Prevalence and prognostic value of exercise-induced ventricular arrhythmias

Objective The purpose of this study was to determine the prevalence and prognostic significance of exercise-induced ventricular arrhythmias (EIVAs) in patients referred for exercise testing, considering the arrhythmic substrate and exercise-induced ischemia.Background EIVAs are frequently observed during exercise testing, but their prognostic significance is uncertain. The design of this study was a retrospective analysis of prospectively collected data, and it took place in 2 university-affiliated Veterans Affairs Medical Centers. Patients comprised 6213 consecutive males referred for exercise tests. We measured clinical exercise test responses and all-cause mortality after a mean follow-up of 6 ± 4 years. EIVAs were defined as frequent premature ventricular contractions (PVCs) constituting >10% of all ventricular depolarizations during any 30 second electrocardiogram recording, or a run of ≥3 consecutive PVCs during exercise or recovery.Results A total of 1256 patients (20%) died during follow-up. EIVAs occurred in 503 patients (8%); the prevalence of EIVAs increased in older patients and in those with cardiopulmonary disease, resting PVCs, and ischemia during exercise. EIVAs were associated with mortality irrespective of the presence of cardiopulmonary disease or exercise-induced ischemia. In those without cardiopulmonary disease, mortality differed more so later in follow up than earlier. In those without resting PVCs, EIVAs were also predictive of mortality, but in those with resting PVCs, poorer prognosis was not worsened by the presence of EIVAs.Conclusions Exercise induced ischemia does not affect the prognostic value of EIVAs, whereas the arrhythmic substrate does. EIVAs and resting PVCs are both independent predictors of mortality after consideration of other clinical and exercise-test variables. These findings are of limited clinical significance because of the modest change in risk and the lack of any established intervention. However, they explain some of the previous controversy and highlight the need to consider resting PVCs and follow-up duration in assessing the clinical implications of EIVAs. (Am Heart J 2003;145:139-46.)     

Rest Premature Ventricular Contractions on Routine ECG and Prognosis in Heart Failure Patients

Background: Premature ventricular contractions (PVC) at rest are frequently seen in heart failure (HF) patients but conflicting data exist regarding their importance for cardiovascular (CV) mortality. This study aims to evaluate the prognostic value of rest PVCs on an electrocardiogram (ECG) in patients with a history of clinical HF. Methods and Results: We considered 352 patients (64 ± 11 years; 7 females) with a history of clinical HF undergoing treadmill testing for clinical reasons at the Veterans Affairs Palo Alto Health Care System (VAPAHCS) (1987–2007). Patients with rest PVCs were defined as having ≥1 PVC on the ECG prior to testing (n = 29; 8%). During a median follow‐up period of 6.2 years, there were 178 deaths of which 76 (42.6%) were due to CV causes. At baseline, compared to patients without rest PVCs, those with rest PVCs had a lower ejection fraction (EF) (30% vs 45%) and the prevalence of EF ≤ 35% was higher (75% vs 41%). They were more likely to have smoked (76% vs 55%).The all‐cause and CV mortality rates were significantly higher in the rest PVCs group (72% vs 49%, P = 0.01 and 45% vs 20%, P = 0.002; respectively). After adjusting for age, beta‐blocker use, rest ECG findings, resting heart rate (HR), EF, maximal systolic blood pressure, peak HR, and exercise capacity, rest PVC was associated with a 5.5‐fold increased risk of CV mortality (P = 0.004). Considering the presence of PVCs during exercise and/or recovery did not affect our results. Conclusion: The presence of PVC on an ECG is a powerful predictor of CV mortality even after adjusting for confounding factors. Ann Noninvasive Electrocardiol 2010;15(1):56–62     

Prognostic impact of morphology and duration of premature ventricular contractions in a population without structural heart disease

Background

Premature ventricular contractions (PVCs) are a common form of arrhythmia associated with an unfavorable prognosis in patients with structural heart disease. It is unclear whether PVCs site of origin and QRS-width has a prognostic significance in patients without structural heart disease. The aim of this study was to assess the prognostic importance of PVCs morphology and duration in this patient group.

