Classes of vitamin D status and functional outcome after hip fracture: a prospective, short-term study of 1350 inpatients.

BACKGROUND: Vitamin D depletion is associated with unfavourable outcomes after hip fracture. However, the classes of vitamin D status currently in use, which are defined according to serum calcifediol levels, have not been validated for their predictive capability of the functional recovery. AIM: To investigate the association between serum calcifediol categorized into 4 classes and the functional recovery after hip fracture. DESIGN: Prospective, short-term observational study. SETTING: Rehabilitation hospital in Italy. POPULATION: We evaluated 1350 of 1412 inpatients with hip fracture. METHODS: Serum calcifediol was measured by an immunoenzymatic assay 14.7±4.4 (mean±SD) days after surgery and categorized into 4 classes: I class <12 ng/mL; II class 12-20 ng/mL; III class 21-29 ng/mL; IV class ≥30ng/mL. The functional outcome was assessed by using the Barthel Index. RESULTS: We found a significant difference in Barthel index scores at the end of inpatient rehabilitation across the 4 classes of vitamin D status: χ2 (3, N.=1350) 27.2; P<0.001. The difference persisted after adjustment for 8 covariates (P=0.004). By comparing pairs of classes, we found that Barthel index scores were lower in the 829 patients of the I class than in the 275 of the II (P=0.005) who had in turn Barthel index scores lower than the 132 patients of the III class (P=0.038). Conversely, no significant differences emerged between the patients of the III class and the 114 patients of the IV class (P=0.421). The results did not materially change when Barthel Index effectiveness was substituted for Barthel Index scores as the outcome measure. CONCLUSIONS: Calcifediol levels below 12ng/mL were associated with a worse recovery than those between 12 and 20ng/mL that were in turn associated with a worse recovery than those between 21 and 29 ng/mL. Conversely, no significant differences were found between the patients with calcifediol between 21 and 29ng/mL and those with calcifediol ≥30 ng/mL. CLINICAL REHABILITATION IMPACT: Despite caution due to the observational design, our study suggests that vitamin D depletion should be treated after hip fracture to optimize the functional outcome, with a target level for serum calcifediol of 21-29ng/mL and no further advantages associated with calcifediol levels of 30ng/mL or higher.

Age and QT variability index during free breathing, controlled breathing and tilt in patients with chronic heart failure and healthy control subjects.

UNLABELLED: The QT variability index (QTVI) indicates temporal dispersion in myocardial repolarization, and a high QTVI is associated with a propensity for sudden death from malignant ventricular arrhythmias in subjects at high risk. In this study, the authors assessed the effects of free breathing, controlled breathing, and sympathetic stress (tilt) on the QTVI in patients with chronic heart failure (CHF) and healthy control subjects. The authors also examined the influence of age on the same variables. To obtain normative data, they calculated 95% confidence intervals for healthy subjects grouped according to age. Under all experimental conditions, the QTVI was larger in the CHF group overall and in the age subsets than in controls. In patients and controls, the QTVI increased significantly during tilt, although no differences were found between the QTVI measured during free and controlled breathing. In healthy controls, the following variables correlated significantly with the QTVI: age and baseline heart rate (P < 0.001). In patients with CHF, aging had no influence on the QTVI. CONCLUSION: Age, sympathetic stress, and CHF all tend to increase the QTVI and could potentially induce sudden death. Further studies should assess the usefulness of the QTVI as a marker predicting sudden cardiac death under the various conditions of risk.

Influence of cardiac-resynchronization therapy on heart rate and blood pressure variability: 1-year follow-up.

BACKGROUND: Several studies have shown that cardiac-resynchronization therapy (CRT) improves haemodynamic function, cardiac symptoms, and heart rate variability (HRV) and reduces the risk of mortality and sudden death in subjects with chronic heart failure (CHF). In subjects with CHF, power spectral values for the low-frequency (LF) component of RR variability < or =13 ms2, are associated with an increased risk of sudden death. AIMS AND METHODS: To assess whether spectral indexes obtained by power spectral analysis of HRV and systolic blood pressure (SBP) variability could predict malignant ventricular arrhythmias in patients with severe CHF treated with an implantable cardioverter-defibrillator (ICD) alone or with ICD+CRT. In addition, changes in non-invasive spectral indices using short-term power spectral analysis of HRV and SBP variability during controlled breathing in 15 patients with CHF treated with an ICD alone and 16 patients receiving ICD+CRT, were assessed pre-treatment and at 1 year. RESULTS: Arrhythmias necessitating an appropriate ICD shock were more frequent in subjects who had low LF power. CRT improved all spectral components, including LF power. CONCLUSIONS: Low LF power values predict an increased risk of malignant ventricular arrhythmias; after 1 year of CRT most non-spectral and spectral data, including LF power, improved. Whether these improvements lead to better long-term survival in patients with CHF remains unclear.

