Safety and characteristics of exercise testing early after acute myocardial infarction

Time of the low-level cardiopulmonary exercise test does not affect the evaluation of acute myocardial infarction in stable status

Introduction

Cardiopulmonary exercise test (CPET) provides the means to evaluate the cardiopulmonary function and guide cardiac rehabilitation. The performance of acute myocardial infarction (AMI) patients at different times is different on CPET.

Materials and methods

This was a cross-sectional study. Patients diagnosed as AMI in stable status were included and performed the low- level CPET (RAMP 10W). CPET variables at different times were compared among four groups.

Results

Sixty and one patients with AMI conducted the low-level CPET from 3 to 15 days after AMI. Patients were stratified according to quartiles of CPET's time: 5 in 3-6 days group, 34 in 7-9 days group, 14 in 10-12 days group, 8 in 13-15 days group. Only VO2/HR at rest showed statistically different among the four groups.VO2/HR at rest in 3-6 days group and 10-12 days group were higher than in 13-15 days group (3.4 ± 0.85, 3.18 ± 0.78 vs. 2.50 ± 0.49 ml/beat, p < 0.05). Patients with complete revascularization had higher peak heart rate and blood pressure product and peak breathing reserve (BR), and lower Borg score compared with incomplete revascularization. And patients with LVEF >50% had higher peak BR compared with LVEF 40-50%.

Conclusion

It was safe and efficient to conduct the low-level CPET in stable AMI patients 3 days after onset. Time was not an effector on cardiopulmonary function and exercise capacity and prognosis in AMI during CPET. Complete revascularization and normal LVEF should be good for exercise test in AMI.

Reduced inspiratory muscle strength increases pneumonia in patients with acute myocardial infarction

BACKGROUND

Inspiratory muscle strength is associated with pneumonia in patients after surgery or those with subacute stroke. However, inspiratory muscle strength in patients with acute myocardial infarction (AMI) has not been studied.

OBJECTIVE

To evaluate the predictive value of inspiratory muscle strength for pneumonia in patients with AMI.

METHODS

Patients with AMI were consecutively enrolled from March 2019 to September 2019. Measurements of maximal inspiratory pressure (MIP) were used to estimate inspiratory muscle strength and mostly were taken within 24 hr after culprit-vessel revascularization. Patients were divided into 3 groups by MIP tertile (T1: < 56.1 cm H2O, n = 88; T2: 56.1-84.9 cm H2O, n = 88; T3: > 84.9 cm H2O, n=89). The primary endpoint was in-hospital pneumonia.

RESULTS

Among 265 enrolled patients, pneumonia developed in 26 (10%). The rates of pneumonia were decreased from MIP T1 to T3 (T1: 17%, T2: 10%, T3: 2%, P = 0.004). In-hospital all-cause mortality and major adverse cardiovascular events (MACEs) did not differ between groups. Multivariate logistic regression confirmed increased MIP associated with reduced risk of pneumonia (odds ratio 0.78, 95% confidence interval 0.65-0.94, P = 0.008). Receiver operating characteristic curve analysis indicated that MIP had good performance for predicting in-hospital pneumonia, with an area under the curve of 0.72 (95% confidence interval 0.64-0.81, P < 0.001).

CONCLUSIONS

The risk of pneumonia but not in-hospital mortality and MACEs was increased in AMI patients with inspiratory muscle weakness. Future study focused on training inspiratory muscle may be helpful.

The Safety and Efficacy of Inspiratory Muscle Training for Patients With Acute Myocardial Infarction Undergoing Percutaneous Coronary Intervention: Study Protocol for a Randomized Controlled Trial

Background: Uncommonly high rates of pneumonia in patients with acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI) have been observed during recent years. Inspiratory muscle training (IMT) could reduce pneumonia in patients undergoing coronary artery bypass grafting and other cardiac surgeries. The relationship between IMT and AMI is unknown. Here, we describe the feasibility and potential benefit of IMT in patients at high risk for pneumonia with AMI who have undergone primary PCI.

