Clinical relevance of exercise-induced ventricular arrhythmias in suspected coronary artery disease

Revisiting exercise-induced premature ventricular complexes as a prognostic factor for mortality in asymptomatic patients: A systematic review and meta-analysis

Background

Recent investigations suggest that premature ventricular complexes (PVCs) during an exercise test are associated with an elevated risk of mortality in asymptomatic individuals. However, given the small number of studies included, the association between these two entities in the asymptomatic population remains obscure. Our aim was to evaluate this matter.

Methods

A comprehensive literature search was conducted utilizing several online databases up to April 2022. The study comprised cohort studies examining the relationship between exercise-induced premature ventricular complexes (EI-PVCs) and all-cause mortality (ACM) as well as cardiovascular mortality (CVM) in asymptomatic populations. To provide diagnostic values across the statistically significant parameters, we additionally calculated sensitivity, specificity, and area under the curve (AUC).

Results

A total of 13 studies consisting of 82,161 patients with a mean age of 49.3 years were included. EI-PVCs were linked to an increased risk of ACM (risk ratio (RR) = 1.30 (95% confidence interval (CI) = 1.18–1.42); p < 0.001; I2 = 59.6%, p-heterogeneity < 0.001) and CVM (RR = 1.67 (95% CI = 1.40–1.99); p < 0.001; I2 = 7.5%, p-heterogeneity = 0.373). Subgroup analysis based on the frequency of PVCs revealed that frequent PVCs were similarly related to a higher risk of ACM and CVM, but not infrequent PVCs. Moreover, diagnostic test accuracy meta-analysis showed that recovery phase EI-PVCs have a higher overall specificity than exercise phase EI-PVCs regarding our outcomes of interest.

Conclusion

EI-PVCs are correlated with a higher risk of ACM and CVM. When compared to the exercise phase, the specificity of PVCs generated during the recovery period in predicting interest outcomes is higher. As a result, we propose that the exercise ECG be utilized on a regular basis in middle-aged asymptomatic individuals to measure the frequency of PVCs and stratify the risk of mortality.

Systematic review registration

[https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=328852], identifier [CRD42022328852].

Clinical Significance of Ventricular Premature Contraction Provoked by the Treadmill Test

Background and Objectives: The treadmill test (TMT) is a predictive tool for myocardial ischemia. Recently, exercise-provoked ventricular premature contracture (VPC) during TMT was shown to have a relation with coronary artery disease and cardiovascular mortality. Therefore, we evaluate clinical correlates of exercise-provoked VPC and compare the predictive power for myocardial ischemia and cardiovascular events. Method: Data of 408 patients (≥18 years of age) who underwent TMT for work up of angina, palpitation, dyspnea, syncope, or arrhythmia between February 2015, and January 2016, were collected with consent at Samsung Medical Center, Seoul, Republic of Korea. Among total of 408 patients, 208 were excluded according to the previous history of PCI or CABG, previous MI, decreased left ventricular ejection fraction lower than 50%, arrhythmia that could affect ST-segment change on ECG. Results: Among 200 patients, 32 (16.0%) developed exercise-provoked VPC (21 patients in the exercise phase, 20 patients in the recovery phase). Of them, 20 patients (10.0%) showed positive TMT, and 4 patients (2.0%) underwent revascularization after TMT. Among 21 patients showing exercise phase VPC, 5 (23.8%) showed positive TMT results. In patients younger than 65 years, exercise phase VPC was associated with positive TMT (odds ratio 6.879, 1.458–32.453) considering demographics and previous medical history in multivariable analysis. Among the 20 patients showing recovery phase VPC, 2 (10.0%) underwent revascularization after TMT. In multivariable analysis, recovery phase VPC was associated with revascularization (odds ratio 9.381, 1.144–76.948) considering age, sex, BMI, and TMT result. Conclusion: VPC during the treadmill test was a useful predictor of myocardial ischemia in this study.

