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.     

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.     

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.     

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.)     

Value of exercise capacity and heart rate recovery in older people

OBJECTIVES: To evaluate the prognostic value in older adults of two predictors of mortality: impaired functional capacity and an attenuated heart rate recovery. SETTING: Academic medical center. DESIGN: Prospective study with mean 3.7 years follow-up. PARTICIPANTS: Seven thousand three hundred fifty-four adults aged 65 and older consecutively referred for exercise testing between 1990 and 1999. Patients with heart failure, valvular disease, atrial fibrillation, and pacemakers were excluded. MEASUREMENTS: The primary endpoint was all-cause mortality. Impaired functional capacity was defined as the peak exercise workload in the lowest quintile of metabolic equivalents achieved according to prespecified strata of age and sex. Heart rate recovery was defined as the fall in heart rate during the first minute after exercise and was abnormal if 12 or fewer beats per minute, except for patients undergoing stress echocardiography, in which case 18 or fewer beats per minute was abnormal. RESULTS: There were 842 deaths. Patients with impaired functional capacity were at increased risk for death (23% vs 9%, hazard ratio (HR) = 2.7, 95% confidence interval (CI) = 2.2-3.1, P <.0001) as were patients with an abnormal heart rate recovery (17% vs 9%, HR = 2.0, 95% CI = 1.8-2.3, P <.0001). After adjusting for age, sex, coronary history, and other confounders, impaired functional capacity (adjusted HR = 2.1, 95% CI = 1.8-2.4) and an abnormal heart rate recovery (adjusted HR = 1.5, 95% CI = 1.3-1.7) independently predicted death. No interactions between these two variables with age were noted. CONCLUSIONS: In older patients, impaired functional capacity and heart rate recovery were independent predictors of death.     

Severe frequent ventricular ectopy after exercise as a predictor of death in patients with heart failure

OBJECTIVES: The study was done to determine the prognostic importance of frequent ventricular ectopy in recovery after exercise among patients with systolic heart failure (HF). BACKGROUND: Although ventricular ectopy during recovery after exercise predicts death in patients without HF, its prognostic importance in patients with significant ventricular dysfunction is unknown. METHODS: Systematic electrocardiographic data during rest, exercise, and recovery were gathered on 2,123 consecutive patients with left ventricular systolic ejection fraction 相似文献   

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。     

Comparison of the chronotropic response to exercise and heart rate recovery in predicting cardiovascular mortality.

BACKGROUND: Both an impaired capacity to increase heart rate during exercise testing (chronotropic incompetence), and a slowed rate of recovery following exercise (heart rate recovery) have been shown to be associated with all-cause mortality. It is, however, unknown which of these responses more powerfully predicts risk, and few data are available on their association with cardiovascular mortality or how they are influenced by beta-blockade. METHODS: Routine symptom-limited exercise treadmill tests performed on 1910 male veterans at the Palo Alto Veterans Affairs Medical Center from 1992 to 2002 were analyzed. Heart rate was determined each minute during exercise and recovery. Chronotropic incompetence was defined as the inability to achieve > or =80% of heart rate reserve, using a population-specific equation for age-predicted maximal heart rate. An abnormal heart rate recovery was considered to be a decrease of <22 beats/min at 2 min in recovery. Cox proportional hazards analyses including pretest clinical data, chronotropic incompetence, heart rate recovery, the Duke Treadmill Score (abnormal defined as <4), and other exercise test responses were performed to determine their association with cardiovascular mortality. RESULTS: Over a mean follow-up of 5.1+/-2.1 years, there were 70 deaths from cardiovascular causes. Both abnormal heart rate recovery and chronotropic incompetence were associated with higher cardiovascular mortality, a lower exercise capacity, and more frequent occurrence of angina during exercise. Both heart rate recovery and chronotropic incompetence were stronger predictors of risk than pretest clinical data and traditional risk markers. Multivariately, chronotropic incompetence was similar to the Duke Treadmill Score for predicting cardiovascular mortality, and was a stronger predictor than heart rate recovery [hazard ratios 3.0 (95% confidence interval 1.9-4.9), 2.8 (95% confidence interval 1.7-4.8), and 2.0 (95% confidence interval 1.1-3.5) for abnormal Duke Treadmill Score, chronotropic incompetence, and abnormal heart rate recovery, respectively]. Having both chronotropic incompetence and abnormal heart rate recovery strongly predicted cardiovascular death, resulting in a relative risk of 4.2 compared with both responses being normal. Beta-blockade had minimal impact on the prognostic power of chronotropic incompetence and heart rate recovery. CONCLUSION: Both chronotropic incompetence and heart rate recovery predict cardiovascular mortality in patients referred for exercise testing for clinical reasons. Chronotropic incompetence was a stronger predictor of cardiovascular mortality than heart rate recovery, but risk was most powerfully stratified by these two responses together. The simple application of heart rate provides powerful risk stratification for cardiovascular mortality from the exercise test, and should be routinely included in the test report.     