Methods: Our study is a prospective, randomized, controlled, single-center clinical trial. A total of 60 participants will be randomized into an IMT group and control group with 30 participants in each group. Participants in the IMT group will undergo training for 15 min per session, twice a day, from 12 to 24 h after primary PCI, until 30 days post-randomization; usual care will be provided for the control group. The primary endpoint is the change in inspiratory muscle strength, the secondary endpoint included feasibility, pneumonia, major adverse cardiovascular events, length of stay, pulmonary function tests measure, and quality of life.

Discussion: Our study is designed to evaluate the feasibility of IMT and its effectiveness in improving inspiratory muscle strength in participants with AMI who have undergone primary PCI.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT04491760.

Safety of symptom-limited cardiopulmonary exercise testing in patients with chronic heart failure due to severe left ventricular systolic dysfunction

BACKGROUND

To assess the safety of symptom-limited exercise testing in patients with New York Heart Association class II-IV heart failure symptoms due to left ventricular systolic dysfunction, we investigated the frequency of all-cause fatal and nonfatal major cardiovascular (CV) events among subjects enrolled in a prospective clinical trial (HF-ACTION). We hypothesized that exercise testing would be safe, as defined by a rate for all-cause death of <0.1 per 1,000 tests and a rate of nonfatal CV events <1.0 per 1,000 tests.

METHODS

Before enrollment and at 3, 12, and 24 months after randomization, subjects were scheduled to complete a symptom-limited graded exercise test with open-circuit spirometry for analysis of expired gases. To ensure the accurate reporting of exercise test-related events, we report deaths and nonfatal major CV events per 1,000 tests at months 3, 12, or 24 after randomization.

RESULTS

A total of 2,331 subjects were randomized into HF-ACTION. After randomization, 2,037 subjects completed 4,411 exercise tests. There were no test-related deaths, exacerbation of heart failure or angina requiring hospitalization, myocardial infarctions, strokes, or transient ischemic attacks. There was one episode each of ventricular fibrillation and sustained ventricular tachycardia. There were no exercise test-related implantable cardioverter defibrillator discharges requiring hospitalization. These findings correspond to zero deaths per 1,000 exercise tests and 0.45 nonfatal major CV events per 1,000 exercise tests (95% CI 0.11-1.81).

CONCLUSIONS

In New York Heart Association class II-IV patients with severe left ventricular systolic dysfunction, we observed that symptom-limited exercise testing is safe based on no deaths and a rate of nonfatal major CV events that is <0.5 per 1,000 tests.

Low agreement of ventilatory threshold between training modes in cardiac patients

In cardiac rehabilitation, different endurance exercises such as walking and cycling are often performed. The training intensity for these modes is determined from a single treadmill or bicycle test by ventilatory threshold (VT). In this study, differences of VT between walking and cycling and agreement of VT between training modes were assessed in cardiac patients. A total of 46 cardiac rehabilitation patients (mean age 59.5+/-8.4 years, 45 males) (31 untrained and 15 trained) completed a maximal exercise test on bicycle and treadmill, with breath-by-breath analysis of oxygen uptake (VO2), carbon dioxide production and expiratory volume. VT was determined by V-slope method. Correlations of VT and VO2peak were calculated between exercise modes. Bland-Altman plots were made for determining VT agreement between modes. VT was significantly different between walking and cycling in trained patients (P<0.05), but not in untrained patients (P>0.05). When untrained and trained patients were compared, VT correlation was lower (r=0.50) in the former group, as compared to the latter group (r=0.78). Also, Bland-Altman plots showed smaller limits of agreement for VT in trained (2 SD -1.6 to 7.8 ml/min/kg), as compared to untrained patients (2 SD -7.0 to 9.6 ml/min/kg). In trained patients, VT correlates well between training methods, but is highly exercise mode specific. In untrained patients, VT is not exercise mode specific, but the VT has a low correlation between training modes. This study shows that VT should be assessed by the appropriate exercise model for determining exercise intensity in cardiac rehabilitation.

