Subcutaneous Electrical Nerve Stimulation:A Feasible and New Method for the Treatment of Patients With Refractory Angina

Introduction: Patients suffering from chronic angina pectoris, insufficiently controllable with medication and revascularization, are an increasing medical and psychosocial problem. Although spinal cord stimulation (SCS) is proven to employ, safe, long-term anti-angina, and anti-ischemic effects for these patients, the use of SCS in this group remains limited. The reason for this restricted use is largely unknown. However, among other reasons, it may be related to the difficulties in positioning an electrode in the epidural space. We studied the feasibility and efficacy of subcutaneous implantation of an entire system. Methods: Seven male patients, mean age 67 +/- 3.6 years, received complete subcutaneously implanted electrical nerve stimulation (SENS) systems, with one or more leads fixed in parallel with the sternum, covering the angina area. At baseline and 2 months follow-up patients performed exercise and quality of life tests (Seattle Angina Questionnaire and diaries number angina attacks and glyceryl trinitrate use). Results: All patients showed clinical relevant improvement (baseline vs. follow-up), in exercise (63%) and quality of life (Seattle Angina Questionnaire 59%). The number of angina attacks dropped 82% and the number of glyceryl trinitrate use decreased by 90%. No major adverse events were observed. Conclusion: This small feasibility study demonstrates SENS to be an effective and safe method to treat patients suffering from refractory angina. Furthermore, SENS is less invasive and appears to have less lead migrations compared with SCS

CT coronary angiography is feasible for the assessment of coronary artery disease in chronic dialysis patients, despite high average calcium scores.

PURPOSE: Significant obstructive coronary artery disease (CAD) is common in asymptomatic dialysis patients. Identifying these high risk patients is warranted and may improve the prognosis of this vulnerable patient group. Routine catheterization of incident dialysis patients has been proposed, but is considered too invasive. CT-angiography may therefore be more appropriate. However, extensive coronary calcification, often present in this patient group, might hamper adequate lumen evaluation. The objective of this study was to assess the feasibility of CT-angiography in this patient group. METHODS: For this analysis all patients currently participating in the ICD2 trial (ISRCTN20479861), with no history of PCI or CABG were included. The major epicardial vessels were evaluated on a segment basis (segment 1-3, 5-8, 11 and 13) by a team consisting of an interventional and an imaging specialist. Segments were scored as not significant, significant and not interpretable. RESULTS: A total of 70 dialysis patients, with a mean age of 66±8 yrs and predominantly male (70%) were included. The median calcium score was 623 [79, 1619]. Over 90% of the analyzed segments were considered interpretable. The incidence of significant CAD on CT was 43% and was associated with cardiovascular events during follow-up. The incidence of cardiovascular events after 2-years follow-up: 36% vs. 0% in patients with no significant CAD (p<0.01). CONCLUSION: Despite the high calcium scores CT-angiography is feasible for the evaluation of the extent of CAD in dialysis patients. Moreover the presence of significant CAD on CT was associated with events during follow-up

Serum Cardiac Troponin-I is Superior to Troponin-T as a Marker for Left Ventricular Dysfunction in Clinically Stable Patients with End-Stage Renal Disease

<div><p>Background</p><p>Serum troponin assays, widely used to detect acute cardiac ischemia, might be useful biomarkers to detect chronic cardiovascular disease (CVD). Cardiac-specific troponin-I (cTnI) and troponin-T (cTnT) generally detect myocardial necrosis equally well. In dialysis patients however, serum cTnT levels are often elevated, unlike cTnI levels. The present study aims to elucidate the associations of cTnI and cTnT with CVD in clinically stable dialysis patients.</p><p>Methods</p><p>Troponin levels were measured using 5^th generation hs-cTnT assays (Roche) and STAT hs-cTnI assays (Abbott) in a cohort of dialysis patients. Serum troponin levels were divided into tertiles with the lowest tertile as a reference value. Serum troponins were associated with indicators of CVD such as left ventricular mass index (LVMI), left ventricular ejection fraction (LVEF) and the presence of coronary artery disease (CAD). Associations were explored using regression analysis.</p><p>Results</p><p>We included 154 consecutive patients, 68±7 years old, 77% male, 70% hemodialysis. Median serum cTnT was 51ng/L (exceeding the 99^th percentile of the healthy population in 98%) and median serum cTnI was 13ng/L (elevated in 20%). A high cTnI (T3) was significantly associated with a higher LVMI (Beta 31.60; p=0.001) and LVEF (Beta -4.78; p=0.005) after adjusting for confounders whereas a high serum cTnT was not. CAD was significantly associated with a high cTnT (OR 4.70 p=0.02) but not with a high cTnI. Unlike cTnI, cTnT was associated with residual renal function (Beta:-0.09; p=0.006).</p><p>Conclusion</p><p>In the present cohort, serum cTnI levels showed a stronger association with LVMI and LVEF than cTnT. However, cTnT was significantly associated with CAD and residual renal function, unlike cTnI. Therefore, cTnI seems to be superior to cTnT as a marker of left ventricular dysfunction in asymptomatic dialysis patients, while cTnT might be better suited to detect CAD in these patients.</p></div

Baseline Characteristics.

<p>Baseline Characteristics.</p

Logistic regression for the association between tertiles of serum cardiac troponins and the presence of CAD.

<p>Logistic regression for the association between tertiles of serum cardiac troponins and the presence of CAD.</p

Unadjusted markers for cardiovascular disease divided per tertile of cTnI and cTnT.

<p>Box and Whisker plot of serum cTnI and cTnT concentrations divided into tertiles (T1, T2, T3) indicating the median, interquartile range, 2.5^th and 97.5^th percentile for unadjusted LVMI (A) and LVEF (B). The percentage of patients with significant CAD divided per tertile of serum cTnI and cTnT are shown in graph C. Serum cTnI is shown in shades of blue and serum cTnT is shown in shades of green. LVMI: Left Ventricular Mass Index; LVEF: Left Ventricular Ejection Fraction; CAD: Coronary Artery Disease.</p

Linear regression for the association between tertiles of serum cardiac troponins, LVMI and LVEF.

<p>Linear regression for the association between tertiles of serum cardiac troponins, LVMI and LVEF.</p

Univariate association of serum troponins with baseline characteristics using linear regression.

<p>Univariate association of serum troponins with baseline characteristics using linear regression.</p

Distribution of serum cTnI and serum cTnT.

<p>(A) Box Whisker plot of serum cTnI and cTnT concentrations indicating the median, interquartile range, 2.5^th and 97.5^th percentile. The dotted lines represent the 99^th percentile cut-off for a positive test. (B) Box and Whisker plot of serum cTnI and cTnT expressed as multiples of the 99^th percentile. ***; p<0.001.</p