Nonsustained ventricular tachycardia in the setting of acute myocardial infarction: tachycardia characteristics and their prognostic implications

Hyperuricemia is associated with an increased prevalence of ventricular tachycardia and fibrillation in patients with ST-elevation myocardial infarction after primary percutaneous coronary intervention

Background

Little is known about the association between hyperuricemia and ventricular tachycardia and fibrillation (VT/VF) in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI).

Methods

The data from a cohort of STEMI patients undergoing PPCI at our center from January 2013 to December 2018 were retrospectively analyzed. The endpoint of the study was the occurrence of VT/VF, including (1) non-sustained ventricular tachycardia (nsVT) on Holter monitoring; (2) sustained ventricular tachycardia (SVT)/VF on cardiac monitoring.

Results

Of the 634 patients included in the study, 147 (23.2%) of them had hyperuricemia. The occurrence of VT/VF after PPCI was significantly higher in patients with hyperuricemia (19.0 vs. 9.4%, p = 0.001) compared with those without hyperuricemia. Hyperuricemia was associated with a significantly higher risk of VF/VT (odds ratio (OR) 2.11; 95% CI 1.11–4.03; p = 0.024). The strength of this association remained statistically after adjustments for age, sex, history of hypertension, estimated glomerular filtration rate, hypersensitive C reactive protein, plasma natrium, peak troponin I, fasting glucose, B-type natriuretic peptides and VT/VF in PPCI (adjusted odds ratio 2.73; 95% CI 1.19–6.27; p = 0.018).

Conclusions

There is a significant association between hyperuricemia and increased prevalence of VT/VF in STEMI patients after PPCI, independently of multiple risk factors and potential confounders.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02635-4.

Electrical storm reveals worse prognosis compared to myocardial infarction complicated by ventricular tachyarrhythmias in ICD recipients

Both acute myocardial infarction complicated by ventricular tachyarrhythmias (AMI–VTA) and electrical storm (ES) represent life-threatening clinical conditions. However, a direct comparison of both sub-groups regarding prognostic endpoints has never been investigated. All consecutive implantable cardioverter-defibrillator (ICD) recipients were included retrospectively from 2002 to 2016. Patients with ES apart from AMI (ES) were compared to patients with AMI accompanied by ventricular tachyarrhythmias (AMI–VTA). The primary endpoint was all-cause mortality at 3 years, secondary endpoints were in-hospital mortality, rehospitalization rates and major adverse cardiac event (MACE) at 3 years. A total of 198 consecutive ICD recipients were included (AMI–VTA: 56%; ST-segment elevation myocardial infarction (STEMI): 22%; non-ST-segment myocardial infarction (NSTEMI) 78%; ES: 44%). ES patients were older and had higher rates of severely reduced left ventricular ejection fraction (LVEF) < 35%. ES was associated with increased all-cause mortality at 3 years (37% vs. 19%; p = 0.001; hazard ratio [HR] = 2.242; 95% CI 2.291–3.894; p = 0.004) and with increased risk of first cardiac rehospitalization (44% vs. 12%; p = 0.001; HR = 4.694; 95% CI 2.498–8.823; p = 0.001). This worse prognosis of ES compared to AMI–VTA was still evident after multivariable adjustment (long-term all-cause mortality: HR = 2.504; 95% CI 1.093–5.739; p = 0.030; first cardiac rehospitalization: HR = 2.887; 95% CI 1.240–6.720; p = 0.014). In contrast, the rates of MACE (40% vs. 32%; p = 0.326) were comparable in both groups. At long-term follow-up of 3 years, ES was associated with higher rates of all-cause mortality and rehospitalization compared to patients with AMI–VTA.

Nonsustained ventricular tachycardia in heart failure with preserved ejection fraction

BACKGROUND

Ventricular tachycardia (VT) is a common arrhythmia in heart failure with reduced ejection fraction but its incidence, predictors, and significance have not been determined in heart failure with preserved ejection fraction (HFpEF).

METHODS

We performed a retrospective review of arrhythmias in two cohorts of patients with an HFpEF diagnosis. Patients in cohort 1 (n = 40) underwent routine arrhythmia surveillance with a 14-day ambulatory electrocardiogram (ECG) monitor. Patients in cohort 2 (n = 85) had cardiac pacemakers and underwent routine device interrogations.

RESULTS

In cohort 1, 13 patients (32.5%) had one or more episodes of nonsustained VT (NSVT) on ambulatory ECG. In cohort 2, 38 patients (44.7%) had NSVT on cardiac pacemaker interrogations. During a median (interquartile range) follow-up of 3.0 (1.6 to 5.1) years, 15 (12%) patients died (20% of patients with NSVT versus 6.8% of those without NSVT; P = .03). In logistic regression analysis, NSVT was associated with a 3.4-fold higher odds of death (95% confidence interval 1.08 to 10.53; P = .04) in HFpEF.

CONCLUSIONS

In conclusion, patients with HFpEF have a relatively high, and possibly underappreciated, burden of NSVT, which confers a higher risk of mortality. The frequent episodes of NSVT in these patients may provide insight into the mechanism of sudden cardiac death in HFpEF.

Prognostic significance of non-sustained ventricular tachycardia on stored electrograms in pacemaker recipients

Background

Little is known about the prognostic significance of non-sustained ventricular tachycardia (NS-VT) in outpatients scheduled for routine pacemaker controls. We therefore sought to investigate the prognostic significance of non-sustained ventricular tachycardia on stored electrograms in pacemaker recipients.

Methods

We enrolled patients implanted with dual chamber pacemaker for atrioventricular block or sinus node dysfunction from 2010 to 2016, with LVEF> 45%, older than 18 years, with at least 3 device interrogations at follow-up. Data were collected about medical history, pharmacological therapy at implantation, pacemaker programming, NS-VT occurrence, long-term survival.

