Search

We evaluated 250 males and 250 females 4 to 17.99 years old, randomly recruited among school-children. Cardiac and other diseases were excluded. All the subjects were studied with a standard ECG iun the standing and supine position for a minute. Three hundred children underwent a treadmill exercise test according to Bruce's protocol and 50 of them had a 24-hour ambulatory ECG monitoring. Sinus arrhythmia was present in 94% of the children in supine position and in 87% of them while they were standing. Only one child had atrial and ventricular premature beats. In a boy a slow ventricular tachycardia was recorded. One child had a WPW and a girl a short PR interval; both were asymptomatic. The exercise test did not induce any arrhythmias and the slow ventricular tachycardia, in the previously mentioned boy was suppressed during exercise and reappeared during the recovery period. The premature beats were greatly reduced in the child who had them during the standard ECG recording. The 24-hour ambulatory ECG monitoring showed only minor degrees of premature atrial and ventricular beats in 24% of the children studied by this method. The maximum number of premature beats was 39 in 24 hours and never exceeded the first grade of Lown's classification. We conclude that a good correlation exists among the three employed techniques in the study of the prevalence of tachyarrhythmias in healthy children. This is the first study that compares these three techniques in a pediatric population.

The meaning of exercise-induced arrhythmias was studied in 409 patients who underwent a maximal treadmill test, coronary and ventricular angiography and were followed for 31 +/- 10.6 months. The original population consisted of 1720 patients, of whom 520 were assigned to a group of known or strongly suspected coronary artery disease (Group I) and 1200 were assigned to a group with low likelihood of coronary artery disease (Group II). This division was based on age, history and symptoms. Two hundred and forty-seven (47.5%) patients of group I and 218 (18%) of group II developed ventricular premature beats during the exercise test or the recovery period. The test was positive in 378 (72.6%) patients of group I and in 190 (15.8%) of group II. A complete invasive angiographic study was performed in 233 (44%) patients of group I and 176 (14.6%) of group 2. Exercise-induced ventricular premature beats (VPBs) predicted neither coronary anatomy nor subsequent coronary or surgical events, but a weak relationship was observed with a lower ejection fraction among group I patients. On the other hand, a positive test was predictive of coronary anatomy in both groups and of coronary events in group I. We conclude that, despite a higher prevalence of exercise-induced ventricular premature beats among patients with definite coronary artery disease, an exercise test presenting ventricular premature beats as the only abnormality should not be classified as positive. Patients with such results require further investigation.

In this study, 321 patients discharged from hospital after an acute myocardial infarction were followed for 10 years or until death. Death rate was 46.4% and 30.8% of all fatalities was sudden. In over 80% of the cases death was from cardiac causes and frequently occurred out of hospital. Univariate analysis showed that age, female sex, previous infarction, diabetes, heart failure during hospitalization, heart murmur, NYHA class III or IV, post-infarction angina, intraventricular conduction defects, cardiomegaly, ST displacement, were all associated with an increased death rate. A positive exercise test 6-17 months after infarction, was associated with a 4-fold mortality increase. Bypass played a minor role in this series since only 6.8% of the patients underwent this operation. A nonfatal infarction recurred in 71 patients (22.1%) with an annual rate of 2.2%. Annual death rate after the first 2 years of follow-up was 3.9%, as in most recent reports on survival after myocardial infarction.

Our follow-up after myocardial infarction consists of 321 patients followed for 10 years or until death. 147 patients, free of clinical features associated with high risk of subsequent events, underwent a late exercise test at cycloergometer 6 to 17 months after infarction. Ten year mortality was 48.3% and 10.3% in patients with a positive or a negative test respectively (p less than 0.0001). Incidence of nonfatal reinfarction was 4.6% and 33.3% respectively (p less than 0.001). 108 patients underwent a second test later in the follow-up (2.8 +/- .9 years): in 27 patients who were positive at first test the second test was also positive and mortality was 33.3%. Sixteen out of 81 patients with a former negative test resulted positive at a repeat test and mortality was 37.5% vs a 3% mortality rate among 65 patients who were negative at both tests. Thus long-term prognostic significance of exercise stress testing after acute myocardial infarction is confirmed and extended, despite limitation of a late test. Moreover, the second test along the follow-up allows further stratification. In conclusion, patients with a negative test and without clinical features predictive of poor prognosis constitute a very low risk group who need not undergo invasive testing, whereas patients with a positive result or who become positive at following test deserve further evaluation and may become bypass candidates in the ensuing years.

The 10-year survival rate of 66 patients discharged after an acute myocardial infarction associated with intraventricular conduction delay is reported. The whole population under study consisted of 321 patients followed for 10 years or until death. In 46 patients (69.7%) the conduction delay was a definite complication of infarction, in 15 (22.7%) it preceded the acute event and in 5 (7.5%) the time of onset was undetermined. Mortality in the presence of a conduction delay was 74.2% in 10 years vs 39.2% in its absence (p less than .001). Death was sudden in 41.6% of fatalities when a conduction defect was present and 28% in its absence (p less than .01). The 10-year survival was 55% in patients with conduction defects and QRS less than .12 sec duration, 23.8% if QRS was between .12 and .14 sec, and 4% when QRS duration was greater than .14 sec. 72% of patients of this latter group was in NYHA class 3 or 4, whereas 70% of patients with QRS less than .12 sec and 47% of patients with QRS .12 to .14 sec were in class 1 or 2. These data show that long-term prognosis of conduction delay associated to myocardial infarction is poor and stratification of risk of death is possible among these patients on the basis of QRS duration.