Relation between left ventricular dysfunction and ventricular arrhythmias after myocardial infarction

Are Tp-e interval and QT dispersion values important in children with coeliac disease?

OBJECTIVES

Coeliac disease is an autoimmune intestinal disease that develops with permanent intolerance to gluten and similar cereal proteins. It can damage to many tissues, including myocardium, by autoimmune mechanisms. In our study, we aimed to investigate the effect of coeliac disease on cardiac electrical activity by comparing the Tp-e interval and Qt dispersion values of coeliac patients with healthy children.

METHODS

Fifty-seven coeliac patients and 57 healthy children were included in the study. Sociodemographic findings, physical examinations, symptoms, laboratory values, dietary compliance, endoscopy, and pathological findings were recorded into a standardised form. Electrocardiogram parameters were calculated, and echocardiography findings were noted.

RESULTS

No statistically significant difference was found between the two groups in terms of age, gender, heart rate, electrocardiogram parameters such as p wave, PR interval, QRS complex, QT interval, and QTc values. Tp-e interval, Tp-e / QT ratio, and Tp-e / QTc ratio were statistically significantly higher in the patient group compared to the control group. Ejection fraction and fractional shortening values were significantly lower in the patient group compared to the control group. In the patient group, Tp-e interval, Tp-e / QT ratio, Tp-e / QTc ratio, and QTc dispersion were statistically significantly higher in patients with tissue transglutaminase IgA positive compared to patients with tissue transglutaminase IgA negative.

CONCLUSION

Our study gives important findings in terms of detecting early signs of future cardiovascular events in childhood age group coeliac patients.

Identifying high risk patients post myocardial infarction with reduced left ventricular function using loop recorders INSPIRE-ELR clinical study

Aims

Sudden cardiac death (SCD) continues to be a devastating complication amongst survivors of myocardial infarction (MI). Mortality is high in the initial months after MI. The aims of the INSPIRE-ELR study were to assess the proportion of patients with significant arrhythmias early after MI and the association with mortality during 12 months of follow-up.

Methods

The study included 249 patients within 14 days after MI with left ventricular ejection fraction (LVEF) ≤35% at discharge in 11 hospitals in India. Patients received a wearable external loop recorder (ELR) 5 ± 3 days after MI to monitor arrhythmias for 7 days.

Results

Patients were predominantly male (86%) with a mean age of 56 ± 12 years. In 82%, reperfusion had been done and all received standard of care cardiovascular medications at discharge. LVEF was 32.2 ± 3.9%, measured 5.1 ± 3.0 days after MI. Of the 233 patients who completed monitoring (7.1 ± 1.5 days), 81 (35%) experienced significant arrhythmias, including Ventricular Tachycardia/Fibrillation (VT/VF): 10 (4.3%); frequent Premature Ventricular Contractions (PVCs): 65 (28%); Atrial Fibrillation (AF): 8 (3.4%); chronic atrial flutter: 4 (1.7%); 2nd or 3rd degree Atrioventricular (AV) block: 4 (1.7%); and symptomatic bradycardia: 8 (3.4%). In total, 26 patients died. Mortality was higher in patients with clinically significant arrhythmia (at 12 months: 23.6% vs 4.8% with 19 vs 7 deaths, hazard ratio (HR) = 5.5, 95% confidence interval (CI) 2.3 to 13.0, p < 0.0001). Excluding 7 deaths during ELR monitoring, HR = 4.5, p < 0.001.

Conclusion

ELR applied in patients with acute MI and LV dysfunction at the time of discharge identifies patients with high mortality risk.

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External Loop Recorder applied in patients with acute MI and LV dysfunction showed a high incidence of clinically significant arrhythmias.

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Significant arrhythmias within 14 days of hospital discharge were associated with 5 times higher mortality at one year.

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A simple ELR-based risk score was an independent predictor of mortality.

Tp-e interval and Tp-e/QT ratio in patients with celiac disease

OBJECTIVES

Celiac disease is a chronic immune-mediated disease of the small intestine. It has been known that dilated cardiomyopathy and ischemic coronary artery disease have become more frequent in patients with celiac disease. The aim of the study was to assess Tp-e interval and Tp-e/QT ratio in patients with celiac disease.

MATERIAL AND METHODS

This study was conducted at a single center in collaboration with gastroenterology and cardiology clinics. Between January 2014 and June 2015, a total of 76 consecutive patients were enrolled (38 patients with celiac disease and 38 control subjects). Tp-e interval, Tp-e/QT and Tp-e/QTc ratio were measured from the 12-lead electrocardiogram.

RESULTS

Tp-e interval (64.2±11.0 vs. 44.5±6.0; p<0.001), Tp-e/QT ratio (0.18±0.02 vs. 0.13±0.02; p<0.001) and Tp-e/QTc ratio (0.16±0.02 vs. 0.11±0.01; p<0.001) were significantly higher in patients with celiac disease than control subjects. There was a significant positive correlation between Tp-e/QTc ratio and disease duration in patients with celiac disease (r=0.480, p=0.003) and also there was a significant positive correlation between Tp-e/QTc ratio and erythrocyte sedimentation rate (r=0.434, p<0.001).

CONCLUSIONS

Our study showed that Tp-e interval, Tp-e/QT and Tp-e/QTc ratios were increased in patients with celiac disease. Whether these changes increase the risk of ventricular arrhythmia deserve further studies.

Tp-e interval and Tp-e/QT ratio before and after catheter ablation in patients with premature ventricular complexes

Aim: Tp-e/QT ratio is a novel marker of ventricular repolarization. The aim of the study is to evaluate the Tp-e interval and Tp-e/QT ratio before and after radiofrequency ablation (RFA) for patients with frequent premature ventricular complexes (PVCs). Patients & methods: The study included 151 consecutive patients who underwent RFA for treatment of symptomatic frequent PVCs. Results: Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio (all p < 0.001) were significantly different before and after RFA. After the procedure, mean left ventricular ejection fraction of the population were significantly increased than before RFA (p < 0.001). There was a significant correlation between preprocedural Tp-e/QTc ratio and PVC burden in patients (p = 0.023). Conclusion: Our study shows that PVCs may have a negative effect on ventricular repolarization.

Different prognostic factors according to left ventricular systolic function in patients with acute myocardial infarction

BACKGROUND

Initial left ventricular (LV) systolic function is a main determinant of clinical outcomes in patients with acute myocardial infarction (AMI). This study was performed to investigate whether AMI patients have different prognostic factors according to their baseline LV systolic function.

METHODS

A total of 12,988 patients with AMI from a nationwide database were analyzed. Major adverse cardiovascular events (MACEs) within 12months of AMI, including death, nonfatal myocardial infarction (MI), and revascularization, were assessed.