Independent contribution of myocardial perfusion defects to exercise capacity and heart rate recovery for prediction of all-cause mortality in patients with known or suspected coronary heart disease

OBJECTIVES: The goal of this study was to determine the value of thallium201 single photon emission computed tomography (SPECT) imaging for prediction of all-cause mortality when considered along with functional capacity and heart rate recovery. BACKGROUND: Myocardial perfusion defects identified by thallium201 SPECT imaging are predictive of cardiac events. Functional capacity and heart rate recovery are exercise measures that also have prognostic implications. METHODS: We followed 7,163 consecutive adults referred for symptom-limited exercise thallium SPECT (mean age 60 +/- 10, 25% women) for 6.7 years. Using information theory, we identified a probable best model relating nuclear findings to outcome to calculate a prognostic nuclear score. RESULTS: There were 855 deaths. Intermediate- and high-risk prognostic nuclear scores were noted in 28% and 10% of patients. Compared with those with low-risk scans, patients with an intermediate-risk score were at increased risk for death (14% vs. 9%, hazard ratio: 1.67, 95% confidence interval [CI]: 1.44 to 1.95, p < 0.0001), while those with high-risk scores were at greater risk (24%, hazard ratio: 2.98, 95% CI: 2.49 to 3.56, p < 0.0001). In multivariable analyses that adjusted for clinical characteristics, functional capacity and heart rate recovery, an intermediate-risk nuclear score remained predictive of death (adjusted hazard ratio: 1.50, 95% CI: 1.28 to 1.76, p < 0.0001), as did a high-risk score (adjusted hazard ratio: 2.76, 95% CI: 2.13 to 2.56, p < 0.0001). Impaired functional capacity and decreased heart rate recovery provided additional prognostic information. CONCLUSIONS: Myocardial perfusion defects detected by thallium SPECT imaging are independently predictive of long-term all-cause death, even after accounting for exercise capacity, heart rate recovery and other potential confounders.     

Prognostic value of late heart rate recovery after treadmill exercise

Recovery from exercise can be divided into an early, rapid period and a late, slower period. Although early heart rate (HR) recovery 1 minute after treadmill exercise independently predicts survival, the prognostic value of late HR recovery has not been well studied. The aim of this study was to evaluate the independent prognostic value of late HR recovery for all-cause mortality. A total of 2,082 patients referred to the nuclear cardiology laboratory of an urban academic medical center for treadmill exercise with imaging from August 1998 to December 2003 were followed for all-cause mortality. During 9.9 ± 1.5 years of follow-up, 196 deaths (9%) occurred. To avoid overlap with early HR recovery or the baseline HR, late HR recovery was defined as the percentage of the cycle length change between rest and peak exercise that had been recovered after 5 minutes. Lower values represent impaired recovery, by analogy with 1-minute HR recovery. Impaired late HR recovery was a significant univariate predictor of all-cause mortality (hazard ratio 0.28 per percentage, 95% confidence interval 0.17 to 0.46, p <0.001). It significantly improved a nested, multivariate model (change in chi-square 8.66, p = 0.003), including 1-minute HR recovery, with independent prognostic value (adjusted hazard ratio 0.58, 95% confidence interval 0.41 to 0.84, p = 0.004). In conclusion, late HR recovery after treadmill exercise stress adds prognostic value for all-cause mortality to a multivariate model including early, 1-minute HR recovery.     

