Genotype-phenotype dilemma in a case of sudden cardiac death with the E1053K mutation and a deletion in the SCN5A gene.

Mutations in the cardiac sodium channel gene SCN5A may result in various arrhythmia syndromes such as long QT syndrome type 3 (LQTS), Brugada syndrome (BrS), sick sinus syndrome (SSS), cardiac conduction diseases (CCD) and possibly dilated cardiomyopathy (DCM). In most of these inherited cardiac arrhythmia syndromes the phenotypical expression may range from asymptomatic phenotypes to sudden cardiac death (SCD). A 16-year-old female died during sleep. Autopsy did not reveal any explanation for her death and a genetic analysis was performed. A variant in the SCN5A gene (E1053K) that was previously described as disease causing was detected. Family members are carriers of the same E1053K variant, some even in a homozygous state, but surprisingly did not exhibit any pathological cardiac phenotype. Due to the lack of genotype-phenotype correlation further genetic studies were performed. A novel deletion in the promoter region of SCN5A was identified in the sudden death victim but was absent in other family members. These findings demonstrate the difficulties in interpreting the results of a family-based genetic screening and underline the phenotypic variability of SCN5A mutations.

Intracoronary beta-irradiation with a liquid (188)re-filled balloon: six-month results from a clinical safety and feasibility study.

BACKGROUND: Coronary irradiation is a new concept to reduce restenosis. We evaluated the feasibility and safety of intracoronary irradiation with a balloon catheter filled with (188)Re, a liquid, high-energy beta-emitter. METHODS AND RESULTS: Irradiation with 15 Gy at 0.5-mm tissue depth was performed in 28 lesions after balloon dilation (n=9) or stenting (n=19). Lesions included 19 de novo stenoses, 4 occlusions, and 5 restenoses. Irradiation time was 515+/-199 seconds in 1 to 4 fractions. There were no procedural complications. One patient died of noncardiac causes at day 23. One asymptomatic patient refused 6-month angiography. Quantitative angiography after intervention showed a reference diameter of 2. 77+/-0.35 mm and a minimal lumen diameter of 2.36+/-0.43 mm. At 6-month follow-up, minimal lumen diameter was 1.45+/-0.88 mm (late loss index 0.57). Target lesion restenosis rate (>50% in diameter) was low (12%; 3 of 26). In addition, we observed 9 stenoses at the proximal or distal end of the irradiation zone, potentially caused by the short irradiation segment and the decreasing irradiation dose at its borders ("edge" stenoses). The total restenosis rate was 46% and was significantly lower (29% vs 70%, P=0.042) when the length of the irradiated segment was more than twice the lesion length. CONCLUSIONS: Coronary irradiation with a (188)Re-filled balloon is technically feasible and safe, requiring only standard percutaneous transluminal coronary angioplasty techniques. The target lesion restenosis rate was low. The observed edge stenoses appear to be avoidable by increasing the length of the irradiated segment.

A randomized trial of elective stenting after balloon recanalization of chronic total occlusions.

OBJECTIVES: The aim of this study was to assess the role of Wiktor stent implantation after recanalization of chronic total coronary occlusions with regard to the clinical and angiographic outcome after six months. BACKGROUND: Beside the common use of stents in clinical practice, the number of stent indications proven by randomized trials is still limited. METHODS: Eighty-five patients with a thrombolysis in myocardial infarction grade 0 chronic coronary occlusion were examined. After standard balloon angioplasty, the patients were randomly assigned to stent implantation, or percutaneous transluminal coronary angioplasty (PTCA) alone (no further intervention). Quantitative coronary angiography was performed at baseline and after six months. RESULTS: The minimal lumen diameter did not differ immediately after recanalization (stent group 1.61 +/- 0.30 mm vs. PTCA group 1.65 +/- 0.36 mm), and increased after stent implantation to 2.51 +/- 0.41 mm. After six months, the stent group still had a significantly greater lumen (1.57 +/- 0.59 vs. 1.06 +/- 0.90 mm; p < 0.01) and a significantly lower restenosis and reocclusion rate (32% and 3%) compared with the PTCA group (64% and 24%); restenosis analysis according to treatment was 72% (PTCA) versus 29% (stent, p < 0.01). Late loss was equal in both groups. At follow-up, the stent patients had a better angina class (p < 0.01), and fewer cardiac events (p < 0.03). A meta-analysis including this trial and three other controlled trials with the Palmaz-Schatz stent showed concordant results. CONCLUSIONS: Stent implantation after reopening of a chronic total occlusion provides a better angiographic result, corresponding to a better clinical outcome with fewer recurrence of symptoms and reinterventions after six months.

