Electrogram voltage and pacing threshold before ablation, measured by mini-electrodes, predict parameters indicative of transmural lesions in the human atrium.

PURPOSE: An important attenuation of the atrial signal recorded with mini-electrodes (ME) embedded in an 8-mm tip was associated with a transmural radiofrequency lesion. Our aim was to assess if parameters obtained from ME or conventional bipoles before applications predict successful atrial lesions. METHODS: We prospectively included 33 consecutive patients undergoing cavotricuspid isthmus (CTI) ablation. Electrogram voltages and pacing thresholds were measured with ME and conventional bipoles before and after radiofrequency (RF) applications. The time before the loss of capture during applications was recorded. Lesions were considered successful, in accordance with preclinical data, if ME voltage decreased > 54%. RESULTS: Of 207 applications, 107 could be analyzed. During applications, voltages decreased more in the ME than in the conventional bipoles (66.8 ± 26.1% vs 37.5 ± 42.5%, P = 0.001). Likewise, pacing threshold increased significantly more using the ME (86.3 ± 22.9% ME, 52.6 ± 35.6% conventional, P = 0.001). ME pre-ablation voltages were significantly higher and pacing thresholds significantly lower in successful lesions (voltage 0.88 ± 0.71 vs 0.26 ± 0.18 mV, P = 0.0001; threshold 1.6 ± 1.7 vs 2.8 ± 3.0, P = 0.04). Neither of these parameters with conventional bipoles nor time to loss of capture showed differences. A ME voltage > 0.33 mV and a pacing threshold < 1.5 mA predicted a successful lesion with 0.78 and 0.6 sensitivity and 0.78 and 0.59 specificity. CONCLUSIONS: Certain pre-ablation parameters derived from ME such as electrogram voltage and pacing threshold differ from those obtained by a conventional configuration and can predict a successful atrial lesion.

A genetic risk score predicts recurrent events after myocardial infarction in young adults.

INTRODUCTION AND OBJECTIVES: To evaluate whether a genetic risk score (GRS) improves prediction of recurrent events in young nondiabetic patients presenting with an acute myocardial infarction (AMI) and identifies a more aggressive form of atherosclerosis. METHODS: We conducted a prospective study with consecutive nondiabetic patients aged <55 years presenting with AMI. We performed a genetic test, cardiac computed tomography, and analyzed several biomarkers. We studied the association of a GRS composed of 11 genetic variants and a primary composite endpoint (cardiovascular mortality, a recurrent event, and cardiac hospitalization). RESULTS: A total of 81 patients were studied and followed up for a median of 4.1 years. There were 24 recurrent cardiovascular events. Compared with the general population, study participants had a higher prevalence of 9 out of 11 risk alleles. The GRS was significantly associated with recurrent cardiovascular events, especially when baseline low-density lipoprotein cholesterol (LDL-C) levels were elevated. Compared with the low-risk GRS tertile, the multivariate-adjusted HR for recurrences was 10.2 (95%CI, 1.1-100.3; P=.04) for the intermediate-risk group and was 20.7 (2.4-181.0; P=.006) for the high-risk group when LDL-C was≥2.8mmol/L (≥ 110mg/dL). Inclusion of the GRS improved the C-statistic (ΔC-statistic=0.086), cNRI (continuous net reclassification improvement) (30%), and the IDI (integrated discrimination improvement) index (0.05). Cardiac computed tomography frequently detected coronary calcified atherosclerosis but had limited value for prediction of recurrences. No association was observed between metalloproteinases, GRS and recurrences. CONCLUSIONS: A multilocus GRS may identify individuals at increased risk of long-term recurrences among young nondiabetic patients with AMI and improve clinical risk stratification models, particularly among patients with high baseline LDL-C levels.

Atrial mapping during pulmonary vein pacing to detect conduction gaps in a second pulmonary vein isolation procedure.