Results

A total of 308 patients were included in the final analysis, with median follow-up time of 56 months. No ventricular arrhythmic episodes were documented in 221 patients (Group 1), whereas 87 had at least 1 episode of NS-VT during follow-up (Group 2). As a whole, 282 episodes of NS-VT were documented. There was a higher prevalence of previous myocardial infarction and slightly lower left ventricular ejection fraction (LVEF) in Group 2. The primary endpoint (all-cause mortality) occurred in 50 patients (22%) of Group 1 and 12 (14%) patients of Group 2 (p = 0.07). Clinical predictors of all-cause mortality at univariate analysis included age, LVEF and coronary artery disease (CAD). Only age and CAD, however, remained as predictors of mortality at multivariable analysis. A sizeable, but not statistically significant, portion of patients who died had a de novo occurrence of NS-VT at the last pacemaker check.

Conclusion

Our data do not support a prognostic role for the detection of NS-VT during pacemaker controls.

Long term follow-up of patients with ventricular high rate events detected on remote monitoring of pacemakers

Aims

Previous data suggest ventricular high rate episodes (VHREs) on pacemakers are frequent and not associated with overall mortality on short term follow up. We sought to determine whether VHREs are associated with mortality, device upgrade, or change in ejection fraction on long term follow up.

Methods

A single center, retrospective study was performed on 542 patients with permanent pacemakers followed between 2011 and 2013. Follow-up was extended to 2017 for determination of long term outcomes. “True” VHREs were defined as episodes adjudicated to be due to non-sustained ventricular tachycardia on review of electrograms and “false” VHREs were defined as supraventricular arrhythmias or noise.

Results

VHRE occurred in 202(37.2%)/542 included patients. True VHRE was detected in 148(27.3%) while 54(10%) had false VHRE. The mean age of the population was 72 ± 15 years and 46% were women. Mean follow-up was 3.3 ± 1.4 years. The baseline characteristics of the true, false and no VHRE patients were similar. There was no difference in all-cause mortality between groups (27% mortality in true VHRE, 33% in false VHRE and 29% in no VHRE). Furthermore, there was no difference between groups with regards to any device upgrade (5% any upgrades in the VHRE, 9% in false VHRE and 5% in no VHRE.) On follow up, EF declined in all groups: −4% vs −2.4% vs −3.5% for true, false and no VHRE.

Conclusion

VHRE are frequently encountered on remote monitoring of pacemakers and not associated with increased risk of mortality or need for downstream device upgrade.

How to manage various arrhythmias and sudden cardiac death in the cardiovascular intensive care

In the clinical practice of cardiovascular critical care, we often observe a variety of arrhythmias in the patients either with (secondary) or without (idiopathic) underlying heart diseases. In this manuscript, the clinical background and management of various arrhythmias treated in the CCU/ICU will be reviewed. The mechanism and background of lethal ventricular tachyarrhythmias vary as time elapses after the onset of MI that should be carefully considered to select a most suitable therapy. In the category of non-ischemic cardiomyopathy, several diseases are known to be complicated by the various ventricular tachyarrhythmias with some specific mechanisms. According to the large-scale registry data, the most common arrhythmia is atrioventricular block. It is essential for the decision of permanent pacemaker indication to rule out the presence of transient causes such as ischemia and electrolyte abnormalities. The prevalence of atrial fibrillation (AF) is very high in the patients with heart failure (HF) and myocardial infarction (MI). AF and HF have a reciprocal causal relationship; thus, both are associated with the poor prognosis. Paroxysmal AF occurs in 5 to 20% during the acute phase of MI and triggered by several specific factors including pump failure, atrial ischemia, and autonomic instability. After the total management of patients with various arrhythmias and basic heart diseases, the risk of sudden cardiac death should be stratified for each patient to assess the individual need for preventive therapies. Finally, it is recommended that the modalities of the treatment and prophylaxis should be selected on a case-by-case basis in the scene of critical care.

Prognostic significance of nonsustained ventricular tachycardia in patients receiving cardiac resynchronization therapy for primary prevention: Analysis of the Japan cardiac device treatment registry database

Background

Whether nonsustained ventricular tachycardia (NSVT) is a marker of increased risk of sustained ventricular tachyarrhythmias (VTAs) remains to be established in patients receiving cardiac resynchronization therapy with a defibrillator (CRT‐D) for primary prevention.

Methods

Among the follow‐up data of the Japan cardiac device treatment registry (JCDTR) with an implantation date between January 2011 and August 2015, information regarding a history of NSVT before the CRT‐D implantation for primary prevention had been registered in 269 patients. Outcomes were compared between two groups with and without NSVT: NSVT group (n = 179) and No NSVT group (n = 90).

Results

There was no significant difference with regard to age, gender, and NYHA class between the two groups. Left ventricular ejection fraction (LVEF) was 25.6% in the NSVT group and 28.0% in the No NSVT group (P = .046). The rate of appropriate therapy at 24 months was 26.0% and 18.4% in the NSVT and No NSVT groups (P = .22), respectively. Survival free from heart failure death was reduced in the NSVT group, as compared with the No NSVT group, with the rate of 90.2% vs 97.2% at 24 months (P = .030). A multivariate analysis identified a history of NSVT, anemia, and no use of angiotensin‐converting enzyme inhibitor (ACEI) or angiotensin‐receptor blocker (ARB) as predictors of heart failure death.

Conclusions

NSVT appears to be a surrogate marker of severe heart failure rather than a substrate for subsequent sustained VTAs in patients with CRT‐D for primary prevention.

Effects of rosuvastatin and atorvastatin on nonsustained ventricular tachycardia in patients with ST-elevation myocardial infarction: a retrospective analysis

BACKGROUND/AIMS

Early and intensive atorvastatin treatment can decrease nonsustained ventricular tachycardia (nsVT) in patients with ST-segment elevation myocardial infarction (STEMI). The objective of this study was to compare the effects of hydrophilic rosuvastatin and lipophilic atorvastatin on nsVT in STEMI patients treated with primary percutaneous coronary intervention (PCI).

