Prognostic value of heart rate reserve in patients with suspected coronary artery disease undergoing stress myocardial perfusion imaging

Funding Acknowledgements

Type of funding sources: None.

Background. The prognostic value of stress myocardial perfusion single-photon emission computed tomography (MPS) has been widely demonstrated. Also, chronotropic incompetence, evaluated by heart rate reserve (HRR) is associated with increased risk of adverse events. Yet, the incremental prognostic value of HRR over stress MPS data has not been fully investigated.

Purpose. To assess the incremental prognostic value of HRR over stress MPS finding in patients with suspected coronary artery disease (CAD) undergoing exercise stress MPS.

Methods. The study population consisted of 866 consecutive patients with suspected CAD undergoing exercise stress-MPS at University of Naples Federico II, between May 2002 and January 2014 as part of their diagnostic program. The primary study endpoint was all-cause mortality. All patients were followed for at least 60 months. HRR was calculated as the difference between peak exercise and resting HR, divided by the difference of age-predicted maximal and resting HR and expressed as percent. The summed difference score (SDS) was considered an index of ischemic burden. Patients were considered to have mild ischemia with a SDS of 2 to 6, and moderate-severe ischemia with a SDS ≥6. During follow-up, the occurrence of all-cause of deaths was noted and considered as event. Follow-up was censored at 84 months.

Results. During follow-up, 61 deaths occurred, with a 7% cumulative event rate. Patients experiencing death were older (56.2 ± 10.7 years vs. 66.4 ± 8.6 years), with a higher prevalence of male gender (56% vs. 87 %, P < 0.05) and diabetes mellitus (23% vs. 36%, P < 0.05). At stress-MPS, patients with event had lower mean values of HRR (53.2 ± 21.3% vs. 61.5 ± 16.4%, P < 0.0001) and higher prevalence of moderate-severe ischemia (24% vs. 8%, P < 0.0001). The best trade-off between sensitivity and specificity for identifying chronotropic incompetence was a HRR <67% with an area under the receiver operating characteristic curve of 0.62. The event free survival was lower in patients with HRR <67% compared to those with HRR ≥67% (log-rank 9.75, P < 0.005). Accordingly, the annualized event rate was 0.006 in patients with HRR <67% and 0.014 in those with HRR ≥67% (P < 0.001). At Cox regression analysis, univariable predictors of all-cause mortality were age, male gender, diabetes mellitus, HRR and moderate-severe ischemia (all P < 0.05). At multivariable analysis age, male gender, HRR and moderate-severe ischemia were independent predictors of all-cause mortality (all P < 0.05). HRR improved the prognostic power of a model including clinical data and MPS findings for the prediction of all-cause mortality, increasing the global chi-square from 76.16 to 82.68 (P < 0.005).

Conclusion. Chronotropic incompetence assessed by HRR evaluation, has independent and incremental prognostic value in predicting all cause of death in patients with suspected CAD undergoing exercise stress-MPS.

Prognostic value of pericoronary adipose tissue and coronary vascular function by cardiac 82Rb PET/CT imaging in patients with suspected coronary artery disease and normal myocardial perfusion imaging

Funding Acknowledgements

Type of funding sources: None.

Introduction

Pericoronary adipose tissue, due to its proximity to coronary arteries, has been proposed contribute to the progression of coronary atherosclerosis.

Purpose

The aim of this study was to evaluate the prognostic value of pericoronary fat thickness (PCFT), coronary artery calcium (CAC) score and myocardial perfusion reserve (MPR) by hybrid 82Rubidium (82Rb) PET/CT imaging in patients with suspected coronary artery disease (CAD) and normal myocardial perfusion imaging (MPI).

Methods

A total of 640 patients without overt CAD and with normal rest-stress 82Rb PET/CT MPI were studied. PCFT was calculated on CT images as the maximum fat thickness (mm) between heart surface and visceral epicardium surrounding the main coronary arteries. CAC score was categorized as 0, <400 or ≥400. MPR was considered reduced when <2. Endpoints events were cardiac death, nonfatal myocardial infarction and coronary revascularization.

Results

During a follow-up of 42 ± 13 months, 29 events occurred (cumulative event rate 5%). Patients with events were older (66 ± 13 vs. 60 ± 13 years, p < 0.01), had higher PCFT (13 ± 2 vs 11 ± 2 mm, p < 0.001), higher prevalence of CAC score ≥400 (48% vs. 21%, p < 0.01), and lower MPR (2.1 ± 0.7 vs. 2.7 ± 0.7, p < 0.001) compared to those without. A higher prevalence of MPR <2 was observed in patients with events (48% vs. 18, p < 0.001) compared to those without. Patients with reduced MPR had higher PCFT compared to those with normal MPR (12 ± 2 vs. 11 ± 1 mm, p < 0.01). A PCFT value of 11.2 mm was the best trade-off between sensitivity and specificity to detect a reduced MPR. Event rate was higher in patients above this threshold compared to those below (8% vs. 1.5%, p < 0.001). At Cox univariate analysis, age (p < 0.05), PCFT >11.2 mm (p < 0.001), CAC score ≥400 (p < 0.01), and MPR <2 (p < 0.001) were predictors of events. At multivariate analysis, only PCFT >11.2 mm and MPR <2 were independent predictors of events (both p < 0.01). At incremental analysis, adding PCFT >11.2 to a model including clinical data and MPR <2 increased the global chi-square from 26 to 35 (p < 0.01). Classification tree analysis produced 3 terminal groups. For patients with MPR <2, no further split was needed (event rate 12% vs. 3%, p < 0.001). On the contrary, patients with MPR ≥2 were further stratified by PCFT (event rate 7% in patients with and 0.3% in those without (p < 0.001) PCFT >11.2.

Conclusions

In patients with suspected CAD and normal stress MPI, coronary vascular dysfunction and high PCFT are associated with increased cardiac risk. PCFT could help in identifying patients at higher risk of events. Combined evaluation of anatomical and functional vascular abnormalities by 82Rb PET/CT might allow a better risk stratification.

Vitamin E supplementation improves neutropenia and reduces the frequency of infections in patients with glycogen storage disease type 1b

BACKGROUND

Neutropenia and/or neutrophil dysfunction are part of glycogen storage disease type 1b (GSD1b) phenotype. Recent studies indicated that activation of apoptosis and increased reactive oxygen species are implicated in the pathogenesis of neutropenia in GSD1b.

METHODS

We studied seven GSD1b patients over a 2-year-period to evaluate the efficacy of vitamin E, a known antioxidant, in preventing or improving the clinical manifestations associated with neutropenia and neutrophil dysfunction. Frequency and severity of infections, neutrophil counts and function, ileocolonoscopy and intestinal histology, were monitored. During the first year, patients did not assume vitamin E; during the second year of the study, vitamin E supplementation was added to their therapeutic regimens.

RESULTS

During vitamin E supplementation, the mean values of neutrophil counts were significantly higher (p < 0.05) and neutrophil counts lower than 500/mm(3) were found less frequently (p < 0.05); the frequency and severity of infections, mouth ulcers and perianal lesions, was reduced (p < 0.05); ileocolonoscopy and histology showed a mild improvement. Vitamin E supplementation did not result in changes in neutrophil function.

CONCLUSIONS

These results suggest that vitamin E supplementation might be beneficial in GSD1b patients and may alleviate disease manifestations associated with neutropenia.