Abnormal heart rate recovery immediately after cardiopulmonary exercise testing in heart failure patients

An attenuated heart rate recovery (HRR) immediately after exercise has been shown to be predictive of mortality. It is not known whether HRR predicts mortality when measured in patients with heart failure. The present study was undertaken to evaluate the ability of HRR to predict mortality in patients with heart failure. We studied 84 NYHA class II or III chronic congestive heart failure patients who had a left ventricular ejection fraction < or = 40%. All patients underwent symptom limited cardiopulmonary exercise testing. The value for the HRR was defined as the difference in heart rate between peak exercise and one-minute later; a value < or = 18 beats per minute was considered abnormal. The patients were divided into 2 groups according to the value of HRR. Those with abnormal HRR were assigned to group I and those with normal HRR were assigned to group II. The 2 groups were compared with each other regarding baseline characteristics and exercise capacity assessed by peak VO2. There were 26 patients (31%) in group I and 58 patients (69%) in group II. Group II patients had better performance on treadmill exercise testing than group I patients. They had greater exercise duration (7.5 +/- 3.8 minutes versus 5 +/- 3.5 minutes, P = 0.006), better heart-rate reserve (79 +/- 25% versus 63 +/- 27%, P = 0.01), and higher values of maximal heart-rate (141 +/- 18 beats/min versus 132 +/- 17 beats/min, P = 0.04). Group II patients also had higher peak VO2 values (16.8 +/- 4.4 mL/kg/min versus 14.4 +/- 3.6 mL/kg/min, P = 0.01). When we separated the groups according to beta-blocker usage, beta-blockers had no prominent effect on HRR. In the follow-up period (mean 14.1 +/- 6.1 months), the presence of abnormal HRR and lower peak VO2 (< or = 14 mL/kg/min) were the only significant predictors of mortality in our patient population (adjusted hazard ratio [HR] 5.2, 95% CI, 1.3 to 24, P = 0.03 and adjusted HR 13, 95% CI, 2.1 to 25.6, P = 0.005, respectively). It seems that the attenuated HRR value one minute after peak exercise appears to be a reliable index of the severity of exercise intolerance in heart failure patients and this study supports the value of HRR as a prognostic marker among heart failure patients referred for cardiopulmonary exercise testing for prediction of prognosis.     

儿童先天性长QT综合征患者的QT滞后现象

目的观察儿童先天性长QT综合征(LQTS)患者进行运动试验时QT间期的变化。方法因QT间期延长而行运动平板试验的患儿共33例入选本研究,按照1993年Schwartz等的LQTS诊断标准的计分分值分为两组:LQTS组:总计分值为4分及以上的患者17例,男13例、女4例,年龄11.6±3.7岁;可疑组:评分为1.5~3.5分的患者16例,男9例、女7例,年龄13.8±4.2岁。另选行运动试验的18例正常儿童作为对照组,男11例、女7例,年龄12.4±3.1岁。记录整个运动试验中和恢复期的心电图,观察QT间期和心率的变化,记录并计算恢复期第1,2,4,6 m in QT间期与运动过程中同心率时QT间期的差值(ΔQT)。结果三组患者在运动中随着心率的增加,QT间期逐渐缩短。运动恢复期,随着心率的减慢,三组的QT间期也逐渐延长,但LQTS组恢复期QT间期却显著短于运动过程中处于同心率时的QT间期。LQTS组在恢复期1,2,4 m in的ΔQT值均显著大于其它两组(P均<0.05)。LQTS组在QT间期与心动周期的关系图上呈现明显的“QT滞后环”。结论儿童LQTS患者运动试验恢复期与运动过程中相比,QT间期的变化明显滞后于心率的变化。     