METHODS

The data from a cohort of patients undergoing primary PCI at Jinhua Municipal Central Hospital from January 1, 2013 through June 30, 2016 were analyzed. The patients were divided into the rosuvastatin group and the atorvastatin group based on which kind of statins that they had received. The endpoint of the study was the occurrence of nsVT on either electrocardiogram monitoring or Holter monitoring.

RESULTS

A total of 301 patients were enrolled in the study (rosuvastatin group: n = 103; atorvastatin group: n = 198). The baseline and procedural characteristics were similar between the two groups, except that total ischemic time in the rosuvastatin group was markedly longer than that in the atorvastatin group (8 (5-16) h vs. 6 (4-12) h; P = 0.001). The administration of rosuvastatin was significantly associated with lower occurrence of nsVT than that of atorvastatin (9.71 vs. 19.70%; P = 0.026). Multivariable logistic regression analysis suggested that the independent predictors of nsVT included rosuvastatin (odds ratio (OR) 0.397, 95% confidence interval (CI) 0.176-0.894), current smoking (OR 2.307, 95% CI 1.011-5.262), and left ventricular ejection fraction (LVEF) (OR 1.060, 95% CI 1.023-1.098).

CONCLUSIONS

The effects of rosuvastatin on nsVT might be better than that of atorvastatin in STEMI patients undergoing primary PCI.

2017 ISHNE-HRS expert consensus statement on ambulatory ECG and external cardiac monitoring/telemetry

Ambulatory ECG (AECG) is very commonly employed in a variety of clinical contexts to detect cardiac arrhythmias and/or arrhythmia patterns which are not readily obtained from the standard ECG. Accurate and timely characterization of arrhythmias is crucial to direct therapies that can have an important impact on diagnosis, prognosis or patient symptom status. The rhythm information derived from the large variety of AECG recording systems can often lead to appropriate and patient-specific medical and interventional management. The details in this document provide background and framework from which to apply AECG techniques in clinical practice, as well as clinical research.

Clinical Significance of Nonsustained Ventricular Tachycardia on Stored Electrograms in Permanent Pacemaker Patients

BACKGROUND

Permanent pacemaker electrograms record a variety of arrhythmias, including nonsustained ventricular tachycardia (NSVT). Little has been reported regarding incidence and clinical significance of NSVT in pacemaker patients after long-term monitoring.

METHODS

Records from all patients implanted with Medtronic pacemakers (Medtronic, Minneapolis, MN, USA) at a single institution from January 1, 2009 to February 27, 2012 were reviewed. Demographic characteristics, imaging studies, pacemaker interrogations, and the Social Security Death Index were examined in patients older than 18 years of age who had ≥ 2 follow-up device interrogations.

RESULTS

A total of 262 patients with an ejection fraction (EF) >40% were included in the final analysis with a mean follow-up of 29.2 months. Of these patients, 83.2% (n = 218) had hypertension (HTN) and 45.4% (n = 119) had NSVT. Among patients with an EF ≥ 55%, hypertensive patients had a NSVT burden 2.46 times greater than normotensive patients (incidence rate ratio: 2.46, 95% confidence interval: 1.10-5.50; P < 0.028). NSVT was not associated with increased mortality (P < 0.1229).

CONCLUSION

In this cohort of patients, there was a high prevalence of HTN and while hypertensive subjects had a significantly higher NSVT burden, NSVT was not associated with an increased mortality.

Prognostic Significance of Nonsustained Ventricular Tachycardia Episodes Occurring Early After Implantable Cardioverter-Defibrillator Implantation Among Patients With Left Ventricular Dysfunction

Nonsustained ventricular tachycardias (NSVTs) are frequently observed in patients with left ventricular (LV) dysfunction. The prognostic implications of such NSVTs are conflicting. Our objective was to determine the relation between the burden of NSVT occurring early (within the first 6 months after ICD implant) and prognosis among ICD patients with LV dysfunction. We followed 416 ICD patients (age: 65 ± 11 years; LV ejection fraction: 30 ± 8; ischemic origin: 62%; primary prevention: 63%) with LV dysfunction for 41 ± 27 months. ICD programming was standardized. NSVT was defined as any VT of ≥5 beats at ≥150 beats/min which did not meet the detection criteria occurring within the first 6 months after ICD implant. A total of 250 patients (60%) presented at least one NSVT (median = 2; interquartile range 0 to 7). We classified the patients into 3 groups according to the number of NSVTs: no NSVT (n = 166); 1 to 5 NSVTs (n = 130); and >5 NSVTs (n = 120). The incidence of cardiac mortality (7.2% vs 17.7% vs 31.7%; p = 0.003), hospitalizations for heart failure (10.6% vs 24.4% vs 44.7%; p <0.001), and appropriate shock (15.7% vs 24.8% vs 43.8%; p <0.001) increased significantly with the number of NSVTs. By multivariate analysis, >5 NSVTs were found to be an independent predictor of cardiac mortality (hazard ratio [HR] 1.75; p = 0.03), hospitalization due to heart failure (HR 1.72; p = 0.001), and appropriate shock (HR 1.89; p <0.001) but not of inappropriate therapy (HR 0.9; p = 0.6). In conclusion, among ICD patients with LV dysfunction, NSVT episodes occurring in the first 6 months after implant are independently associated with a poor prognosis. Subjects with >5 NSVTs are at the highest risk.

When to consider an implantable cardioverter defibrillator following myocardial infarction?

After reading this article the reader should be familiar with: Current guidelines for implantable cardioverter defibrillator (ICD) use post myocardial infarction (MI) and ischaemic cardiomyopathy. Primary prevention ICD guidelines. Secondary prevention ICD guidelines. Non-sustained ventricular tachycardia in patients post MI and the use of ICDs. Programming ICDs.

Rapid-rate nonsustained ventricular tachycardia found on implantable cardioverter-defibrillator interrogation: relationship to outcomes in the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial)

OBJECTIVES

The aim of this study was to examine rapid-rate nonsustained ventricular tachycardia (RR-NSVT) during routine implantable cardioverter-defibrillator (ICD) evaluation in patients with heart failure and its relationship to outcomes.