RESULTS

Patients were stratified into two groups according to LV ejection fraction (LVEF): those with LVEF<40% and those with LVEF≥40%. Patients with LVEF<40% (n=1962, 15.1%) were older and had more unfavorable cardiovascular risk factors than those with LVEF≥40% (n=11,026, 84.9%). The rate of MACE was higher in patients with LVEF<40% than in those with LVEF≥40% (26.8% vs 11.4%, p<0.001). Independent predictors of 12-month MACEs in patients with LVEF≥40% were history of MI, high Killip stage, three-vessel disease, and lower renal function, which are already known as risk factors. However, diabetes mellitus (hazard ratio [HR], 1.68; 95% confidence interval [CI], 1.17-2.40; p=0.008), and the use of rennin-angiotensin system (RAS) blockers (HR, 0.63; 95% CI, 0.41-0.95; p=0.029) were independent factors for 12-month MACE in patients with LVEF <40%.

CONCLUSIONS

Prognostic factors determining 12-month MACE after AMI are different according to LVEF. Management following AMI should be tailored according to their LV systolic function.

Improve the prevention of sudden cardiac arrest in emerging countries: the Improve SCA clinical study design

AIMS

This study aims to demonstrate that primary prevention (PP) patients with one or more additional risk factors are at a similar risk of life-threatening ventricular arrhythmias when compared with secondary prevention (SP) patients, and would receive similar benefit from an implantable cardioverter defibrillator (ICD), or cardiac resynchronization therapy-defibrillator (CRT-D) implant. The study evaluates the benefits of therapy for high-risk patients in countries where defibrillation therapy for PP of SCA is underutilized.

METHODS

Enrolment will consist of 4800 ICD-eligible patients from Asia, Latin America, Eastern Europe, the Middle East, and Africa. Upon enrolment, patients will be categorized as SP or PP. Primary prevention patients will be assessed for additional risk factors: syncope/pre-syncope, non-sustained ventricular tachycardia, frequent premature ventricular contractions, and low left ventricular ejection fraction. Those PP patients with one or more risk factors will be categorized as '1.5' patients. Implant of an ICD/CRT-D will be left to the patient and/or physician's discretion. The primary endpoint will compare the appropriate ICD therapy rate between SP and 1.5 patients. The secondary endpoint compares mortality between 1.5 implanted and non-implanted patients.

CONCLUSION

The Improve SCA study will investigate a subset of PP patients, believed to be at similar risk of life-threatening ventricular arrhythmias as SP patients. Results may help clinicians identify and refer the highest risk PP patients for ICDs, help local societies expand guidelines to include PP of SCA utilizing ICDs, and provide additional geographical-relevant evidence to allow patients to make an informed decision whether to receive an ICD.

TRIAL REGISTRATION

NCT02099721.

Endothelial dysfunction, measured by reactive hyperaemia using strain-gauge plethysmography, is an independent predictor of adverse outcome in heart failure

AIMS

In congestive heart failure (CHF), arterial response is regulated by endothelial molecules. The aim of this study was to evaluate whether endothelial dysfunction (ED) was a predictor of outcome in a cohort of patients with heart failure.

METHODS AND RESULTS

Endothelial function was assessed in 242 patients with CHF by forearm reactive hyperaemia measured with intermittent venous occlusion plethysmography using a mercury strain gauge. The main endpoints were: 'total events' (death, heart attack, angina, stroke, NYHA class IV, or hospitalization due to heart failure) analysed using Cox regression for repeated events and 'death'. Patients were followed-up for 5 years. Post-hyperaemia forearm blood flow (PHFABF) was an independent predictor of total events [P = 0.01; hazard ratio [Exp(B)] 0.665, standard error (SE) 0.182]. Risk stratification by basal forearm blood flow (BFABF) showed that patients with basal blood flow above the median (3.03 mL min(-1) 100 mL(-1)) benefited from an increase in PHFABF, whereas in patients with a BFABF below the median, the increase in PHFABF did not diminish the risk of events. There was no relation between variations in PHFABF and death.

CONCLUSION

Post-hyperaemia forearm blood flow, as a measure of ED, is an independent predictor of major events in patients with CHF. A BFABF below the median is more predictive of an increased risk of complications.

Prognostic implications of ventricular ectopy one week, one month, and sixteen months after an acute myocardial infarction. Danish Study Group on Verapamil in Myocardial Infarction

BACKGROUND

Ventricular ectopy early after an acute myocardial infarction (AMI) has previously been demonstrated to predict mortality. Less information is available about the prognostic implications of ventricular ectopy occurring late after an AMI, and no information is available about the prognostic implication of the development of ventricular ectopy during the first year after an AMI.

HYPOTHESIS

The purpose of the present prospectively conducted trial, a part of the Danish Verapamil Infarction Trial II (DAVIT II), was to evaluate the prognostic implication of (1) ventricular premature complexes (VPCs) recorded by 24-h Holter monitoring 1 week, 1 month, and 16 months after an AMI; and (2) development of > 10 VPCs/h or of any complex ventricular ectopy, that is, pairs, more than two types of VPCs, ventricular tachycardia, or > 10 VPCs/h during follow-up after an AMI.

METHODS

Patients were monitored 1 week (n = 250), 1 month (n = 210), and 16 months (n = 201) after AMI.

RESULTS

Multivariate analyses based on history, clinical findings, and ventricular ectopy showed the following results: After 1 week, > 10 VPCs/h (p = 0.0006) and heart failure (p < 0.007); after 1 month, > 10 VPCs/h (p = 0.003) and resting heart rate (p < 0.02); and after 16 months, ventricular tachycardia (p = 0.002) independently predicted long-term mortality. Mortality was significantly predicted by the development of > 10 VPCs/h from 1 week to 1 month (p = 0.003) and 16 months (p = 0.03), and from 1 to 16 months (p = 0.007) after AMI, as well as by the development of any complex ventricular ectopy from 1 week to 1 month (p = 0.02) and 16 months (p = 0.01), and from 1 to 16 months (p = 0.04) after AMI.

CONCLUSION

The present study demonstrated that 1 week and 1 month after an AMI the quantity of VPCs, that is, > 10 VPCs/h, predicted mortality, whereas 16 months after an AMI the quality of VPCs, that is, ventricular tachycardia, predicted mortality.

Prognostic role of post-infarction C-reactive protein in patients undergoing implantation of cardioverter-defibrillators: design of the C-reactive protein Assessment after Myocardial Infarction to GUide Implantation of DEfibrillator (CAMI GUIDE) study

BACKGROUND

Patients at risk of sudden cardiac death (SCD) after myocardial infarction (MI) can currently be offered effective means of prevention, such as implantable cardioverter-defibrillators (ICD). However, predictors of SCD able to identify those patients who are at higher risk are still lacking. Whether C-reactive protein (CRP), a serum inflammatory marker with established prognostic accuracy after MI, can also be a predictor of SCD is unclear.

