Usefulness of low doses of atropine to quantify the vagal stimulus-response relation in patients with congestive heart failure

Early heart rate recovery after exercise predicts mortality in patients with chronic heart failure

BACKGROUND

Patients with chronic heart failure (CHF) have multiple abnormalities of autonomic regulation that have been associated to their high mortality rate. Heart rate recovery immediately after exercise is an index of parasympathetic activity, but its prognostic role in CHF patients has not been determined yet.

METHODS

Ninety-two stable CHF patients (83M/9F, mean age: 51+/-12 years) performed an incremental symptom-limited cardiopulmonary exercise testing. Measurements included peak O2 uptake (VO2p), ventilatory response to exercise (VE/VCO2 slope), the first-degree slope of VO2 for the 1st minute of recovery (VO2/t-slope), heart rate recovery [(HRR1, bpm): HR difference from peak to 1 min after exercise] and chronotropic response to exercise [%chronotropic reserve (CR, %)=(peak HR-resting HR/220-age-resting HR)x100]. Left ventricular ejection fraction (LVEF, %) was also measured by radionuclide ventriculography.

RESULTS

Fatal events occurred in 24 patients (26%) during 21+/-6 months of follow-up. HRR1 was lower in non-survivors (11.4+/-6.4 vs. 20.4+/-8.1; p<0.001). All cause-mortality rate was 65% in patients with HRR1<or=12 bpm versus 11% in patients with HRR1>12 bpm (log-rank: 32.6; p<0.001). By multivariate survival analysis, HRR1 resulted as an independent predictor of mortality (chi2=19.2; odds ratio: 0.87; p<0.001) after adjustment for LVEF, VO2p, VE/VCO2 slope, CR and VO2/t-slope. In a subgroup of patients with intermediate exercise capacity (VO2p: 10-18, ml/kg/min), HRR1 was a strong predictor of mortality (chi2: 14.3; odds ratio: 0.8; p<0.001).

CONCLUSIONS

Early heart rate recovery is an independent prognostic risk indicator in CHF patients and could be used in CHF risk stratification.

Heart rate recovery in heart failure patients after a 12-week cardiac rehabilitation program

Heart rate recovery (HRR) after maximal exercise is a predictor of all-cause mortality. It was hypothesized that aerobic exercise training would increase HRR in patients with heart failure (HF), because it has been shown to be accelerated in athletes and improved in patients with coronary artery disease after cardiac rehabilitation. To date, no study has examined the effects of exercise training on HRR in HF. This was a retrospective study of patients with HF who had completed a phase II aerobic cardiac rehabilitation program with entry and exit maximal stress tests (n = 46). Thirty-five patients exhibited a training effect, 18 had abnormal HRR of < or =12 beats/min and the lowest initial functional capacity (L12), and 17 had HRR of >12 beats/min before training (G12). A group of 11 other patients did not achieve a training effect. After training, the L12 and G12 groups improved their estimated peak oxygen uptake (by 6.7 +/- 3.1 and 8.6 ml/kg/min, respectively) and treadmill time (by 117 +/- 62 and 181 +/- 108 seconds, respectively) compared with the no-training effect group (p <0.05). Only the L12 group demonstrated improvement in HRR (7 +/- 1 to 12 +/- 2 beats/min). In conclusion, the results indicate that short-term aerobic training can favorably modify HRR in patients with HF with low exercise capacity.

Negative chronotropic response to low-dose atropine is associated with parasympathetic nerve-mediated cardiovascular response in postoperative patients with congenital heart disease

OBJECTIVES

To investigate the negative chronotropic response (NCR) to low-dose atropine in postoperative patients with congenital heart disease (CHD).

BACKGROUND

Low-dose atropine causes a NCR through the central nervous system muscarinic receptor and is attenuated in adult heart failure patients. It has never been evaluated in CHD patients.

METHODS

NCR corrected for basal heart rate (HR) (minimal HR/basal HR=cNCR) was determined after low-dose atropine (3 microg/kg) administration in 124 postoperative CHD patients (97 biventricular repair and 27 Fontan patients) and 11 controls and was compared with the cardiac autonomic nervous and functional status.