BACKGROUND

The clinical implications of RR-NSVT identified during routine ICD interrogation are unclear. In this study, the occurrence of RR-NSVT and its association with ICD shocks and mortality in SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) were examined.

METHODS

The 811 patients who received ICDs in SCD-HeFT constituted the study population. The occurrence of RR-NSVT and its association with ICD shocks and mortality in SCD-HeFT were examined.

RESULTS

RR-NSVT was documented on ICD interrogation in 186 of 811 patients (22.9%). The mean duration of RR-NSVT was 26.4 ± 9.1 beats (7.5 ± 2.6 s), with a mean cycle length of 259 ± 32 ms. Polymorphic RR-NSVT accounted for 56% of episodes. Compared with patients without RR-NSVT, those with RR-NSVT were less likely to be taking beta-blockers, statins, or aspirin at enrollment. After adjusting for other known predictors of mortality in SCD-HeFT, RR-NSVT was independently associated with appropriate ICD shocks (hazard ratio: 4.25; 95% confidence interval: 2.94 to 6.14; p < 0.0001), with all-cause mortality (hazard ratio: 2.40; 95% confidence interval: 1.62 to 3.54; p < 0.0001), and with a composite of all-cause mortality and appropriate ICD shocks (hazard ratio: 3.03; 95% confidence interval: 2.21 to 4.15; p < 0.0001).

CONCLUSIONS

RR-NSVT identified on routine ICD interrogation should be considered an important clinical event. RR-NSVT during ICD interrogation is associated with appropriate ICD shocks and all-cause mortality. The clinical evaluation of patients with RR-NSVT should include intensification of medical therapy, particularly beta-blockers, or other appropriate clinical interventions. (Sudden Cardiac Death in Heart Failure Trial [SCD-HeFT]; NCT00000609).

Nonsustained ventricular tachycardia

Nonsustained ventricular tachycardia (NSVT) has been recorded in a wide range of conditions, from apparently healthy individuals to patients with significant heart disease. In the absence of heart disease, the prognostic significance of NSVT is debatable. When detected during exercise, and especially at recovery, NSVT indicates increased cardiovascular mortality within the next decades. In trained athletes, NSVT is considered benign when suppressed by exercise. In patients with non-ST-segment elevation acute coronary syndrome, NSVT occurring beyond 48 h after admission indicates an increased risk of cardiac and sudden death, especially when associated with myocardial ischemia. In acute myocardial infarction, in-hospital NSVT has an adverse prognostic significance when detected beyond the first 13 to 24 h. In patients with prior myocardial infarction treated with reperfusion and beta-blockers, NSVT is not an independent predictor of long-term mortality when other covariates such as left ventricular ejection fraction are taken into account. In patients with hypertrophic cardiomyopathy, and most probably genetic channelopathies, NSVT carries prognostic significance, whereas its independent prognostic ability in ischemic heart failure and dilated cardiomyopathy has not been established. The management of patients with NSVT is aimed at treating the underlying heart disease.

Clinical characteristics and prevalence of early repolarization associated with ventricular arrhythmias following acute ST-elevation myocardial infarction

Early repolarization (ER) on a 12-lead electrocardiogram has recently been associated with ventricular tachyarrhythmias (VTAs) in patients without structural heart disease and in patients with healed myocardial infarction (MI). An association between ER and VTAs in the setting of acute ST-segment elevation MI (STEMI) has not been explored. In a single-center retrospective case-control design, 50 patients with STEMI complicated by VTAs (cases), defined as ventricular fibrillation, sustained ventricular tachycardia, or nonsustained ventricular tachycardia within 72 hours of the index hospitalization, were matched for age and gender with 50 subjects with STEMI without VTAs (controls). Electrocardiograms obtained an average of 1 year before STEMI were analyzed for ER pattern, defined as notching or slurring of the terminal QRS complex or J-point elevation >0.1 mV above baseline in ≥ 2 contiguous leads. A higher prevalence of ER was associated with VTAs overall in cases compared to controls (26% vs 4%, p = 0.01) and localized to anterior (16% vs 0%) and inferior (14% vs 2%, p = 0.07) leads but not lateral limb leads. Notching (10% vs 2%, p = 0.1) and J-point elevation (16% vs 0%) were more common in cases. Slurring was uncommon. ER was associated with VTAs (odds ratio [OR] 6.5, 95% confidence interval [CI] 1.5 to 28.8, p = 0.01), even after adjustment for creatine kinase-MB (OR 9.2, 95% CI 1.6 to 53.4, p = 0.01) and ejection fraction (OR 5.7, 95% CI 1.2 to 27.1, p = 0.03). In conclusion, ER is associated with VTAs in patients with STEMI even after adjustment for left ventricular ejection fraction or creatine kinas-MB levels. Larger prospective studies exploring potential associations and mechanisms of ventricular arrhythmogenesis with ER pattern are needed.

Myocardial ischemia and ventricular tachycardia on continuous electrocardiographic monitoring and risk of cardiovascular outcomes after non-ST-segment elevation acute coronary syndrome (from the MERLIN-TIMI 36 Trial)

