Richard S. Crow

Community education for cardiovascular disease prevention: risk factor changes in the Minnesota Heart Health Program.

OBJECTIVESnThe Minnesota Heart Health Program is a 13-year research and demonstration project to reduce morbidity and mortality from coronary heart disease in whole communities.nnnMETHODSnThree pairs of communities were matched on size and type; each pair had one education site and one comparison site. After baseline surveys, a 5- to 6-year program of mass media, community organization, and direct education for risk reduction was begun in the education communities, whereas surveys continued in all sites.nnnRESULTSnMany intervention components proved effective in targeted groups. However, against a background of strong secular trends of increasing health promotion and declining risk factors, the overall program effects were modest in size and duration and generally within chance levels.nnnCONCLUSIONSnThese findings suggest that even such an intense program may not be able to generate enough additional exposure to risk reduction messages and activities in a large enough fraction of the population to accelerate the remarkably favorable secular trends in health promotion activities and in most coronary heart disease risk factors present in the study communities.

Community-wide prevention of cardiovascular disease: Education strategies of the Minnesota Heart Health Program

The Minnesota Heart Health Program (MHHP) is a research and demonstration project of population-wide primary prevention of cardiovascular disease. Study goals are to achieve reductions in cardiovascular disease risk factors and morbidity and mortality in three education communities compared with three reference communities. The program in the first of the three intervention communities, Mankato, has been operating for 3 of the planned 5 years. Early objectives of the program have been achieved based on data obtained from population-based random samples surveyed in education and comparison communities. After 2 years of participation, Mankato was significantly more exposed to activities promoting cardiovascular disease prevention. In this town of 38,000 inhabitants, 190 community leaders were directly involved as program volunteers, 14,103 residents (over 60% of adults) attended a screening education center, 2,094 attended MHHP health education classes, 42 of 65 physicians and 728 other health professionals participated in continuing education programs offered by MHHP, and distribution of printed media averaged 12.2 pieces per household. These combined educational strategies have resulted in widespread awareness of MHHP and participation by the majority of the Mankato adult population in its education activities.

Physical activity, smoking, and exercise-induced fatigue.

This study determined whether persons with coronary risk factors have increased fatigue during or after exercise. Ratings of perceived exertion were first shown to be a valid measure of fatigue; i.e., ratings of perceived exertion correlated with heart rate both during and after exercise and at each of three exercise tests (all within-subjects r>0.88). Physical inactivity and smoking were associated with increased fatigue. Inactive men and smokers had higher levels of fatigue during both exercise and recovery conditions and at each of three exercise tests. The increased fatigue of men who were inactive and smoked was not entirely due to their lower level of fitness. The risk factors of age, Type A behavior pattern, blood pressure, serum cholesterol, serum high-density lipoprotein, and obesity were not associated with increased fatigue. The increased fatigue experienced by inactive persons and smokers may account for their decreased compliance to exercise programs.

Ventricular premature contractions: a randomized non-drug intervention trial in normal men.

The influence of a 6-week intervention on factors thought to be related to ectopic cardiac rhythms was tested in normal men with frequent ventricular premature contractions (VPCs), using a randomized, controlled and partial crossover design. The VPC intervention trial experimental regimen included total abstinence from caffeine and smoking, reduction of alcohol intake, and a physical conditioning program. Effects were studied in detail among 81 healthy men with persistent VPCs. VPCs were measured during standard states of rest, dynamic and isometric exercise and other stresses, and 24-hour ambulatory monitoring. Adherence to the treatment was excellent. The experimental group achieved more than 80% of activities asked of them, and little contamination occurred in the control group.VPCs were analyzed according to VPC/min, VPC/man and VPC/total number of heart beats. Moderate changes in VPC rates occurred in both experimental and control groups but no significant group differences were found at rest or during any induction test. This 6-week, multiple-factor hygienic intervention program had no significant influence on the frequency or occurrence of VPCs in apparently normal men with persistent and frequent VPCs.Because the mechanisms and the significance of VPCs are different in patients with ischemic heart disease, our approach and methods may be useful for similar trials among cardiac patients of adjunct or non-drug therapy for ectopic rhythms.

Ventricular premature beats. Reliability in various measurement methods at rest and during exercise.

The yield and reproducibility of various methods of ventricular premature beat (VPB) detection are examined in otherwise healthy middle-aged men first found to have VPB in a 2-min lead I ECG rhythm strip. With a combination of an isometric and treadmill exercise test, VPB were repeatedly detected in 83%. Test-retest reliability in classifying the subjects by frequency of VPB was 67%. The reliability of detecting complex VPB was 47% for multiform VPB, 35% for pairs of VPB, 17% for runs and 36% for VPB showing the R-on-T phenomenon. These data suggest that simple and complex VPB detected by the described methods among normal men are poorly reproducible in the individual. Taking the VPB reproducibility for the group as a whole, the proportion of subjects having different frequency or kinds of ectopic beats is reasonably stable for the different test occasions.

Ventricular Premature Beats: Screening and Induction Tests in Normal Men

Effective future research on the significance of ventricular premature beats (VPB) and their therapeutic suppression require improved and simpler methods for arrhythmia detection, characterization, and measurement. This study considers the comparative yield, repeatability, and validity of several methods of VPB detection and induction in a sample of the general population of middle-aged men. Isometric exercise inducers VPB. Treadmill exercise both induces and suppresses VPB. Cartotid sinus pressure and cold stress provide a small extra yield of VPB.

Reliability of sampling during long-term ECG recordings in the detection of ventricular ectopy and abnormal ST segment depression

Two ambulatory ECG recording-analysis methods were each compared in 10 subjects with a careful hand counted analysis of 16 continuously recorded hr and examined for total VEB count, complex VEB and ST-depression. The sampling method made a 28-sec tape recording every 15 min and was visually coded. The other method (conventional Holter) continuously recorded ECG data and used a dedicated computer with technician editing. Both recorders were simultaneously worn by study participants for 16 hr. Neither method showed a statistically significant difference from the hand counted data or systematic over- or under-estimation of clinically important ECG detections. A probability model is presented which provides a theoretical basis for the success of ECG sampling. Findings from this pilot study indicate electrocardiographic sampling may provide event detection comparable with the more conventional analyses, with considerably less data acquisition. The choice of ambulatory ECG recording mode should be governed by the level of quantification required, specific events to be detected and cost.