Two cases are reported (both men, one 72 and one 54 years old) of inappropriate shocks delivered by an implantable cardiac defibrillator (ICD) device, which oversensed the myopotentials induced by deep breathing and Valsalva manoeuvre. No damage to leads was associated with the oversensing of myopotentials. The mechanism of the inappropriate shocks was determined using real time electrograms. Modification of the duration of ventricular detection and decrease in sensitivity made it possible to avoid the oversensing of myopotentials and to deliver ICD treatment. (Heart 1999;81:94-96) Keywords: implantable cardiac defibrillator; inappropriate shocks; myopotentials Delivery of inappropriate shocks by implantable cardioverter defibrillators (ICDs) is a common complication.1 2 The mostfrequent cause is the occurrence of supraventricular tachycardia that cannot be diVerentiated by the ICD from ventricular tachycardia. 1 2 Other causes are oversensing of T waves, pacing artefacts from a separate pacemaker, and noise from electronic devices, and lead damage. [1][2][3][4][5][6] We report, for the first time, inappropriate shock by oversensing of diaphragmatic muscular activity in two patients implanted with third and fourth generation ICDs. Case 1A 74 year old man with coronary heart disease and recurrent ventricular fibrillation refractory to amiodarone and blocker treatment received a pectoral ICD (Mini1763; CPI Inc, St Paul, Minnesota, USA) with a bipolar endocardial catheter (Endotak model 0125; CPI Inc) in the right ventricular apex. The intraoperatively sensed R wave amplitude was measured at 8 mV and the pacing threshold was 0.7 V at 0.5 ms pulse width. The ICD was programmed

Funding Acknowledgements Type of funding sources: None. Background. Month and season of birth may be indicators for a variety of prenatal and early postnatal exposures and they have been associated with life expectancy in adulthood. It is suggested that people born in the autumn on the northern hemisphere live longer than those born during the spring or summer, who may have an increase in cardiovascular disease specific mortality. Only few studies have followed populations longitudinally and no study has investigated the relation between season of birth and mortality in patients with established cardiac conditions. Methods. All patients with atrial fibrillation (AF) seen in an academic institution were identified in a database. We examined the clinical course of 8962 consecutive patients with AF seen over a 10-year period. The adverse outcomes were investigated during follow-up and we identified the causes of death. The relation between season of birth (autumn, winter, spring and summer) and mortality risk was assessed using Cox proportional hazard regression models using autumn as the reference. Analyses were also made separately for men and women.  Results. In these 8962 patients (age 70 ± 10 years, CHA2DS2VASc score 3.1 ± 1.7), 1253 deaths were recorded during a follow-up of 2.5 ± 3.0 years (median 1.2, interquartile 4.3 years, yearly rate of death 5.5%) and 97% of causes of death were identified. Cardiovascular deaths accounted for 54% and 43% for non-cardiovascular. The three main causes of death were heart failure (29%), infection (18%) and cancer (12%).  Season of birth was a significant predictor of cardiovascular mortality (overall p = 0.0006). The lowest mortality was seen for people born in autumn or winter and the highest mortality in those born in spring and summer. This was mainly related to a higher cardiovascular mortality in males (hazard ratio [HR] 1.46, 95%CI 1.10-1.93, p = 0.009 for males born in spring and HR 1.44, 95%CI 1.08-1.91, p = 0.01 for those born in summer when compared to males born in autumn as the reference) while this effect was not seen in women. In a model adjusted for age, CHA2DS2VASc score, HASBLED score, cardiovascular risk factors, other comorbidities, AF pattern, antithrombotic use and other cardiovascular drugs use, a higher cardiovascular mortality was still seen in males born in spring (adjusted HR 1.43, 95%CI 1.05-1.96, p = 0.03) or in summer (adjusted HR 1.46, 95%CI 1.07-1.99, p = 0.02) when compared to those born in autumn while this was not seen in women. Conclusion. Birth in spring or summer is associated with a higher risk of cardiovascular mortality in male AF patients. Further studies should aim at clarifying the mechanisms behind this association, which would support the so-called fetal origins hypothesis.

