Bruce protocol

Abstract: Background Previous reports have suggested that an attenuated exercise heart rate response may be associated with coronary heart disease risk and with mortality. These observations may parallel the association between reduced heart rate variability during normal activities and adverse outcome. This investigation was designed to look at the prognostic implications of exercise heart rate response in a population-based sample. Methods and Results In this prospective cohort investigation, 1575 male participants (mean age, 43 years) in the Framingham Offspring Study who were free of coronary heart disease, who were not taking β-blockers, and who underwent submaximal treadmill exercise testing (Bruce protocol) were studied. Heart rate response was assessed in three ways: (1) failure to achieve 85% of the age-predicted maximum heart rate, which has been the traditional definition of chronotropic incompetence; (2) the actual increase in heart rate from rest to peak exercise; and (3) the ratio of heart rate to met...

Abstract: Background—Magnesium blocks many of the physiological actions of calcium. Nevertheless, the impact of magnesium supplementation on endothelial function and exercise tolerance in stable coronary artery disease (CAD) patients has not been assessed. Methods and Results—In a randomized, double-blind, placebo-controlled trial, 50 stable CAD patients (41 men and 9 women, mean±SD age 67±11 years, age range 42 to 82 years) were randomized to receive either magnesium (n=25) (30 mmol/d Magnosolv-Granulat; Asta Medica Company, Inc) or placebo (n=25) for 6 months. Before and after 6 months, endothelium-dependent brachial artery flow-mediated vasodilation (FMD) and endothelium-independent NTG-mediated vasodilation were assessed with high-resolution (10-MHz) ultrasound. Exercise stress testing was performed with use of the Bruce protocol. Intracellular magnesium concentrations ([Mg2+]i) were assessed from sublingual cells through x-ray dispersion (EXA) (normal mean±SD values 37.9±4.0 mEq/L). The magnesium therapy signi...

Abstract: Background Uncontrolled studies have shown that short atrioventricular delay dual chamber pacing reduces outflow tract obstruction in hypertrophic obstructive cardiomyopathy. Although the exact mechanism of this beneficial effect is unclear, this seems a promising potential new treatment for hypertrophic obstructive cardiomyopathy. Method In order to evaluate the impact of pacing therapy, we performed a randomized multicentre double-blind crossover (pacemaker activated vs non activated) study to investigate modification of echocardiography, exercise tolerance, angina, dyspnoea and quality of life in 83 patients with a mean age of 53 (range 22–87) years with symptoms refractory or intolerant to classical drug treatment. Results After 12 weeks of activated or inactivated pacing, independent of which phase was first, the pressure gradient fell from 59±36 mmHg to 30±25 mmHg ( P <0·001) with active pacing. Exercise tolerance improved by 21% in those patients who at baseline tolerated less than 10 min of Bruce protocol; symptoms of dyspnoea and angina also improved significantly from NYHA class 2·4 to 1·4 and 1·0 to 0·4, respectively ( P <0·007). Quality of life assessment with a validated questionnaire objectivated the subjective improvement. Conclusion Pacemaker therapy is of clinical and haemodynamic benefit for patients with hypertrophic obstructive cardiomyopathy, left ventricular outflow gradient at rest over 30 mmHg who are symptomatic despite drug treatment.