RESULTS

The cNCR in simple CHD (post atrial or ventricular septal defect closure), complex biventricular CHD, and Fontan patients were 0.92+/-0.04, 0.94+/-0.04 and 0.96+/-0.04, respectively, and higher than in controls (0.87+/-0.03, p<0.001). In the complex CHD patients, higher cNCR was mainly associated with the lower pharmacologically determined cardiac parasympathetic nervous tone (PST), HR variability, high atrial natriuretic peptide, and lower right ventricular ejection fraction (p<0.0001). In Fontan patients, the lower beta sensitivity of the sinus node and the PST mainly determined the higher cNCR (p<0.01) and the cNCR did not correlate with either hemodynamics or exercise capacity.

CONCLUSIONS

NCR is attenuated in proportion to the impaired cardiac parasympathetic nervous system and hemodynamics in postoperative complex biventricular CHD patients. In addition to PST, beta sensitivity of the sinus node significantly influences the NCR in Fontan patients.

Decreased Heart Rate Recovery in Patients With Heart Failure Effect of Fluvastatin Therapy

Heart rate recovery is the difference in heart rate at peak exercise and at a specific time interval following the onset of recovery. Attenuated heart rate recovery is an independent predictor of mortality in patients with a history of coronary artery disease. The aim of the present study was to evaluate the effect of a statin on heart rate recovery, particularly in patients with ischemic heart failure and hyperlipidemia. Twenty-nine consecutive hyperlipidemic, stable coronary artery disease patients with heart failure and 19 healthy subjects were enrolled. Heart rate recovery values at the 1st and 3rd minutes and lipid profiles of the patients were evaluated at baseline and following 3 months of treatment with fluvastatin. Compared with healthy subjects, the heart rate recovery values were significantly lower in the heart failure patients in both the 1st and 3rd minutes, respectively (31 +/- 6 versus 19 +/- 7, P < 0.0001; 66 +/- 7 versus 47 +/- 8, P < 0.0001). Heart rate recovery in the 1st and 3rd minutes increased from 19 +/- 7 to 24 +/- 9 and 47 +/- 8 to 57 +/- 11, respectively, following treatment (P < 0.001, P < 0.001). There were no significant correlations among the changes in lipid parameters or HRR in the first and third minutes in the recovery period. The results revealed an improvement in heart rate recovery in heart failure patients by fluvastatin treatment. If this association can be confirmed by other studies, it would be interesting to perform further studies into the mechanism underlying this finding.

Decreased heart rate recovery after exercise in patients with congestive heart failure: Effect of β-blocker therapy

BACKGROUND

Decreased heart rate recovery (HRR) is a predictor of mortality in patients with coronary artery disease and preserved left ventricular function. We investigated the changes in HRR and assessed the impact of beta-blockade therapy on these parameters in patients with symptomatic congestive heart failure (CHF).

METHODS AND RESULTS

HRR, defined as the difference from peak exercise heart rate (HR) to HR measured at 1, 2, and 3 minutes after maximal exercise test, was studied in 23 stable CHF patients and 12 healthy subjects. Patients with CHF performed a maximal exercise test using a Ramp protocol before and after 6 months of therapy with either metoprolol or carvedilol. Patients with CHF exhibited a significantly attenuated HRR compared with healthy subjects at 1 minute (17.8 +/- 5.8 versus 26.8 +/- 16.2 beats), 2 minutes (34.0 +/- 10.6 versus 48.0 +/- 11.2 bpm) and 3 minutes (41.0 +/- 12.4 versus 60.0 +/-12.4 bpm) after exercise (P<.05 for all parameters). Beta-blocker therapy for 6 months did not significantly improve HRR.

CONCLUSION

HRR is markedly attenuated in stable CHF patients compared with healthy subjects. Long-term beta-blocker therapy appears to cause no significant improvement in HRR up to 3 minutes after maximal exercise.