Ventricular arrhythmias and risk stratification of cardiac sudden death in athletes

Sudden cardiac death (SCD) of young athletes is an unexpected and tragic event that could occur during sport activities and is frequently related to ventricular arrhythmias. Identifying athletes at risk of SCD remains a major challenge. While specific characteristics of premature ventricular contractions are considered common and benign, other "uncommon" features should require more accurate investigations, in order to determine eligibility for competitive sports. The most common type of idiopathic premature ventricular contractions originates from ventricular outflow tract and is characterized by an ECG pattern with left bundle branch block and inferior QRS axis (infundibular pattern). Another pattern associated with a good prognosis is the "fascicular" morphology, characterized by a typical right bundle branch block, superior QRS axis morphology and QRS duration <130 ms. Conversely, other morphological features (such as left bundle branch block /intermediate or superior axis or right bundle branch block/intermediate or superior axis and wide QRS) correlate to an underlying substrate. In risk stratification setting, cardiac magnetic resonance plays a key role allowing an accurate identification of myocardial tissue abnormalities, which could affect athletes' prognosis. This review focuses on characteristics of premature ventricular contractions characteristics in terms of morphology, distribution, complexity and response to exercise and describes the possible underlying myocardial substrates. This review also critically analyzes the evaluation process of athletes with premature ventricular contractions necessary for an accurate risk stratification.

Long-term prognostic significance of right bundle-branch morphology ventricular ectopy induced during stress test in patients with intermediate to high probability of coronary artery disease

Aims

Stress-induced right bundle-branch block morphology ventricular ectopy (SI-RBVE) may be caused by left ventricular myocardial anomalies. While frequent ventricular ectopy (FVE) has been linked to poor outcomes, the prognostic value of SI-RBVE has not been established. The study aims to determine whether SI-RBVE is associated with increased mortality.

Methods and results

Three hundred forty-three patients with an intermediate to high probability of coronary artery disease were prospectively included. Patients were referred for a single-photon emission computed tomography and underwent a stress test according to standard protocols. Stress-induced right bundle-branch block morphology ventricular ectopy (VE) was defined as one or more induced premature beats with positive predominance in V1. Frequent VE was defined as the presence of seven or more ventricular premature beats per minute or any organized ventricular arrhythmia. During a mean follow-up of 4.5 ± 1.3 years, 59 deaths occurred. The death rate was higher in the SI-RBVE group (23.4% vs. 14.0%, P = 0.021). Age [odds ratio (OR) = 1.09 (95% CI: 1.06-1.13), P < 0.001] and peripheral artery disease [OR = 2.47 (95% CI: 1.35-4.50) P = 0.003] were independent factors of mortality, but single-photon emission computed tomography findings were not. There was an interaction between SI-RBVE and left ventricular ejection fraction (LVEF). In patients with LVEF > 50%, SI-RBVE was an incremental risk factor for mortality [OR = 2.83 (95% CI: 1.40-5.74), P = 0.004]. Stress-induced right bundle-branch block morphology VE patients also presented higher rates of known coronary artery disease, ischaemia, scar, and ST-segment changes. Frequent VE was not related to mortality.

Conclusion

Stress-induced right bundle-branch block morphology VE is associated with an increased mortality in patients with preserved LVEF.

Prognostic significance of exercise-induced premature ventricular complexes: a systematic review and meta-analysis of observational studies

BACKGROUND

Exercise-induced premature ventricular complexes (EI-PVCs) are common during exercise stress tests. Their optimal management and prognostic significance remain uncertain.

AIM

To perform meta-analysis of observational studies on the prognostic significance of EI-PVCs.

METHODS

A search was conducted on Medline and Embase. Inclusion criteria were observational studies comparing the prognosis of patients with and without EI-PVCs whilst exclusion criteria were studies without confounder adjustment and studies with zero endpoints. Composite endpoints included all-cause mortality, cardiac mortality and cardiovascular events. Relative risk of endpoints were analysed with random effects model. Meta-regression and sensitivity analysis were performed.

RESULTS

Ten studies were included. In asymptomatic patients who had no clinical evidence of heart disease, EI-PVCs were associated with a pooled risk ratio of 1.82 (95% CI 1.44 to 2.30) of developing adverse cardiovascular events over 16 years. The corresponding pooled RR for patients with symptomatic heart disease was 1.36 (95% CI 1.18 to 1.57) over 5.4 years. Sensitivity analysis: only EI-PVCs on the recovery phase of an exercise test, not during exercise, had adverse prognostic significance.