METHODS

The CAMI GUIDE study is designed to evaluate the prognostic role of CRP in patients undergoing ICD implantation after MI according to MADIT II criteria (i.e. left ventricular ejection fraction<or=30%). CAMI GUIDE is a prospective observational study aimed at assessing the role of CRP in the risk-stratification of SCD after MI. CRP will be measured on the basis of a pre-specified cut-off value of 3 mg/l, before and 1 month after ICD implantation; clinical follow-up will last 24 months. The primary endpoint is the combined rate of SCD or fast ventricular tachycardia/ventricular fibrillation. Secondary endpoints will be total mortality, death due to acute coronary syndromes, death from pump failure, non-fatal MI, coronary revascularization, hospitalization for congestive heart failure or unstable angina and inappropriate ICD shocks. Twenty-four Italian centers will participate in enrollment of the 290 patients planned according to power analysis.

CONCLUSIONS

The CAMI GUIDE study will assess the predictive role of CRP in SCD in patients with previous MI undergoing ICD implantation. Its results will improve risk stratification, thereby enabling better-tailored and more cost-effective therapies to be undertaken in those patients whose need is greatest.

Late ventricular potentials in risk assessment of the occurrence of complex ventricular arrhythmia in patients with myocardial infarction and heart failure

AIM

To determine the prognostic significance of late ventricular potentials on signal-averaged electrocardiogram and left ventricular ejection fraction for the occurrence of complex ventricular arrhythmia in patients treated with accelerated tissue-type plasminogen activator, using the rapid protocol, within six months of acute myocardial infarction.

METHODS

In this analytic observational prospective study patients were divided into four groups: patients with left ventricular ejection fraction bellow 40% and late ventricular potentials, patients with left ventricular ejection fraction bellow 40% and without late ventricular potentials, patients with left ventricular ejection fraction over 40% and late ventricular potentials, and patients with left ventricular ejection fraction over 40% and without late ventricular potentials. Complex ventricular arrhythmias (Lown grade IVa, IVb, and V) were recorded using standard electrocardiography and 24-hour Holter monitoring 21, 60, and 90 days after acute myocardial infarction, respectively. Serial recordings of signal-averaged electrocardiogram were obtained 30, 90, and 180 days after acute myocardial infarction. Left ventricular ejection fraction was determined by echocardiography between 15 and 21 days after acute myocardial infarction. Multivariant logistic regression analysis was used to evaluate the relation between late ventricular potentials and left ventricular ejection fraction with the occurrence of complex ventricular arrhythmias. Sensitivity, specificity, positive and negative predictive values of late ventricular potentials and left ventricular ejection fraction for the occurrence of complex ventricular arrhythmias were determined.

RESULTS

The prospective study included 80 patients (73% men), mean age 64 +/- 3.5 years. Complex ventricular arrhythmias were recorded in 34 (42.5%) of patients, all 17 (50%) of which were from the first group (p < 0.01). Complex ventricular arrhythmias were recorded in 25 (73.5%) patients with late ventricular potentials, and in 23 (67.6%) patients with left ventricular ejection fraction bellow 40%. Left ventricular ejection fraction bellow 40% and late ventricular potentials represented independent predictors for the occurrence of complex ventricular arrhythmias (RR = 14.33, p < 0.01). When combined with left ventricular ejection fraction bellow 40%, late ventricular potentials had sensitivity (0.50), specificity (0.93), and positive predictive accuracy (0.85) higher than late ventricular potentials alone (0.44, 0.67, and 0.37, respectively) for the occurrence of complex ventricular arrhythmias following acute myocardial infarction.

CONCLUSION

In this study, late ventricular potentials in patients with left ventricular ejection fraction bellow 40% represented the independent predictor for the occurrence of complex ventricular arrhythmias in the first six months after the first myocardial infarction treated with accelerated tissue-type plasminogen activator, using the rapid protocol.

Risk Stratification and Primary Prevention of Sudden Cardiac Death

The initial challenge in primary prevention of sudden cardiac death (SCD) lies in identifying those at greatest risk, before the index event. Ventricular fibrillation is the leading cause of SCD; however, many clinical conditions predispose fatal ventricular dysrhythmias. In patients with structural heart disease, left ventricular dysfunction is the strongest predictor of SCD. Noninvasive markers such as nonsustained ventricular tachycardia, delayed potentials, decreased heart rate variability and baroreflex sensitivity, and repolarization alternans are further observed to assess risk in ischemic cardiomyopathy; however, most of these markers have poor positive predictive value and lack specificity. The electrophysiologic study has strong positive predictive value, but remains a costly and invasive method for risk stratification. In patients with normal hearts, genetic predisposition may identify patients at risk but clinical markers are not readily recognized. The implantable loop recorder is a useful tool in detecting dysrhythmic causes of syncope and identifying patients at risk for SCD.

Comparison of the prognostic value of RR-interval variability after acute myocardial infarction in patients with versus those without diabetes mellitus

Diabetic patients have substantially greater long-term mortality after acute myocardial infarction (AMI) than nondiabetic patients. Traditionally, cardiac autonomic neuropathy is believed to contribute significantly to the increased mortality rate in patients with diabetes mellitus. In contrast, a recent study suggested that RR-interval variability (RRV) did not predict mortality after AMI in diabetic patients. We compared, in diabetic and nondiabetic patients, the relation between low RRV and long-term mortality in the Multicenter Post Infarction Program (MPIP), a longitudinal observational study of 715 survivors of AMI, including 117 diabetic patients. We studied the association between mortality and 6 frequency-domain measurements and 1 time-domain measurement of RRV. We tested 2 hypotheses: (1) RRV is lower in diabetic patients; and (2) low RRV is less predictive of mortality in diabetic patients. Reduced RRV was significantly more frequent in diabetic patients than nondiabetic patients for all measurements, except high-frequency (HF) power. In diabetic patients, the association between reduced RRV and long-term mortality was at least as strong as it was in nondiabetic patients for all measurements except HF power; this pattern was found for all-cause, cardiac, and arrhythmic death. In multivariable models, reduced RRV was significantly associated with all-cause mortality in diabetic patients even when adjusted for left ventricular ejection fraction, heart failure class, and ventricular arrhythmias. In our post-AMI sample, RRV provided valuable prognostic information among diabetic patients. Our findings suggest that cardiac autonomic neuropathy plays a role in the high mortality rate seen in diabetic patients after AMI.