Significance of noninvasive diagnostic techniques in patients with long QT syndrome.

The idiopathic long QT syndrome (LQTS) is an infrequently occurring disorder. Affected patients may have electrocardiographic alterations and are prone to syncope and sudden arrhythmogenic cardiac death. Adequate therapy may improve the prognosis of affected patients significantly. Therefore the early and precise diagnosis of LQTS has major prognostic impact. This study reports the diagnostic significance of standard electrocardiographic techniques and autonomic maneuvers in 14 patients with LQTS. The findings are compared with those of 14 healthy age-matched control persons. QTc duration was significantly longer in patients with LQTS during standard 12-lead electrocardiography (489 +/- 56 vs 412 +/- 30 ms, p < 0.005), exercise stress testing (490 +/- 38 vs 409 +/- 18 ms, p < 0.001), cold pressor testing (512 +/- 45 vs 407 +/- 19 ms, p < 0.001), Valsalva maneuver (497 +/- 49 vs 407 +/- 19 ms, p < 0.001), minimal heart rate during 24-hours of ambulatory electrocardiographic recording (482 +/- 69 vs 402 +/- 22 ms, p < 0.01) and maximal heart rate during Holter monitoring (460 +/- 47 vs 411 +/- 27 ms, p < 0.005). Four of 14 patients with LQTS had pathologic findings during ambulatory electrocardiographic monitoring (2 patients with short episodes of torsades de pointes tachyarrhythmia, 1 patient with intermittent sinoatrial block, and 1 patient with intermittent TU-wave alterations), whereas all control persons had normal ambulatory electrocardiographic recordings (p < 0.05). Thus, noninvasive standard electrocardiographic techniques in combination with autonomic maneuvers may contribute significant information for a precise diagnosis in patients with suspected LQTS.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of physical activity on 24-hour measurements of heart rate variability in patients with coronary artery disease.

This study assessed the influence of physical activity on time domain variables of heart rate variability (HRV) during 24-hour electrocardiographic registrations. Changes in time domain variables of HRV (in particular SDNN) obtained from Holter recordings were proven as strong predictors of cardiac events in patients with coronary artery disease. Although 24-hour measurements of HRV recordings are a standard technique, little is known about the effects of the environment during the registration period. This applies especially to the type and nature of physical activity. In a prospective study, 106 patients with angiographically proven coronary artery disease were randomized into 2 groups. Group 1 consisted of 54 patients with recordings under normal daily physical activities. Group 2 consisted of 52 patients who were immobilized during the recording. Both groups were comparable concerning clinical parameters. The results of 24-hour measurements of HRV with analysis of time domain variables (SDNN, SDANN, SDNN index, rMSSD, and pNN50) were compared among the 2 patients groups, and with a healthy control group. Comparison of immobilized patients with healthy controls showed statistically significant differences of all HRV parameters (p <0.01). However, when comparing the activity group with healthy controls, none of the parameters showed any significant differences. Comparison of the subgroups revealed statistically significant differences of the parameters SDNN, SDANN (p <0.01), and borderline results for rMSSD and pNN50 (p = 0.05). Our results indicate that time domain variables of HRV calculated from 24-hour recordings are significantly influenced by the level of physical activity and the upright posture during registration. This methodologic aspect has to be considered, especially if HRV measurements are used as prognostic markers in patients with coronary heart disease.

Management of unstable angina in patients over 75 years old.

