BACKGROUND: Marathon training and running have many beneficial effects on human health and physical fitness; however, they also pose risks. To date, no comprehensive review regarding both the benefits and risks of marathon running on different organ systems has been published. MAIN BODY: The aim of this review was to provide a comprehensive review of the benefits and risks of marathon training and racing on different organ systems. A predefined search strategy including keywords (e.g., marathon, cardiovascular system, etc.) and free text search was used. Articles covering running regardless of sex, age, performance level, and event type (e.g., road races, mountain marathons) were considered, whereas articles examining only cycling, triathlon, stress-tests or other sports were excluded. In total, we found 1021 articles in PubMed, Scopus, and Google Scholar, of which 329 studies were included in this review. Overall, marathon training offers several benefits for different organ systems and reduces all-cause mortality. As such, it improves cardiovascular risk factors, leads to favorable cardiac adaptations, enhances lung function, and improves quality of life in chronic kidney disease patients. It also enhances gastrointestinal mobility and reduces the risk of specific tumors such as colorectal cancer and hepatocellular carcinoma. Marathon training enhances bone health and skeletal muscle metabolism. It further positively affects hematopoiesis and cytotoxic abilities of natural killer cells, and may act neuroprotective on a long-term basis. After a marathon, changes in biomarkers suggesting pathological events in certain organ systems such as cardiovascular, renal, gastrointestinal, liver, hematological, immune, musculoskeletal, central nervous, and endocrine systems can often be observed. Mostly, these changes are limited to 1-3 days post-race and usually normalize within a week. Moreover, marathon running poses the risk of serious adverse events such as sudden cardiac death or acute liver failure. Concerning lung function, a decrease after a marathon race was observed. Acute kidney injury, as well as electrolyte imbalances, are relatively common amongst marathon finishers. Many runners complain of gastrointestinal symptoms during or after long-distance running. Many runners suffer from running-related musculoskeletal injuries often impairing performance. A marathon is often accompanied by an acute inflammatory response with transient immunosuppression, making runners susceptible to infections. Also, hormonal alterations such as increased cortisol levels or decreased testosterone levels immediately after a race are observed. Disturbances in sleep patterns are commonly found in marathon runners leading up to or directly after the race. CONCLUSION: All in all, marathon training is generally safe for human health and individual organ systems. Considering the high popularity of marathon running, these findings supply athletes, coaches, sports scientists, and sports medicine practitioners with practical applications. Further large-scale studies examining long-term effects on the cardiovascular, renal, and other system are needed.

• Klíčová slova
• Athletic injury, Endurance training, Exercise overtraining, Sex differences, sports performance,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Increases in beat-to-beat variability of electrocardiographic QT interval duration have repeatedly been associated with increased risk of cardiovascular events and complications. The measurements of QT variability are frequently normalized for the underlying RR interval variability. Such normalization supports the concept of the so-called immediate RR effect which relates each QT interval to the preceding RR interval. The validity of this concept was investigated in the present study together with the analysis of the influence of electrocardiographic morphological stability on QT variability measurements. The analyses involved QT and RR measurements in 6,114,562 individual beats of 642,708 separate 10-s ECG samples recorded in 523 healthy volunteers (259 females). Only beats with high morphology correlation (r > 0.99) with representative waveforms of the 10-s ECG samples were analyzed, assuring that only good quality recordings were included. In addition to these high correlations, SDs of the ECG signal difference between representative waveforms and individual beats expressed morphological instability and ECG noise. In the intra-subject analyses of both individual beats and of 10-s averages, QT interval variability was substantially more strongly related to the ECG noise than to the underlying RR variability. In approximately one-third of the analyzed ECG beats, the prolongation or shortening of the preceding RR interval was followed by the opposite change of the QT interval. In linear regression analyses, underlying RR variability within each 10-s ECG sample explained only 5.7 and 11.1% of QT interval variability in females and males, respectively. On the contrary, the underlying ECG noise contents of the 10-s samples explained 56.5 and 60.1% of the QT interval variability in females and males, respectively. The study concludes that the concept of stable and uniform immediate RR interval effect on the duration of subsequent QT interval duration is highly questionable. Even if only stable beat-to-beat measurements of QT interval are used, the QT interval variability is still substantially influenced by morphological variability and noise pollution of the source ECG recordings. Even when good quality recordings are used, noise contents of the electrocardiograms should be objectively examined in future studies of QT interval variability.

