensive disease and a propensity for inducible VT at programmed electrical stimulation, and is now considered a minor diagnostic criterion.8,81,100, T-wave alternans (TWA) is a test that is thought to reflect dispersion of repolarization and has been shown to predict VT inducibility and future arrhythmic events better than SAECG.101 In patients similar to those in MADIT II, a microvolt TWA (MTWA) test was found to be better than QRS duration at identifying high-risk patients as well as patients unlikely to benefit from ICD therapy.102 Recently, in patients with reduced LV function (LVEF <40%) and NSVT, MTWA also predicted unstable ventricular tachyarrhythmias better than electrophysiology testing and LVEF less than 30%.103 However, in a later study, although TWA predicted higher total mortality in a MADIT II–like population, the risk of tachyarrhythmic events did not differ according to TWA results.104 The Alternans Before Cardioverter Defibrillator (ABCD) study was the first trial to use MTWA to guide prophylactic ICD insertion in patients with LVEF less than 40% and NSVT. Left ventricular function in post-MI patients remains the most important prognostic tool for overall mortality and risk for sudden cardiac death. The odds ratio of SCD for patients aged 30 years or younger with NSVT was 4.35, in comparison with 2.16 in those older than 30. Atrial or ventricular pacing may suppress sustained monomorphic VT in some patients with monomorphic VT, particularly when the arrhythmia is aggravated by bradycardia. Stress-induced ventricular arrhythmias after tetralogy of Fallot repair. If a heart disease is subsequently discovered, treatment should be directed toward that. No characteristic electrocardiographic morphology of NSVT exists in patients with HCM. VTs with a left bundle branch block (LBBB) pattern and inferior axis originate in the right ventricular outflow tract (RVOT).45 Left ventricular outflow tract (LVOT) tachycardias may produce a right bundle branch block (RBBB) morphology with inferior axis or a variable QRS morphology, depending on the site of origin. The incidences of major arrhythmic events in patients without NSVT, in those with 5- to 9-beat NSVT, and in those with more than 10-beat NSVT were 2%, 5%, and 10% per year, respectively. Caruso , Duc J, Berger EE et al. NSVT is also seen with hypertrophic cardiomyopathy and heart valve disease (especially aortic stenosis and mitral regurgitation).. Cameron , Hadjis T, Hallett N et al. Both RBBB and LBBB patterns can be seen in the same patient when the infarct scar involves the interventricular septum (Figure 43-3). DJ , Auricchio A, Reek S et al. Mittal 2000 May;18(2):327-36,viii. The cardiac mortality rate at 2 years in MADIT was still 11% despite the use of defibrillators.10 Furthermore, reduction of arrhythmic death does not necessarily imply a concomitant reduction in total mortality, and even a nonsignificant increase in mortality has been demonstrated despite the reduction of SCD by using amiodarone in patients with acute MI.124–126, Table 43-2 Clinical Significance of Nonsustained Ventricular Tachycardia. Kowey Bigger Holter studies have revealed that the tachycardia begins with a fusion complex or with an ectopic beat that has the same morphology as the subsequent beats (Figure 43-1).50 The salvos of VT are generally short (3 to 15 beats) and the coupling interval of the first beat is usually long (>400 ms). Individuals with elevated risk to CAD may also be asked to undergo a stress thallium test to confirm the occurrence of CAD. Ritchie Prevalence and prognostic significance of ventricular arrhythmias after acute myocardial infarction in the fibrinolytic era: GISSI results. Klein A meta-analysis of 11 prognostic studies that involved more than 100 patients per study revealed that NSVT contributed significantly to the prediction of SCD in patients with left ventricular dysfunction, and this contribution was independent of LVEF (Figure 53-8).69 It was concluded that the absence of NSVT indicated a low probability of SCD in patients with a left ventricular systolic dysfunction. Thus, a negative SAECG might obviate the need for further investigations when the suspicion of a ventricular arrhythmia is low, but in the case of a high suspicion of ventricular arrhythmia, a negative SAECG is not sufficient evidence for the exclusion of sustained VT or NSVT as the cause of syncope. Signal-averaged ECG, baroreflex sensitivity, heart rate variability, and T-wave alternans were not helpful for arrhythmia risk stratification. Strategies that use MTWA, EPS, or both might identify subsets of patients least likely to benefit from ICD insertion.105. D We are therefore dealing with a probabilistic event in which each of the currently considered risk factors such as NSVT identifies only a small fraction of the risk process. In