BACKGROUND: Finding the conduction gaps in redo PV isolation procedures is challenging, and several maneuvers have been described. In the present study, we analyze the pace and map (P&M) maneuver [atrial mapping during pulmonary vein (PV) pacing] to locate the gaps in redo PV isolation procedures. METHODS: Consecutive patients undergoing a second PV isolation procedure at a single institution over a 4-year period were included. For the last 2 years, all the patients (n = 38) studied underwent PV isolation based on the P&M maneuver and were compared to the previous patients (n = 45). The atrial side of the ablation line was mapped with the ablation catheter during PV pacing, and the earliest site was considered a gap site. RESULTS: Shorter radiofrequency time was required to obtain PV isolation in the P&M group (485 ± 374 vs. 864 ± 544 s; p < 0.001), which remained significant after adjusting for the number of reconnected PVs (p = 0.01). We did not find significant differences in the procedure duration (106 ± 46 vs. 112 ± 53 min; p = 0.57) and arrhythmia recurrence during 1-year follow-up (26.6 vs. 28.9%; p = 0.82) after adjusting for several confounding factors (HR 1.32; 95% CI 0.5-3.4; p = 0.57). CONCLUSIONS: P&M is a simple maneuver to identify the gaps in ablation lines around the PV. It remains efficacious in redo procedures despite the difficulties in localizing the ablation lines performed in the first procedure. The P&M maneuver reduced the radiofrequency time required to isolate the PV without compromising the efficacy.

Relationship between left atrium catheter contact force and pacing threshold.

PURPOSE: The purpose of this study is to analyze the relationship between contact force (CF) and pacing threshold in left atrium (LA). METHODS: Six to ten LA sites were studied in 28 consecutive patients with atrial fibrillation undergoing pulmonary vein isolation. Median CF, bipolar and unipolar electrogram voltage, impedance, and bipolar and unipolar thresholds for consistent constant capture and for consistent intermittent capture were measured at each site. RESULTS: Pacing threshold measurements were performed at 188 LA sites. Both unipolar and bipolar pacing thresholds correlated significantly with median CF; however, unipolar pacing threshold correlated better (unipolar: Pearson R -0.45; p < 0.001; Spearman Rho -0.62; p < 0.001, bipolar: Pearson R -0.39; p < 0.001; Spearman Rho -0.52; p < 0.001). Consistent constant capture threshold had better correlation with median CF than consistent intermittent capture threshold for both unipolar and bipolar pacing (Pearson R -0.45; p < 0.001 and Spearman Rho -0.62; p < 0.001 vs. Pearson R -0.35; p < 0.001; Spearman Rho -0.52; p < 0.001). The best pacing threshold cutoff point to detect a good CF (>10 g) was 3.25 mA for unipolar pacing with 69% specificity and 73% sensitivity. Both increased to 80% specificity and 74% sensitivity for sites with normal bipolar voltage and a pacing threshold cutoff value of 2.85 mA. CONCLUSIONS: Pacing thresholds correlate with CF in human not previously ablated LA. Since the combination of a normal bipolar voltage and a unipolar pacing threshold <2.85 mA provide reasonable parameters of validity, pacing threshold could be of interest as a surrogate for CF in LA.

Risk factors for stillbirths in Tete, Mozambique.

OBJECTIVE: To evaluate known risk factors for stillbirth and identify local priorities for stillbirth prevention among institutional deliveries in Tete, Mozambique. METHODS: A case-control study was conducted among 150 women who experienced stillbirths and 300 women who experienced live deliveries at three health facilities between December 1, 2009, and April 30, 2011. Case and control individuals were matched for health facility, age, and parity. Sociodemographic, pregnancy, and delivery characteristics (including HIV and syphilis serology) were assessed. Bivariate associations and a conditional logistic regression model identified variables contributing to fetal outcome. RESULTS: No between-group differences were recorded in the frequency of infection with HIV (25 [16.7%] cases vs 55 [18.3%] controls; P=0.663) or syphilis (6 [4.0%] vs 16 [5.3%]; P=0.536) at delivery. Multivariate analysis revealed that stillbirth was associated with direct obstetric complications (mutually adjusted odds ratio [OR] 6.7; 95% confidence interval [CI] 3.6-12.1), low socioeconomic status (mutually adjusted OR 1.8; 95% CI 1.1-3.1), and referral during childbirth (mutually adjusted OR 3.2; 95% CI 1.7-6.1). CONCLUSION: Stillbirths in Tete, Mozambique, were predominantly caused by direct obstetric complications requiring referral among women of low socioeconomic status. Prenatal management of HIV and syphilis limited effects on fetal outcome. Emergency obstetric care and referral systems should be the focus of interventions aimed at stillbirth prevention.