CONCLUSIONS

EI-PVCs are correlated with a higher risk of all cause death or cardiovascular events in the long term. This risk is elevated in asymptomatic patients without clinical heart disease and in patients with symptomatic heart disease. The fact that only EI-PVCs during recovery, and not during exercise, have poor prognostic value suggests that autonomic dysfunction may play a role in this association. Further studies are needed to see if autonomic manipulation by drugs or catheter-based methods can improve the poor prognosis associated with EI-PVCs.

Meta-Analysis of Prognostic Implications of Exercise-Induced Ventricular Premature Complexes in the General Population

Ventricular premature complexes (VPCs) during stress testing in the general population are commonly seen in clinical practice, but their prognostic value is not well understood. A comprehensive literature search of MEDLINE, Embase, and the Cochrane Library from January 1970 to May 2015 was conducted. Observational cohort studies on general populations evaluating the association between exercise-induced VPCs and all-cause or cardiovascular mortality were included in the analysis. Nine studies comprising 62,488 participants comparing clinical outcomes of patients with and without exercise-induced VPCs were included. The overall combined relative risks (RRs) for all-cause mortality and cardiovascular mortality in patients with exercise-induced VPCs were 1.41 (95% CI 1.23 to 1.61) and 1.86 (95% CI 1.51 to 2.30), respectively. In subgroup analysis, both frequent VPCs (RR 1.35, 95% CI 1.14 to 1.60) and infrequent VPCs (RR 1.57, 95% CI 1.13 to 2.18) were associated with an adverse outcome. VPCs during recovery were associated with an increased risk of death (RR 1.55, 95% CI 1.22 to 1.96). VPCs during exercise did not achieve statistical significance (RR 1.14, 95% CI 0.96 to 1.34), but only a few studies were included in the analysis. In conclusion, our meta-analysis suggests that exercise-induced VPCs in the general population significantly increase the risk of total mortality and cardiovascular mortality. Our study calls for further studies to assess the prognostic significance of exercise-induced VPCs and the utility of efforts to reduce the VPC burden to improve the clinical outcome.

The Acute Risks of Exercise in Apparently Healthy Adults and Relevance for Prevention of Cardiovascular Events

BACKGROUND

Increased physical activity (PA) is associated with improved quality of life and reductions in cardiovascular (CV) morbidity and all-cause mortality in the general population in a dose-response manner. However, PA acutely increases the risk of adverse CV event or sudden cardiac death (SCD) above levels expected at rest. We review the likelihood of adverse CV events related to exercise in apparently healthy adults and strategies for prevention, and contextualize our understanding of the long-term risk reduction conferred from PA.

METHODS

A systematic review of the literature was performed using electronic databases; additional hand-picked relevant articles from reference lists and additional sources were included after the search.

RESULTS

The incidence of adverse CV events in adults is extremely low during and immediately after PA of varying types and intensities and is significantly lower in those with long-standing PA experience. The risk of SCD and nonfatal events during and immediately after PA remains extremely low (well below 0.01 per 10,000 participant hours); increasing age and PA intensity are associated with greater risk. In most cases of exercise-related SCD, occult CV disease is present and SCD is typically the first clinical event.

CONCLUSIONS

Exercise acutely increases the risk of adverse CV events, with greater risk associated with vigorous intensity. The risks of an adverse CV event during and immediately after exercise are outweighed by the health benefits of vigorous exercise performed regularly. A key challenge remains the identification of occult structural heart disease and inheritable conditions that increase the chances of lethal arrhythmias during exercise.

Exercise-induced ventricular arrhythmias: analysis of predictive factors in a population with sleep disorders

OBJECTIVE

To assess the prevalence of ventricular arrhythmias induced by exercise in a population with sleep disorders and to analyze the triggering factors.

METHODS

Patients were consecutively selected from the database of the Sleep Clinic of Universidade Federal de São Paulo. All subjects were submitted to basal polysomnography, blood sample collection, physical examination, 12-lead ECG, spirometry, cardiorespiratory exercise study on a treadmill, and echocardiogram. The Control Group was matched for age and gender.

RESULTS

A total of 312 patients were analyzed. Exercise-induced ventricular arrhythmia was observed in 7%. The aortic diameter was larger (3.44 ± 0.30, 3.16 ± 0.36, p = 0.04) and the minimal saturation was lower (92.75 ± 3.05, 95.50 ± 1.73, p=0.01) in the ventricular arrhythmia group when compared to controls, respectively. After correction of the aortic root to body surface, there was only a trend to a larger diameter being associated with the emergence of arrhythmia.

