Estimation of the QTc interval in the presence of right bundle branch block: A comparative study using validated formulae for left bundle branch block

BACKGROUND

Adequate measurement of the QT interval is of clinical importance in order to identify patients at higher risk for ventricular arrhythmias. Previous studies have described different methods to estimate baseline QT in patients with left bundle branch block (LBBB). However, the evidence regarding the assessment of the QT in patients with right bundle branch block (RBBB) is scarce.

AIM

To analyze the feasibility and reliability of the different formulae described for LBBB in the estimation of the baseline QT in the presence of RBBB.

METHODS

We performed an observational study including patients who underwent electrophysiology study and/or ablation. Two types of RBBB were considered: 1) pacing-induced and 2) transient true RBBB. QRS, JT and QT intervals were measured during baseline and RBBB. Estimated QTc was calculated using LBBB formulae: Bogossian, Rautaharju, Tabatabaei, Tang-Rabkin, Yankelson, Wang. Linear correlation and intraclass correlation coefficients (ICC) were used to assess the reliability of these formulae for the estimation of baseline QTc.

RESULTS

We finally included a total of 100 patients. Correlations between baseline and estimated QTc were strong (R > 0.7) for all the formulae except for Tabatabaei. Yankelson and Wang showed the highest reliability (ICC = 0.775 and 0.727, respectively). Yankelson appeared to be the most accurate formula, with a mean estimated QTc closest to baseline values.

CONCLUSION

Previously described formulae for LBBB exhibited marked differences regarding reliability in the estimation of the QTc interval in the presence of RBBB. According to our results, Yankelson showed the most consistent and accurate agreement in this setting.

Non-HACEK gram negative bacilli endocarditis: Analysis of a national prospective cohort

BACKGROUND

Infective endocarditis (IE) due to non-HACEK bacilli (Haemophilus species, Actinobacillus, Cardiobacterium, Eikenella, or Kingella) is uncommon and poorly described. The objectives of this study were to describe non-HACEK Gram-Negative Bacilli (GNB) IE cases and compare characteristic of IE produced by Enterobacterales and non-fermenting (NF) GNB.

METHODS

From January 2008 to December 2018, 3910 consecutive patients with definitive IE diagnosis, defined with Modified Duke criteria, either clinical or pathological criteria (e.g. demonstration of non-HACEK GNB in valve culture)were prospectively included.

RESULTS

A total of 104 IE cases were caused by non-HACEK GNB (2.6%). Compared to IE due to other microorganisms (excluding HACEK GNB), patients with non-HACEK GNB IE presented with higher age (71 years [IQR 62-78] vs 68 years [IQR: 57-77]; p = 0.026), higher proportion of women (52% vs 31.5%, p < 0.001), higher Charlson Index (5 [IQR: 4-8] vs 4 [IQR 3-7], p = 0.003) and higher in-hospital mortality (36.5% vs 27.1%, p = 0.034). Enterobacterales cases were more frequently associated with genitourinary focus (32.8% vs 5.0%, p = 0.001). NFGNB endocarditis more frequently affected right valves (20.0% vs. 6.3%, p = 0.033), had more common healthcare-related acquisition (67.5% vs. 43.7%, p = 0.030) and venous catheter as focus (40.0% vs. 17.2%, p = 0.019). In the multivariant model, factors related with hospital mortality were: age (OR 1.05, 95%CI 1.00-1.09, p = 0.042), prosthetic valve (OR 2.31, 95%CI 0.90-5.88, p = 0.080), and not performing surgery when indicated (OR 3.60, 95%CI 1.17-11.05, p = 0.025).Patients treated with quinolone combination had lower mortality (OR 0.29; 95%CI 0.09-0.96; p = 0.043).

CONCLUSION

Non-HACEK GNB IE is a rare infection characterized by affecting elderly patients with high comorbidity, nosocomial acquisition and unfavorable outcome. Age, prosthetic valve and not performing surgery when indicated are associated with mortality.