Methods

We included 511 consecutive patients without a history of previous heart disease. They were examined with echocardiography and exercise test with normal findings. We categorized the PVCs from a 12 lead ECG according to morphology and width of the QRS-complex and analyzed the outcome in terms of a composite endpoint of total mortality and cardiovascular morbidity.

Results

During a median follow-up time of 5.3 years, 19 patients (3.5%) died and 61 (11.3%) met the composite outcome. Patients with PVCs originating from the outflow tracts had a significantly lower risk for the composite outcome compared to patients with non-OT-PVCs. Similarly, patients with PVC originating from the right ventricle had a better outcome than patients with left ventricular PCVs. No difference in outcome depending on QRS-width during PVCs was noticed.

Conclusion

In our cohort of consecutively included PVC patients without structural heart disease PVCs from the outflow tracts were associated with a better prognostic outcome than non-OT PVCs; the same was true for right ventricular PVCs when compared to left ventricular ones. The classification of the origin of the PVCs was based on 12-lead ECG morphology. QRS-width during PVC did not seem to have prognostic significance.     

Ventricular arrhythmias during clinical treadmill testing and prognosis

BACKGROUND: Although exercise-associated ventricular arrhythmias are frequently observed during exercise testing, their prognostic significance remains uncertain. Therefore, we aimed to evaluate the clinical correlates and prognostic significance of exercise-associated premature ventricular complexes (PVCs) during and after exercise testing. METHODS: We studied 1847 heart failure-free patients who underwent clinical treadmill testing between March 13, 1997, and January 15, 2004, in the Veterans Affairs Palo Alto Health Care System. Logistic regression was used to evaluate the clinical and exercise test associations of exercise and recovery PVCs. Propensity score-adjusted Cox survival analyses were used to evaluate the prognostic significance of exercise-associated PVCs. RESULTS: Of the 1847 subjects, 850 (46.0%) developed exercise PVCs (median rate, 0.43 per minute) and 620 (33.6%) had recovery PVCs (median rate, 0.60 per minute). Resting PVCs, age, and systolic blood pressure were key predictors of both exercise and recovery PVCs. Whereas exercise PVCs were related to the heart rate increase with exercise, recovery PVCs were related to coronary disease (previous myocardial infarction, coronary revascularization procedure, or pathological Q waves on resting electrocardiogram) and ST-segment depression. During a 5.4-year mean follow-up, 161 subjects (8.7%) died, and 53 of these deaths (32.9%) were due to cardiovascular causes. Recovery PVCs, but not exercise PVCs, were associated with 71% to 96% greater propensity-adjusted mortality rates (hazard ratio, 1.96 [95% confidence interval, 1.31-2.91] for infrequent PVCs; hazard ratio, 1.71 [95% confidence interval, 1.07-2.73] for frequent PVCs compared with subjects without PVCs), and occurrence of recovery PVCs reclassified 33.2% of subjects with intermediate-risk Duke Treadmill Scores into higher-risk subgroups. CONCLUSION: In our heart failure-free population, recovery PVCs were associated with increased mortality and augmented established risk markers.     