Evaluation of heart-rate turbulence as a new prognostic marker in patients with chronic heart failure

The significance of heart-rate turbulence (HRT) in patients with chronic heart failure (CHF) was evaluated to examine whether it is sensitive to the risk of ventricular tachycardia (VT). HRT is reported to predict the prognosis after myocardial infarction (MI), but its prognostic value in patients with CHF remains unknown. HRT was measured in 50 CHF patients (left ventricular ejection fraction <50% and/or left ventricular end-diastolic diameter >55 mm, 34 cardiomyopathy, 16 post-MI) and 21 patients without obvious heart diseases (control). HRT slope and HRT onset were measured by the original definitions using digitized Holter ECG recordings. Cardiac pump function was assessed by echocardiography. The value of the HRT slope was significantly lower in CHF than in control (3.7 +/- 1.7 vs 16.4 +/- 5.3, mean +/- SD, p < 0.01). The value of the HRT onset in patients with CHF was significantly higher than that in control patients (-1.1 +/- 1.9 vs -3.6 +/- 1.7, mean +/- SD, p < 0.05). The HRT slope and onset in CHF patients with VT were nearly identical to those without VT. The HRT slope appears to be a powerful prognostic marker that shows significant differences between CHF subgroups when divided by clinical events; that is, CHF death and CHF hospitalization. However, it has limited value for predicting fatal ventricular arrhythmias.

n-3 fatty acids and the risk of sudden cardiac death

Sudden cardiac death (SCD) is a major cause of mortality in Western countries. Furthermore, SCD is often the first manifestation of coronary artery disease, making it difficult to prevent. Heart rate variability (HRV), which can be determined by extended recording of the heart rate by 24-h Holter monitoring, has been shown to be one of the best predictors of the risk of SCD. There is increasing evidence from animal experiments and clinical trials in humans that n-3 fatty acids reduce the risk of SCD. We have studied the effect of n-3 fatty acids on HRV and present data clearly showing that n-3 fatty acids increase HRV. This adds further to the hypothesis that an increased intake of n-3 fatty acids may reduce the risk of SCD.

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.

A comparison of MRI and echocardiography in hypertrophic cardiomyopathy

This study compares MRI and echocardiography as imaging modalities in hypertrophic cardiomyopathy, with particular reference to measurement of left ventricular wall thickness and mass. 10 subjects underwent echocardiography and MRI. Contiguous 10 mm short axis 35 degrees flip angle cine gradient recalled echo MR images were acquired from the apex to the base of the left ventricle at 1.5 tesla. Standard M-mode and cross-sectional echocardiographic views of the left ventricle were obtained. Excellent agreement between measurements occurred with MRI and M-mode echocardiographic assessment of the thickness of the anterior interventricular septum (95% limits of agreement -1.5 to +1.5 mm). Other comparisons of MRI vs M-mode echocardiographic measurements had the following limits of agreement: posterior free wall -3.3 to +2.9 mm; end-diastolic dimension -5 to +8 mm, left ventricular mass -291 to +55.5 g. Comparing MRI with cross-sectional echocardiographic measurements, the limits of agreement were: anterior interventricular septum -2.4 to +1.7 mm, posterior interventricular septum -2.4 to +2.9 mm, posterior free wall -3.4 to +2.5 mm, anterior free wall -2.4 to +1.7 mm, end-diastolic dimension -4.1 to +8 mm. MRI estimates of LVM in systole vs diastole showed good agreement with 95% limits of agreement of -20 to +17 g, with excellent interobserver variability in diastole (-9 to +5 g) and in systole (-7 to +12 g). In conclusion, MRI is superior to echocardiography for the quantification of ventricular mass in the abnormal left ventricle because it does not make invalid geometrical assumptions. Comparisons of wall thickness show greater discrepancy with increasing distance from the echocardiographic transducer. This study suggests that sequential echocardiography could rationalize the need for MRI in left ventricular hypertrophy. A change in anterior septal thickness of > or = 3 mm on echocardiography merits a further MRI study.

The usefulness of Holter monitoring in selecting pharmacologic therapy for patients with sustained monomorphic ventricular tachycardia: studies in patients in whom no effective pharmacologic therapy could be determined by electrophysiologic study

The usefulness of Holter monitoring (HM) in selecting pharmacologic therapy for patients with sustained monomorphic ventricular tachycardia (VT) was evaluated in patients in whom no effective pharmacologic therapy could be determined in an electrophysiologic study (EPS). The study population consisted of 49 consecutive patients with sustained VT who were receiving long-term pharmacologic therapy despite the fact that no pharmacologic therapy had been found to be effective in the EPS. The efficacy of the pharmacologic therapies was assessed by HM. A reduction in frequent (10/h) premature ventricular contractions (PVCs) was used as an index of treatment efficacy, with therapies achieving substantial PVC suppression (>70% of all PVCs) being considered to be effective (HM effective group). When no therapy was found to be effective when assessed by HM, a drug with any other beneficial effect, eg, reduction in VT rate, was chosen (HM ineffective group). VT recurrence and survival were compared between groups. During the follow-up period of 31+/-28 months, VT recurrence was observed in a total of 25/49 patients: 3/17 patients in the HM effective group, in 18/25 in the HM ineffective group, and in 4/7 in the HM undetermined group (p=0.0487). Sudden cardiac death occurred in a total 7/49 patients: 2/17 patients in the HM effective group, 4/25 patients in the HM ineffective group, and 1/7 patient in the HM undetermined group (p=0.2828). Among patients in whom no effective therapy could be determined by EPS, the VT recurrence rate was significantly lower in the group in whom treatment was effective as assessed by HM than among those in whom treatment was assessed by HM to be ineffective. Sudden cardiac death rate was also lowest in the HM effective group, although the difference was not statistically significant. HM assessment was considered useful in selection of pharmacologic therapy for patients in whom no effective therapy could be determined in the EPS.

Heart rhythms, ventricular arrhythmias, and death in chronic heart failure

BACKGROUND

The aim of this study was to evaluate whether abnormalities in heart rate variability (HRV) could act as markers of ventricular tachycardia and prognosis in patients with advanced, chronic heart failure. Fifty patients with chronic heart failure (45 men; mean age, 59 +/- 9 years; New York Heart Association [NYHA] class II-III; left ventricular ejection fraction [LVEF], 19 +/- 9% and peak oxygen consumption, 16.6 +/- 5.4 mL/kg/min) caused by idiopathic dilated cardiomyopathy (n = 12) and ischemic heart disease (n = 38) were included in the study. Heart rate variability measures derived from 24-hour electrocardiographic (ECG) monitoring (Marquette 8500 recorder, Marquette Electronics, Milwaukee, WI) were calculated in the time domain and frequency domain.

METHODS AND RESULTS

Twenty-five patients (50%) revealed episodes of ventricular tachycardia on 24-hour ECG monitoring (1-143 episodes). The presence of ventricular tachycardia was associated with lower LVEF but there was no difference in NYHA class and peak oxygen consumption between patients with and without ventricular tachycardia (LVEF, 16 vs 22%, P = .01; NYHA class, 2.6 vs 2.4; peak oxygen consumption, 16.5 vs 16.8 mL/kg/min, not significant). Patients with ventricular tachycardia exhibited markedly lower HRV measures. Multiple regression analysis was used to test HRV parameters as potential predictors of ventricular tachycardia. Among them, high-frequency power was the only independent predictor of the presence of ventricular tachycardia, and this predictive correlation was independent of LVEF and mean R-R interval duration. During a follow-up period of 24 +/- 18 months, 12 patients (24%) died. No difference was found in age, etiology, NYHA class, peak oxygen consumption, or occurrence of ventricular tachycardia, but a lower LVEF (15 +/- 6 vs 21 +/- 9%, P = .046) was observed in those who died compared with those who survived. Certain estimates of HRV were in contrast, lower in those who subsequently died: standard deviation of all normal R-R intervals (61 +/- 30 vs 101 +/- 33 ms), standard deviation of 5-minute mean R-R intervals (55 +/- 27 vs 92 +/- 31 ms), mean of all 5-minute standard deviations of R-R intervals (22 +/- 12 vs 37 +/- 11 ms), and the low-frequency (3.2 +/- 1.8 vs 4.8 +/- 0.9 ln ms2) and high-frequency (3.0 +/- 1.1 vs 3.8 +/- 0.8 ln ms2) components of the HRV spectrum (all differences, P < .01). In univariate Cox analysis, all of these HRV measures were independent predictors of death. Kaplan-Meier survival analysis revealed that the standard deviations of all normal R-R intervals and of 5-minute mean R-R intervals dichotomized at median values (99 and 90.5 ms, respectively) were the best predictors of mortality.

