Blunted hemodynamic response and reduced oxygen delivery with exercise in anemic heart failure patients with systolic dysfunction.

Anemic heart failure patients with systolic dysfunction are known to have reduced exercise capacity. Whether this is related to poor hemodynamic adaptation to anemia is not known. Peak exercise oxygen consumption (VO2) and hemodynamics at rest and peak exercise were assessed among 209 patients and compared among those who were (n=90) and were not (n=119) anemic. Peak VO2 was significantly lower among anemic patients (11.7+/-3.3 mL/min/kg vs 13.4+/-3.1 mL/min/kg; P=.01). At rest, right atrial pressure was higher (10+/-5 mm Hg vs 8+/-4 mm Hg; P=.02) and venous oxygen saturation lower (62%+/-8% vs 58%+/-10%; P<.01) among anemic patients. At peak exercise, anemic patients had a higher wedge pressure (27+/-9 mm Hg vs 24+/-10 mm Hg; P=.04). No significant differences in stroke volume, cardiac index, systemic vascular resistance, or oxygen saturation were noted between the 2 groups. In conclusion, the relative hemodynamic response to exercise among anemic heart failure patients appears blunted and may contribute to worse exercise tolerance.

Beta-blocker therapy for heart failure: should the therapeutic target be dose or heart rate reduction?

Therapeutic target with beta blockers in heart failure, i.e., target heart rate reduction or beta-blocker dose, is controversial. To resolve this controversy, the authors studied 152 heart failure patients on beta blockers who were divided into four groups based on median peak exercise heart rate reduction as compared with predicted and prescription of at least 50% recommended beta-blocker dose. Event-free survival (vs. death or assist device placement or urgent transplantation) was compared. Baseline and peak exercise heart rates were 74 +/- 14 and 116 +/- 21 bpm, respectively. Median heart rate reduction at peak exercise was 35%. When median or higher peak heart rate reduction was achieved, there were no significant survival differences noted between patients on different beta-blocker doses. With below-median peak heart rate reduction, there was a strong trend toward better event-free survival with higher beta-blocker doses. In conclusion, the results suggest that higher heart rate reduction is associated with better outcomes for heart failure patients overall and, for patients with persistently elevated heart rates, higher beta-blocker doses provided additional benefit.

Cardiac rehabilitation outcomes: impact of comorbidities and age.

PURPOSE: Medical comorbidities (CM) contribute to cardiac rehabilitation (CR) underutilization. Whether individuals with coronary heart disease and an increased CM burden achieve similar benefits from CR as those with a low CM burden is unknown. METHODS: We analyzed 794 patients with coronary heart disease completing CR from 1/96 to 4/08. Medical CM burden was assessed using a comorbidity index (CMI) previously validated in a CR population. Distance achieved on a 6-minute walk test, body mass index, and the physical and mental component scores on the Medical Outcomes Short Form 36 were measured at baseline and at CR completion. We performed multivariable linear regression to compare changes in these parameters between individuals with a low CM burden (CMI = 0) and those with a moderate (CMI = 1-2) or high (CMI > 2) CM burden by age group (<56, 56-65, and >65 years of age). RESULTS: Mean age was 61.6 ± 10.6 years, 29% were women, 31% nonwhite; 305 individuals had a CMI = 0, 305 had a CMI = 1 to 2, and 184 had a CMI > 2. All subgroups, regardless of age or CMI, demonstrated improvements with CR on virtually all parameters measured. Among individuals younger than 56 years, those with a CMI = 0 had greater improvements in these parameters after multivariable adjustment than those with a CMI of 1 to 2 or more than 2. In contrast, in older age groups, the degree of improvement was similar regardless of CMI. CONCLUSION: All patient groups, regardless of CM burden, benefited from CR. Medical CM burden, especially among older patients, should not discourage referral to CR.