Statin Use and Ventricular Arrhythmias During Clinical Treadmill Testing

Background: Premature ventricular complexes (PVCs) during exercise are associated with adverse prognosis, particularly in patients with intermediate treadmill test findings. Statin use reduces the incidence of resting ventricular arrhythmias in patients with coronary artery disease; however, the relationship between statin use and exercise-induced ventricular arrhythmias has not been investigated.
Methods and Results: We evaluated the association between statin use and PVCs in 1,847 heart-failure-free patients (mean age 58, 95% male) undergoing clinical exercise treadmill testing between 1997 and 2004 in the VA Palo Alto Health Care System. PVCs were quantified in beats per minute and frequent PVCs were defined as PVC rates greater than the median value (0.43 and 0.60 PVCs per minute for exercise and recovery, respectively). Propensity-adjusted logistic regression was used to evaluate the odds of developing PVCs during exercise and recovery periods associated with statin use. There were 431 subjects who developed frequent PVCs during exercise and 284 subjects had frequent recovery PVCs. After propensity score adjustment, subjects treated with statins (n = 145) had 42% lower odds of developing frequent PVCs during exercise (odds ratio [OR] 0.58, 95% confidence interval [CI] 0.37–0.93) and 44% lower odds of developing frequent PVCs during recovery (OR 0.56, 95% CI 0.30–0.94). These effects were not modified by age, prior coronary disease, hypercholesterolemia, exercise-induced angina, or exercise capacity.
Conclusions: Statin use was associated with reduced odds of frequent PVCs during and after clinical exercise testing in a manner independent of associations with coronary disease or ischemia in our study population.     

Diagnostic Value of Exercise‐Induced ST‐Segment Elevation in Q‐Wave Leads. After Recent Myocardial Infarction

Background: Exercise‐induced ST‐segment elevation in an infarct territory with abnormal Q waves is a known marker for more severe left ventricular wall‐motion abnormalities. However, it is reported, that exercise‐induced ST‐segment elevation in infarct leads may indicate residual viability in the intarctregion. The aim of the study was to test whether exercise‐induced ST‐segment elevation is related to left ventricular (LV) dysfunction or to persistent viability in patients with previous myocardial infarction (MI). Methods: 145 consecutive patients (119 men, 26 women, age 58 ± 11 years) 2–3 weeks after Q‐wave Ml but without ST elevation at rest ECG were enrolled in the study. All patients underwent a target heart rate or symptom‐limited exercise testing (ET) with Bruce protocol. Exercise‐induced ST‐segment elevation < 1 mm above the baseline ST segment level (80 ms after J point) in more than 1 ECG lead with Q wave was considered to be significant. Patients were divided in two groups according to ET results: group I, 25 patients with significant exercise‐induced ST‐segment elevation and group II, 120 patients without exercise‐induced ST‐segment elevation. All patients underwent rest ECHO and low dose dobutamine stress echo (LOSE) within 7 days after ET. LV function was estimated using ejection fraction (EF). Results: More severe LV dysfunction was observed in patients from group 1 (EF 31 ± 8.16% vs EF 45 ± 10.3%). Myocardial viability (defined as an improvement of regional systolic wall thickening in the regions with resting regional wall‐motion abnormalities during LOSE 5 to 15 g/kg/min was recognized in 8 patients (32%) in group I and 31 patients (25.8%) in group II. There was no relation between exercise‐induced ST‐segment elevation and myocardial viability (chi‐square test: 2,809; NS). Conclusions: Exercise‐induced ST‐segment elevation in most cases is associated with left ventricular dysfunction. Patients with exercise‐induced ST‐segment elevation have a lower EF than those without and greater severity of resting wall‐motion abnormalities. Our results suggest that exercise‐induced ST‐segment elevation is not related to residual myocardial viability.     

Relationship between QT interval duration and exercise-induced ventricular arrhythmias

This study was performed to determine if QT prolongation beforeand during early exercise is related to the occurrence of exercise-inducedventricular arrhythmias (EIVA). EIVA occurred in 47 of 142 patientswith angiographic evidence of coronary artery disease (CAD);no EIVA occurred among the 22 patients without CAD (OV). RestingQTc and QT intervals during early exercise were similar in patientswithout EIVA, irrespective of the presence or absence of CAD;however resting QTc was significantly longer in CAD patientswho showed EIVA (443±40ms; ?<0·01) than inCAD patients without EIVA (424 ± 37 ms) and in OV patients(421 ±32 ms). During early exercise, the QT intervalremained significantly longer in patients with than in thosewithout EIVA. There was a trend toward increasing resting QTc in patients who exhibited EIVA more severe than grade 3.When resting QTc was longer than 440 ms, subsequent EIVA werecorrectly predicted in CAD patients with a sensitivity of 43%,a specificity of 72% and a predictive accuracy of 63%. Thus, a trend toward longer resting QTc values exists in CADpatients who develop EIVA; however, a long resting QTc (>440 ms) appears to be only a weak predictor of subsequent EIVA.     