• Klíčová slova
• ECG noise contents, QT variability, RR variability, healthy volunteers, immediate RR interval effect, long-term ECG, regression-based correction, short-term ECG measurements,
• Publikační typ
• časopisecké články MeSH

AIMS: Present society is constantly ageing and elderly frequently suffer from conditions that are difficult and/or costly to treat if detected late. Effective screening of the elderly is therefore needed so that those requiring detailed clinical work-up are identified early. We present a prospective validation of a screening strategy based on a Polyscore of seven predominantly autonomic, non-invasive risk markers. METHODS AND RESULTS: Within a population-based survey in Germany (INVADE study), participants aged ≥60 years were enrolled between August 2013 and February 2015. Seven prospectively defined Polyscore components were obtained during 30-min continuous recordings of electrocardiogram, blood pressure, and respiration. Out of 1956 subjects, 168 were excluded due to atrial fibrillation, implanted pacemaker, or unsuitable recordings. All-cause mortality over a median 4-year follow-up was prospectively defined as the primary endpoint. The Polyscore divided the investigated population (n = 1788, median age: 72 years, females: 58%) into three predefined groups with low (n = 1405, 78.6%), intermediate (n = 326, 18.2%), and high risk (n = 57, 3.2%). During the follow-up, 82 (4.6%) participants died. Mortality in the Polyscore-defined risk groups was 3.4%, 7.4%, and 17.5%, respectively (P < 0.0001). The Polyscore-based mortality prediction was independent of Framingham score, diabetes, chronic kidney disease, and major stroke and/or myocardial infarction history. It was particularly effective in those aged <75 years (n = 1145). CONCLUSION: The Polyscore-based mortality risk assessment from short-term non-invasive recordings is effective in the elderly general population, especially those aged 60-74 years. Implementation of a comprehensive Polyscore screening of this age group is proposed to advance preventive medical care.

• Klíčová slova
• Autonomic markers, Elderly general population, Polyscore, Prospective validation, Risk assessment,
• MeSH
• autonomní nervový systém MeSH
• cévní mozková příhoda * MeSH
• hodnocení rizik MeSH
• infarkt myokardu * MeSH
• lidé MeSH
• prospektivní studie MeSH
• rizikové faktory MeSH
• senioři MeSH
• Check Tag
• lidé MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

While it is now well-understood that the extent of QT interval changes due to underlying heart rate differences (i.e., the QT/RR adaptation) needs to be distinguished from the speed with which the QT interval reacts to heart rate changes (i.e., the so-called QT/RR hysteresis), gaps still exist in the physiologic understanding of QT/RR hysteresis processes. This study was designed to address the questions of whether the speed of QT adaptation to heart rate changes is driven by time or by number of cardiac cycles; whether QT interval adaptation speed is the same when heart rate accelerates and decelerates; and whether the characteristics of QT/RR hysteresis are related to age and sex. The study evaluated 897,570 measurements of QT intervals together with their 5-min histories of preceding RR intervals, all recorded in 751 healthy volunteers (336 females) aged 34.3 ± 9.5 years. Three different QT/RR adaptation models were combined with exponential decay models that distinguished time-based and interval-based QT/RR hysteresis. In each subject and for each modelling combination, a best-fit combination of modelling parameters was obtained by seeking minimal regression residuals. The results showed that the response of QT/RR hysteresis appears to be driven by absolute time rather than by the number of cardiac cycles. The speed of QT/RR hysteresis was found decreasing with increasing age whilst the duration of individually rate corrected QTc interval was found increasing with increasing age. Contrary to the longer QTc intervals, QT/RR hysteresis speed was faster in females. QT/RR hysteresis differences between heart rate acceleration and deceleration were not found to be physiologically systematic (i.e., they differed among different healthy subjects), but on average, QT/RR hysteresis speed was found slower after heart rate acceleration than after rate deceleration.