Heart rate recovery after exercise is a predictor of mortality,independent of the angiographic severity of coronary disease

OBJECTIVES: We sought to determine whether abnormal heart rate recovery predicts mortality independent of the angiographic severity of coronary disease. BACKGROUND: An attenuated decrease in heart rate after exercise, or heart rate recovery (HRR), has been shown to predict mortality. There are few data on its prognostic significance once the angiographic severity of coronary artery disease (CAD) is ascertained. METHODS: For six years we followed 2,935 consecutive patients who underwent symptom-limited exercise testing for suspected CAD and then had a coronary angiogram within 90 days. The HRR was abnormal if < or =12 beats/min during the first minute after exercise, except among patients undergoing stress echocardiography, in whom the cutoff was < or =18 beats/min. Angiographic CAD was considered severe if the Duke CAD Prognostic Severity Index was > or =42 (on a scale of 0 to 100), which corresponds to a level of CAD where revascularization is associated with better long-term survival. RESULTS: Severe CAD was present in 421 patients (14%), whereas abnormal HRR was noted in 838 patients (29%). There were 336 deaths (11%). Mortality was predicted by abnormal HRR (hazard ratio [HR] 2.5, 95% confidence interval [CI] 2.0 to 3.1; p < 0.0001) and by severe CAD (HR 2.0, 95% CI 1.6 to 2.6; p < 0.0001); both variables provided additive prognostic information. After adjusting for age, gender, standard risk factors, medications, exercise capacity, and left ventricular function, abnormal HRR remained predictive of death (adjusted HR 1.6, 95% CI 1.2 to 2.0; p < 0.0001); severe CAD was also predictive (adjusted HR 1.4, 95% CI 1.1 to 1.9; p = 0.008). CONCLUSIONS: Even after taking into account the angiographic severity of CAD, left ventricular function, and exercise capacity, HRR is independently predictive of mortality.     

Exercise is superior to pacing for T wave alternans measurement in subjects with chronic coronary artery disease and left ventricular dysfunction

INTRODUCTION: T wave alternans (TWA) is a heart rate-dependent marker of vulnerability to ventricular arrhythmias. Atrial pacing and exercise both are used as provocative stimuli to elicit TWA. However, the prognostic value of the two testing methods has not been compared. The aim of this prospective study was to compare the prognostic value of TWA measured during bicycle exercise and atrial pacing in a large cohort of high-risk patients with ischemic heart disease and left ventricular dysfunction. METHODS AND RESULTS: This was a prospective study of 251 patients with coronary artery disease and left ventricular dysfunction who were referred for electrophysiologic studies (EPS) for standard clinical indications. Patients underwent TWA testing using bicycle ergometry (exercise TWA, n = 144) and/or atrial pacing (pacing TWA, n = 178). The primary endpoint was the combined incidence of death, sustained ventricular arrhythmias, and appropriate implantable cardioverter defibrillator therapy. The predictive value of exercise and pacing TWA for EPS results and for endpoint events was determined. Exercise and pacing TWA both were significant predictors of EPS results (odds ratios 3.0 and 2.9 respectively, P < 0.02). Kaplan-Meier survival analysis of the primary endpoint revealed that exercise TWA was a significant predictor of events (hazard ratio 2.2, P = 0.03). In contrast, pacing TWA had no prognostic value for endpoint events (hazard ratio 1.1, P = 0.8). CONCLUSION: TWA should be measured during exercise when it is used for clinical risk stratification. EPS results may not be an adequate surrogate for spontaneous events when evaluating new risk stratification tests.     