Akinesia becoming dyskinesia after exercise testing: prevalence and relationship to clinical outcome

OBJECTIVES: The aim of this study was to determine the prevalence and prognostic implications of dyskinesia developing after exercise. BACKGROUND: The prevalence and prognostic implications of new-onset dyskinesia with exercise testing have not been previously described. METHODS: We considered 1005 consecutive patients who underwent exercise echocardiography and had akinetic segments at rest. Patients were divided according to the presence or absence of exercise-induced dyskinesia. Baseline clinical and echocardiographic parameters were compared, and patients were followed up for a median of 2.7 years. RESULTS: One hundred four (10%) patients developed dyskinesia after exercise. Compared to patients with segments that remained akinetic, these patients were more likely to have electrocardiographic (ECG) evidence of prior myocardial infarction and, during exercise, had a less pronounced rise in systolic blood pressure and more often had ECG evidence of ischemia. Their resting left ventricular (LV) ejection fraction was worse and improved little after exercise. However, all-cause mortality and the incidence of major adverse cardiac events were similar in the two groups, even after correction for age, gender, and resting LV function (hazard ratio for major adverse cardiac events = 1.36, 95% confidence interval [CI] 0.82 to 2.26, p = 0.23; hazard ratio for total mortality = 1.20, 95% CI 0.75 to 1.94, p = 0.45). CONCLUSIONS: One in 10 patients with akinetic myocardium at rest will develop dyskinesia after exercise. This is associated with poorer LV function at rest and little improvement in systolic function after exercise. However, this response has no impact on prognosis.     

Prediction of mortality in patients with left ventricular hypertrophy by clinical,exercise stress,and echocardiographic data

OBJECTIVES: This study evaluated the clinical, exercise stress test, and echocardiographic predictors of mortality and cardiac events in patients with left ventricular hypertrophy (LVH). BACKGROUND: Left ventricular hypertrophy is associated with an increased risk of cardiovascular morbidity and mortality. METHODS: Symptom-limited treadmill exercise echocardiography was performed for evaluation of coronary artery disease in 483 patients (age, 66 +/- 11 years; 281 men) with LVH. End points during follow-up were all-cause mortality and hard cardiac events (cardiac death and nonfatal myocardial infarction [MI]). RESULTS: Forty-six patients died and 14 had nonfatal MI. The cumulative mortality rate was higher in patients with abnormal exercise echocardiography (3% vs. 0.4% at one year, 11.7% vs. 3.7% at three years, and 18.3% vs. 9.5% at five years, p < 0.001). In a sequential multivariate analysis model of clinical, exercise test, and rest and exercise echocardiographic data, incremental predictors of mortality were workload (hazard ratio [HR], 0.5; 95% confidence interval [CI], 0.3 to 0.9), rate pressure product (HR, 0.7; 95% CI, 0.5 to 0.9), left ventricular (LV) mass index (HR, 1.4; 95% CI, 1.1 to 1.8), and failure to increase ejection fraction (EF) with exercise (HR, 2.1; 95% CI, 1.1 to 3.8). Predictors of cardiac events were history of coronary artery bypass grafting (HR, 2.6; 95% CI, 1.2 to 5.4), lower exercise rate-pressure product (HR, 0.6; 95% CI, 0.5 to 0.8), resting wall motion score index (HR, 1.4; 95% CI, 1.1 to 1.8), and failure to increase EF with exercise (HR, 3.3; 95% CI, 1.6 to 6.9). CONCLUSIONS: In patients with LVH, LV mass index and EF response to exercise are independent predictors of mortality, incremental to clinical and exercise test data and resting LV function. A normal exercise echocardiogram predicts a relatively low mortality rate during the following three years.     