Power spectral analysis of heart rate variability as a predictive test in choosing the most effective length for tilt-training.

BACKGROUND: In patients with refractory neurally mediated syncope, tilt training--standing motionless against a wall for increased periods of time per day over one month--can often eliminate recurrent episodes and reduce presyncopal symptoms. We designed dual retrospective and prospective studies to assess cardiovascular autonomic function in subjects with recurrent syncope and identify the most effective length of tilt training between one and three months. METHODS AND RESULTS: In the retrospective study, before tilt training, and in the prospective study, before and after training, all subjects underwent a recording for short-term spectral analysis of heart rate and systolic blood pressure variability. Before tilt-training, autonomic nervous system function differs in patients with recurrent neurally mediated syncope who respond to tilt training for one month and those who do not. "Responders", patients experiencing no episodes of syncope during the 12-month follow-up, had higher low-frequency power of RR (LF(RR)) (p < 0.05) and LF(RR) in normalized units (NU) (p < 0.001) and lower high-frequency power (HF(RR)) (p < 0.05) and HF(RR)NU (p < 0.001) than "non-responders", patients reporting at least one syncopal episode during the 12-month follow-up. In the retrospective study, no difference was found between spectral data for "non-responders" with positive responses to tilt test with and without nitro derivatives. Prolonging tilt-training to three months increased the number of responders (late-responders) by 80% (p < 0.001) and power spectral analysis of heart rate variability (HRV) before tilt training can identify late-responders by their low LF(RR)NUs (<40) and high HF(RR)Nus (>60). Furthermore in late-responders, tilt training brings about a change in cardiovascular autonomic function: at 3 months, LF(RR)NUs increase and HF(RR)NU diminish. CONCLUSION: Power spectral analysis of HRV seems to be a useful tool to preselect patients who are most likely to benefit from prolonged therapy, thus increasing compliance.

Heart rate and blood pressure variability in subjects with vasovagal syncope.

Autonomic nervous system control in subjects with vasovagal syncope is controversial. In the present study, we used short-term spectral analysis to evaluate autonomic control in subjects with recurrent vasovagal syncope. We assessed the ability of spectral indices of HR (heart rate) variability to predict tilt-test responses. A series of 47 outpatients with recurrent vasovagal syncope and with positive responses to head-up tilt testing underwent a further study of RR variability during controlled breathing at rest and during tilt testing. During controlled breathing, RR interval variability of total power (TP(RR); P<0.001), low-frequency power (LF(RR); P<0.05), high-frequency power (HF(RR); P<0.001) and HF expressed in normalized units (HFnu(RR); P<0.001) were all higher, and LF expressed in normalized units (LFnu(RR)) and LF/HF ratio were lower in subjects with vasovagal syncope than in controls (P<0.001). To assess the ability of spectral components of RR variability to predict tilt-test responses, we prospectively studied 109 subjects with recurrent vasovagal syncope. The two normalized measures, HFnu(RR) and LFnu(RR), determined during controlled breathing alone predicted a positive tilt-test response (sensitivity, 76%; specificity, 99%; positive predictive value, 96%; and negative predictive value, 90%). During tilting, subjects with vasovagal syncope had lower SBP (systolic blood pressure; P<0.05), LF component of peak SBP variability (LF(SBP)) and LFnu(RR) than controls, and higher TP(RR), HF(RR), HFnu(RR) and alpha HF (P<0.001). These spectral data indicate that vagal sinus modulation is increased at rest in subjects with vasovagal syncope. Spectral analysis of RR variability during controlled breathing, a procedure that predicts tilt-test responses, could be a useful guide in choosing the method of tilt testing.