Return to full normal activities including work at two weeks after acute myocardial infarction

Patients are generally advised to return to full normal activities, including work, 6 to 8 weeks after acute myocardial infarction (AMI). We assessed the outcomes of early return to normal activities, including work at 2 weeks, after AMI in patients who were stratified to be at a low risk for future cardiac events. Patients were considered for randomization before discharge if they had no angina, had left ventricular ejection fraction >40%, a negative result from a symptom-limited exercise stress test for ischemia (<2 mm ST depression) at 1 week, and achieved >7 METs. Patients with left ventricular ejection fraction <40% were included only if they did not have inducible ventricular tachycardia at electrophysiologic studies. Seventy-two patients were randomized to return to normal activities at 2 weeks and 70 patients to undergo standard cardiac rehabilitation and return to normal activities at 6 weeks after AMI. There were no deaths or heart failure in either group. There was no significant difference in the incidence of reinfarction, revascularization, left ventricular function, lipids, body mass index, smoking, or exercise test results at 6 months. In conclusion, return to full normal activities, including work at 2 weeks, after AMI appears to be safe in patients who are stratified to a low-risk group. This should have significant medical and socioeconomic implications.

Fatal Cardiac Rupture during Stress Exercise Testing: Case Series and Review of the Literature

Mortality rates of exercise testing are low and cardiac rupture and sudden death are rare. Three cases of fatal cardiac rupture that occurred during exercise stress testing are reported. Once thought to be a fatal complication, there are increasing reports of ante-mortem diagnosis and survival. Cardiac rupture is a stuttering process with recognizable clinical symptoms that allow early recognition and treatment. Certain clinical, biochemical, ECG and hemodynamic markers may allow identification of patients likely to sustain rupture. Strategies for diagnosis, resuscitation, and definitive intervention are reviewed.

Supervision of occupational fitness assessments

Controversy continues regarding an appropriate level of supervision for occupational fitness assessments. A bout of vigorous physical activity can augment the immediate risk of a cardiac catastrophe by a factor of 5-100 depending on age, cardiac risk factors, and the physical and emotional circumstances of the participant. However, if a person engages regularly in such activity, the immediate risk is more than offset by an improvement in prognosis during intervening periods of rest. During demanding physical work, there is a small but measurable risk of sudden death (3 to 7 episodes per 100,000 personnel per year). The risk associated with a brief (< 15 min) but vigorous occupational fitness assessment is so low as to preclude attempts to reduce it still further by direct medical supervision. If testing encourages an increase in personal fitness, any immediate increase in risk is enormously offset by a reduction in the number of cardiac deaths while resting. Furthermore, evidence is unconvincing that the average medical practitioner can prevent or treat any emergencies that may arise better than a well-trained professional fitness and lifestyle consultant (PFLC), a person certified by the Canadian Society for Exercise Physiology who has had frequent opportunities to practice the necessary skills. Since occupational fitness assessments are not diagnostic procedures, they appear to fall outside the jurisdiction of medical licensing bodies. In the absence of a history of cardiovascular disease, supervision of such assessments is safely and appropriately undertaken by the PFLC. Unnecessary insistence on medical supervision could preclude annual evaluation of occupational fitness and a resulting enhancement of physical condition, thus increasing rather than diminishing the risk to the worker.

[Survival after recurrent left ventricular free wall rupture, with an atypical occurrence after post-infarction exercise test]

Left ventricular free wall rupture is an unusual but highly lethal complication of acute myocardial infarction. We report on the extremely rare occurrence of a patient surviving two episodes of free wall rupture within a seven-month period. The first event happened in the course of an exercise testing after a seemingly uncomplicated inferior acute myocardial infarction; the second, seven months after the first, as a pseudoaneurysm in the setting of a new inferior wall infarction. Surgical repair was successful in both instances, with patient remaining asymptomatic in follow-up.

Cardiac rupture during exercise stress echocardiography: a case report

Stress echocardiography is widely used in the evaluation of coronary artery disease. Dobutamine stress echocardiography has been the preferred method, but many centers have adopted exercise stress echocardiography, which can visualize myocardial motion during physiologic stress testing. The complications of this method in the post-myocardial infarction period are the same as those identified in conventional exercise testing. We report a case of myocardial rupture in the postinfarction period during exercise stress echocardiography.

Feasibility and safety of early exercise testing using the Bruce protocol after acute myocardial infarction

OBJECTIVE

To assess the feasibility and safety of exercise testing (ET) using a Bruce protocol (BPR) within three days of an acute myocardial infarction (AMI) with the data obtained from a prospectively managed database.