Prognostic significance of risk stratifiers of mortality, including T wave alternans, after acute myocardial infarction: results of a prospective follow-up study

INTRODUCTION: Occurrence of sustained microvolt-level T wave alternans (TWA) at a specified heart rate has been suggested to predict life-threatening arrhythmic events, but its prognostic value has not been well established in patients who survived an acute myocardial infarction (AMI). The purpose of this prospective study was to assess the predictive significance of various noninvasive risk indicators of mortality, including TWA, in consecutive post-AMI patients with optimized medical therapy. METHODS AND RESULTS: In addition to a symptom-limited predischarge exercise test with measurement of TWA, mortality risk was assessed using heart rate variability, 24-hour ECG recordings, baroreflex sensitivity, signal-averaged ECG, QTc interval, QT dispersion, and echocardiographic wall-motion index in 379 consecutive patients. Twenty-six patients (6.9%) died during a mean follow-up of 14 +/- 8 months. Sustained TWA was found in 56 patients (14.7%), none of whom died. Several risk variables, e.g., incomplete TWA test (inability to perform the exercise test or reach the required target heart rate of 105 beats/min), increased QRS duration on signal-averaged ECG, increased QT dispersion, long QTc interval, nondiagnostic baroreflex sensitivity result, and low wall-motion index, predicted all-cause mortality in univariate analyses. In multivariate analysis, the incomplete TWA test was the most significant predictor of cardiac death (relative risk 11.1, 95% confidence interval 2.4 to 50.8; P < 0.01). CONCLUSION: Sustained TWA during the predischarge exercise test after AMI does not indicate increased risk for mortality. An incomplete TWA test and several common risk variables provided prognostic information in this post-AMI population.     

Correlation of the standard electrocardiogram and continuous ambulatory monitoring in the detection of ventricular arrhythmias in coronary patients

To evaluate the efficacy of ventricular arrhythmia detection in ambulatory patients with stable coronary artery disease, 101 coronary patients documented by arteriography or remote myocardial infarction underwent concurrent evaluation by 10-hour portable ambulatory ECG monitoring and standard 12-lead electrocardiograms (ECGs) obtained serially over 24 months. Portable ECG recorded premature ventricular contractions (PVCs) in 77 patients: 50% serious PVCs (multifocal, paired, >5/minute, R on T) and 9% patients with ventricular tachycardia. Standard ECG was insensitive (p<.001) in arrhythmia detection both by one tracing (PVC prevalence 17%) obtained within 12 hours of portable ECG or by four serial standard ECGs during the subsequent two weeks (PVC prevalence 18%). Although a total of 1,414 standard ECGs during 24 months recorded PVCs in 49% of patients, serious PVCs were limited (p<.001) to 25% and ventricular tachycardia to 1% of patients. However, ventricular ectopy present by any standard ECG (10 per patient) within three months of ambulatory monitoring was associated with high prevalence of hazardous ectopics by portable ECG (p<.05): serious PVC 92%; ventricular tachycardia 17% patients. Even in patients free of ventricular ectopy by 24-month serial standard ECG, portable ECG detected serious PVCs in 62% and ventricular tachycardia in 6% of patients. Thus stable coronary patients manifested frequent ventricular ectopics by portable ECG which were usually undetected by even multiple serial standard ECGs. Importantly, presence of PVCs by standard ECG was related to increased risk of hazardous ventricular arrhythmias by portable ECG.     