CONCLUSIONS

In patients with moderate to severe chronic heart failure, depressed indices of HRV on 24-hour ambulatory ECG monitoring could be related to higher risk of ventricular tachycardia and death, suggesting that analysis of HRV could be usefully applied to risk stratification in chronic heart failure patients.

Exercise-induced ischemic arrhythmias in patients with previous myocardial infarction: role of perfusion and tissue viability

OBJECTIVES

This study sought to investigate whether residual viability of infarcted myocardium may play a role in the pathogenesis of exercise-induced ventricular arrhythmias.

BACKGROUND

We previously showed that transient ischemia within partially infarcted areas often precipitates ventricular arrhythmias during exercise that are consistently obliterated by intravenous nitrates.

METHODS

We studied 60 patients with chronic stable angina and a previous myocardial infarction. All underwent at least two consecutive exercise stress tests, coronary angiography and stress/rest myocardial perfusion tomography by Tc-99m 2-methoxy isobutyl isonitrile (MIBI). In the last 26 consecutive patients, residual viability was assessed by single-photon emission computed tomography (SPECT) using fluorine (F)-18 fluorodeoxyglucose. Perfusion and metabolic data were evaluated qualitatively by three independent observers in blinded manner.

RESULTS

With exercise, 30 patients (group A) consistently developed ventricular arrhythmias (> 10 ventricular ectopic beats/min, couplets, nonsustained ventricular tachycardia); the remaining 30 patients (group B) did not. The severity of coronary artery disease (Gensini score) was similar in the two groups. Postexercise SPECT showed partial reperfusion of an infarcted area in 28 of 30 patients of group A but in only 9 of 30 of group B (p < 0.0001). Uptake of F-18 fluorodeoxyglucose was observed within the infarcted zone in 10 of 13 and 1 of 13 patients in groups A and B, respectively (p = 0.0003).

CONCLUSIONS

In patients with myocardial infarction, exercise-induced ventricular arrhythmias appear to be triggered by transient ischemia occurring within a partially necrotic area containing large amounts of viable myocardium. Therefore, occurrence of arrhythmias during exercise may represent a clue to the presence of residual viability within a previously infarcted area.

Data-driven Decisions: The Importance of Clinical Trials in Arrhythmia Management

As a result of clinical trials, the measurement of arrhythmias has evolved over the past three decades. In the late 1960s, customary teaching was that ventricular premature depolarizations were dangerous and antiarrhythmic therapy, in hopes of reducing fatal consequences, became common place; however, following clinical trials such as CAST, IMPACT, and SWORD, we learned that, at least in postinfarct patients, arrhythmia suppression may lead to increased rather than reduced mortality. Such trials have led to a marked reduction in therapy of indiscriminate ventricular ectopy and have led to ongoing testing of specific subgroups identified as having particularly higher adverse prognostic risk. With the advent of cardiac monitoring and the confirmation that ventricular tachyarrhythmias are the most common cause for sudden death, their therapy, too, has evolved and matured, again aided by clinical trials. The ESVEM study prospectively examined the role of monitor-guided versus electrophysiologically guided drug therapy of ventricular tachyarrhythmias and confirmed that both approaches may have a role in reducing arrhythmic deaths-though the specific benefits of each technique remain somewhat unsettled. Both the ESVEM and CASCADE studies suggested that the most effective drugs for ventricular tachyarrhythmias are the class II/III drugs, sotalol and amiodarone, both appearing more effective than our older class I agents. These should now be viewed as the first-line drugs for these arrhythmias. The relative benefits of these two agents with respect to each other and to implantable cardioverter defibrillators, however, remains to be determined by further clinical trials, such as AVID and CIDS. The therapy of atrial tachyarrhythmias has similarly evolved with the aid of clinical observations. While rate control is required in all patients with atrial fibrillation, we have come to realize that the applications of antiarrhythmic drugs for the purpose of maintaining sinus rhythm must be used only selectively rather than uniformly. Both a meta-analysis by Coplen and colleagues and a report by the SPAF investigators suggested that with atrial arrhythmias, too, antiarrhythmic drug therapy may result in enhanced rather than reduced mortality in some circumstances. Additional clinical trials are needed to further elucidate the role of antiarrhythmic therapy of atrial fibrillation.

Lack of long-term ventricular arrhythmia reduction by enalapril in heart failure. SOLVD Investigators

Previous studies have indicated that angiotensin-converting enzyme inhibitors may reduce the frequency of ventricular arrhythmias in patients with heart failure. These reports were mostly small and of short duration. We prospectively studied 734 patients recruited in 11 universities for 1 year who were enrolled in the Studies of Left Ventricular Dysfunction (SOLVD) to determine the long-term effects of enalapril and placebo on the frequency and complexity of ventricular arrhythmias in patients with symptomatic (treatment trial) or asymptomatic (prevention trial) heart failure and depressed left ventricular function (ejection fraction < or = 35%). Five hundred fifty-three patients from the prevention trial and 181 from the treatment trial of SOLVD underwent ambulatory electrocardiographic monitoring at baseline, and then at 4 and 12 months of double-blind therapy with either placebo or enalapril (2.5 to 10 mg twice daily). The prospectively defined primary analysis was by intent-to-treat and revealed no significant differences in ventricular premature complexes between the placebo and enalapril groups at baseline (87 +/- 13 vs 84 +/- 13/hour), 4 months (100 +/- 15 vs 85 +/- 12/hour), or 12 months (80 +/- 12 vs 90 +/- 14/hour). Likewise, there was no difference between the placebo and enalapril groups in runs of nonsustained ventricular tachycardia: baseline (8.3 +/- 4.1 vs 1.9 +/- 0.4 runs/day), 4 months (16 +/- 12 vs 7.2 +/- 4.1 runs/day), or after 12 months of blinded therapy (11 +/- 7.0 vs 6.1 +/- 4.4 runs/day).(ABSTRACT TRUNCATED AT 250 WORDS)

Use of electrophysiological studies in the diagnosis and treatment of cardiac patients with left ventricular dysfunction and high grade ventricular ectopy

We studied the sudden death occurrence in 28 patients (23 males, age 59.2 +/- 15.6 years) who had a documented cardiac disease with left ventricular dysfunction (ejection fraction < or = 0.4) and high grade ventricular ectopy. None had suffered from spontaneous sustained ventricular arrhythmia and/or syncope. Their diagnosis and treatment were guided by electrophysiological studies. Electrophysiological studies were performed in the antiarrhythmic drug-free state. In cases when sustained ventricular arrhythmias could be induced, antiarrhythmic treatment was prescribed according to the results of the electrophysiological studies. In cases of non-inducibility, no antiarrhythmic treatment was prescribed. The patients were followed up for a period of 20.6 +/- 11.2 months. The end points were occurrence of documented spontaneous sustained ventricular arrhythmia and sudden death. None of the 19 non-inducible patients experienced sudden death or spontaneous sustained ventricular arrhythmia. Two of the nine inducible patients died suddenly (P = 0.1). The 3-year sudden death mortality rate of the whole group was 7.5%. We conclude that when cardiac patients with high grade ventricular ectopy and left ventricular systolic dysfunction are treated according to the results of electrophysiological studies, it can be expected that their 3-year mortality rate will be low and significantly inferior to that reported for conventionally treated patients.

