Nancy Houston

Exercise training soon after myocardial infarction

Abstract To assess the cardiovascular effects of exercise training soon after clinically uncomplicated myocardial infarction, 70 men (mean age 54 years) underwent gymnasium training (no. = 28), home training (no. = 12) or no training (no. = 30) 3 to 11 weeks after the acute event. During this 8 week interval functional capacity increased significantly ( P P

A new method for evaluating antiarrhythmic drug efficacy.

To develop standards for distinguishing antiarrhythmic drug effect from spontaneous variability of premature ventricular complexes (PVCs), 21 males (mean age 56 ± 8 years) with chronic ischemic heart disease and PVCs underwent symptom-limited treadmill exercise testing and 24-hour ambulatory monitoring before and after 2 weeks of placebo medication. Linear regression analysis was used to describe the relationship between baseline and placebo PVC frequency for various indexes of ventricular ectopic activity and to establish 95% and 99% one-tailed confidence intervals for this relationship within the group of 21 patients. The lower limit of baseline PVC frequency for which the procedure could distinguish a placebo from a true drug response, termed the “sensitivity threshold,” was an average frequency of 2.2 PVCs/hour for ambulatory electrocardiographic monitoring and 1.2 PVCs/min for treadmill exercise testing. All patients exceeded the sensitivity threshold on baseline ambulatory ECGs, but only 38% of patients did so on baseline treadmill exercise tests. To establish antiarrhythmic efficacy with 95% confidence, the minimal percent reduction of PVCs between baseline and placebo visits was 68% for treadmill exercise testing and 65% for ambulatory electrocardiography. Although these standards were developed in patients with chronic ischemic heart disease, the model can be used to establish antiarrhythmmic drug efficacy in any patient group.

Cardiovascular responses to dynamic and static effort soon after myocardial infarction. Application to occupational work assessment.

SUMMARY Static and dynamic work involving the arms and the legs was performed by 40 men seven weeks after myocardial infarction. Leg ergometry produced a significantly higher peak work load, systolic blood pressure (BPs), heart rate (HR), and HR X BPs X 10-2 product (DP) than did arm ergometry: 842 ± 178 vs 546 ± 135 kg-m/min, 176 ± 24 vs 154 ± 19 mm Hg and 256 ± 54 vs 219 ± 48 (SD). Peak heart rates were 145 and 142. Endpoints were primarily muscular and generalized fatigue and dyspnea. Ischemic abnormalities and ventricular ectopy were more frequent with leg ergometry. Sustained forearm lifting elicited higher HR, BPs and DP responses than sustained handgrip contraction: 95 ± 16 vs 91 ± 16 beats/min, 162 ± 18 vs 152 ± 17 mm Hg and 154 ± 33 vs 139 ± 33 (SD). Ischemic ST segment depression and significant ventricular arrhythmias were infrequent with static effort. Dynamic leg testing is superior to dynamic or static arm testing in assessing the capacity of patients to perform physical work tasks after myocardial infarction.

Serial ambulatory electrocardiography and treadmill exercise testing after uncomplicated myocardial infarction

To compare the diagnostic and prognostic utility of ambulatory electrocardiography and treadmill exercise testing after clinically uncomplicated myocardial infarction, 90 men (mean age 52 years) were evaluated 3 weeks after the acute event and a variable number were evaluated 11, 26 and 52 weeks after the acute event. The prevalence of “any” premature ventricular complex and of “complex” ventricular ectopic activity was greater with ambulatory electrocardiography than with treadmill testing (78 versus 49 percent; p

Antiarrhythmic efficacy of encainide and quinidine: Validation of a model for drug assessment☆

The antiarrhythmic efficacy of encainide and quinidine was compared in 20 ambulatory men (mean age 56 ± 8 years) with a history of premature ventricular complexes. All but one patient had a history of chronic ischemic heart disease. A longitudinal crossover design was used to study the effects of encainide and quinidine on premature ventricular complexes recorded on treadmill excercise tests and on 24 hour ambulatory electrocardiograms. After a baseline evaluation, patients were randomized to one of two drug sequences consisting of 2 weeks of treatment with placebo followed by 2 weeks of treatment with the first drug, after which the same sequence was repeated for the second drug. Encainide was generally better tolerated than quinidine. The reduction in the average number of premature ventricular complexes/hour on ambulatory electrocardiograms and in the average number of premature ventricular complexes/min on treadmill exercise tests was greater With encainide than with quinidine (p <0.01 and <0.025, respectively). Encainide suppressed all premature ventricular complexes recorded on ambulatory electrocardiograms in 44 percent of patients, reduced them by at least 80 percent in 88 percent of patients and suppressed complex forms in 100 percent of patients. By contrast, no patient demonstrated total suppression of premature ventricular complexes with quinidine, only 44 percent demonstrated at least 80 percent reduction and only 53 percent demonstrated suppression of complex forms on 24 hour ambulatory electrocardiograms. Encainide Is safe and effective for the treatment of chronic ventricular ectopic activity. In this study, It appeared to be superior to average doses of quinidine.