Exercise induced ventricular arrhythmias. Angiographic correlation with the severity of coronary artery disease

We correlated the incidence and degree of exercise induced ventricular arrhythmias (EIVA) with the angiographic severity of coronary artery disease (CAD) in 162 patients with a history of stable effort angina, all showing a positive exercise stress test for myocardial ischemia and a greater than or equal to 70% stenosis of a major coronary artery. Patients were grouped according to the following criteria: presence of electrocardiographic evidence of old transmural myocardial infarction (MI), number of significant coronary stenoses and number of left ventricular (LV) areas showing abnormal segmental wall motion (ASWM). The incidence of EIVA in patients with multivessel CAD was higher than in patients with single vessel CAD, but this difference was not statistically significant. The number of LV areas with ASWM was better correlated with the frequency of EIVA, which was 20.0% in patients with normal LV wall motion, 31.2% in patients with 1 area of ASWM, 54.0% in patients with 2 areas of ASWM (p less than 0.005 vs normal LV wall motion), 74.1% in patients with 3 or more areas of ASWM (p less than 0.001 vs normal LV wall motion and 1 area of ASWM), and 81.8% in patients with LV aneurysm (p less than 0.001 vs normal LV wall motion and 1 area of ASWM, p less than 0.005 vs 2 areas of ASWM). Patients with old MI showed a significantly higher incidence of EIVA than those without MI (p less than 0.001), but this difference was due to the more severe LV asynergy in the MI group. In conclusion, our results show that, in a selected population of patients with CAD, the incidence of EIVA correlates better with the extent of LV segmental wall motion abnormalities than with the number of diseased coronary arteries or the presence of an old transmural MI.     

Added Value of a Resting ECG Neural Network That Predicts Cardiovascular Mortality

Background: The resting 12‐lead electrocardiogram (ECG) remains the most commonly used test in evaluating patients with suspected cardiovascular disease. Prognostic values of individual findings on the ECG have been reported but may be of limited use. Methods: The characteristics of 45,855 ECGs ordered by physician's discretion were first recorded and analyzed using a computerized system. Ninety percent of these ECGs were used to train an artifical neural network (ANN) to predict cardiovascular mortality (CVM) based on 132 ECG and four demographic characteristics. The ANN generated a Resting ECG Neural Network (RENN) score that was then tested in the remaining ECGs. The RENN score was finally assessed in a cohort of 2189 patients who underwent exercise treadmill testing and were followed for CVM. Results: The RENN score was able to better predict CVM compared to individual ECG markers or a traditional Cox regression model in the testing cohort. Over a mean of 8.6 years, there were 156 cardiovascular deaths in the treadmill cohort. Among the patients who were classified as intermediate risk by Duke Treadmill Scoring (DTS), the third tertile of the RENN score demonstrated an adjusted Cox hazard ratio of 5.4 (95% CI 2.0–15.2) compared to the first RENN tertile. The 10‐year CVM was 2.8%, 8.6% and 22% in the first, second and third RENN tertiles, respectively. Conclusions: An ANN that uses the resting ECG and demographic variables to predict CVM was created. The RENN score can further risk stratify patients deemed at moderate risk on exercise treadmill testing.     

心电图运动试验对急性心肌梗塞后患者残余心肌缺血的评价

５２例急性心肌梗塞后２～１２周患者进行次极量蹬车心电图运动试验，心肌缺血发生率为４４．２％。与冠状动脉造影对比，多支病变者阳性率高于单支病变（Ｐ＜０．０１）；与运动２０１铊心肌显像对比，前者阳性率较低（Ｐ＜０．０１）；心电图运动试验中非梗塞区心肌缺血组阳性率高于梗塞周围缺血组（Ｐ＜０．０２５）；ＳＴ段抬高组左室射血分数低于ＳＴ段正常或压低组（Ｐ＜０．０１）。心电图运动试验对诊断梗塞后残余心肌缺血，特别是非梗塞区心肌缺血有一定价值，运动中ＳＴ段抬高可能预示较差的心功能。     

Value of exercise testing to evaluate the indication for surgery in asymptomatic patients with valvular aortic stenosis