Among patients with non-ST-segment elevation acute coronary syndromes, recurrent ischemia and ventricular arrhythmias detected on continuous electrocardiographic monitoring remain common events that are associated with worse outcomes. The relative clinical significance of both events together is not well described. We determined the risk associated with ischemia (≥1 mm ST depression lasting ≥1 minutes) and ventricular tachycardia (VT) (≥4 beats) detected on 7-day continuous electrocardiographic monitoring in 6,355 patients with non-ST-segment elevation acute coronary syndromes from the Metabolic Efficiency with Ranolazine for Less Ischemia in Non-ST-elevation Acute Coronary Syndrome-Thrombolysis In Myocardial Infarction (MERLIN-TIMI) 36 trial. The patients were categorized into 4 groups according to the presence or absence of VT and ischemia. Cardiovascular death, sudden cardiac death (SCD), myocardial infarction, and recurrent ischemia were assessed during a median follow-up of 348 days. A total of 60.0% patients had no VT or ischemia, 20.0% had VT alone, 14.7% had ischemia alone, and 5.3% had both. The patients with either VT or ischemia were at increased risk of cardiovascular outcomes. The combination of ischemia and VT identified a particularly high-risk population for cardiovascular death (10.1% vs 3.0%, p <0.001), SCD (7.8% vs 0.9%, p <0.001), and myocardial infarction (15.4% vs 6.2%, p <0.001) compared to patients with neither. The addition of arrhythmia and ischemia significantly improved the clinical model for predicting cardiovascular death or SCD (p <0.001). In patients with both ischemia and VT, 66.6% of SCD occurred within 90 days of the non-ST-segment elevation acute coronary syndromes. In conclusion, in >6,300 patients with non-ST-segment elevation acute coronary syndromes, the presence of myocardial ischemia or VT alone, and particularly in combination, was independently associated with poor cardiovascular outcomes and thus provides incremental improvement in early risk stratification.

The persistent sodium current blocker riluzole is antiarrhythmic and anti-ischaemic in a pig model of acute myocardial infarction

BACKGROUND

The potential of the cardiac persistent sodium current as a target for protection of the myocardium from ischaemia and reperfusion injury is gaining increasing interest. We have investigated the anti-ischaemic and antiarrhythmic effects of riluzole, a selective INaP blocker, in an open chest pig model of infarction.

METHODS AND PRINCIPAL FINDINGS

The left anterior descending coronary artery (LAD) was ligated in 27 anesthetised pigs (landrace or large white, either sex, 20-35 kg) which had received riluzole (8 mg/kg IP; n = 6), lidocaine (2.5-12 mg/kg bolus plus 0.05-0.24 mg/kg/min; n = 11) or vehicle (n = 10) 50 min prior. Arrhythmias could be delineated into phase 1a (0 to 20 min), phase 1b (20 to 50 min) and phase 2 (from 50 min to termination at 180 min) and were classified as premature ventricular contractions (PVCs), non-sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) (spontaneously reverting within 15 s) or sustained VT or VF (ie. requiring cardioversion at 15 s). Riluzole reduced the average number of all arrhythmias in Phase 2 (PVCs from 484+/-119 to 32+/-13; non sustained arrhythmias from 8.9+/-4.4 to 0.7+/-0.5; sustained arrhythmias from 3.9+/-2.2 to 0.5+/-0.4); lidocaine reduced the average number of non-sustained and sustained arrhythmias (to 0.4+/-0.3 and 0.4+/-0.3 respectively) but not PVCs (to 390+/-234). Riluzole and lidocaine reduced the average number of sustained arrhythmias in phase 1b (from 1.8+/-0.4 to 0.17+/-0.13 (p<0.02) and to 0.55+/-0.26 (p = ns) respectively). Neither lidocaine or riluzole changed the ECG intervals: there was no statistical significance between groups at time zero (just before ligation) for any ECG measure. During the course of the 3 hour period of the ischaemia R-R, and P-R intervals shortened slightly in control and riluzole groups (not significantly different from each other) but not in the lidocaine group (significantly different from control). QRS and QTc did not change appreciably in any group Riluzole reduced the degree of histopathological tissue damage across the infarct zone considerably more than did lidocaine.

CONCLUSIONS

At the doses used, riluzole was at least as effective as lidocaine at reducing the number of episodes of ischaemic VT or VF in pigs, and much more effective at reducing the number of PVCs. We propose that this is related to the ability of riluzole to block cardiac persistent sodium current.

beta-Blocker use following myocardial infarction: low prevalence of evidence-based dosing

BACKGROUND

Quality improvement programs have shown increased use of beta-blockers post-myocardial infarction (MI), but there are no data on whether appropriate doses are administered.

METHODS

In a prospective registry that enrolled consecutive patients with MI, we evaluated beta-blocker dosing at discharge after MI and 3 weeks later and assessed clinical predictors for treatment with very low doses. We studied 1,971 patients (70.8% male) with a mean age of 63.9 +/- 13.7 years, of whom 48.2% had an ST-elevation MI.

RESULTS

beta-Blocker utilization rates following MI were 93.2% at discharge: 20.1% received <25% of target dose, 36.5% received 25% of target dose, 26.4% received 26% to 50% of target dose, and 17.0% received >50% of target dose. Between discharge and 3 weeks, 76.4% had no change in beta-blocker dose, with 11.9% and 11.6% having their dose reduced and increased, respectively. Absence of hypertension, acute percutaneous coronary intervention, older age, and no angiotensin-converting enzyme inhibitor therapy were consistent predictors of treatment with very low beta-blocker doses.

CONCLUSIONS

Underdosing of beta-blockers is highly prevalent among patients post-MI. This represents an important opportunity in quality improvement for the care of patients who have suffered an MI.

Defibrillator implantation early after myocardial infarction

BACKGROUND

The rate of death, including sudden cardiac death, is highest early after a myocardial infarction. Yet current guidelines do not recommend the use of an implantable cardioverter-defibrillator (ICD) within 40 days after a myocardial infarction for the prevention of sudden cardiac death. We tested the hypothesis that patients at increased risk who are treated early with an ICD will live longer than those who receive optimal medical therapy alone.

METHODS

This randomized, prospective, open-label, investigator-initiated, multicenter trial registered 62,944 unselected patients with myocardial infarction. Of this total, 898 patients were enrolled 5 to 31 days after the event if they met certain clinical criteria: a reduced left ventricular ejection fraction (< or = 40%) and a heart rate of 90 or more beats per minute on the first available electrocardiogram (ECG) (criterion 1: 602 patients), nonsustained ventricular tachycardia (> or = 150 beats per minute) during Holter monitoring (criterion 2: 208 patients), or both criteria (88 patients). Of the 898 patients, 445 were randomly assigned to treatment with an ICD and 453 to medical therapy alone.