BACKGROUND: Although there have been reports of successful percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG) in elderly patients, few data are available on the optimal management of unstable angina in such patients. This study was therefore designed to identify the preferred revascularization strategy in patients with unstable angina over 75 years of age. METHODS: Early and late results were evaluated for patients over 75 years with unstable angina undergoing PTCA (n = 51) or CABG (n = 53). The two groups were comparable with respect to age, sex distribution, clinical manifestation of symptoms, left ventricular ejection fraction and accompanying non-cardiac diseases. In the CABG group, significantly more patients had left main coronary artery stenosis (13 and 2%, respectively). RESULTS: Both PTCA and CABG treatment showed similar procedural success rates (91 and 94% respectively) and hospital mortality rates (4 and 6% respectively). Procedural complications were comparable regarding Q-wave myocardial infarction, stroke, renal failure and vascular complications. Patients undergoing CABG received significantly more blood transfusions than those undergoing PTCA (17 and 2% respectively). During follow-up, the mortality rate was comparable in both groups (4% with CABG and 8% with PTCA), but significantly fewer patients in the CABG group developed unstable angina (8 versus 21% in the PTCA group), fewer patients were readmitted to hospital for cardiac reasons (CABG group 17%, PTCA group 31%) and fewer patients needed repeat coronary interventions (CABG group 4%, PTCA group 18%). CONCLUSION: Both PTCA and CABG were comparable with regard to short- and long-term mortality, but CABG treatment was favourable with regard to clinical symptoms, readmission to hospital and repeat coronary interventions.

Improved detection of transient myocardial ischemia by a new lead combination: value of bipolar lead Nehb D for Holter monitoring.

The investigations of ST-segment changes by Holter monitoring demonstrate asymptomatic and symptomatic episodes of myocardial ischemia, which may occur during daily activities. One factor, which is of great importance for the detection of silent myocardial ischemia during ambulatory monitoring, is the combination of the leads. Former studies showed that the analysis of two channels alone may not adequately detect silent myocardial ischemia. We therefore used a three-channel ambulatory ECG monitoring system with a new lead combination. The Holter monitoring results were correlated with the distribution of coronary stenosis detected by coronary angiography. In 54 patients with single coronary vessel disease and ischemic ST-segment depressions during exercise testing, standard Holter lead combination CM2/CM5 was extended by a bipolar Nehb D-like lead. Lead combination CM2/CM5 identified 23 patients (43%) with ST-segment depressions (total number of ischemic episodes = 372). Additional Nehb D-like lead identified 30 patients (55%) with ST-segment depressions (total number of ischemic episodes = 1048). The combination of leads CM2/CM5 and Nehb D raised the number of patients with documented ST-segment depressions to 33 of 54 (61%). Lead Nehb D showed the highest sensitivity for the detection of inferior wall ischemia (stenosis of the right coronary artery); nevertheless, this lead may not be regarded as specific for ST-segment alterations only caused by inferior wall ischemia. The correlation of ischemic ST-segment depressions during exercise testing (classified as anterior, inferior, or anterior and inferior type of ischemia) and documented ST-segment changes in the different Holter leads underline these results.(ABSTRACT TRUNCATED AT 250 WORDS)

Time-dependent changes of heart rate variability after percutaneous transluminal angioplasty.

OBJECTIVES: It is not known whether the improvement of myocardial perfusion by percutaneous transluminal coronary angioplasty (PTCA) is followed by a response of the autonomic nervous system depending on the recovery of the myocardium. In this study we investigated changes of heart rate variability parameters in patients before and after PTCA at different time intervals. METHODS: In 42 patients with coronary artery disease documented on angiography, before and after PTCA 24-hour measurements of heart rate variability (HRV) were performed from Holter tapes. The time elapsed between the two measurements was 3 to 4 days in 26 patients and 6 to 8 months in 16 patients. Time domain parameters of HRV were calculated. RESULTS: Comparison of the two recordings showed that the parameters rMSSD, pNN50, and SDNN index decreased, whereas SDNN and SDANN increased. These changes were not statistically significant. A subgroup analysis revealed different results for patients with and without previous myocardial infarction: the parasympathetically and more sympathetically influenced parameters revealed different changes in these groups. Other variables such as ejection fraction or severity of coronary artery disease did not influence the HRV results. Although no statistically significant difference was seen on comparison of the patients with different recording intervals, patients with a longer interval between the two measurement periods showed higher values of all HRV parameters closer to normalized values. This observation may be explained by a delayed recovery of myocardial function after successful revascularization by PTCA.

Heart-rate variability for discrimination of different types of neuropathy in patients with insulin-dependent diabetes mellitus.