Stress recovery index for risk stratification of asymptomatic patients following coronary bypass surgery

OBJECTIVE: To prospectively assess the prognostic value of the stress recovery index (SRI) following coronary bypass surgery. DESIGN AND PATIENTS: Two hundred seventy-eight patients who had undergone coronary bypass surgery and participated in a secondary prevention program were exercise tested and prospectively followed up for a median of 36 months. Cardiac death, nonfatal infarction, and need for further revascularization were target end points. SRI, defined as the difference in absolute values between the area of heart rate-adjusted ST-segment depression during exercise and recovery, was derived in all. Clinical data, resting ejection fraction, and exercise testing data of patients were entered into a sequential Cox model; SRI was entered last. Model validation was performed by bootstrap adjusted by the degree of optimism in estimates. Survival curves were set up using Kaplan-Meier method and compared by the log-rank test. RESULTS: SRI was the only significant and independent prognostic indicator (hazard ratio, 0.68; 95% confidence interval, 0.53 to 0.89) and increased the prognostic power of the model on top of clinical and exercise testing variables, as demonstrated by the significant (p = 0.01) increase of the area under the receiver operating characteristic curve of the risk function. Survival analysis showed ascending SRI quartiles to identify a significant (p = 0.001) increase in event-free survival. CONCLUSIONS: SRI is of value in predicting outcome after coronary bypass surgery and provides additional prognostic information over clinical and exercise testing data.     

Prognostic characteristics of cardiopulmonary exercise testing in heart failure: comparing American and European models.

BACKGROUND: Cardiopulmonary exercise testing (CPET) in the heart failure population is a standard of care in both American and European clinics, although the mode of exercise typically differs. The purpose of the present study was to compare the prognostic characteristics of peak oxygen consumption (VO2) and the minute ventilation-carbon dioxide production (VE/VCO2) slope between two independent heart failure groups. DESIGN AND METHODS: One hundred and two subjects underwent maximal exercise CPET using bicycle ergometry at San Paolo Hospital in Milan, Italy (SPH) and 105 subjects underwent treadmill CPET at Virginia Commonwealth University in Richmond, Virginia (VCU). Subjects were tracked for cardiac-related mortality for a 1-year period after CPET. RESULTS: There were 13 cardiac-related deaths over the 1-year tracking period in both groups. Optimal prognostic threshold values for peak VO2 were 12.9 ml O2/kg per min (sensitivity 81%, specificity 69%) in the SPH group and 12.0 ml O2/kg per min (sensitivity 74%, specificity 69%) in the VCU group. An optimal prognostic threshold value for the VE/VCO2 slope was 34.4 in the SPH (sensitivity 61%, specificity 85%) and 34.5 in the VCU (sensitivity 64%, specificity 93%) groups. DISCUSSION: The prognostic characteristics of peak VO2 and the VE/VCO2 slope were similar between the two centers. These results suggest that the mode of exercise does not greatly impact the prognostic utility of CPET responses in heart failure. They further suggest that prognostic guidelines for the application of CPET in heart failure may be applied globally, irrespective of differences in testing modality.     

Influence of the Maximum Heart Rate Attained during Exercise Testing on Subsequent Heart Rate Recovery

Background: Abnormal heart rate recovery (HRR) following exercise testing has been shown to be a predictor for adverse cardiovascular events. The actual maximum heart rate (MHR) attained during the exercise test does not however have a distinct significance in traditional HRR assessment. The objective of this study was to investigate the role of MHR in HRR. Methods: This prospective study consisted of 164 patients (62% male, mean age 53.7 ± 11.7 years) who were referred for a symptom‐limited standard Bruce Protocol treadmill exercise test, based on clinical indications. The patients were seated immediately at test completion and the heart rate (HR) recorded at one and two minutes postexercise. A normal HRR was defined as a HR drop of 18 beats per minute or more at the end of the first minute of recovery. The HRR profile of patients who reached ≥85% of their maximum predicted heart rate (MPHR) during peak exercise were then compared to HRR profile of those who could not. Results: One hundred twelve patients (Group A) achieved a MHR ≥ 85% of MPHR during peak exercise whereas 52 patients (Group B) did not. Chi‐square analysis showed a higher incidence of normal HRR in Group A compared to Group B (p = 0.029). Analysis of variance with repeated measures showed that group A had a greater HRR at the first minute F_1,162= 6.98, p = <0.01) but not the second minute (F_1,162=1.83, p = .18) postexercise. Conclusion: There is a relation between the peak heart rate attained during exercise and the subsequent HRR. A low peak heart rate increases the likelihood of a less than normal HRR. Assessment of the entire heart‐rate response seems warranted for more thorough risk‐stratification. Ann Noninvasive Electrocardiol 2010;15(1):43–48     

