Role of TBX20 Truncating Variants in Dilated Cardiomyopathy and Left Ventricular Noncompaction.

BACKGROUND: Less than 40% of patients with dilated cardiomyopathy (DCM) have a pathogenic/likely pathogenic genetic variant identified. TBX20 has been linked to congenital heart defects; although an association with left ventricular noncompaction (LVNC) and DCM has been proposed, it is still considered a gene with limited evidence for these phenotypes. This study sought to investigate the association between the TBX20 truncating variant (TBX20tv) and DCM/LVNC. METHODS: TBX20 was sequenced by next-generation sequencing in 7463 unrelated probands with a diagnosis of DCM or LVNC, 22 773 probands of an internal comparison group (hypertrophic cardiomyopathy, channelopathies, or aortic diseases), and 124 098 external controls (individuals from the gnomAD database). Enrichment of TBX20tv in DCM/LVNC was calculated, cosegregation was determined in selected families, and clinical characteristics and outcomes were analyzed in carriers. RESULTS: TBX20tv was enriched in DCM/LVNC (24/7463; 0.32%) compared with internal (1/22 773; 0.004%) and external comparison groups (4/124 098; 0.003%), with odds ratios of 73.23 (95% CI, 9.90-541.45; P<0.0001) and 99.76 (95% CI, 34.60-287.62; P<0.0001), respectively. TBX20tv was cosegregated with DCM/LVNC phenotype in 21 families for a combined logarythm of the odds score of 4.53 (strong linkage). Among 57 individuals with TBX20tv (49.1% men; mean age, 35.9±20.8 years), 41 (71.9%) exhibited DCM/LVNC, of whom 14 (34.1%) had also congenital heart defects. After a median follow-up of 6.9 (95% CI, 25-75:3.6-14.5) years, 9.7% of patients with DCM/LVNC had end-stage heart failure events and 4.8% experienced malignant ventricular arrhythmias. CONCLUSIONS: TBX20tv is associated with DCM/LVNC; congenital heart defect is also present in around one-third of cases. TBX20tv-associated DCM/LVNC is characterized by a nonaggressive phenotype, with a low incidence of major cardiovascular events. TBX20 should be considered a definitive gene for DCM and LVNC and routinely included in genetic testing panels for these phenotypes.

Prevalence of cardiac amyloidosis among elderly patients with systolic heart failure or conduction disorders.

Objective: Cardiac amyloid infiltration can lead to systolic heart failure (HF) or to conduction disorders (CD). Patients with transthyretin (ATTR) amyloidosis are particularly exposed. We sought to determine the prevalence of ATTR and AL among patients >60 years admitted with CD or unexplained systolic HF and increased wall thickness. Materials and Methods: We studied 143 patients (57% males, 79 ± 9 years) with HF (N = 28) or CD requiring pacemaker implantation (N = 115). In total, 139 (97%) patients (28 with HF and 111 with CD) underwent 99mTc-DPD scintigraphy to detect ATTR, and 105 (73%; 19 HF and 86 CD) underwent AL screening. Results: Five patients (4%; 95%CI:0-7%) exhibited wild-type ATTR (ATTRwt) amyloidosis, 2 (2%; 95%CI:0-4%) had CD and 3 (11%; 95%CI:0-23%) HF. No patient showed AL. The 2 ATTRwt patients with CD were previously asymptomatic, did not show classical ECG signs and exhibited mild LV hypertrophy with preserved LVEF. By contrast, all ATTRwt patients with HF had ECG and echocardiographic signs of amyloid. During a mean follow-up of 18 ± 11 months, 3(60%) patients with ATTRwt amyloidosis (1 CD and 2 HF) and 14(10.4%) without died. Conclusion: Prevalence of ATTRwt amyloidosis in patients with CD requiring pacemaker is low. Although, additional studies are needed, prevalence seems to be higher in elderly patients with systolic HF.

Genetically Confirmed Familial Hypercholesterolemia in Patients With Acute Coronary Syndrome.

BACKGROUND: Genetic screening programs in unselected individuals with increased levels of low-density lipoprotein cholesterol (LDL-C) have shown modest results in identifying individuals with familial hypercholesterolemia (FH). OBJECTIVES: This study assessed the prevalence of genetically confirmed FH in patients with acute coronary syndrome (ACS) and compared the diagnostic performance of FH clinical criteria versus FH genetic testing. METHODS: Genetic study of 7 genes (LDLR, APOB, PCSK9, APOE, STAP1, LDLRAP1, and LIPA) associated with FH and 12 common alleles associated with polygenic hypercholesterolemia was performed in 103 patients with ACS, age ≤65 years, and LDL-C levels ≥160 mg/dl. Dutch Lipid Clinic (DLC) and Simon Broome (SB) FH clinical criteria were also applied. RESULTS: The prevalence of genetically confirmed FH was 8.7% (95% confidence interval [CI]: 4.3% to 16.4%; n = 9); 29% (95% CI: 18.5% to 42.1%; n = 18) of patients without FH variants had a score highly suggestive of polygenic hypercholesterolemia. The prevalence of probable to definite FH according to DLC criteria was 27.2% (95% CI: 19.1% to 37.0%; n = 28), whereas SB criteria identified 27.2% of patients (95% CI: 19.1% to 37.0%; n = 28) with possible to definite FH. DLC and SB algorithms failed to diagnose 4 (44%) and 3 (33%) patients with genetically confirmed FH, respectively. Cascade genetic testing in first-degree relatives identified 6 additional individuals with FH. CONCLUSIONS: The prevalence of genetically confirmed FH in patients with ACS age ≤65 years and with LDL-C levels ≥160 mg/dl is high (approximately 9%). FH clinical algorithms do not accurately classify patients with FH. Genetic testing should be advocated in young patients with ACS and high LDL-C levels to allow prompt identification of patients with FH and relatives at risk.

[Smoking paradox in acute coronary syndrome without ST-segment elevation]. / La paradoja del tabaco en el síndrome coronario agudo sin elevación del ST.

BACKGROUND AND OBJECTIVE: Although smoking habit is a well-known cardiovascular risk factor, it has been described that smokers admitted because of myocardial infarction have better prognosis than non smoker patients, which is known as "the smoking paradox". The purpose of our work is to investigate whether this phenomenon occurs among patients admitted because of acute coronary syndrome without ST-segment elevation (NSTACS), and which factors help to explain it. PATIENTS AND METHODS: We analysed 563 consecutive patients admitted because of NSTACS on the Coronary Unit of our hospital from January 2005 to December 2006. We analysed clinic and angiographic characteristics and their relationship with in-hospital complications and prognosis. RESULTS: 155 Patients were smokers (27.53%). Smoker patients were younger, more often male, had less risk factors, and more often had a Killip I class at admission (91.6% vs. 79.3%). They had less commonly the combined endpoint of death, reinfarction or Killip Class IV (6.5 vs 13.6%, odds ratio 0.439, confidence interval 0.218 a 0.885, P=.018). This relationship was lost after adjusting to other significant clinical and angiographic data by logistic regression. CONCLUSIONS: Our study confirms the "smoking paradox" amongst NSTACS patients, which is explained by the lower prevalence of previous myocardial infarction, diabetes or multivessel disease. It is essential to recommend quitting the smoking habit.