Left ventricular dilatation and high-grade ventricular arrhythmias in the first year after myocardial infarction. CATS Investigators. Captopril and Thrombolysis Study

Progressive left ventricular dilatation is an important determinant of prognosis after myocardial infarction. The association of this process with the occurrence of ventricular arrhythmias is less well established. Of 153 patients with a first anterior myocardial infarction treated with thrombolytic therapy, 34 (22%) had high-grade ventricular arrhythmias (Lown 4A and B) during Holter monitoring after 1 year. Patients with high-grade ventricular arrhythmias had a larger end-systolic volume (38 +/- 12 vs 25 +/- 11 mL/m2; P < .001) at hospital discharge and more left ventricular dilatation (10 +/- 18 vs 1 +/- 9 mL/m2; P = .011) during the follow-up period. Increased end-systolic volume at discharge and subsequent dilatation proved to be independent predictors of high-grade ventricular arrhythmias. Six patients died suddenly during the first 12 months after myocardial infarction. Four of these patients had an enlarged end-systolic volume (> 22 mL/m2) at discharge, and the three patients who died suddenly after 3 months showed a significant increase in end-systolic volume from discharge to 3 months compared to survivors (16 +/- 6 vs 2 +/- 9; P = .008). Left ventricular remodeling after myocardial infarction is an independent predictor of the occurrence of ventricular arrhythmias late after myocardial infarction.

Ventricular arrhythmias in heart failure

Heart failure is an increasingly common disorder leading to reduced quality and expectancy of life. Asymptomatic and symptomatic ventricular arrhythmias are a frequent complication and have been found to be independent prognostic predictors for sudden cardiac death in patients with heart failure. Unfortunately, the positive predictive failure for this finding is low, but in patients with sustained ventricular arrhythmias, variables indicating impaired pump function are the most important predictors of sudden and of nonsudden cardiac death. Arrhythmias in heart failure may have many different underlying mechanisms. Indications for, and mode of treatment of, arrhythmias in heart failure depend on the symptoms and prognostic significance of the arrhythmia. Primarily, pump function should be optimized and antiarrhythmic drug therapy instituted only when the arrhythmia persists. In poorly tolerated and life-threatening arrhythmias, implantable devices allowing pacing and defibrillation must be considered. No data are presently available indicating a protective role of antiarrhythmic drugs in the prevention of sudden cardiac death in heart failure. Future directions should concentrate on the development of better stratification of risk for sudden death, better delineation of mechanisms of arrhythmias in heart failure (allowing the development of mechanism-specific antiarrhythmic drugs), and research into new nonpharmacologic techniques such as cardiomyoplasty and molecular biologic techniques to rebuild the failing heart muscles.

The prognostic significance of very low frequency ventricular ectopic activity in survivors of acute myocardial infarction. BHAT Study Group

Survivors of myocardial infarction with less than 2 PVC/h on 24-h ambulatory electrocardiography were followed up for an average of 25 months (11 to 40 months) while receiving a placebo (1,222 patients) or propranolol, 180 or 240 mg/day (1,234 patients). Three quarters of the participants with PVCs had an average of less than 2 PVC/h. Only 16 percent did not have any ventricular ectopic activity during the 24 h. Analysis of total mortality according to the number of premature ventricular complexes per hour showed that patients who had PVCs with a very low frequency (less than 0.5/h) had 49 percent higher mortality than patients who did not have any PVC. Patients who had greater than 0.5 PVC/h but less than 1 PVC/h had a statistically significant higher mortality rate, 11.7 vs 4.1 percent (p less than 0.0001) than patients who had no PVC. These data indicate that low ventricular ectopic activity frequency is associated with increased mortality in survivors of acute myocardial infarction.

Prophylactic use of the intra-aortic balloon pump in high-risk cardiac patients undergoing noncardiac surgery: a decision analytic view

OBJECTIVE

As the indications for the intra-aortic balloon pump (IABP) continue to evolve, a potential new use may be the prophylactic preoperative insertion of the IABP in the high-risk cardiac patient undergoing noncardiac surgery. Our objective is to present a general approach to the high-risk cardiac patient who may benefit from the prophylactic insertion of the IABP.

DESIGN

Case reports and a decision analysis.

METHODS

A decision model was constructed that weighs the risk of life-threatening postoperative complications against the risk of vascular complications, including surgery and possible amputation, from IABP insertion.

RESULTS AND CONCLUSIONS

A review of the literature identified 10 patients who underwent IABP placement prior to noncardiac surgery. These patients, along with our three cases, define a population of patients for whom the prophylactic IABP may be useful. This population includes patients with coronary artery disease (CAD) for whom bypass grafting is not an option due to: (1) inoperable CAD; (2) a severe coexisting disease process (such as a malignancy); or (3) the emergent nature of the noncardiac procedure. The decision analysis suggests that patients whose preoperative assessment places them at very high risk for postoperative complications (Goldman class IV or Detsky class III undergoing major surgery) may benefit the most from prophylactic placement of an IABP prior to noncardiac surgery.

Sudden death in patients with congestive heart failure: future directions

Sudden, unexpected cardiac death continues to be a major clinical problem in patients with congestive heat failure. This review summarizes the current state of knowledge regarding the identification and management of these patients. The roles of ambulatory ECG monitoring, electrophysiological testing, signal-averaged ECG, and other methods of predicting increased risk of sudden death are discussed. The modes of sudden cardiac death and the potential mechanisms of ventricular arrhythmias in congestive heart failure are reviewed. Current therapeutic options including antiarrhythmic drugs, neurohormonal blockade, and automatic implantable cardioverter defibrillators are discussed. Finally, future directions and ongoing clinical investigations of the management of these complex patients are considered.