BACKGROUND AND AIMS OF THE STUDY: The study aim was to assess the value of exercise stress testing in identifying asymptomatic patients with moderate or severe valvular aortic stenosis (AS). These patients generally develop symptoms during follow up, and require valvular replacement surgery (VRS) at one to three years after single symptom-limited exercise stress testing. Limited data are available on predictors of outcome in asymptomatic patients with valvular AS. A single symptom-limited exercise stress test might offer more precise risk stratification of patients referred for cardiological evaluation. METHODS: The safety and diagnostic accuracy of exercise testing to predict symptom development and need for surgery was assessed prospectively in 30 asymptomatic patients (mean age 62+/-14 years) with valvular AS. Twenty patients had moderate AS (mean Doppler gradient 30-49 mmHg), and 10 severe AS (gradient > or =50 mmHg). Patients underwent a symptom-limited maximal exercise test with upright bicycle ergometry. There were no complications during and after exercise testing. All patients were followed up for at least 36 months. RESULTS: Ergometry was abnormal in 18 patients (60%); two patients had a fall in systolic blood pressure, one patient had a fall in systolic blood pressure with angina and ECG signs of myocardial ischemia, one had angina and ECG signs of myocardial ischemia, three patients had ECG signs of myocardial ischemia without symptoms, and 11 had dyspnea at low workload. During the following 12 months all patients with a normal exercise test remained asymptomatic (negative predictive value 100%). Ten of the 18 patients with abnormal exercise test experienced symptoms and required VRS, but eight did not (positive predictive value 55%). After 36 months, only two of 12 patients with a normal exercise test developed symptoms and required VRS (negative predictive value 83%); among subjects with abnormal exercise test, four of 18 required VRS. At three years after exercise testing, 10 patients with a normal exercise stress test and four with an abnormal test did not require VRS as they remained asymptomatic (positive predictive value 78%). There was no statistically significant difference in valvular aortic area, maximal and mean gradient between patients with normal and abnormal exercise tests. CONCLUSION: Exercise stress testing may be performed safely in asymptomatic patients with moderate or severe valvular AS. Tests which meet criteria for normal patients allow physicians confidently to postpone VRS and to suggest a simple, cost-effective method of follow up in such cases. An abnormal test may reveal symptoms or identify a population for closer follow up.     

The effect of ethnicity on survival in male veterans referred for electrocardiography and treadmill testing

BACKGROUND: Ethnic differences in the relationship between access to health care and survival are difficult to define because of many confounding factors, such as socioeconomic status and baseline differences in health. Because the Veterans Affairs health care system offers health care largely without financial considerations, it provides an ideal setting in which to identify and understand ethnic differences in health outcomes. Previous studies in this area have lacked clinical and cardiovascular data with which to adjust for baseline differences in patients' health. METHODS: Data were collected from consecutive men referred for resting electrocardiography (ECG) (n = 41 087) or exercise testing (n = 6213) during 12 years. We compared ethnic differences in survival between whites, blacks, and Hispanics after considering baseline differences in age and hospitalization status. We also adjusted for electrocardiogram abnormalities and cardiac risk factors, exercise test results, and cardiovascular comorbidities. RESULTS: White patients tended to be older and had more baseline comorbidities and cardiovascular interventions when they presented for testing. White patients had increased mortality rates compared with blacks and Hispanics. In the ECG population, after adjusting for demographics and baseline electrocardiogram abnormalities, Hispanics had improved survival compared with whites and blacks. In the exercise test population, after adjusting for the same factors, as well as adjusting for the presence of cardiovascular comorbidities, cardiac risk factors, and exercise test findings, Hispanics also exhibited improved survival compared with the other 2 ethnicities. There were no differences in mortality rates between whites and blacks. CONCLUSION: Our findings demonstrate that the health care provided to veterans referred for routine ECG or exercise testing is not associated with poorer survival in ethnic minorities.     