BACKGROUND

Exercise testing after AMI is usually done between days 4 and 6 and often using a "low-level" protocol. Earlier testing with BPR may allow for efficient triage.

METHODS

Patients were considered for early ET when off intravenous nitroglycerine with no rest angina, uncontrolled cardiac failure or arrhythmias.

RESULTS

Of 300 consecutive AMI patients who underwent an ET, 216 (72.0%; M = 163, F = 53; age mean 59 +/- 0.8 SEM, range 34 to 83 years) had ET within three days of admission. There were 124 (57%) negative, 56 (26%) positive and 36 (17%) indeterminate tests. The maximum heart rate achieved was 116 +/- 1 beats/min (range 64 to 163), which was 72.2 +/- 0.8% of predicted maximum (86.6% on beta-adrenergic blocking agents at ET; exercise duration = 6.7 +/- 0.2 min). Reasons for termination: maximum effort-89 (41%); low-level test target (stage III/IV of BPR)-63 (29%); positive ST segment change-19 (9%); severe chest pain-12 (5.5%); reaching 90% predicted maximum heart rate-6 (3%); nonsustained ventricular tachycardia-1 (0.5%); other-26 (12%). Fourteen (6.5%) patients had minor complications (i.e., drop in systolic pressure, chest pain >5 min) with no cardiac arrests, AMIs or deaths. After the ET, 87 (40%) patients were discharged the same day, 73 (34%) the next day.

CONCLUSIONS

The majority of ETs after an AMI can be done using the Bruce protocol within three days of admission with a very low incidence of complications. This can lead to early triage and potential cost savings.

Risk stratification after acute myocardial infarction in the reperfusion era

Historically, risk stratification for survivors of acute myocardial infarction (AMI) has centered on 3 principles: assessment of left ventricular function, detection of residual myocardial ischemia, and estimation of the risk for sudden cardiac death. Although these factors still have important prognostic implications for these patients, our ability to predict adverse cardiac events has significantly improved over the last several years. Recent studies have identified powerful predictors of adverse cardiac events available from the patient history, physical examination, initial electrocardiogram, and blood testing early in the evaluation of patients with AMI. Numerous studies performed in patients receiving early reperfusion therapy with either thrombolysis or primary angioplasty have emphasized the importance of a patent infarct related artery for long-term survival. The predictive value of a variety of noninvasive and invasive tests to predict myocardial electrical instability have been under active investigation in patients receiving early reperfusion therapy. The current understanding of the clinically important predictors of clinical outcomes in survivors of AMI is reviewed in this article.

Use of stress echocardiography for risk assessment of patients after myocardial infarction

The main predictors of outcome after infarction (exercise capacity, ejection fraction, and extent of jeopardized myocardium) can all be identified using stress echocardiography. This review addresses the place of stress echocardiography in postinfarct risk evaluation, relative to clinical evaluation, and other technologies. The test is accurate for identification of multivessel disease and for predicting outcomes, is versatile, and can be used early after infarction.

Acute cardiac rupture complicating pre-discharge exercise testing. A case report with complete echocardiographic follow-up

The case of a 76 year-old male who suffered acute free wall rupture and sudden hemodynamic deterioration during the recovery phase of a pre-discharge exercise testing (performed 7 days after a noncomplicated myocardial infarction) is presented. Usefulness of echocardiography in early diagnosis, management (guiding pericardiocentesis) and follow-up is remarked and, on the other hand, medical treatment after a successful resuscitation is confirmed as an alternative option in these cases.

Risk stratification of patients with medically treated unstable angina using exercise echocardiography