RESULTS

During a mean follow-up of 37 months, 233 patients died: 116 patients in the ICD group and 117 patients in the control group. Overall mortality was not reduced in the ICD group (hazard ratio, 1.04; 95% confidence interval [CI], 0.81 to 1.35; P=0.78). There were fewer sudden cardiac deaths in the ICD group than in the control group (27 vs. 60; hazard ratio, 0.55; 95% CI, 0.31 to 1.00; P=0.049), but the number of nonsudden cardiac deaths was higher (68 vs. 39; hazard ratio, 1.92; 95% CI, 1.29 to 2.84; P=0.001). Hazard ratios were similar among the three groups of patients categorized according to the enrollment criteria they met (criterion 1, criterion 2, or both).

CONCLUSIONS

Prophylactic ICD therapy did not reduce overall mortality among patients with acute myocardial infarction and clinical features that placed them at increased risk. (ClinicalTrials.gov number, NCT00157768.)

The use of periinfarct contrast-enhanced cardiac magnetic resonance imaging for the prediction of late postmyocardial infarction ventricular dysfunction

BACKGROUND

Although ejection fraction (EF) both perimyocardial infarction (MI) and late post-MI are important prognostic factors, only implantable cardioverter-defibrillator trials of post-MI patients with depressed late EF have shown improved survival. This may relate to imprecision of early EF because of post-MI stunning. We sought to determine if peri-MI infarct size, as measured by cardiac magnetic resonance (CMR), is superior to early EF to predict late post-MI EF.

METHODS

Seventy-three patients with ST-elevation MI had infarct size and EF quantified using CMR early (<1 week) and late (>3 months) post-MI.

RESULTS

Late EF was significantly correlated with early EF (R = 0.734, P < .001), and with infarct size (R = -0.661, P < .001), and both early EF and infarct size were significant predictors of late EF. Subgroup analyses showed that low late EF (<or=35%) was better predicted by infarct size than early EF. Half of the patients with early EF <or=35% had a late EF >35%. There was no difference in early EF between the subgroup with a late EF >35% compared to the subgroup with late EF </=35% (29.7% +/- 4.6% vs 28.0% +/- 4.9%, P = .414). There was, however, a significant difference between these 2 groups in infarct size (22.6% +/- 10.8% vs 34.7% +/- 7.8%, P = .011).

CONCLUSIONS

Infarct size as determined by CMR immediately post-MI is a significant predictor of late EF and is superior to early EF in patients with initially depressed EF. Further studies are warranted to assess whether infarct size estimation by CMR after acute MI can better identify patients who are at risk for sudden cardiac death than early EF.

Nonsustained ventricular tachycardia in dilated cardiomyopathy

In patients with structural heart disease, ventricular arrhythmias are associated with an increased risk of overall mortality and sudden cardiac death (SCD). Nonsustained ventricular tachycardia (NSVT) is common in patients with dilated cardiomyopathy of both ischemic and nonischemic origin. Recent studies suggest that NSVT may be a marker, but not a significant predictor, of mortality and SCD in that suppression of NSVT in these patients using antiarrhythmic drugs is of questionable benefit. Additionally, indications for implantable cardioverter defibrillator implantation do not include NSVT. This article focuses on the prognostic significance and treatment of patients with NSVT and ischemic or nonischemic dilated cardiomyopathy.

Time-dependent bias was common in survival analyses published in leading clinical journals

OBJECTIVE

In survival analysis, "baseline immeasurable" time-dependent factors cannot be recorded at baseline, and change value after patient observation starts. Time-dependent bias can occur if such variables are not analyzed appropriately. This study sought to determine the prevalence of such time-dependent bias in highly-cited medical journals.

STUDY DESIGN AND SETTING

We searched Medline databases to identify all observational studies that used a survival analysis in American Journal of Medicine, Annals of Internal Medicine, Archives of Internal Medicine, British Medical Journal, Chest, Circulation, Journal of the American Medical Association, Lancet, and New England Journal of Medicine between 1998 and 2002. Studies with "baseline immeasurable" time-dependent factors were susceptible to time-dependent bias if a time-dependent covariate analysis was not used.

RESULTS

Of 682 eligible studies, 127 (18.6%, 95% CI 15.8-21.8%) contained a "baseline immeasurable" time-dependent factor and 52 (7.6% [5.8-9.9%] of all survival analyses/40.9% [32.3-50.0%] of studies with a time-dependent factor) were susceptible to time-dependent bias. In 35 studies (5.1% [3.7-7.1%]/27.6% [20.5-35.9%]), the bias affected a variable highlighted in the study abstract and correction of the bias could have qualitatively changed the study's conclusion in over half of studies.

CONCLUSION

In medical journals, time-dependent bias is concerningly common and frequently affects key factors and the study's conclusion.

Incidence of nonsustained and sustained ventricular tachyarrhythmias in patients with an implantable cardioverter defibrillator

INTRODUCTION

Nonsustained ventricular tachycardia (NSVT) is a frequent phenomenon in some patients with heart disease, but its association with sustained ventricular tachycardias (ventricular tachycardia [VT]/ventricular fibrillation [VF]) is still not clear. The aim of this study was to determine whether NSVT incidence was associated with sustained VT/VF in patients with an implantable cardioverter defibrillator (ICD).

METHODS AND RESULTS

Retrospective data analysis was conducted in 923 ICD patients with a mean follow-up of 4 months. NSVT and sustained VT/VF were defined as device-detected tachycardias. The incidence rates of NSVT and sustained VT/VF as well as ICD therapies were determined as episodes per patient. The NSVT index was defined as the product of NSVT episodes/day times the mean number of beats per episode, i.e., total beats/day. The NSVT index peak was defined as the highest value on or prior to the day with sustained VT/VF episodes. Patients (n = 393) with NSVT experienced a higher incidence of sustained VT/VF (17.2 +/- 63.0 episodes/patient) and ICD therapies (15.2 +/- 61.4 episodes/patient) than patients (n = 530) without NSVT (sustained VT/VF: 0.5 +/- 6.6 and therapies: 0.5 +/- 5.6; P < 0.0001). Approximately 74% of NSVT index peaks occurred on the same day or <3 days prior to sustained VT/VF episodes. The index was higher for peaks < or =3 days prior to the day with sustained VT/VF (94.3 +/- 140.1 total beats/day) than for peaks >3 days prior to the day with sustained VT/VF (32.7 +/- 55.9 total beats/day; P < 0.0001).