CONCLUSIONS

Exercise-induced ventricular arrhythmia was observed in 7% of sample and it was associated with lower oxygen saturation during exercise.

Utility of the exercise electrocardiogram testing in sudden cardiac death risk stratification

BACKGROUND

Sudden cardiac death (SCD) remains a major public health problem. Current established criteria identifying those at risk of sudden arrhythmic death, and likely to benefit from implantable cardioverter defibrillators (ICDs), are neither sensitive nor specific. Exercise electrocardiogram (ECG) testing was traditionally used for information concerning patients' symptoms, exercise capacity, cardiovascular function, myocardial ischemia detection, and hemodynamic responses during activity in patients with hypertrophic cardiomyopathy.

METHODS

We conducted a systematic review of MEDLINE on the utility of exercise ECG testing in SCD risk stratification.

RESULTS

Exercise testing can unmask suspected primary electrical diseases in certain patients (catecholaminergic polymorphic ventricular tachycardia or concealed long QT syndrome) and can be effectively utilized to risk stratify patients at an increased (such as early repolarization syndrome and Brugada syndrome) or decreased risk of SCD, such as the loss of preexcitation on exercise testing in asymptomatic Wolff-Parkinson-White syndrome.

CONCLUSIONS

Exercise ECG testing helps in SCD risk stratification in patients with and without arrhythmogenic hereditary syndromes.

Effect of physical activity assessment on prognostication for peripheral artery disease and mortality

OBJECTIVE

To examine whether a simple question about the performance of regular vigorous activity is associated with peripheral artery disease (PAD) and mortality.

METHODS

A total of 1288 individuals undergoing nonemergency coronary angiography were assessed for participation in regular vigorous activity by questionnaire. Data on demographic characteristics, ankle-brachial indexes, and cardiovascular outcomes were prospectively collected.

RESULTS

Compared with those who denied participation in regular vigorous activity, those who reported participation were less likely to have PAD (odds ratio, 0.58; 95% CI, 0.39-0.86), had higher ankle-brachial indexes, had better Walking Impairment Questionnaire scores (P<.001), and experienced reduced all-cause mortality rates (hazard ratio, 0.48; 95% CI, 0.31-0.74). When added to the Framingham Risk Score, the response improved the net reclassification index for all-cause (32.6%) and cardiovascular (32.0%) mortality.

CONCLUSION

Among at-risk individuals, regular vigorous activity is associated with decreased PAD and all-cause mortality. Simple and readily available, a single yes/no query about participation in regular vigorous exercise could be used to improve risk stratification.

Exercise induced non-sustained ventricular tachycardia and indication for invasive management

Diagnostic stress echo testing is commonly performed in patients with known or suspected cardiovascular disease. There has been considerable debate in management of exercise induced non-sustained ventricular tachycardia (NSVT). In this case report, we present our experience with a case of exercise induced NSVT, and subsequent angiographically significant left anterior descending (LAD) coronary artery lesion.

Evidence-based risk assessment and recommendations for physical activity clearance: established cardiovascular disease1This paper is one of a selection of papers published in this Special Issue, entitled Evidence-based risk assessment and recommendations for physical activity clearance, and has undergone the Journal’s usual peer review process

Physical activity is an effective lifestyle therapy for patients at risk for, or with, documented cardiovascular disease (CVD). Current screening tools — the Physical Activity Readiness Questionnaire (PAR-Q) and the Physical Activity Readiness Medical Evaluation (PARmed-X) — require updating to align with risk/benefit evidence. We provide evidence-based recommendations to identify individuals with CVD at lower risk, intermediate risk, or higher risk of adverse events when participating in physical activity. Forms of exercise and the settings that will appropriately manage the risks are identified. A computer-assisted search of electronic databases, using search terms for CVD and physical activity risks and benefits, was employed. The Appraisal of Guidelines for Research and Evaluation were applied to assess the evidence and assign a strength of evidence rating. A strength rating for the physical activity participation clearance recommendation was assigned on the basis of the evidence. Recommendations for physical activity clearance were made for specific CVD groups. Evidence indicates that those who are medically stable, who are involved with physical activity, and who have adequate physical ability can participate in physical activity of lower to moderate risk. Patients at higher risk can exercise in medically supervised programs. Systematic evaluation of evidence indicates that clinically stable individuals with CVD may participate in physical activity with little risk of adverse events. Therefore, changes in the PAR-Q should be undertaken and a process of assessment and consultation to replace the PARmed-X should be developed. Patients at lower risk may exercise at low to moderate intensities with minimal supervision. Those at intermediate risk should exercise with guidance from a qualified exercise professional. Patients at higher risk should exercise in medically supervised programs.