It has been shown that patients with insulin-dependent diabetes mellitus (IDDM) may reveal abnormal alterations in heart-rate variability (HRV) due to autonomic neuropathy. This study was performed to prove whether heart-rate variability can be used to stratify diabetic patients with different types of neuropathy. 48 patients with IDDM (age 17-64 yr) underwent standard function tests to assess autonomic and peripheral neuropathy. According to the results of these tests they were divided into 4 groups: Group 1: 18 patients without autonomic or peripheral neuropathy. Group 2: 13 patients with peripheral neuropathy. Group 3: 7 patients with autonomic neuropathy. Group 4: 9 patients with autonomic and peripheral neuropathy. HRV was measured by continuous 24-hours monitoring and time domain parameters were calculated. The results were compared with sex and age-matched healthy controls according to the individual characteristics of the groups and among each subgroup. Our results showed that in Group 1 there was a significant difference of time domain parameters indicative of parasympathetic influence, i.e. rMSSD and pNN50 in comparison to the control subjects (p = 0.002, p = 0.008). These results depended on the duration of diabetes; a subgroup of patients with a duration of IDDM of less than 2 years had no significant differences of HRV values. Group 2 showed the same significant differences. Group 3 and 4 showed significant differences in all measured time domain variables (SDNN, SDANN, SDNN index, rMSSD and pNN50) in comparison to the control subjects (p < 0.04). A comparison of group 1 with group 2 offered significant differences in rMSSD and pNN50 (p = 0.004, p = 0.003). Comparing group 1 with group 3 and 4, all HRV parameters showed significant differences (p < 0.03). In conclusion, HRV is able to distinguish between patients with different types of neuropathy depending on the involvement of parasympathetic or more sympathetic influenced parameters. Furthermore, this method is able to unmask early manifestations of neurological disorders prior to their detection by neurological function tests.

Value of different non-invasive methods for the recognition of arrhythmogenic complications in high-risk patients with sustained ventricular tachycardia during programmed ventricular stimulation.

UNLABELLED: It is well known that patients with coronary heart disease and ventricular tachycardia show a high incidence of arrhythmogenic complications and sudden cardiac death. The best predictor of spontaneous ventricular tachycardia and sudden death in these patients is programmed ventricular stimulation, but this invasive method is limited to specialized institutions. The purpose of our study was to assess the predictive value of Holter monitoring, late potentials and heart rate variability as markers for these high-risk patients. We investigated 20 patients (18 m, 2 f, age range 31-79 years) with coronary artery disease documented angiographically (6 patients with single vessel disease (vd), nine patients with 2 vd, five patients with 3 vd) and previous myocardial infarction. Each patient underwent 24-h ambulatory monitoring with analysis of rhythm of heart rate variability (24-h spectral and non-spectral analysis) and a signal-averaged ECG with late potential measurement. In all patients, sustained ventricular tachycardia was inducible during programmed ventricular stimulation. Late potentials were recorded in 12 out of the 20 patients (60%). Ventricular arrhythmias of Lown classes IVa, IVb or V were recorded in 12 patients. Analysis of heart rate variability compared to 20 age- and sex-matched healthy controls revealed a loss of parasympathic activity and increased sympathic activity in 16 of the 20 patients (80%). CONCLUSION: in this study, heart rate variability was the most sensitive method with which to recognize patients at a high risk of arrhythmogenic complications. Evaluation of the above parameters in large controlled clinical trials may help predict arrhythmogenic complications and sudden cardiac death.

The arrhythmogenic substrate of the long QT syndrome: genetic basis, pathology, and pathophysiologic mechanisms.

The Long QT syndrome (LQTS) is a relatively rare disorder. It has a major clinical impact as affected individuals are prone to syncope and sudden arrhythmogenic cardiac death. The LQTS comprises three groups of patients. The Jervell-Lange-Nielsen syndrome is characterized by an autosomal recessive pattern of inheritance and congenital neural deafness. The Romano-Ward syndrome shows an autosomal dominant pattern of inheritance and normal hearing. Patients with the sporadic form of LQTS have no evidence of familial transmission and have normal hearing. Imbalance of sympathetic cardiac innervation with predominance of the left stellate ganglion and an intrinsic myocardial defect leading to early afterdepolarization are the two pathogenetic mechanisms of LQTS discussed today. More recently a genetic basis for the Romano-Ward LQTS has been reported. The genetic linkage to the Harvey ras-1 gene provides the basis for a new hypothesis that an impairment of guanine nucleotide binding proteins is responsible for symptoms observed in LQTS. This paper discusses the genetic basis, pathology and pathophysiology of LQTS and tries to unify the different theories.

[Long-term electrocardiography in the idiopathic QT syndrome]. / Langzeit-Elektrokardiographie bei idiopathischem QT-Syndrom.