CONCLUSION

ICD patients with NSVT represent a population more likely to experience sustained VT/VF episodes with a temporal association between an NSVT surge and sustained VT/VF occurrence.

Predictors of new malignant ventricular arrhythmias after coronary surgery

OBJECTIVES

We sought to investigate the relationship between perioperative factors and the occurrence of ventricular tachycardia (VT) and ventricular fibrillation (VF), as well as the impact of VT/VF on early and late mortality.

BACKGROUND

Both VT and VF are rare but serious complications after coronary artery bypass graft surgery (CABG), and their etiology and implications remain uncertain.

METHODS

Data on 4,411 consecutive patients undergoing CABG (1,154 [25.8%] had off-pump surgery) between April 1996 and September 2001 were extracted from a prospective database and analyzed. Odds ratios (ORs) describing associations between possible risk factors and VT/VF were estimated separately. Factors observed to be significantly associated with VT/VF were further investigated using multivariate logistic regression.

RESULTS

Sixty-nine patients suffered VT/VF (1.6%). There were 61 (1.4%) in-hospital/30-day deaths, 15 among patients who had postoperative VT/VF (21.7%). Patient factors independently associated with an increase in the odds of VT/VF included age <65 years, female gender, body mass index <25 kg/m(2), unstable angina, moderate or poor ejection fraction, and the need for inotropes and an intra-aortic balloon pump (OR 1.72 to 4.47, p < 0.05). After adjustment, off-pump surgery was associated with a substantial but nonsignificant protective effect against VT/VF (OR 0.53, 95% confidence interval [CI] 0.25 to 1.13; p = 0.10). Actuarial survival at two years was 98.2% among patients who had VT/VF and who survived to discharge/30 days, compared with 97.0% for the control group (adjusted hazard ratio 0.96 (95% CI 0.40 to 2.31, p = 0.92).

CONCLUSIONS

The incidence of VT/VF is low in patients undergoing coronary surgery but is associated with high in-hospital mortality. The late survival of the discharged VT/VF patients compares favorably with that of controls.

Noninvasive risk stratification in postinfarction patients with severe left ventricular dysfunction and methodology of the MADIT II noninvasive electrocardiology substudy

Sudden cardiac death occurs as a result of a complex interplay of changes in myocardial substrate, imbalance of autonomic regulation of the heart, and myocardial vulnerability. Noninvasive electrocardiology serves as a comprehensive tool for investigating factors representing mechanistic pathways leading to cardiac events. Heart rate variability, nonlinear dynamics of heart rate, and heart rate turbulence provide insight into autonomic control of the heart. Prognostic value of these parameters in postinfarction patients is well established for predicting cardiac death, but there is less evidence for their association with sudden death or arrhythmic events. Electrical manifestation of changes in myocardial substrate include QRS and QTc prolongation, presence of conduction disturbances, presence of late potentials, abnormalities of repolarization morphology, and presence of nonsinus rhythm, namely atrial fibrillation. Electrocardiogram (ECG) measures reflecting myocardial vulnerability to arrhythmias include frequent ventricular premature beats, T wave alternans, or QT variability. Prognostic significance of these parameters is documented in studies focused mostly on them as individual markers of risk. The noninvasive electrocardiology substudy of the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) allows for simultaneous analysis of several of the above ECG markers of risk and will provide insight about relative contribution of mechanistic pathways leading to cardiac death in postinfarction patients with severe left ventricular dysfunction. Combination of a standard 12-lead ECG and 10-minute high-resolution Holter recordings serves to evaluate the prognostic significance of noninvasive electrocardiology parameters for mortality in patients randomized to conventional treatment and for arrhythmic events in patients randomized to implantable cardioverter defibrillator therapy.

Nonsustained ventricular tachycardia. A guide to the clinical significance and management

The patient with nonsustained ventricular tachycardia represents a common management problem for the cardiologists and internists. Treatment is sometimes needed for the suppression of symptoms. More commonly, nonsustained ventricular tachycardia is asymptomatic, and the clinician must determine the prognostic importance. The prognostic implications, the role of electrophysiologic study, and the potential role of pharmacologic and defibrillator intervention depend on the underlying cardiac substrate present in the individual patient.

Ischaemic heart disease presenting as arrhythmias

Despite considerable progress in management over the recent years, coronary artery disease (CAD) remains the leading cause of death in the industrialised world. It is estimated that CAD is responsible for causing 152,000 deaths per year in the UK and one in eight deaths world-wide. Many of these deaths are attributed to the development of ventricular tachyarrhythmias during periods of myocardial ischaemia or infarction. Myocardial ischaemia is characterised by ionic and biochemical alterations, creating an unstable electrical substrate capable of initiating and sustaining arrhythmias, and infarction creates areas of electrical inactivity and blocks conduction, which also promotes arrhythmogenesis. The purpose of this chapter is to review some of the metabolic changes associated with cardiac ischaemia, their relevance to electrophysiological instability, and the clinical manifestation and management of some of the more common arrhythmias that follow cardiac ischaemia. Particular attention is given to the peri-infarction period (arbitrarily accepted as within 48 h of the index myocardial infarction) as arrhythmias are most likely to be seen around this time, and are considered to be non-indicative of long-term prognosis. In contrast, arrhythmias developing in the post-infarction period (after 48 h) have been demonstrated to be associated with an adverse outcome. Regardless of the anti-arrhythmic therapy used in treating peri- and post-infarction arrhythmias, it is presumed that patients who had a myocardial infarction or who have left ventricular dysfunction will also receive other appropriate therapies, such as aspirin, ss-blockers, cholesterol lowering agents and angiotensin converting enzymes inhibitors.

