Microbiologic characteristics and in vitro susceptibility to antimicrobials in a large population of patients with cardiovascular implantable electronic device infection.

INTRODUCTION: The incidence of cardiovascular implantable electronic device (CIED) infection is steadily increasing. However, no consensus has been reached with respect to the type and duration of antimicrobial therapy in this specific population of patients. The role played by new anti-Staphylococcus agents has not been defined. The aims of this study were to describe the microbiological characteristics of a large population of patients with CIED infections and to test the in vitro susceptibility of the various strains to different antimicrobials. METHODS: Two hundred eighty-six patients with CIED infection were included. The minimal inhibitory concentrations of 9 antimicrobials, including linezolid, tigecycline, and daptomycin were measured against all strains of staphylococci isolated. RESULTS: Microbiologic confirmation was obtained in 252 (88%) patients, the vast majority were from Staphylococcus species (86%), 90% of these were coagulase negative strains and 10% were Staphylococcus aureus; 30.5% were methicillin-resistant. All strains were susceptible to vancomycin, nearly 15% of coagulase negative strains were nonsusceptible to teicoplanin, and nearly 100% of the strains were susceptible to the 3 new antimicrobials. CONCLUSIONS: In this large contemporary study, we show that Staphylococcus is by far the most common cause of CIED infections, with the majority due to coagulase negative strains. Methicillin-resistance is common in this population. Currently, we would recommend vancomycin as first-line empirical therapy. However, given that not all patients tolerate vancomycin, we believe that newer antimicrobial therapies should now be tested in clinical trials to establish their clinical effectiveness in treating patients with device infections.

Long-term outcomes after pocket or scar revision and reimplantation of pacemakers with preerosion.

INTRODUCTION: Cardiac pacemakers with preerosion are often reimplanted. Preerosion may be caused by an evolving local infectious process affecting the entire pacing system or by mechanical migration of the device causing ischemic necrosis of the skin tissues. We examined the long-term outcome of 33 patients who underwent pocket or scar revision and submuscular reimplantation of cardiac pacemakers in our institution. METHODS: Before undergoing pocket or scar revision and reimplantation, all patients (1) had negative serial blood cultures, (2) had no vegetation on transesophageal echocardiography, (3) had a normal blood C-reactive protein concentrations, (4) were afebrile, (5) had no cutaneous breakthrough, and (6) presented with preerosion of the pulse generator or granulomatous-like scar abnormality. RESULTS: THE mean follow-up was 37 ± 12 months. Among 16 patients presenting with preerosion associated with signs of local cutaneous inflammation, 62.5% developed an infection of the pacing system requiring later explantation. Of eight patients presenting initially with migration of the pulse generator and mechanical protrusion, none required subsequent explantation of the system. Among nine patients presenting initially with granulomatous-like scar abnormalities, 55.6% underwent explantation of the pacing system during follow-up for management of documented local infection. CONCLUSIONS: The reimplantation of pulse generators with preerosion in the presence of local inflammatory manifestations or granulomatous-like changes of the scar is complicated by documented cardiac pacemaker infection in >50% of cases. In these patients, the explantation of the pacing system is recommended before the development of prognostically much more serious spread of infection to the leads and cardiac tissues.

Determination of central blood pressure by a noninvasive method (brachial blood pressure and QKD interval): a noninvasive validation.