The Predictive Value of Exercise QRS Duration Changes for Post‐PTCA Coronary Events

Background: The sensitivity and predictive values of exercise ECG testing using ST‐T criteria after percutaneous transluminal coronary angioplasty (PTCA) are low, precluding its routine use for screening for restenosis. The predictive value of QRS duration criteria during exercise testing (ET) ECG after PTCA for future coronary events has not been reported. The aim of the study was to compare QRS duration changes with ST‐T criteria during ET, as a predictor of coronary events after PTCA. Methods: A prospective study of 206 consecutive patients who underwent ET at a mean of 34 ± 14 days after their first PTCA, and were the followed for a mean of 23 ± 9 months. Patients were divided by QRS duration into two groups—Q1: ischemic response (QRS duration prolongation of more than 3 ms relative to the resting duration), and Q2: normal response (QRS duration shortening or without change from resting duration). Patients were also divided by their ST‐T response, S1: ischemic response, and S2: normal response. Results: During follow‐up 52 patients (58%) experienced restenosis or MI, or underwent CABG—Q1: 44 (85%), Q2: 8(15%) (P < 0.0002), S1: 8 (15%), S2: 44 (85%), (P < 0.641) , two patients died—Q1: 1 (1%) and Q2: 1 (1%). For QRS and ST‐T, the relative risk of having at least one of the coronary events was 4.02 (CI 2.1–9.9) versus 1.13 (CI 0.8–2.9), respectively. The sensitivity for future coronary events was 85% and 52% and the specificity was 48% and 98% for the QRS and ST‐T criteria, respectively. Conclusion: QRS prolongation during peak ET ECG after PTCA is a more sensitive marker than ST‐T criteria for detection of patients at risk for later coronary events.     

Prognostic value of supine scintigraphic heart function and simultaneous conventional exercise response in patients after myocardial infarction

A total of 240 survivors of one or more myocardial infarctions were consecutively admitted to perform supine exercise radionuclide ventriculography. Within 3 years after the test, 22 died; this group was compared to an age-matched control group of 22 survivors for left and right ventricular function during rest, exercise, and simultaneously assessed exercise performance as well as ECG variables. Evaluation of 3-year survival by linear discriminant analysis revealed an accuracy of 82% for discriminant models using ECG and exercise performance variables. Implementation of resting left ventricular ejection fraction and change of right ventricular ejection fraction during exercise, as well as scintigraphic presence or absence of dyskinesia, improved the accuracy of the model to 91% of correctly classified patients.     

Electrocardiographic evidence of ischemia during ventricular paced rhythms

Exercise-induced electrocardiographic (ECG) changes are the most widely recognized noninvasive means for detecting myocardial ischemia. The specificity of these changes depends on the normalcy of the resting ECG. Right ventricular pacing produces major QRS and ST-T changes very similar to those of complete left bundle-branch block. They alter the resting ECG such that ischemic changes are considerably difficult to detect. Because of these resting abnormalities, ECG changes during treadmill exercise testing usually do not facilitate the diagnosis of ischemia or coronary artery disease. The following are two cases of ischemic ECG changes that occurred during right ventricular pacing. To our knowledge, there have been no reports of the classic ECG changes of ST-segment depression suggestive of ischemia which occurred during right ventricular pacing and which were discemible from the resting ECG changes.     

无器质性心脏病的室性早搏对运动试验反应的意义

探讨运动试验中室性早搏 (简称室早 )对运动的反应能否预测 2 4h动态心电图监测 (Holter)中自发性室早与心率的关系。无器质性心脏病的频发室早患者 73例 ,其中男 2 0例、女 5 3例 ,年龄 4 5± 12 (18～ 71)岁。根据运动试验达终点时室早的数量与运动前相比较 ,将患者分为室早增加组 17例以及室早减少或不变组 (简称室早减少组 )5 6 ,对二组患者的运动试验资料和Holter监测资料进行对比分析。结果 :两组运动试验检查的运动时间、最大运动级数、最大心率等无明显差异。经Holter监测在室早增加组 ,所有患者以小时为单位计算心率与室早数量的相关性 ,均显示心率与室早的数量呈正相关 ,而在室早减少组 ,则 4 7例 (83% )心率与室早的数量正相关 ,余 9例呈负相关。结论 :对无器质性心脏病的室早患者 ,在运动试验中室早数量增加与Holter检查的心率与室早数量的相关性具有一致性。而在运动试验中室早减少或不变的患者与Holter检查结果并不一致。