Evidence-based risk assessment and recommendations for exercise testing and physical activity clearance in apparently healthy individuals1This paper is one of a selection of papers published in this Special Issue, entitled Evidence-based risk assessment and recommendations for physical activity clearance, and has undergone the Journal’s usual peer review process

Increased physical activity (PA) is associated with improved health and quality of life in the general population. A dose–response effect is evident between increasing levels of PA participation and a lower relative risk for cardiovascular disease and all-cause mortality. However, there is also clear evidence that PA acutely increases the risk of an adverse cardiovascular (CV) event and sudden cardiac death (SCD) significantly above levels expected at rest. Adverse CV events during PA may be triggered acutely by the physiological stress of exercise. This investigation will review the available literature describing the CV risks of exercise testing and PA participation in apparently healthy individuals. A systematic review of the literature was performed using electronic databases, including Medline, CINAHL, SPORT discus, EMBASE, Cochrane DSR, ACP Journal Club, and DARE; additional relevant articles were hand-picked and the final grouping was used for the review using the AGREE process to assess the impact and quality of the selected articles. Six hundred and sixteen relevant articles were reviewed with 51 being identified as describing adverse CV events during exercise and PA. Data suggests the risks of fatal and nonfatal events during maximal exercise testing in apparently healthy individuals rarely occur (approximately <0.8 per 10 000 tests or 1 per 10 000 h of testing). The incidence of adverse CV events is extremely low during PA of varying types and intensities, with data limited almost exclusively to fatal CV events, as nonfatal events are rarely reported. However, this risk is reduced by 25%–50% in those individuals who have prior experience with increased levels of PA, particularly vigorous PA. Throughout a wide age range, the risk of SCD and nonfatal events during PA remain extremely low (well below 0.01 per 10 000 participant hours), but both increasing age and PA intensity are associated with greater risk. In most cases of exercise-related SCD, undetected pre-existing disease is present and SCD is typically the first clinical event. The risks of an adverse CV event during exercise testing and PA are rare and are outweighed by the health benefits. Given this risk-benefit relationship, the PAR-Q is an appropriate method to identify those at higher risk across a wide age span and should be used in conjunction with appropriate clinical guidelines for guiding individuals towards graduated PA. There are not adequate data to describe the risks of PA in those individuals considered to be at higher risk but without cardiovascular disease.

[Coronary artery disease--relevance of total coronary revascularization on the incidence of malignant arrhythmias]

Myocardial ischemia induces redistribution of different ions (H(+), K(+), Na(+), Ca(++)) across the cardiomyocyte membrane, as well as the loss of intracellular ATP content. This results in changes in the electrical properties including shortening of the action potential, appearance of delayed afterpotentials, and a modified refractoriness of the cardiomyocyte. These changes may induce or support malignant cardiac arrhythmias. Supersensitivity of sympathetic denervated myocardium may further support the electrical instability of ischemic myocardium.Virtues of studies indicate that patients with coronary artery disease who develop complex arrhythmias during or after exercise bear a substantially increased risk for sudden cardiac death. Other studies report about arrhythmic stabilization and reduced mortality if patients with reversible myocardial ischemia receive complete revascularization. However, none of these studies is without methodological flaws. Due to the lack of methodologically sound studies in sufficiently large patient cohorts, the question whether complete coronary revascularisation improves the prognosis of patients with coronary artery disease and which strategy (medical, interventional, or surgical) warrants the best outcomes remains open.

Exercise-induced ventricular arrhythmias and cardiovascular death

BACKGROUND

Exercise-induced ventricular arrhythmias (EIVA) are frequently observed during exercise testing. However, the clinical guidelines do not specify their significance and so we examined this issue in our population.

METHODS

A retrospective analysis of prospectively collected data was performed on 5754 consecutive male veterans referred for exercise testing at two university-affiliated Veterans Affairs Medical Centers. Exercise test responses were recorded and cardiovascular mortality was assessed after a mean follow-up of 6 +/- 4 years. EIVA were defined as frequent premature ventricular complexes (PVCs) constituting more than 10% of all ventricular depolarizations during any 30-second ECG recording, or a run of three or more consecutive PVCs during the exercise test or recovery.