Application of noninvasive and invasive tests for risk assessment in patients with ventricular arrhythmias

Sudden cardiac death remains a major public health problem in western society. Because most patients who experience cardiac arrest are not successfully resuscitated, primary prevention of sudden death remains an important challenge. A number of noninvasive risk stratification techniques have been suggested as providing useful information in patients with underlying structural heart defects. Unfortunately, the positive predictive value of most of these techniques has been limited. Left ventricular ejection fraction, the presence of nonsustained ventricular tachycardia on Holter monitoring, and inducible sustained ventricular tachycardia at electrophysiologic testing in patients with coronary artery disease remain the best established prognostic test. However, with the exception of two ICD studies using the combination of these markers, prospective studies have not yet completely validated the use of these and other prognostic markers. Further understanding of the pathophysiology of ventricular fibrillation and other risk stratification techniques will be necessary before a clear algorithm can be developed for application to patients at risk for sudden death.

Nonsustained ventricular tachycardia

The patient with nonsustained ventricular tachycardia represents a common management problem for the cardiologist. The challenges posed by this type of arrhythmia differs from those posed by other arrhythmias, because most instances of nonsustained ventricular tachycardia do not cause symptoms. This article reviews common situations in which nonsustained ventricular tachycardia occurs and their appropriate management.

[Predictors of sudden death in coronary artery disease]

Although advances in the management of acute myocardial infarction have resulted in a decline in long-term risk of sudden death, it continues to be high in certain subsets of patients. Thus, it is important to identify and treat these patients. Left ventricular ejection fraction less than 0.40, frequent premature ventricular ectopy on Holter monitoring, late potentials on signal-averaged electrocardiogram, impaired heart rate variability, abnormal baroreflex sensitivity and inducible sustained monomorphic ventricular tachycardia during electrophysiological study are predictors of sudden death and arrhythmic events. Although the negative predictive value of each factor is high, the positive predictive accuracy is low. Several tests can be combined to obtain higher positive predictive values. In fact, in some studies combined noninvasive tests have been used to select patients for ventricular stimulation study. Some preventive treatment can be applied in these patients. Available data do not justify prophylactic therapy with amiodarone in high-risk survivors of acute myocardial infarction. Sudden death and total mortality have been significantly reduced in postinfarction patients by long-term beta blockade. Hence, beta blockers should be given to all patients with acute myocardial infarction who do not have contraindications to their use. The MADIT study has shown the beneficial effect of implantable cardioverter defibrillator in reducing mortality in patients with prior myocardial infarction, an ejection fraction less than 0.36, asymptomatic nonsustained ventricular tachycardia, and inducible sustained ventricular tachycardia, unsuppressable by procainamide. Besides, several studies are under way to evaluate the prophylactic use of implantable defibrillator for improving survival in high-risk patients.

Implantable defibrillators and antiarrhythmic drugs in patients at risk for lethal arrhythmias

The high mortality rate and frequency of ventricular arrhythmias in patients with congestive heart failure has prompted numerous clinical trials aimed at reducing mortality by addressing arrhythmic death. Recently completed trials have suggested that for patients who have survived cardiac arrest, the preferred treatment may be an implantable cardioverter defibrillator (ICD). From the standpoint of primary prevention, implantable defibrillators and amiodarone have received the most attention. It remains unclear, however, to which patients these studies apply, and if and how the results might be generalized. No available studies confirm an additional benefit of pharmacologic or device-based antiarrhythmic therapy beyond that offered by optimal treatment with beta blockers, angiotensin-converting enzyme inhibitors, and lipid-lowering drugs in the majority of patients with cardiomyopathy. Clinical trials are ongoing to address these issues.

Prevalence, characteristics and prognostic value during long-term follow-up of nonsustained ventricular tachycardia after myocardial infarction in the thrombolytic era

OBJECTIVES

The purpose of this study was to determine the prevalence, characteristics and the predictive value of nonsustained ventricular tachycardia (VT) for subsequent death and arrhythmic events after acute myocardial infarction (AMI).

BACKGROUND

Nonsustained VT has been linked to an increased risk for sudden death in coronary patients. It is unknown whether this parameter can be used for selection of high-risk patients to receive an implantable defibrillator for primary prevention of sudden death in patients shortly after AMI.

METHODS

In 325 consecutive infarct survivors, 24-h Holter monitoring was performed 10+/-6 days after AMI. All patients underwent coronary angiography, determination of left ventricular function and assessment of heart rate variability (HRV). Mean follow-up was 30+/-22 months.

RESULTS

There was a low prevalence (9%) of nonsustained VT shortly after AMI. Nonsustained VT together with depressed left ventricular ejection fraction (LVEF) was found in only 2.4% of patients. During follow-up, 25 patients reached one of the prospectively defined end points (primary composite end point of cardiac death, sustained VT or resuscitated ventricular fibrillation; secondary end point: arrhythmic events). Kaplan Meier event probability analyses revealed that only HRV, LVEF and status of the infarct-related artery were univariate predictors of death or arrhythmic events. The presence of nonsustained VT carried a relative risk of 2.6 for the primary study end point but was not a significant predictor if only arrhythmic events were considered. On multivariate analysis, only HRV, LVEF and the status of the infarct artery were found to be independently related to the primary study end point.

CONCLUSIONS

There is a low prevalence of nonsustained VT shortly after AMI. Only 2% to 3% of all infarct survivors treated according to contemporary guidelines demonstrate both depressed LVEF and nonsustained VT. The predictive value of nonsustained VT for subsequent mortality and arrhythmic events is inferior to that of impaired autonomic tone, LVEF or infarct-related artery patency. Accordingly, the use of nonsustained VT to select patients for primary implantable cardioverter/defibrillator prevention trials shortly after AMI appears to be limited.