Cardiac imaging in prosthetic paravalvular leaks.

Prosthetic paravalvular leaks (PVL) is an uncommon but serious complication after surgical valve replacement. Although surgery has been the traditional treatment of choice in hemodynamically significant PVL, percutaneous transcatheter closure is emerging as a novel and less invasive option for patients with high operative risk. Cardiac imaging, especially two- and three-dimensional transoesophageal echocardiography, plays an essential role in the diagnosis, guidance of intervention and subsequently in the evaluation of the outcomes of the procedure. The aim of this manuscript is to review the role of cardiac imaging techniques in the interventional management of patients with symptomatic PVL.

Reproductive health services for populations at high risk of HIV: Performance of a night clinic in Tete province, Mozambique.

BACKGROUND: Different models exist to provide HIV/STI services for most-at-risk populations (MARP). Along the Tete traffic corridor in Mozambique, linking Malawi and Zimbabwe, a night clinic opening between 4 and 10 PM was established targeting female sex workers (FSW) and long-distance truck drivers (LDD). The clinic offers free individual education and counselling, condoms, STI care, HIV testing, contraceptive services and outreach peer education. To evaluate this clinic model, we assessed relevance, service utilisation, efficiency and sustainability. METHODS: In 2007-2009, mapping and enumeration of FSW and LDD was conducted; 28 key informants were interviewed; 6 focus group discussions (FGD) were held with FSW from Mozambique and Zimbabwe, and LDD from Mozambique and Malawi. Clinic outputs and costs were analysed. RESULTS: An estimated 4,415 FSW work in the area, or 9% of women aged 15-49, and on average 66 trucks stay overnight near the clinic. Currently on average, 475 clients/month visit the clinic (43% for contraception, 24% for counselling and testing and 23% for STI care). The average clinic running cost is US$ 1408/month, mostly for human resources. All informants endorsed this clinic concept and the need to expand the services. FGD participants reported high satisfaction with the services and mentioned good reception by the health staff, short waiting times, proximity and free services as most important. Participants were in favour of expanding the range of services, the geographical coverage and the opening times. CONCLUSIONS: Size of the target population, satisfaction of clients and endorsement by health policy makers justify maintaining a separate clinic for MARP. Cost-effectiveness may be enhanced by broadening the range of SRHR-HIV/AIDS services, adapting opening times, expanding geographical coverage and targeting additional MARP. Long-term sustainability remains challenging and requires private-public partnerships or continued project-based funding.

Frequency of chromosomal aberrations in peripheral lymphocytes of tannery workers in Brazil.

To evaluate the incidence of chromosomal aberrations (CA) in peripheral lymphocytes of workers chronically exposed to chemical hazards in a tannery in Franca, São Paulo, Brazil. The exposed group consisted of 10 male workers employed in the same tannery. The duration of work in the tannery ranged from 5 months to 14 years. The control group consisted of 10 males without a history of exposure to chemicals or other potentially genotoxic substances. A total of 100 well-spread metaphases were analyzed per subject. The frequency of CA was higher in the exposed group than in the control group. Smoking had a significant effect on the frequency of CA in both the control and the exposed groups. Chronic occupational exposure of tannery workers represents a relevant risk factor for the development of diseases associated with genetic damage.