Exercise versus recovery electrocardiography in predicting mortality in patients with uncomplicated myocardial infarction.

BACKGROUND: Exercise testing after acute myocardial infarction has limited prognostic accuracy. We prospectively used stress-recovery, heart rate-adjusted, ST-segment analysis to predict cardiac death in this clinical setting. METHODS: The stress-recovery index, defined as the difference in absolute values of the areas designated by ST depression in the heart-rate domain during exercise and recovery, was derived in 708 survivors of a first myocardial infarction. To assess whether it contributed additional prognostic information to routinely obtained information, clinical data, resting ejection fraction, and exercise testing data were entered into a sequential Cox model; the stress-recovery index was entered last. Model validation was performed by bootstrapping adjusted for the degree of optimism in estimates. Survival curves were set up using Kaplan-Meier analysis and compared by the log-rank test. RESULTS: Hypertension (OR 1.3, 95%CI 0.9-4.6), exercise capacity (OR 0.6, 95%CI 0.3-1.1 for the interquartile difference in kilopounds per minute), and the stress-recovery index (OR 0.7, 95%CI 0.5-0.9 for the interquartile difference) were independent predictors of cardiac death at a median follow-up of 32 months. However, the stress-recovery index enhanced the prognostic power of the model on top of clinical and exercise testing variables in all diagnostic subgroups according to ST-segment analysis and significantly discriminated survival. A simple nomogram was generated from the fitted Cox model to estimate risk in individual patients. CONCLUSIONS: Stress-recovery, heart rate-adjusted, ST-segment analysis predicts cardiac death after acute myocardial infarction and provides additional prognostic information over clinical and exercise testing data.     

Exercise capacity and heart rate recovery as predictors of coronary heart disease events, in patients with heterozygous Familial Hypercholesterolemia

BACKGROUND: Several clinical and observational studies have established that exercise capacity and activity status are strong predictors of cardiovascular and overall mortality. We aimed to evaluate the relationship between exercise tolerance test (ETT) indices and occurrence of coronary heart disease (CHD), in patients with heterozygous Familial Hypercholesterolemia (eFH). METHODS: During 1987-1997, we enrolled 639 cardiovascular disease-free patients with heterozygous eFH; 58 (9%) patients were excluded since they had a positive ETT. A fatal or non-fatal CHD event was the end point. Cox proportional hazards models were applied to evaluate the association between the investigated outcome and ETT indices. RESULTS: During the follow-up (1987-2002), 53 (18%) men and 34 (10%) women developed a CHD event (11 were fatal). The age-adjusted event rate was 87 events per 2915 person-years (3%). Statistical analysis revealed that exercise capacity (hazard ratio = 0.82, P < 0.001), heart rate recovery at 1 min (hazard ratio = 0.91, P < 0.05), and peak pulse pressure levels (hazard ratio = 1.03, P < 0.001), were predictors of CHD, after controlling for several potential confounders. CONCLUSION: Decreased exercise capacity, a delayed decrease in heart rate during the first minute of graded exercise, and increased peak pulse pressure are strong predictors of coronary events in patients with eFH. Physical activity should be strongly recommended in these patients.