The value of long-term electrocardiographic (ECG) monitoring was assessed in 14 patients (8 males, 6 females; mean age 21 [17-30] years) with the idiopathic long QT syndrome (LQTS), 14 healthy subjects of the same age serving as controls. Twelve patients had the typical history of syncopes or sudden cardiac death among family members; seven patients had a history of syncope, while four patients had been successfully resuscitated. None had associated cardiac disease. Among the group with LQTS the rate-corrected QT interval at rest was 498 + 56 ms, in the control group 412 +/- 30 ms (P < 0.005). Resting and maximal heart rates on exercise were similar in the two groups. The rate-corrected QT interval on exercise was significantly longer in the LQTS patients (P < 0.001). In the control group the maximal heart rate in the long-term ECG was significantly higher (144 +/- 28/min) than in the LQTS patients (128 +/- 17/min; P < 0.01). The long-term ECG recorded abnormal findings in five patients: torsade-de-pointes tachycardia in two, T-wave alternans in two, and bradycardia resulting from intermittent sinoatrial block in one. No abnormal findings were recorded in the control group (P < 0.03).

[Effect of a pressure dressing on angiologic complications after diagnostic coronary angiography]. / Einfluss des Druckverbandes auf angiologische Komplikationen nach diagnostischer Koronarangiographie.

500 consecutive patients undergoing diagnostic coronary angiography were studied for vascular complications using either a conventional (n = 250) or a special mechanical device for compression dressing (n = 250). In both groups one case of arterial occlusion occurred. Using the conventional pressure dressing, we observed four pseudoaneurysms, whereas there were none in the special mechanical device dressing group (p < 0.05). In contrast, eight patients developed a deep vein thrombosis after mechanical device pressure dressing compared to only 1 venoust in the conventional dressing group (p < 0.02). Five patients, four of the eight patients with mechanical device dressing, suffered from clinical apparent pulmonary embolism (p = 0.1801). Thus, a mechanical device pressure dressing may decrease the number of arterial pseudoaneurysms but is associated with an increased risk of deep vein thrombosis and pulmonary embolism. Therefore, we recommend the use of the mechanical device pressure dressing only in selected patients with severe obesity.

[Implantation of Strecker stents in the iliac and femoropopliteal region]. / Implantation von Strecker-Stents in der Iliakal- und Femoropoplitealregion.

The aim of implanting vascular endoprosthesis is to avoid acute complications and restenosis after percutaneous transluminal angioplasty. The Strecker stent is a new development, based on the principle of balloon-expandable endoprosthesis. We treated seven patients (five male, two female) aged 48 to 84 years (average 68 years) with Strecker stents in the iliac and femoropopliteal region. The indications for the implantation of stents were restenosis, reocclusion, recoiling, and kink stenosis. Also, acute complications as dissection or intimal flaps after PTA were stented. The implantation of the Strecker stents was in every case without technical complications. The condition of three patients suffering from a stage III, according to Fontaine's classification, improved to stage IIa after treatment. In three out of four patients with a stage IIb, clinical symptoms were changed to stage IIa after stenting. One patient had an acute thrombosis during the intervention, which could not be solved by local thrombolysis. The Doppler sonographic index increased after treatment to an average of 0.31. The follow-up period up to six months showed persistent clinical improvement. Intimal hyperplasia with stent occlusion or thromboembolic occlusions was not observed. The Strecker stent is a technically non-problematic system, which is qualified for the endoprosthetic therapy of the iliac and femoropopliteal region.

Value of Holter monitoring in patients with the long QT syndrome.

The idiopathic long QT syndrome (LQTS) is an infrequently occurring disorder. It has major clinical impact as patients are prone to syncope, ventricular tachyarrhythmias and sudden arrhythmogenic cardiac death. This paper reports the value of ambulatory electrocardiogram (ECG) monitoring as a diagnostic tool to establish the diagnosis of LQTS. 14 patient with idiopathic LQTS were studied. The results were compared to those of 14 age- and sex-matched healthy control individuals. A 24-hour ambulatory ECG tracing was obtained in each individual. 5/14 patients with LQTS had pathological findings during ambulatory ECG monitoring (2 patients with episodes of torsade de pointes tachycardia, 2 patients with T-wave alternans and 1 patient with bradycardia due to an intermittent SA block), whereas all control persons had normal ambulatory ECG recordings (p < 0.03). Thus, ambulatory ECG recordings may contribute significant diagnostic information in patients with suspected LQTS.

