Ventricular late potentials: a critical overview and current applications
Introduction
Sudden cardiac death (SCD) is a leading cause of mortality in our society and remains a major clinical challenge for the cardiologists. In recent years, implantable cardioverter defibrillators (ICDs) have allowed a significant reduction of mortality in patients at high risk of SCD. However, the identification of these patients remains less than optimal, and a considerable number of patients receive a prophylactic ICD without any therapeutic intervention over time and, therefore, without any actual clinical benefit. Clinical trials of primary prevention of SCD focused mainly on left ventricular (LV) function to select patients at risk eligible for ICD implant, and current international guidelines give prophylactic ICD indications on the basis of LV ejection fraction (LVEF) only.
However, it is now clear that depressed LV function by itself is not sufficient to correctly identify patients at highest risk of SCD and, therefore, that current guidelines lack the precision and convenience that clinical cardiologists seek to accept the costs and some possible annoying and dangerous consequences of ICD therapy.1
Thus, the improvement of risk stratification of cardiac patients by other diagnostic (in particular, noninvasive) tests would be welcome because it would have evident individual and social favorable impact. In the previous decades, several variables based on electrocardiographic (ECG) signal analysis have been suggested to be potential powerful predictors of major cardiac events and SCD, but there has been limited attention about how most of these findings could be used in clinical practice.1
In this article, the evidence for the prognostic value of ventricular late potentials (VLPs), a marker of anatomical substrate for reentry ventricular arrhythmias, will be briefly reviewed. Because most of the clinical research in this field concerned risk stratification of patients with a history of myocardial infarction (MI), the article is largely focused on this population of patients, but the role of VLPs in some specific cardiac diseases is also briefly discussed.
Section snippets
Definition and technical aspects
The VLPs represent low-amplitude electrical signals at the end of the QRS complex that are generated by diseased myocardium, activated slower and later than its usual timing in the cardiac cycle.1, 2
Because of their very low amplitude (in the order of microvolts), VLPs cannot be usually recognized on standard 12-lead ECG, thus requiring an amplified high-resolution ECG recording for their identification. Also in this case, the correct identification of VLPs could be hindered by electrical noise
Pathophysiological bases for VLPs
As anticipated previously, VLPs represent delayed conduction through a diseased myocardium and therefore indicate the presence of a potential anatomical substrate for reentry ventricular arrhythmias.1, 2
Such anatomical substrate is theoretically able to cause delayed conduction and produce VLPs, which have been reported in several clinical conditions, including in particular not only dilated cardiomyopathy4 and arrhythmogenic right ventricular cardiomyopathy,5 but also hypertrophic
VLPs after AMI
Most studies on VLPs in AMI patients were performed before the reperfusion era.7 The VLPs were found as early as 3 hours after MI onset and to increase in prevalence during the first 7 to 10 days. The VLPs usually remain stable thereafter, although they can disappear in some patients in the next year. If not present at discharge, on the other hand, VLPs do not usually appear later.8 For these reasons, to achieve the best prognostic value, SA-ECG to assess VLPs should be recorded 7 to 10 days
Effect on VLPs of other therapeutic interventions in AMI patients
The effect on the prevalence of VLPs of modern pharmacologic therapy in patients with AMI has been assessed in several studies. Santarelli et al,18 analyzing data from the multicenter Late Potential Italian Study, reported that VLPs were less frequent to occur in AMI patients treated with β blockers compared with those not treated by β blockers during hospitalization, although this effect was found only in patients with a sufficiently preserved LVEF (Œ40%). Junker et al,19 on the other hand, in
VLPs in predicting sustained VT in patients with ischemic heart disease
The value of VLPs in patients who have documented sustained VT and chronic ischemic heart disease has also been largely investigated. The prevalence of VLPs in these patients was shown to range from 52% to 90%. On the other hand, VLPs are less frequent (21%-65%) in patients resuscitated from ventricular fibrillation. The clinical value of these findings, however, is less useful in these populations of patients because they have clear clinical indications to specific antiarrhythmic treatment