Funding Acknowledgements Type of funding sources: None. Introduction / Background Leadless ventricular permanent pacemakers (leadless VVI, LPM) were designed to reduce lead-related complications of conventional VVI pacemakers (CPM). Purpose The aim of our study was to assess and compare real-life clinical outcomes within the first 30 days and during a mid-term follow-up with the two techniques at a nationwide level. Methods This French longitudinal cohort study was based on the national hospitalization database covering hospital care from for the entire population. All adults (age ≥18 years) hospitalized in French hospitals From January 1, 2017 to September 1, 2020, who underwent a first LPM or CPM implantation were included. Results Of 42,315 patients included in the cohort, 40,828 patients (96%) had a CPM and 1,487 had a LPM. Using propensity score, 1,344 patients with CPM were adequately matched in a 1:1 fashion with LPM patients. Clinical outcomes at day 30 In the unmatched population, within the 30 days after implantation, patients with LPM had a lower rate of all-cause mortality (OR: 0.635, 95%CI: 0.527-0.765, p <0.0001) and from a cardiovascular cause (OR: 0.568, 95%CI: 0.405-0.797, p = 0.001). They also had lower rates of major bleeding and need for transfusion. There was no significant difference between groups regarding tamponade, pneumothorax or hemothorax. In the matched population, LPM implantation was still significantly associated with a lower rate of all-cause death (OR: 0.583, 95%CI: 0.456-0.744, p < 0.0001), cardiovascular death (OR: 0.413, 95%CI: 0.271-0.629, p < 0.0001) or transfusion (OR: 0.481, 95%CI: 0.296-0.780, p < 0.0001). However, tamponade, pneumothorax or hemothorax and major bleeding were not significantly different between the two groups. Clinical outcomes during mid-term follow-up In the unmatched patients, mean follow-up was 8.6 ± 10.5 months. Annual incidence of all-cause death was high in both groups, and significantly higher in the LPM group than in CPM group (31%/year vs. 20%/year, p < 0.0001) with a HR of 1.519 (95%CI: 1.296-1.780). Cardiovascular death was not significantly different between groups. Infective endocarditis was higher in the LPM group than in the CPM group with a HR of 2.108 (95%CI: 1.119-3.973). In the matched patients, mean follow-up was 6.2 ± 8.7 months. All-cause death, cardiovascular death and infective endocarditis were not significantly different between groups. Conclusion Patients treated with leadless VVI pacemakers had better clinical outcomes in the first month compared to the patients treated with conventional VVI pacing. During a mid-term follow-up, risk of all-cause death, cardiovascular death and endocarditis in patients treated with leadless VVI pacemaker was not statistically different after propensity score matching.

Background Patients with hypertrophic cardiomyopathy (HCM) have high risk of death related to cardiovascular (CV) death. Improvements in risk stratification are needed to help identify those HCM patients at higher risk of all-cause death and cardiovascular death. Methods This French longitudinal cohort study from the database covering hospital care from 2010 to 2019 analyzed adultshospitalized with isolated HCM. The overall sample of 52,091 patients was randomly partitioned into derivation (n=26,067) and validation (n=26,024) populations. A logistic regression model was used to construct HCM death and CV-death scores in the derivation sample, which were compared to the Charlson index, Frailty index and CHA2DS2VASc scores using c-indexes and calibration analysis. Results In 52,091 patients with isolated HCM, 12,676 (24.0%) died during follow-up of 3.0±2.8 years (median 2.3, interquartile range 0.4–5.0). Rate of all-cause death was 8.10%/year (7.96–8.24) and was 2.76%/year (2.68–2.84) for CV death.Independent predictors of CV death in HCM were older age, diabetes mellitus, heart failure, history of pulmonary edema, atrial fibrillation, ventricular tachycardia or fibrillation, ischemic stroke, while smoking and poor nutrition were associated with better survival (all p<0.05). In addition to these, male sex, vascular disease, alcohol related diagnoses, kidney disease, lung disease, liver disease anemia and cancer were independent predictors of all-cause death. In the derivation cohort, c-indexes for the HCM death score were 0.720 (0.713–0.727) for all-cause death and 0.695 (0.685–0.705) for CV death. For the HCM CV-death score, c-indexes were 0.679 (0.671–0.686) for all-cause death and 0.723 (0.712–0.733) for CV death. Performances were very similar in the validation cohort. Both scores had good calibrations. Charlson and Frailty indexes however had a better clinical usefulness than the HCM death score and HCM CV-death scores for predicting all-cause death. Decision curve analysis for CV death demonstrated that the HCM CV-death score had the best clinical usefulness of all the tested risk scores. Conclusion HCM patients have a high risk of all-cause and CV mortality. Independent predictors of CV-mortality in HCM were used to derive and validate a simple risk prediction model (French HCM CV-mortality score) which performed better than clinical scores, Charlson Index and Frailty Index; showing the best clinical usefulness, with good calibration. FUNDunding Acknowledgement Type of funding sources: None.