[Control of the effectiveness of nitrate therapy with long-term ECG based on spontaneous ST segment changes]. / Effektivitätskontrolle einer Nitrattherapie mit dem Langzeit-EKG anhand spontaner ST-Streckenveränderungen.

In a population of 40 patients with coronary artery disease the overall incidence of spontaneous ischemic episodes during 24-h Holter monitoring could be significantly reduced with ISDN 120 mg ret. and ISDN 120 mg plus Diltiazem 120 mg ret. However, the intraindividual day-to-day variability of ischemic episodes on three consecutive days of Holter monitoring is taken into consideration, an intraindividual reduction of ischemic episodes of at least 97% is required to separate a true therapeutic effect from the considerable spontaneous variability.

[Comparison of stress ECG and long-term ECG for detection of myocardial ischemia in patients with coronary heart disease]. / Vergleich von Belastungs-EKG und Langzeit-EKG zur Erfassung myokardialer Ischämien bei Patienten mit koronarer Herzkrankheit.

Holter-monitoring and exercise-ECG can be employed for the detection of myocardial ischemia. Exercise-ECG is capable of detecting ischemias caused by physical activity. In contrast, Holter monitoring can detect episodes of myocardial ischemia independent of exertion, but possibly connected with other factors such as mental stress. In 60 patients (49 male, 11 female, mean age 55.1 years) with angiographically documented coronary artery disease (26 x 1-vessel, 21 x 2-vessel, 13 x 3-vessel diseases) exercise-ECG and ambulatory 24-h monitoring were performed (3-channel recordings, ST-segment analysis). The assessment of the exercise-ECG showed 31 out of 60 patients with pathological results. 34 patients had pathological ST-segment changes during Holter monitoring (56%). Since both methods detected different patients, a combination of these techniques is useful. The combination of Holter monitoring and exercise-ECG raised the sensitivity to 78% (47/60 patients). Different heart rates were found at the point of maximal ST-segment changes in exercise-ECG as compared to the episodes of ST-segment changes recorded by Holter monitoring. This finding clearly illustrates the fact that different pathophysiological mechanisms are causing myocardial ischemia in respective cases. Using the coronary arteriogram as standard, the sensitivity of the two methods was different. While both techniques could detect multi-vessel disease at a similar level, Holter monitoring was significantly more sensitive in detecting patients with single-vessel disease. Thus, exercise-ECG and Holter monitoring supplement each other in detecting myocardial ischemia. In the future, larger clinical trials will have to confirm these results.

[Risk stratification after myocardial infarct]. / Risikostratifizierung nach Myokardinfarkt.

In industrialized countries the rate of sudden cardiac death remains unchanged. The most frequently encountered structural heart disease in these patients is coronary artery disease. Despite the era of thrombolytic therapy of acute myocardial infarction patients carry an increased risk of sudden cardiac arrhythmogenic death within a time period of one to two years following the acute event. Therefore, risk stratification post-MI before patient discharge is furthermore mandatory. The spectrum of non-invasive techniques for risk stratification includes the clinical risk profile, measurement of left ventricular global function (LV ejection fraction), the resting ECG (QT dispersion), an ECG stress test (detection and severity of myocardial ischemia), ambulatory ECG monitoring (number and type of ventricular arrhythmias), surface high resolution ECG (detection of ventricular late potentials), measurement of T wave alternans (TWA, alternans ratio), and measurements of the activity and balance of the autonomous nervous system (heart rate variability, baroreflex sensitivity = BRS). Programmed ventricular stimulation (PVS) serves as an invasive risk stratification technique (detection of an arrhythmogenic substrate). The prognostic power of the non-invasive techniques is limited; in general, the prognostic value of a negative test is reasonably high (90 to 100% depending on the test used), whereas the prognostic value of a positive test is rather low (4 to 42% depending on the test used). Combining several non-invasive tests may significantly improve the positive predictive value above 50%, but this goes along with a significant decreases of sensitivity below 50%. Therefore, a combination of several non-invasive tests (detection and exclusion of a large number of low-risk individuals) with the invasive method of PVS (detection of an arrhythmogenic substrate, i.e. a high-risk patient) seems reasonable, as has been convincingly shown by several smaller prognostic studies.