addition, several other clinical parameters and tests can provide specific information about the potential risk of future arrhythmic events in patients who have presented with nonsustained ventricular arrhythmias. Repetitive nonsustained episodes of ventricular tachycardia. S In the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico-2 (GISSI-2, Italian Group for the Study of Survival after Myocardial Infarction-2) trial, NSVT was a significant predictor of mortality in univariate analysis, but not independently in multivariate analysis involving other clinical variables.35 Similarly, in the electrophysiologic study versus electrocardiographic monitoring (ESVEM) trial, although univariate analysis suggested that there was an association between the presenting arrhythmia and outcome, multivariate analysis failed to establish the predictive value of the presenting arrhythmia.38 Left ventricular ejection fraction was the single most important predictor of arrhythmic death or cardiac arrest in patients with life-threatening arrhythmias who were treated with antiarrhythmic drugs. BJ Arrhythmic episodes occurring later (after the first 24 hours, and particularly after the first week), in the course of acute MI portend a worse prognosis. The bottom line is that the importance of NSVT is often not about the NSVT itself. Most often, NSVT either does not cause any symptoms at all, or it may just cause palpitations. Survival was estimated using Kaplan–Meier curves and compared using log-rank test. most common; associated with MI; Polymorphic. Nonsustained ventricular tachycardia (NSVT) has been recognized as a usually asymptomatic rhythm disorder detected in an extremely wide range of conditions, from asymptomatic, apparently healthy, young individuals to patients with significant heart disease. However, the Multiple Risk Factor Analysis Trial (MRFAT) show that in the β-blocking era, the common arrhythmia risk variables, particularly the autonomic and standard ECG markers, have limited predictive power in identifying patients at risk of SCD.82 In 43 ± 15 months of follow-up in 675 patients, SCD was weakly predicted only by reduced LVEF (<40%), NSVT, and abnormal SAECG but not by autonomic markers or ECG variables. Monserrat Relatively slow, often asymptomatic nonsustained episodes of monomorphic VT may be documented on prolonged ambulatory recordings. W Brugada However, cases with an inferior axis, that is, of anterior fascicular origin, have also been described.47,48, The most systematic attempts to characterize the electrocardiographic pattern of NSVT have been reported to be successful in patients with the so-called repetitive monomorphic VT, originally described by Gallavardin.49 This arrhythmia represents a form of the spectrum of idiopathic ventricular outflow tachycardias, which includes repetitive uniform premature ventricular contractions (PVCs) and exercise-triggered paroxysmal VT. Non-sustained ventricular tachycardia in hypertrophic cardiomyopathy: an independent marker of sudden death risk in young patients. Call 911 or seek emergency care if you have difficulty breathing or chest pains lasting for more than a few minutes. and Stevenson, W.G. Link, in Encyclopedia of Cardiovascular Research and Medicine, 2018. In contrast, another study of 355 patients with a dilated cardiomyopathy demonstrated that NSVT evident on ambulatory monitoring was an independent predictor of mortality (risk ratio = 1.63; P = .02).68 Other findings on ambulatory monitoring that were predictive of risk included mean heart rate and heart rate range. Nonsustained VT is commonly detected during ECG monitoring in heart failure patients with both ischemic and nonischemic cardiomyopathies.46 The frequency and complexity of ventricular ectopy are likely to increase during periods of worsening heart failure. Sustained ventricular tachycardia is considered more deadly than non-sustained ventricular tachycardia; however the latter is more prevalent. Pires , Henderson E, Morris KI et al. If no cardiac condition is detected, then typically no treatment is required as non-sustained ventricular tachycardiadoes not pose any substantial risks to cardiac arrests. Demosthenes G Katritsis, A.John Camm, Nonsustained ventricular tachycardia: where do we stand?, European Heart Journal, Volume 25, Issue 13, 1 July 2004, Pages 1093–1099, https://doi.org/10.1016/j.ehj.2004.03.022. Even in the case where it does hold prognostic significance, NSVT is not necessarily involved in the mechanism of death. The independent prognostic significance of NSVT depends on the underlying condition (Table 43-2). Patients at risk for sudden cardiac death and who also have discordant contraction of left ventricular function may benefit from cardiac resynchronisation therapy (CRT).

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