OBJECTIVE: We validated against invasive measurements a measure of central SBP based on the QKD interval. The present objective is a comparison to the SphygmoCor device. MATERIALS AND METHODS: A first cohort was used to redefine an algorithm for estimating ascending aorta SBP (cSBP) with respect to SphygmoCor. This algorithm was then tested in a second cohort under static conditions and in a third cohort during a head-up tilt to study blood pressure variations. RESULTS: The first cohort (36 patients, mean age: 46 ± 20 years, SBP: 114 ± 19 mm Hg) defined the estimation algorithm as cSBP =62.687+1.35 × meanBP-0.207 × heart rate-0.251 × height-0.1 × QKD (mean difference with SphygmoCor=0 ± 7 mmHg).In the second cohort (105 patients, mean age: 51 ± 19 years, SBP: 132 ± 22 mmHg), the average difference between the two techniques was 2 ± 6 mm Hg (R=0.93). The dynamic cohort included 31 patients (mean age: 49 ± 23 years, SBP: 110 ± 19 mmHg) with 224 pairs of measurement. We studied the changes in central blood pressures compared with the basal state of each of the two techniques during head-up tilt. With QKD, the average cSBP was 104 ± 19 mmHg, the average variation was -13.00 mmHg ± 15 (range 7-74 mmHg). With SphygmoCor, average cSBP was 10  mmHg ± 18, the average variation was -14 mmHg   ± 16 (range 2-81 mmHg). The variations in blood pressure with the two techniques were well correlated (R=0.93). CONCLUSION: cSBP estimation based on the QKD interval is comparable in precision to the SphygmoCor. Its ability to measure cSBP variations suggests that it could be employed for ambulatory measurements over 24 h.

Prognostic value of the extent of left ventricular hypertrophy and its evolution in the hypertensive patient.

OBJECTIVE: Left ventricular hypertrophy (LVH) is a marker of cardiovascular risk. However, the progression of the risk as a function of the course of the LVH has only been the subject of few studies. METHODS: We report the consequences of the evolution of the left ventricular mass (LVM) in a cohort of hypertensive patients whose LVM was measured before any antihypertensive treatment. RESULTS: We followed up for an average of 12 years, 763 hypertensives with LVM measurement by echocardiography on inclusion. In this population, 117 cardiovascular complications occurred and the initial LVM appeared to be the most powerful marker of risk. A cutoff of 51 g/m(2.7) for the LVM index (LVMI) offered the best compromise of sensitivity and specificity in the prediction of complications. A second determination of LVM was carried out in 436 patients on average 5 years after inclusion. In this sub-group, 82 complications were recorded after an average interval of 13 years. The 51 g/m(2.7) value of LVMI over the follow-up offered the same sensitivity (74%) and specificity (52%) in the prediction of complications. The progression of the LVM was related to the occurrence of complications independently of the basal value and other risk factors. CONCLUSIONS: We confirm LVMI as a powerful risk factor in hypertension with a cutoff of 51 g/m(2.7), which offers the same sensitivity and specificity whether the LVM was determined before or during treatment. The progression of LVM, on average 5 years after the initial measurement had a prognostic value independent of the initial determination.

ECG detection of left ventricular hypertrophy: the simpler, the better?

OBJECTIVE: ECG is commonly employed to identify left ventricular hypertrophy (LVH) and a high risk of cardiovascular events (CVE) in hypertensive patients. However, the multiplicity of the existing criteria does not simplify interpretation of the data. We compared a number of common criteria in hypertensive patients by taking as references left ventricular mass (LVM) measured by echocardiography and prediction of incident CVE. METHODS: The population was a cohort of 958 hypertensive patients (mean age 48 years) recruited before any treatment and having benefited from an ECG and an echocardiography. We evaluated their outcomes at regular intervals. We examined the relationships between several ECG criteria of LVH and LVM as well the occurrence of CVE. RESULTS: Among the various parameters tested (Sokoloff, Cornell, Cornell product) the simple measurement of the RaVL wave offered the best correlations to LVM and the best prediction of the existence of an echocardiographic LVH (receiver-operating characteristic curves). Its alterations were best correlated with the changes in LVM during the follow-up period. Moreover, this simple measurement offered the best performance for the prediction of the occurrence of CVE (123 events after a mean lapse of 12 years). CONCLUSION: In the interpretation of an ECG in the hypertensive patient, the single measurement of the R wave in aVL gives results at least as good as those of more complicated indices, which do not appear to contribute further to the diagnosis of LVH and the prediction of cardiovascular risk.