The Cardiac Arrhythmia Suppression Trial: first CAST ... then CAST-II

The Cardiac Arrhythmia Suppression Trial (CAST) was a study designed to test the hypothesis that suppression of ventricular premature complexes after a myocardial infarction would improve survival. Preliminary results showed that suppression of ventricular premature complexes with encainide and flecainide worsened survival, and the CAST continued as the CAST-II with moricizine compared with its placebo. The protocol for the CAST-II was changed to attempt to enroll patients more likely to experience serious arrhythmias. The enrollment time was narrowed to 4 to 90 days after myocardial infarction; the qualifying ejection fraction was lowered to less than or equal to 0.40; a higher dose of moricizine could be used; early titration itself was double-blind with a placebo, and the definition of disqualifying ventricular tachycardia was changed to allow patients with more serious arrhythmias to be entered into the trial. The Cardiac Arrhythmia Suppression Trial-II was subsequently terminated prematurely because 1) patients treated with moricizine had an excessive cardiac mortality rate during the 1st 2 weeks of exposure to the drug, and 2) there appeared to be little chance of showing a long-term survival benefit from treatment with moricizine. This report outlines the rationale behind the Cardiac Arrhythmia Suppression Trial and the reasons for selection of the drugs used in the CAST and CAST-II.

Effects of xamoterol in acute myocardial infarction: blood pressure, heart rate, arrhythmias and early clinical course

Xamoterol is a novel partial agonist of beta 1 adrenoceptors that reduces myocardial ischaemia and improves ventricular function in patients with mild to moderate heart failure. In a double blind, randomised, placebo controlled study, the effects of xamoterol given in a dose of 200 mg twice daily were studied in 51 consecutive patients with acute myocardial infarction, including 17 receiving diuretics for left ventricular failure. Treatment was started on the third day of admission and continued for 7 days. Blood pressure was recorded at 0900 daily, and 24 hour ambulatory electrocardiogram monitoring was commenced at this time on days 1 (pre-treatment), 4, 6 and 9 of admission. Additional drug therapy was recorded daily throughout the study. One patient died prior to randomisation and three were withdrawn (1 placebo, 2 xamoterol) with ventricular arrhythmias and/or disturbances of conduction. Compared to placebo, xamoterol had no effect on the rate of ventricular premature beats or ventricular tachycardia. Xamoterol increased nocturnal heart rate (0000-0600 hrs 79 +/- 2; placebo 72 +/- beats/min; P less than 0.03) but did not change blood pressure. Three patients receiving xamoterol, and 7 on placebo, required new (after randomisation) antianginal therapy. One patient treated with placebo developed new heart failure. These results show that xamoterol can be administered safely to selected patients following myocardial infarction, including those treated for mild heart failure.

Survival in patients with depressed left ventricular function treated by implantable cardioverter defibrillator

Mortality in patients with cardiovascular disease is generally due to pump failure or lethal ventricular arrhythmias. In patients with ventricular tachycardia (VT) or ventricular fibrillation (VF) and poor left ventricular (LV) function the death rate is particularly high. The overall incidence of premature arrhythmic death rate in patients with poor LV function is not totally clear. Since implantable cardioverter defibrillator (ICD) could prevent arrhythmic death in any population, we proceeded to analyze mortalities in patients with poor LV function who received ICD. Among a total of 200 consecutive patients receiving ICD at our institution, 68 (34%) had LV ejection fraction (LVEF) of less than 30%. Thirty-one of these (45%) experienced appropriate ICD discharges and 17/31 (55%) had multiple shocks. Survival curves in this population revealed a 5 year projected overall survival of 11% whereas an actual survival was 60%. Even those who ultimately died from nonsudden causes, life was prolonged by ICD in a significant number of cases. Based upon these findings it is concluded that ICD has a major impact on survival in patients with poor LV function suggesting that many of these patients die prematurely from arrhythmia causes.

Long-term effect of mexiletine on left ventricular function and relation to suppression of ventricular arrhythmia

The effects of oral mexiletine on left ventricular (LV) ejection fraction (EF) and ventricular arrhythmias--and a possible relation between these effects--were evaluated during 3 months of therapy in 29 patients with chronic ventricular premature complexes (VPCs) and a moderately reduced to normal LVEF by 24-hour Holter monitoring and by radionuclide ventriculography at rest and during maximum tolerable exercise testing. After an average titration period of 13 days, a mean daily mexiletine dose of 739 mg was maintained throughout the treatment. At the end of titration and after 3 months of treatment, patients with a baseline LVEF less than or equal to 40% (group 2) responded with a median reduction of the hourly VPC rate by 90 and 81%, respectively, compared with 79 and 72% in those with a baseline LVEF greater than 40% (group 1). Couplets and runs of ventricular tachycardia were almost completely suppressed in nearly all patients. A single patient had a proarrhythmic increase in VPCs during treatment. Compared with baseline, there were no significant changes in resting or exercise LVEF after 1 or 3 months of treatment in either of the 2 groups of patients. No correlation was found between treatment-induced changes in arrhythmia frequency and in resting EF. No symptoms of congestive heart failure developed. The study confirms that long-term use of mexiletine is efficacious and relatively free of cardiac depressant effects even in patients with diminished LV function.

Treatment of ventricular tachycardia induced cardiogenic shock by percoronary chemical ablation

Incessant ventricular arrhythmias pose an especially challenging therapeutic dilemma. We describe the successful treatment and follow-up of a patient with refractory ventricular tachycardia-induced cardiogenic shock with percoronary chemical ablation. After endocardial mapping was used to identify the "tachycardia-related" coronary artery, temporary termination of the arrhythmia with balloon occlusion and subselective intracoronary installation of iced saline as previously advocated was unsuccessful. This was probably due to a dual arterial blood supply to the arrhythmogenic focus. However, infusion of 2 cc ethanol (99%) permanently terminated the arrhythmia. Contrary to previous experience, ethanol-induced arrhythmia termination did not result in arterial occlusion, further supporting a direct toxic effect on the myocardium as its mode of action. Use of standard angioplasty balloon inflation prevents "backwash" of distally infused ethanol and more generalized cell death. The only complication of this procedure was temporary third-degree AV block, requiring permanent pacemaker implantation.

The role of ACE inhibitors in the treatment of arrhythmias

Several experimental models have been studied to determine the role of angiotensin-converting enzyme (ACE) inhibitors in reducing ischemic and reperfusion arrhythmias. Studies of left main coronary artery occlusion in isolated perfused rat hearts have shown that the ACE inhibitor captopril reduced reperfusion ventricular fibrillation from 100% to 0% and was associated with a reduction in purine overflow and in norepinephrine release. These effects were abolished in the presence of indomethacin. In an anesthetized rat model of acute myocardial infarction (MI), ACE inhibition reduced mean duration of ventricular fibrillation from 1,133 to 135. ACE inhibition at programmed electrical stimulation of the heart in a closed-chest pig model of acute MI reduced the inducibility of sustained, reproducible ventricular tachycardia from a mean of 42 to 8%. In this model, ventricular tachycardia could not be provoked in animals treated with captopril from the time of acute ischemia. Studies on the rate of ventricular ectopy in patients with poor left ventricular function have demonstrated a significant reduction with ACE inhibition. However, while a protective effect has been shown, the mechanism of action is still speculative.

