Radiotherapy in Patients With a Cardiac Implantable Electronic Device.

Recently, the Heart Rhythm Society published recommendations on management of patients with cardiac implantable electronic device (CIED) who require radiotherapy (RT). We aimed to report the experience of a teaching hospital, and discuss our practice in the context of recently published guidelines. We identified all consecutive CIED recipients (12,736 patients) who underwent RT between March 2006 and June 2017. Among them, 90 (1%) patients (78.2 ± 10 years, 73% male) had a CIED: 82 pacemakers and 8 implantable cardioverter-defibrillators. Two patients required CIED extraction prior to RT for ipsilateral breast cancer (no device replacement in 1 patient). Four patients (5%) were considered at high-risk, 35 (39%) at intermediate-risk, and the remaining 50 (56%) at low-risk for CIED dysfunction. Overall, only a minority of patients followed recommended local protocol during RT delivery (31%) and during follow-up (56%). CIED malfunction was detected in 5 patients (6%), mainly back-up mode resetting (80%), with 4 (including 3 pelvic cancer location) patients initially classified as being at intermediate-risk and 1 at low-risk. Four out of the 5 patients with CEID malfunction had received neutron producing beams. In conclusion, our findings underline the lack of rigorous monitoring of patients undergoing RT (though CIED malfunction appears to be rare and relatively benign in nature), and emphasize the interest of considering neutron producing beam for risk stratification as recommended in recent guidelines. Optimization of patient's management requires a close collaboration between both CIED clinicians and radiation oncologists, and more systematic remote CIED monitoring may be helpful.

Prophylactic pacemaker implantation in familial amyloid polyneuropathy.

BACKGROUND: Familial amyloid polyneuropathy (FAP) is an autosomic dominant disease with a high rate of conduction disorders and increased risk of sudden death. Prophylactic cardiac pacing may be considered in asymptomatic patients with FAP. However, the potential benefits are unknown. OBJECTIVE: To document conduction disorders in a large series of FAP and the incidence of high-degree atrioventricular (AV) block in patients with prophylactic pacemaker (PM). METHODS: From January 1999 to January 2010, 262 patients with FAP were retrospectively evaluated. Prophylactic PM was implanted in patients with His-ventricular interval ≥ 70 ms, His-ventricular interval >55 ms associated with a fascicular block, a first-degree AV block, or a Wenckebach anterograde point ≤ 100 beats/min. The spontaneous AV conduction was then analyzed by temporarily inhibiting the PM. RESULTS: As compared with patients with prophylactic PM (n = 100) and patients implanted given a class I/IIa indication (n = 18), the patients who did not require PM (n = 144) were younger and displayed less severe cardiac involvement. Follow-up after prophylactic PM implantation was analyzed in 95 of the 100 patients over 45 ± 35 months, and a high-degree AV block was documented in 24 of the 95 patients (25%). The risk of high-degree AV block was higher in patients with first-degree AV block or Wenckebach anterograde point ≤ 100 beats/min (hazard ratio 3.5; 95% confidence interval 1.2-10) while microvoltage on surface electrocardiogram reduced the risk (hazard ratio 0.2; 95% confidence interval 0.1-0.7). CONCLUSION: In FAP with conduction disorders, prophylactic PM implantation prevented major cardiac events in 25% of the patients over a 45-month mean follow-up. It is suggested that prophylactic PM implantation prevented symptomatic bradycardia in these patients.

Downregulation of the calcium current in human right atrial myocytes from patients in sinus rhythm but with a high risk of atrial fibrillation.

AIMS: A decrease in L-type calcium current (ICaL) is an important mechanism favouring atrial fibrillation (AF). Here, we aimed to identify pathogenic factors associated with ICaL downregulation. METHODS AND RESULTS: Atrial myocytes were isolated from right atrial appendages obtained from 86 adult patients in sinus rhythm with coronary artery disease, aortic valve disease, or mitral valve disease (MVD). Current was recorded in isolated myocytes using the whole-cell patch-clamp technique. The ICaL recorded in the 172 myocytes studied showed a marked variability of peak density ranging from 0.1 to 9.0 pA/pF. The ICaL peak density did not correlate with membrane capacitance or changes in current biophysical properties. The ICaL peak density was homogeneous for a given sample. Small ICaL values were recorded in patients with MVD or with a low left ventricular ejection fraction (<45%). Small ICaL values were more sensitive to the beta-adrenergic agonist, isoproterenol (1 microM), and to the phosphodiesterase inhibitor, 3-isobutyl-1-methyl-xanthine (10 microM). CONCLUSION: In human atrial myocytes, the variability of ICaL is related to the clinical history of the donors. The downregulation of ICaL is already observed in patients in sinus rhythm with a high risk of AF and is associated with the greatest response to beta-adrenergic agonist.