RESULTS

EIVA occurred in 426 patients (7.4%). There were 550 (10.6%) cardiovascular deaths during follow-up. Seventy two (17%) patients with EIVA died of cardiovascular causes, whereas 478 (9.0%) of patients without EIVA died of cardiovascular causes (P < 0.001). Patients with EIVA had a higher prevalence of cardiovascular disease, resting PVCs, resting ST depression, and ischemia during exercise than patients without EIVA. In a Cox hazards model adjusted for age, cardiovascular disease, exercise-induced ischemia, ECG abnormalities, exercise capacity and risk factors, EIVA was significantly associated with time to cardiovascular death. The combination of both resting PVCs and EIVA was associated with the highest hazard ratio.

CONCLUSIONS

EIVA are independent predictors of cardiovascular mortality after adjusting for other clinical and exercise test variables; combination with resting PVCs carries the highest risk.

Functional and prognostic significance of exercise-induced ventricular arrhythmias in patients with suspected coronary artery disease

Our aims were to assess (1) the relation between exercise-induced ventricular arrhythmia (VA) and myocardial wall motion abnormalities during exercise echocardiography in patients with suspected coronary artery disease (CAD), and (2) the effect of this relation on outcome. We studied the clinical and prognostic significance of exercise-induced VA in 1,460 patients (mean age 64 +/- 10 years; 867 men) with intermediate pretest probability of CAD and no history of previous myocardial infarction or revascularization who underwent exercise echocardiography. Exercise-induced VA occurred in 146 patients (10%). Compared with patients without VA, those with VA had a greater prevalence of abnormal exercise echocardiographic findings (48% vs 29%, p = 0.001) and ischemia on exercise echocardiography (39% vs 22%, p = 0.001), greater increase in wall motion score index with exercise (0.14 +/- 0.28 vs 0.06 +/- 0.18, p <0.0001), and a greater percentage of abnormal segments with exercise (21 +/- 30% vs 9 +/- 19%, p <0.0001). During follow-up (median 2.7 years), cardiac death and nonfatal myocardial infarction occurred in 36 patients. In multivariate analysis of combined clinical and exercise stress test variables, independent predictors of cardiac events were exercise-induced VA (chi-square 4.7, p = 0.03) and exercise heart rate (chi-square 18, p = 0.0001). The percentage of abnormal myocardial segments with exercise echocardiography was the most powerful predictor of VA (chi-square 31, p = 0.0001) and cardiac events (chi-square 15, p = 0.0001). In patients with suspected CAD, exercise-induced VA is associated with a greater risk of cardiac death and nonfatal myocardial infarction. This risk is attributed to the relation between VA and the extent and severity of left ventricular functional abnormalities with exercise.

Relation among exercise-induced ventricular arrhythmias, myocardial ischemia, and viability late after acute myocardial infarction

This study assesses the relation between exercise-induced ventricular arrhythmia (VA) and scintigraphic markers of myocardial ischemia and viability in patients referred for exercise stress testing late after acute myocardial infarction. We studied 171 patients (144 men, age 57 +/- 10 years) with resting wall motion abnormalities by exercise stress testing in conjunction with methoxyisobutyl isonitrile (MIBI) single-photon emission computed tomography at a mean of 4.1 years after myocardial infarction. Ischemia was defined as reversible perfusion abnormalities. Myocardial viability was considered in myocardial segments with resting wall motion abnormalities in the presence of normal perfusion, a reversible defect or a fixed defect with regional MIBI uptake > or = 50% of maximal uptake. Exercise-induced VA occurred in 46 patients (27%). Patients with VA had a higher prevalence of infarct-related artery stenosis (43 [93%] vs 93 [74%], p < 0.01), peri-infarction ischemia (32 [70%] vs 54 [43%], p < 0.005), and ischemia in > or = 2 vascular regions (20 [43%] vs 27 [22%], p < 0.01) than patients without VA. Reversible defects were detected in 39 of 97 dyssynergic segments (40%) in patients with versus 40 of 248 dyssynergic segments (16%) in patients without VA (p < 0.0001). In dyssynergic segments without reversible perfusion abnormalities, the percent resting MIBI uptake was > or = 50% in 39 of 58 segments (67%) in patients with versus 63% in 131 of 208 segments in patients without VA (p = NS). The percentage of viable segments was 80% and 69% in patients with and without VA, respectively (p < 0.05). It is concluded that patients with exercise-induced VA late after myocardial infarction have a higher prevalence of ischemia in the peri-infarction zone and in multivessel distribution. Myocardial ischemia in the dyssynergic myocardium appears to be a major mechanism underlying the occurrence of VA in these patients.