• Klíčová slova
• QT/RR adaptation, QT/RR hysteresis, age influence, best-fit models, healthy subjects, non-linear regression modelling, sex differences,
• Publikační typ
• časopisecké články MeSH

QT interval variability, mostly expressed by QT variability index (QTVi), has repeatedly been used in risk diagnostics. Physiologic correlates of QT variability expressions have been little researched especially when measured in short 10-second electrocardiograms (ECGs). This study investigated different QT variability indices, including QTVi and the standard deviation of QT interval durations (SDQT) in 657,287 10-second ECGs recorded in 523 healthy subjects (259 females). The indices were related to the underlying heart rate and to the 10-second standard deviation of RR intervals (SDRR). The analyses showed that both QTVi and SDQT (as well as other QT variability indices) were highly statistically significantly (p < 0.00001) influenced by heart rate and that QTVi showed poor intra-subject reproducibility (coefficient of variance approaching 200%). Furthermore, sequential analysis of regression variance showed that SDQT was more strongly related to the underlying heart rate than to SDRR, and that QTVi was influenced by the underlying heart rate and SDRR more strongly than by SDQT (p < 0.00001 for these comparisons of regression dependency). The study concludes that instead of QTVi, simpler expressions of QT interval variability, such as SDQT, appear preferable for future applications especially if multivariable combination with the underlying heart rate is used.

• Klíčová slova
• QT variability, QT variability index, RR variability, sequential analysis of regression variance, underlying heart rate,
• Publikační typ
• časopisecké články MeSH

AIMS: The clinical effectiveness of primary prevention implantable cardioverter defibrillator (ICD) therapy is under debate. The EUropean Comparative Effectiveness Research to Assess the Use of Primary ProphylacTic Implantable Cardioverter Defibrillators (EU-CERT-ICD) aims to assess its current clinical value. METHODS AND RESULTS: The EU-CERT-ICD is a prospective investigator-initiated non-randomized, controlled, multicentre observational cohort study performed in 44 centres across 15 European Union countries. We will recruit 2250 patients with ischaemic or dilated cardiomyopathy and a guideline indication for primary prophylactic ICD implantation. This sample will include 1500 patients at their first ICD implantation and 750 patients who did not receive a primary prevention ICD despite having an indication for it (non-randomized control group). The primary endpoint is all-cause mortality; the co-primary endpoint in ICD patients is time to first appropriate shock. Secondary endpoints include sudden cardiac death, first inappropriate shock, any ICD shock, arrhythmogenic syncope, revision procedures, quality of life, and cost-effectiveness. At baseline (and prior to ICD implantation if applicable), all patients undergo 12-lead electrocardiogram (ECG) and Holter ECG analysis using multiple advanced methods for risk stratification as well as detailed documentation of clinical characteristics and laboratory values. Genetic biobanking is also organized. As of August 2018, baseline data of 2265 patients are complete. All subjects will be followed for up to 4.5 years. CONCLUSIONS: The EU-CERT-ICD study will provide a necessary update about clinical effectiveness of primary prophylactic ICD implantation. This study also aims for improved risk stratification and patient selection using clinical and ECG risk markers.

• Klíčová slova
• Implantable cardioverter defibrillator, Mortality, Risk factors, Sudden cardiac death,
• MeSH
• defibrilátory implantabilní * MeSH
• dilatační kardiomyopatie komplikace   mortalita   terapie   MeSH
• elektrokardiografie MeSH
• hodnocení rizik * MeSH
• kvalita života MeSH
• lidé MeSH
• míra přežití trendy   MeSH
• náhlá srdeční smrt epidemiologie   etiologie   prevence a kontrola   MeSH
• následné studie MeSH
• primární prevence metody   MeSH
• prospektivní studie MeSH
• výběr pacientů MeSH
• výsledek terapie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• pozorovací studie MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Geografické názvy
• Evropa epidemiologie   MeSH