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perfusion defects ( ESC CardioMed chapter 11.4).126 CMR is more sensitive than echocardiography to diagnose ARVC,127 is diagnostic in LVNC, and can detect apical aneurysms in HCM. Fibrosis detection by late gadolinium enhancement (LGE) contributes to VA risk stratification in HCM,128 DCM,129 and potentially in mitral valve prolapse arrhythmic syndrome.130,131 Novel myocardial mapping techniques can detect diffuse fibrosis and can suggest the aetiology of left ventricular hypertrophy (LVH) for specific therapy guiding, e.g. Fabry disease and amyloidosis. The prognostic value remains to be evaluated. Cardiac imaging by computed tomography (CT) has the advantage of a high spatial resolution ( ESC CardioMed chapter 12.1).132 ECG synchronization, additional breath-hold sequences, and betablocker to lower the heart rate improve the quality. Radiation exposure is in the range of an invasive coronary angiogram (CAG). Coronary computed tomography angiography (CTA) is the preferred method to rule out coronary artery stenosis in patients with low probability of CAD.133,134 The quality of almost all image modalities is influenced by the presence of frequent PVCs.

5.1.3.5 Provocative diagnostic tests

These are summarized in Table 6. Common tests performed are sodium channel blocker testing for Brugada syndrome (BrS) and adenosine test to exclude latent pre-excitation.135,136 Epinephrine challenge may be useful in CPVT when exercise cannot be performed. Epinephrine test is not recommended for LQTS due to the high false positive rate and utility of exercise testing.137 Coronary vasospasm as a cause of VF in the absence of obstructive coronary diseases/cardiomyopathy can be tested with incremental intracoronary doses of acetylcholine/ergonovine.

5.1.3.6 Electrophysiological study

Electrophysiological studies including measurement of baseline intervals (e.g. atrial–His interval [AH] and His–ventricular interval [HV]), programmed electrical stimulation (PES), and electroanatomical mapping can be used for diagnostic purposes and to guide therapy.145–150 The yield of PES varies with the underlying cardiac condition and its severity, the presence or absence of spontaneous VT, concomitant drug therapy, stimulation protocol, and site(s) of stimulation. Typical protocols include stimulation from 2 right ventricular (RV) sites with 2–3 basic drive cycle lengths, introduction of 3 extrastimuli, and isoprenaline administration.148,151,152 In the current era, PES is mainly employed to confirm the diagnosis of VT and induce mappable VAs with non-inducibility being an ablation endpoint. Patients with heart failure and LVEF ≤35% generally will have an indication for an ICD; therefore, VT/VF induction before implantation is not necessary. In patients with SHD and mildly reduced or preserved LVEF who present with unexplained syncope, induction of SMVT with PES can be helpful to identify the underlying cause and to predict subsequent events.146,153 PVT/VF induction in SHD is in general considered as a non-specific finding.154–156 In primary electrical diseases, PES is not of prognostic value, although there is some evidence to consider its use in BrS.127 Invasive electrophysiological evaluation can have important clinical implications in patients with myotonic dystrophy.157 With advances in high-density mapping, voltage mapping, conduction/repolarisation metrics, and electrogram fractionation can be employed to identify ablation targets, or to diagnose cardiomyopathic disease. Endocardial mapping may be helpful in the differentiation of ARVC from benign outflow tract VT and for targeting biopsy in suspected myocarditis, ARVC, and sarcoidosis cases.158–162

5.1.4 Genetic testing

Massive parallel or next-generation sequencing has led to increasing availability of genetic testing at reduced cost. Most diagnostic cardiac genetic testing employs large gene panels determined by associations with disease generated by prior research, i.e. candidate genes.163 Many previous gene associations have, however, been challenged for their diagnostic utility. Therefore, it is not recommended to include questionable genes in routine diagnostic panels.164–168 Genome-wide association studies have identified that common genetic variation single nucleotide polymorphisms can cause or modify phenotypes in BrS, LQTS, HCM, and DCM. Polygenic risk scores, measures derived from the cumulative effects of these single nucleotide polymorphisms, may therefore play a role in diagnosis and prognostication in these conditions in the future.168–173 Sequencing produces digital data that require subsequent bioinformatic analysis, permitting accurate ascertainment of most DNA alterations affecting the coding frame of each gene.174 The most common findings are single nucleotide variants causing simple amino acid substitutions (missense), premature terminations, or splicing abnormalities. Insertions and/or deletions are rarer. The clinical importance of most non-coding variants is still to be determined.174,175 A framework for the interpretation of disease causation by genetic variants has standardized adjudication into five classes: V ‘pathogenic’; IV ‘likely pathogenic’; III ‘variant of uncertain significance’; II ‘likely benign’; and I ‘benign’. A combination of evidence is employed: gene– disease association; presence of a variant in healthy and/or diseased populations; in silico data; in vitro and in vivo functional data; and family segregation data.176 A mutation (Class IV or V variant) can be used immediately either for confirmation of diagnosis in probands (the first affected family member), or for initial diagnosis of relatives and may help to guide therapy and/or prognosis. Periodic reassessment of all class IV and III variants is indicated.176 Pre-implantation genetic testing is an early form of pre-natal genetic diagnosis. Genetic diagnoses of in vitro fertilized embryos are identified by biopsies, thereby allowing transfer of genetically normal embryos into the uterus. If the technique is available, it is important to provide information to patients with monogenic heart diseases in child-bearing age. The legislation for pre-implantation genetic testing varies in different countries and strategies differ. Genetic and clinical testing should be undertaken only by multidisciplinary teams including professionals with skills to counsel on the implications and the uncertainty of results and experienced cardiologists able to direct testing to the correct phenotype.135,177–179 A negative result does not exclude a diagnosis and should not be used for this purpose. A framework for genetic and other clinical diagnostic tests for primary electrical diseases based on evidence where available has been provided in Table 7. Downloaded from academic.oup.com/eurheartj/article/43/40/3997/6675633 by guest on 07 October 2026