Functional testing is recommended for risk stratification of medically treated patients with unstable angina. Exercise echocardiography is used in this situation, but its safety and prognostic value are not well defined. The objective of this study was to assess the incremental prognostic value of exercise echocardiography in 226 consecutive patients (128 men, age 59+/-13 years) with medically treated unstable angina, who underwent exercise echocardiography from 1991 to 1996. Clinical risk was designated as low in 108 patients, intermediate in 116, and high in 2 patients according to the unstable angina practice guidelines. There were no major complications from the stress tests. The exercise electrocardiogram was nondiagnostic in 57 patients (25%). Ischemia was identified by exercise electrocardiography in 33 patients and exercise echocardiography in 55 patients. Patients were followed for 29+/-18 months. After exclusion of 38 patients who underwent early revascularization, 28 patients had cardiac death, nonfatal infarction, and late (>3 months) revascularization. Ischemia at exercise echocardiography was associated with a 24-month event-free survival of 81%, compared to 95% with negative exercise echocardiography (p=0.02). A positive exercise electrocardiogram was associated with a 24-month event-free survival of 84%, compared to 93% with negative exercise electrocardiograms (p=0.08). In a Cox regression model, event-free survival was predicted by ischemia at exercise echocardiography (relative risk 2.8, confidence interval: 1.3 to 6.3, p=0.05), but not at exercise electrocardiography (relative risk 2.1, confidence interval 0.7 to 5.8, p=0.16).

Cardiac rupture with dobutamine stress echocardiography

Dobutamine stress echocardiography is a safe method for the evaluation of coronary artery disease, myocardial function, and viability. The potential for cardiac rupture exists. Although clinical and electrocardiographic criteria may be helpful in identifying those patients at risk for cardiac rupture, the criteria are neither sensitive nor specific enough to exclude patients or make recommendations regarding which patients should undergo dobutamine stress echocardiography in the post-infarction period. Physicians must be aware of the possibility and be prepared to treat cardiac rupture when performing dobutamine stress echocardiography.

Comparison of dobutamine ECG stress test with predischarge exercise test after acute myocardial infarction

Exercise testing after acute myocardial infarction is commonly used, but in recent years alternative methods have been proposed. Standard exercise testing was compared with dobutamine electrocardiographic (ECG) stress testing in 100 patients after an acute initial myocardial infarction. Dobutamine ECG stress testing was performed in a standard manner at 5 +/- 1 days after the infarction and exercise testing was performed a mean of 10 +/- 2 days following the event. Agreement between both tests was observed in 91 cases (91%), P < .001, Fisher test kappa value, 0.79). The dobutamine test predicted the result of the exercise test with a sensitivity of 100% (95% confidence interval, 87-100) and a specificity of 88% (95% confidence interval 77-93) for a positive predictive value of 75% (95% confidence interval, 62-97) and a negative predictive value of 100% (95% confidence interval, 91-100). Dobutamine ECG stress testing is concluded to be an objective and reliable procedure, which accurately predicts the results of standard exercise testing. It is inexpensive, easy to perform, and although not yet confirmed, could be particularly useful in patients who cannot perform exercise.

Complications of pharmacologic stress echocardiography in coronary artery disease

In the last few years, pharmacologic stress echocardiography is emerging as a promising diagnostic tool with a favorable cost/benefit ratio. Its main clinical applications include the assessment of coronary artery disease, the identification of viable myocardium, and risk stratification before major vascular surgery. However, cardiac (arrhythmic, ischemic, or hemodynamic) as well as noncardiac complications have been reported, so that a risk/benefit analysis is advisable in view of the extensive introduction of this technique in the clinical arena. The most popular pharmacologic agents employed for stress echocardiography are dipyridamole, dobutamine, and adenosine. A comparative analysis with exercise stress testing, the classical standard a reference of all ischemia-provoking tests, confirms that in terms of safety and tolerability pharmacologic stress echocardiography may be considered a good alternative in patients unable to exercise maximally. No appreciable difference among the safety profiles of the most common pharmacologic agents has been found, but a careful evaluation of the risk/benefit ratio is advisable for any stressor in the individual patient by considering the relative importance of the expected diagnostic contribution and the pharmacodynamic impact of the test. Finally, adequate training of the operator and monitoring of the patient during stress and recovery are essential for getting optimal safety conditions.

Acute myocardial infarction shortly after a normal exercise stress test. Case reports

The authors describe 3 cases of AMI occurring shortly after a negative bicycle ergometer stress test. These cases represent an unfortunate but extremely rare complication of a relatively safe diagnostic procedure. The authors also focus on the pathogenesis of the ischemic event, which may be attributed either to intraplaque hemorrhage or to platelet aggregation, both exercise-induced. The prevalence of AMI in this paper (0.06%) is similar to the data described in literature.