Exercise-induced ventricular arrhythmias in patients with healed myocardial infarction

BACKGROUND

Controversy exists about the clinical and prognostic significance of exercise-induced ventricular arrhythmias late after myocardial infarction. The aim of the study was to identify the main clinical and prognostic features of exercise-induced ventricular arrhythmias in out-patients with healed Q-wave myocardial infarction.

METHODS

The study population was 777 consecutive patients who underwent a symptom-limited (Bruce protocol) treadmill test from May 1988 to January 1991 after myocardial infarction (at least 1 year). Clinical and exercise data were prospectively entered in a computerized database and retrospectively two different groups were selected: (1) 228 patients with exercise-induced ventricular arrhythmias; (2) 549 patients without. Incidence and morphology of exercise-induced ventricular arrhythmias, various exercise parameters and a follow-up were evaluated.

RESULTS

Patients with exercise-induced ventricular arrhythmias were older (P < 0.001), had higher blood pressure (P < 0.03) and peak exercise rate pressure product (P < 0.00) than the others. No difference was found in the incidence of exercise-ischaemia: either symptomatic or not. When simple (< or = 2 Lown) versus complex (> or = 3 Lown) exercise-induced ventricular arrhythmias were considered, the latter were more frequent in patients with anterior myocardial infarction, shorter exercise duration (P < 0.001) and lower exercise rate pressure product, lower ejection fraction and lower incidence of exercise-induced ischaemia. In the follow-up (mean 24 +/- 13 month) there were 24 deaths: five (2.2%) in patients with exercise-induced ventricular arrhythmias and 19 (3.4%) in patients without. Cardiac event rate was similar in both groups.

CONCLUSIONS

We conclude that in out-patients with healed myocardial infarction exercise-induced ventricular arrhythmias are quite frequent, but they are not associated with exercise-induced ischaemia, either symptomatic or not. Exercise-induced ventricular arrhythmias seem to be related to age or peak workload. Moreover patients with these arrhythmias have no adjunctive negative risk on prognosis.

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.

Echocardiographic detection of coronary artery disease during dobutamine infusion

BACKGROUND

Two-dimensional echocardiography performed during dobutamine infusion has been proposed as a potentially useful method for detecting coronary artery disease. However, the safety and diagnostic value of dobutamine stress echocardiography has not been established.

METHODS AND RESULTS

In this study, echocardiograms were recorded during step-wise infusion of dobutamine to a maximum dose of 30 micrograms/kg/min in 103 patients who also underwent quantitative coronary angiography. The echocardiograms were digitally stored and displayed in a format that allowed simultaneous analysis of rest and stress images. Development of a new abnormality in regional function was used as an early end point for the dobutamine infusion. No patient had a symptomatic arrhythmia or complications from stress-induced ischemia. Significant coronary artery disease (greater than or equal to 50% diameter stenosis) was present in 35 of 55 patients who had normal echocardiograms at rest. The sensitivity and specificity of dobutamine-induced wall motion abnormalities for coronary artery disease was 89% (31 of 35) and 85% (17 of 20), respectively. The sensitivity was 81% (17 of 21) in those with one-vessel disease and 100% (14 of 14) in those with multivessel or left main disease. Forty-one of 48 patients with abnormal echocardiograms at baseline had localized rest wall motion abnormalities. Fifteen had coronary artery disease confined to regions that had abnormal rest wall motion, and 26 had disease remote from these regions. Thirteen of 15 patients (87%) without remote disease did not develop remote stress-induced abnormalities, and 21 of 26 (81%) who had remote disease developed corresponding abnormalities.

CONCLUSIONS

Echocardiography combined with dobutamine infusion is a safe and accurate method for detecting coronary artery disease and for predicting the extent of disease in those who have localized rest wall motion abnormalities.