Changes in rest and exercise myocardial perfusion and left ventricular function 3 to 26 weeks after clinically uncomplicated acute myocardial infarction: Effects of exercise training

The effects of exercise training on exercise myocardial perfusion and left ventricular (LV) function in the first 6 months after clinically uncomplicated acute myocardial infarction (AMI) were assessed in 53 consecutive men aged 55 +/- 9 years. Symptom-limited treadmill exercise with thallium myocardial perfusion scintigraphy and symptom-limited upright bicycle ergometry with equilibrium gated radionuclide ventriculography were performed 3, 11 and 26 weeks after AMI by 23 men randomized to training and 30 randomized to no training. Peak cycle capacity increased in both groups between 3 and 26 weeks (p less than 0.01), but reached higher levels in trained than in untrained patients (803 +/- 149 vs 648 +/- 182 kg-m/min, p less than 0.01). Reversible thallium perfusion defects were significantly more frequent at 3 than at 26 weeks: 59% and 36% of patients, respectively (p less than 0.05), without significant inter-group differences. Values of LV ejection fraction at rest, submaximal and peak exercise did not change significantly in either group. The increase in functional capacity, i.e., peak treadmill or bicycle workload, that occurred 3 to 26 weeks after infarction was significantly correlated with the increase in peak exercise heart rate (p less than 0.001), but not with changes in myocardial perfusion or LV function determined by radionuclide techniques. Changes in myocardial perfusion or LV function do not appear to account for the improvement in peak functional capacity that occurs within the first 6 months after clinically uncomplicated AMI.

Comparison of cardiovascular responses to static-dynamic effort and dynamic effort alone in patients with chronic ischemic heart disease.

Thirty men, mean age 55 years, known to have treadmill-induced ischemic ST-segment depression, performed static dynamic effort, i.e., forearm lifting treadmill exercise, separately combined. Static effort was sustained at 20%, 25% or 30% of maximal forearm lifting capacity. Two symptomlimited treadmill tests, one with one without added static effort, were performed on each of two visits. Compared with dynamic effort alone, combined static-dynamic effort decreased treadmill work load increased heart rate, systolic blood pressure rate-pressure product at the onset of ischemic ST-segment depression or angina pectoris: 7.1 ± 0.4 vs 8.0 ± 0.5 (SEM) multiples of resting oxygen consumption (mets), estimated; 141 ± 3 vs 134 ± 3 beats/min; 170 ± 4 vs. 162 ± 4 mm Hg 239 ± 8 vs 218 ± 9 (p ≤ 0.001). The prevalence of angina pectoris was significantly less with combined static-dynamic effort than with dynamic effort alone. Static effort causes a resetting of the threshold at which ischemic abnormalities appear during dynamic effort.

Optimal methods for identifying depression following hospitalization for myocardial infarction

Abstract Methods for detecting depression were evaluated in 64 men mean age 53 ± 4 yr who underwent treadmill exercise testing 3 and 7 weeks after clinically uncomplicated myocardial infarction. Following an open-ended interview, a therapist rated 9 33 patients as moderately to severely depressed, of whom 3 33 (9%) were judged to require treatment for depression. Two self report scales identified only 2 of the 9 patients with moderate to severe depression and only 1 of the 3 patients requiring treatment. Following a standardized interview, a technician rated 4 of the next 31 patients as moderately to severely depressed, all of whom ( 4 31 , 13%) were judged by the therapist to require treatment for depression. Self report identified only 2 of the 4 patients judged by the therapist to require treatment. A trained technician and a therapist detect about the same proportion of patients requiring treatment for depression after myocardial infarction. Both methods of interview are superior to self report scales for the detection of moderately severe depression requiring treatment.

The effect of a standardized psychological stressor on the cardiovascular response to physical effort soon after uncomplicated myocardial infarction

To determine whether a standardized psychological stressor combined with physical stress might disclose ischemic abnormalities not evident with physical stress alone, 30 men, mean age 54, were evaluated seven weeks after clinically uncomplicated myocardial infarction. In the first 20 patients, two symptom-limited treadmill tests (TM) were performed on the same day, with and without superimposed psychological quiz (Q). In the next 10 consecutive patients, the Q was administered at a submaximal level (4 METs). When TM and TM + Q responses were compared, no significant differences were noted in the maximal levels of heart rate (HR), systolic blood pressure (SBP), rate pressure product, or in the prevalence of ischemic ST segment depression or angina pectoris. The HR and double product at which ischemic ST segment depression and angina pectoris appeared were similar for the two types of testing. The psychological stress of a psychological quiz may not, of course, approximate the effect of the more severe stressors individuals may encounter in their daily routines.