Programmed ventricular stimulation in patients with left ventricular dysfunction and ventricular tachycardia: effects of acute hemodynamic improvement due to nitroprusside

To assess the electrophysiologic effects of acute hemodynamic improvement in patients with left ventricular systolic dysfunction, 12 patients with a left ventricular ejection fraction less than 0.40 and a history of sustained monomorphic ventricular tachycardia were studied. All patients had underlying coronary artery disease. Patients underwent programmed cardiac stimulation in random order during a baseline period and with nitroprusside infusion. Mean pulmonary capillary wedge pressure decreased from 20 +/- 8 mm Hg at baseline study to 8 +/- 3 mm Hg during nitroprusside infusion (p less than 0.0001). Pulmonary artery, right atrial and systemic arterial pressures also decreased with nitroprusside (p less than 0.01). Cardiac output did not change. Left ventricular dimensions, determined by two-dimensional echocardiography, decreased significantly during nitroprusside infusion. The right ventricular effective refractory period, measured during ventricular drive trains at cycle lengths of 400 and 600 ms, were similar during baseline and nitroprusside periods (271 +/- 30 versus 274 +/- 31 ms at 600 ms, and 249 +/- 25 versus 246 +/- 18 ms at 400 ms). In 2 patients no ventricular arrhythmias were induced during either study period; in the other 10, ventricular tachyarrhythmias were induced during both periods. The mean number of extrastimuli required to induce a ventricular tachyarrhythmia was similar during the baseline period (1.8 +/- 0.6) and during nitroprusside infusion (1.9 +/- 0.7). As well, the mean cycle length of ventricular tachycardia induced was similar during the baseline period (347 +/- 61 ms) and during nitroprusside infusion (342 +/- 70 ms).(ABSTRACT TRUNCATED AT 250 WORDS)

Protective effects of captopril against ischemia/reperfusion-induced ventricular arrhythmias in vitro and in vivo

The effects of the converting enzyme inhibitor captopril on the susceptibility of the heart to ventricular arrhythmias following ischemia, both in vitro and in vivo, were studied. In isolated rat hearts, captopril, administered either before or at the end of ischemia, reduced ventricular fibrillation upon reperfusion after 15 minutes of local ischemia. Reduction of purine overflow, improvement in contractility, and increase in coronary blood flow occurred concomitantly. In vivo, a closed-chest pig model was used to determine the effects of captopril, administered at the end of ischemia and continued orally, on the susceptibility to ventricular arrhythmias during the chronic phase of myocardial infarction. Myocardial ischemia was induced by 60-minute inflation of a balloon catheter in the left anterior descending coronary artery. Upon reperfusion, an accelerated idioventricular rhythm occurred, both in 10 untreated and in 10 captopril-treated animals. Creatine kinase levels during the reperfusion period were significantly lower after captopril treatment. Two weeks after the short-term experiments, monomorphic ventricular tachycardia could be induced with programmed electrical stimulation in six of eight surviving untreated pigs. In contrast, in none of the six surviving captopril-treated animals was ventricular tachycardia inducible. Thus, early intervention with captopril during the development phase of myocardial infarction may have beneficial effects on the subsequent development of ventricular arrhythmias. Salvage of ischemic myocardium, improvement in ventricular function, beneficial effects on coronary flow, and decreased activity of the sympathetic nervous system may all contribute.

QRS morphology-dependent pharmacodynamics in multiform ventricular ectopic activity

The effect of an infusion of intravenous procainamide on the frequency of ventricular premature complexes (VCPs) of differing QRS morphologies was studied in 20 patients with multiform ectopic activity. In 17 of 20 patients, there was differential suppression of single VPCs with different QRS morphologies. VPCs of the most frequent QRS morphology and the second most frequent QRS morphology were compared with respect to the procainamide level at the escape of VPCs from 85% suppression and the duration of suppression measured from the onset of the procainamide infusion. In 8 patients, VPCs of the most frequent QRS morphology remained suppressed at lower procainamide concentrations and for longer times than did VPCs of the second most frequent QRS morphology (escape procainamide concentration = 2.8 +/- 1.7 versus 5.4 +/- 2.3 micrograms/ml, p less than 0.025; time to escape 244 +/- 138 versus 98 +/- 114 min; p less than 0.05). In 9 other patients, VPCs of the second most frequent QRS morphology remained suppressed at lower procainamide concentrations and for longer times than did VPCs of the most frequent QRS morphology (escape procainamide concentration 2.9 +/- 1.4 versus 8.3 +/- 6.3 micrograms/ml, p less than 0.025; time to escape 317 +/- 114 versus 63 +/- 80 min; p less than 0.001). Thus, in individual patients there are specific patterns of suppression of VPCs of different QRS morphologies which are independent of the frequency of each morphology. There is apparently a differential pharmacologic effect of procainamide on the foci or pathways responsible for the different QRS morphologies of multiform VPCs.

Factors causing arrhythmias in chronic congestive heart failure

Severe congestive heart failure (CHF) is a common syndrome with a high mortality rate (about 50% in 1 year among patients with symptoms at rest). Severity of left ventricular dysfunction is the most important adverse prognostic factor. Serious arrhythmias are common in CHF and also increase the mortality rate. Sudden death is the mode of death in about 40% of patients with severe heart failure. Multiple factors contribute to arrhythmias in CHF, including left ventricular dysfunction, myocardial ischemia, catecholamines, electrolyte disturbances, and drugs used to treat the heart failure. Minimizing or correcting these influences may be important in reducing serious arrhythmias. Antiarrhythmic drugs may be important in reducing the incidence of sudden death among patients with severe heart failure, although this has not yet been proved.

Evaluation of the patient with congestive heart failure and ventricular arrhythmias

Although vasodilators and new inotropic agents have been shown to improve ventricular function and reduce symptoms, their effect on mortality is uncertain. In view of our failure to reduce mortality in patients with congestive heart failure (CHF), the identification and amelioration of potentially reversible factors that might alter survival are crucial before initiating therapy. The first step is to establish the diagnosis of CHF and the presence or absence of dilated congestive cardiomyopathy. The extent of myocardial dysfunction, both right and left, must also be evaluated. In post-myocardial infarction patients, left ventricular ejection fraction is an important indicator of prognosis during the first 1 to 2 years. However, in patients with chronic CHF and dilated cardiomyopathy, right ventricular ejection fraction may be a more effective predictor of survival. The presence, frequency and complexity of ventricular arrhythmias must be determined, because these arrhythmias may independently increase the risk of sudden cardiac death in patients with ischemic cardiomyopathy. Their role in patients with idiopathic cardiomyopathy is less certain. In addition, myocardial ischemia, left ventricular dyskinesis or aneurysm, occult myocarditis and neurothrombosis formation must be ruled out. Detection and correction of serum electrolyte and neurohumeral abnormalities are essential. Our failure to reduce mortality in patients with CHF may not entirely lie in the lack of effective therapeutic agents but rather in our failure to apply properly the diagnostic and therapeutic approaches now available.