Early exercise testing after acute myocardial infarction in the elderly: clinical evaluation and prognostic significance

Early exercise testing (EET) after acute myocardial infarction (MI) is a well-established means of detecting patients at high risk for subsequent cardiac events. However, the value of this test is not well documented in elderly patients. We evaluated the clinical and prognostic significance of EET in 188 patients, aged 70 years or more, 14 +/- 3 days after an uncomplicated acute MI. The mean follow-up period was 3.6 years (range 1 to 6 years) in 95% of the patients. The total mortality rate was 13.5% (24/178) and the cardiac-related mortality rate was 7.8% (14/178), with 64% of the deaths occurring in the first 3 years. There were no complications during EET. The following parameters measured during EET on a bicycle ergometer were predictive of subsequent cardiac death: an increase in systolic blood pressure of less than 30 mm Hg (p < 0.001), an increase in the double product of less than 12,500 mm Hg.beats/min (p < 0.001), a maximal load less than 60 W (p < 0.001), and a total duration of exercise less than 5 minutes (p < 0.001). The combination of these four parameters increased the predictive value of the test (p < 0.0001). ST segment depression and ventricular arrhythmias during exercise were not correlated with the incidence of subsequent cardiac death, but the degree of ST segment depression was directly and significantly (p < 0.0001) associated with the incidence of subsequent nonlethal cardiac events (coronary bypass surgery, coronary angioplasty, reinfarction, or unstable angina).(ABSTRACT TRUNCATED AT 250 WORDS)

Symptom-limited versus low level exercise testing before hospital discharge after myocardial infarction

OBJECTIVE

This study was undertaken to compare a low level and a symptom-limited test performed before hospital discharge after an uncomplicated myocardial infarction.

BACKGROUND

Exercise testing after myocardial infarction provides useful prognostic information. Usually either a low level test is performed before hospital discharge or a symptom-limited test is performed at 3 weeks.

METHODS

The study group comprised 202 patients with an uncomplicated myocardial infarction; 58 patients had a non-Q wave infarction and 115 patients had received thrombolytic therapy. Both a low level and a symptom-limited exercise test were performed in 200 of the 202 study patients in randomized order on consecutive days, a mean of 7.4 +/- 2.3 days after infarction.

RESULTS

The symptom-limited test required a considerably greater effort than the low level test: exercise duration was 554 +/- 209 versus 389 +/- 125 s (p less than 0.0001), and peak work load was 5.7 +/- 1.8 versus 4.2 +/- 1.1 METs (p less than 0.0001). The peak heart rate was higher during the symptom-limited test (121 +/- 20 vs. 108 +/- 14 beats/min, p less than 0.0001), as was the rate-pressure product. The number of patients who developed ST segment depression greater than or equal to 1 mm increased from 56 during the low level test to 89 during the symptom-limited test (p less than 0.0001). ST segment depression greater than or equal to 2 mm occurred in 22 patients during the low level test and in 41 patients during the symptom-limited test, an 86% increase (p less than 0.0001). The number of patients with either angina or ST depression greater than or equal to 1 mm increased from 66 to 105 (p less than 0.0001) with the symptom-limited test. Exercise test results were similar for patients with a Q wave or a non-Q wave infarction. Exercise duration was longer and exercise-induced ST depression less frequent in patients who had received thrombolytic therapy.

CONCLUSIONS

A symptom-limited exercise test performed before hospital discharge after uncomplicated myocardial infarction provides a significantly greater cardiovascular stress than does a low level test and is associated with an ischemic response nearly twice as frequently. The prognostic significance of a positive response at higher work loads has not been defined.

Exercise Testing Update

In brief Exercise testing remains an important tool in diagnosing and evaluating cardiorespiratory conditions. The most useful modality of the exercise test depends on the patient's capabilities. If the patient is young or fit, the Bruce treadmill protocol is appropriate. A modified Naughton test is usually best for older or more fragile patients. A thallium perfusion scan may provide useful follow- up. In interpreting exercise tests, non-ECG variables may be as important as ST segment depression. The safety of exercise tests appears to be improving, and they are increasingly supervised by specially trained nonphysicians.