VLPs in nonischemic cardiomyopathies
Although the VLP substrate in patients with ischemic heart disease is localized in regions within and surrounding infarcted tissues, in nonischemic cardiomyopathy, the disease process is usually global, affecting the entire ventricular mass. The diffuse interstitial fibrosis often characterizing the pathology of nonischemic cardiomyopathies leads to conduction abnormalities, including bundle-branch block and nonspecific intraventricular conduction defects. The degree of myocardial fibrosis
VLPs in the evaluation of syncope
A further interesting application of VLPs is in the diagnostic workup of patients with syncope of unknown origin. This is a puzzling problem for the cardiologist, and possible causes include both cardiac bradyarrhythmia and tachyarrhythmia. The SA-ECG might be performed as a screening tool in these patients, as the detection of VLP might implicate a possible VT-related nature of the syncope. Although the absence of VLPs does not allow exclusion of completely ventricular arrhythmias, some data
Conclusions
In summary, VLPs were found to be highly predictive of cardiac events, in particular, of arrhythmic events, in patients with CAD and prior MI, although their prognostic role seems to be reduced in the group of patients who undergo primary mechanical revascularization by PCI. The weakness of VLPs is their low positive predictive value. On the other hand, the negative predictive accuracy is high in the general population of AMI patients. Their absence, therefore, should be reassuring about
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Cited by (38)
A Study of Cardiac Function, Atherosclerosis, and Arrhythmogenicity
2017, The Heart in Rheumatic, Autoimmune and Inflammatory Diseases: Pathophysiology, Clinical Aspects and Therapeutic ApproachesThe ventricular late potentials in children with vasodepressor response of vasovagal syncope
2016, International Journal of CardiologySignal-averaged and standard electrocardiography in patients with newly diagnosed epilepsy
2012, Epilepsy and BehaviorCitation Excerpt :Ventricular late potentials (VLPs) appear in the terminal part of the QRS complex and are seen in patients with delayed activation of the myocardium. In patients with a low ejection fraction after acute myocardial infarction (AMI) [14] or arrhythmogenic right ventricular cardiomyopathy (ARVC) [15], the presence of VLPs is associated with an increased risk of ventricular tachycardia (VT) or fibrillation (VF). Arrhythmogenic right ventricular cardiomyopathy is the most frequent cause of sudden cardiac death in previously healthy young individuals [16].
Ventricular late potentials and myocardial fibrosis in hypertrophic cardiomyopathy
2020, Journal of ElectrocardiologyCitation Excerpt :A study consisting of 64 HCM patients and 50 age- and sex-matched control subjects also demonstrated a VLP incidence of 20% in HCM patients, although it was only 4% in control subjects [23]. As the presence of VLPs is considered to reflect delayed conduction in myocardial areas within and surrounding myocardial fibrosis [24], its clinical value has been extensively explored without success in patients with HCM, leading to rapid decline of the initial enthusiasm for VLPs [24,25]. It is still under investigation how this unique index should be applied to the management of patients with HCM, e.g., risk stratification.
The presence of late potentials after percutaneous coronary intervention for the treatment of acute coronary syndrome as a predictor for future significant cardiac events resulting in re-hospitalization
2019, Journal of ElectrocardiologyCitation Excerpt :In case that LP becomes positive after PCI despite the above-mentioned preventive intervention, we would like to recommend detailed medical interview during the outpatient clinic, frequent ECG examination, and appropriate follow-up of CAG, to minimize a risk of recurrent ischemic events. SAECG has been widely used as a sensitive ECG monitoring especially for potential LP assessment; however, it limits its ability to capture the circadian variation of LP [1]: In contrast, HR ambulatory ECG enables us to perform a 24-h continuous recording providing robust LP time-course variation data including worst, mean and best values of LP-related indices. Our results indicate that LP positive in only the worst value but not mean or best value obtained from the 24-h continuous QRS wave data can be the statistically reliable predictor for a risk of re-hospitalization.