Myocardial fibrosis predicts ventricular arrhythmias and sudden death after cardiac electronic device implantation

Funding Acknowledgements

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Unrestricted educational grants

Background

Increasing evidence supports a link between myocardial fibrosis (MF) and ventricular arrhythmias. We sought to determine whether presence of MF on visual assessment (MFVA) and gray zone fibrosis (GZF) mass predicts SCD and ventricular fibrillation / sustained ventricular tachycardia after cardiac implantable electronic device (CIED) implantation.

Methods

In this prospective study, total fibrosis and GZF mass, quantified using cardiovascular magnetic resonance, was assessed in relation to the primary endpoint of sudden cardiac death (SCD) and the secondary, arrhythmic endpoint of SCD or ventricular arrhythmias after CIED implantation.

Results

Among 700 patients (age 68.0 ± 12.0yrs [mean ± SD]), 27 (3.85%) experienced a SCD and 121 (17.3%) met the arrhythmic endpoint over 6.93 yrs (median; interquartile range 5.82-9.32). MFVA predicted SCD (hazard ratio [HR]: HR:26.3 [95% confidence interval [CI] 3.70-3337]; negative predictive value: 100%). In competing risks analyses, MFVA also predicted the arrhythmic endpoint (subdistribution [sHR]: 19.9 [95% CI 6.40-61.9]; negative predictive value:98.6%). Compared with no MFVA, a GZF mass measured with the 5SD method (GZF5SD) > 17 g was associated with highest risk of SCD (HR: 44.6;95% CI 6.12-5685) and the arrhythmic endpoint (sHR: 30.3 [95% CI 9.60-95.8]). Adding GZF5SD mass to MFVA led to reclassification of 39% for SCD and 50.2% for the arrhythmic endpoint. In contrast, LVEF did not predict either endpoint.

Conclusions

In CIED recipients, MFVA excluded patients at risk of SCD and virtually excluded ventricular arrhythmias. Quantified GZF5SD mass added predictive value in relation to SCD and the arrhythmic endpoint.

Grayzone myocardial fibrosis and ventricular arrhythmias in patients with a left ventricular ejection fraction greater than 35%

Funding Acknowledgements

Type of funding sources: None.

BACKGROUND Clinical guidelines adopt LVEF cut-offs <30 or <35% as an indication for implantable cardioverter defibrillator (ICD) therapy. Most patients succumbing to sudden cardiac death (SCD), however, have a LVEF≥35%.

OBJECTIVES To determine whether myocardial fibrosis (MF) and grayzone fibrosis (GZF) on cardiovascular magnetic resonance (CMR) is associated with ventricular arrhythmias in patients with coronary artery disease (CAD) and a LVEF≥35%.

METHODS In this retrospective study of CAD patients, GZF mass using the 3SD method (GZF3SD) and total fibrosis mass using the 2SD method (TF2SD) on CMR were assessed in relation to the primary, combined endpoint of SCD, ventricular tachycardia, ventricular fibrillation or resuscitated cardiac arrest.

RESULTS Among 701 patients (age: 65.8 ± 12.3 yrs [mean ± SD]), 28 (3.99%) patients met the primary endpoint over 5.91 years (median; interquartile range 4.42-7.64). In competing risks analysis, a GZF3SD mass ≥ 5.0 g was strongly associated with the primary endpoint (subdistribution hazard ratio [sHR]: 17.4 [95% CI 6.64-45.5]); area under receiver operator characteristic curve [AUC]: 0.85, p < 0.001). A weaker association was observed for TF2SD mass ≥ 23 g (HR: 10.4 [95% CI 4.22-25.8]; AUC: 0.80, p < 0.001). The range of sHRs for GZF3SD mass (1 to 526.6) was wider than for TF2SD mass (1 to 37.6).

CONCLUSIONS In CAD patients with a LVEF≥35%, GZF3SD mass was strongly associated with the arrhythmic endpoint. These findings hold promise for its use in identifying patients with CAD and a LVEF≥35% at risk of arrhythmic events. Abstract Figure.

Myocardial fibrosis as a predictor of sudden death in patients with coronary artery disease

Funding Acknowledgements

Type of funding sources: None.

BACKGROUND The ‘grayzone’ of myocardial fibrosis (GZF) on cardiovascular magnetic resonance may be a substrate for ventricular arrhythmias (VAs).

OBJECTIVES To determine whether GZF predicts SCD and VAs (ventricular fibrillation or sustained ventricular tachycardia) in patients with coronary artery disease (CAD) and a wide range of LVEFs.

METHODS In this retrospective study of CAD patients, myocardial fibrosis presence on visual assessment (MFVA) and GZF mass in patients with MFVA was assessed in relation to SCD and the composite, arrhythmic endpoint of SCD or VAs.

RESULTS Among 979 patients (age: 65.8 ± 12.3 yrs [mean ± SD]), 29(2.96%) suffered a SCD and 80(8.17%) met the arrhythmic endpoint over 5.82 years (median; interquartile range: 4.1-7.3). In the whole cohort, MFVA was strongly associated with SCD (hazard ratio [HR]:10.1, 95% CI 1.42-1278.9) and the arrhythmic endpoint (HR:28.0, 95% CI 4.07-3525.4). In competing risks analyses, associations between LVEF < 35% and SCD (subdistribution HR [sHR]:2.99, 95% CI 1.42-6.31) and the arrhythmic endpoint (sHR:4.71, 95% CI 2.97-7.47) were weaker. In competing risks analyses of the MFVA subcohort (n = 832), GZF using the 3SD method (GZF3SD) > 5.0 g was strongly associated with SCD (sHR:10.8, 95% CI 3.74-30.9) and the arrhythmic endpoint (sHR:7.40, 95% CI 4.29-12.8). Associations between LVEF < 35% and SCD (sHR:2.62, 95% CI 1.24-5.52) and the arrhythmic endpoint (sHR:4.14, 95% CI 2.61-6.57) were weaker.

CONCLUSIONS In CAD patients, MFVA plus quantified GZF3SD mass was more strongly associated with SCD and VAs than LVEF. In selecting patients for implantable cardioverter defibrillators, assessment of MFVA followed by quantification of GZF3SD mass may be preferable to LVEF. Abstract Figure.

The myocardial phenotype of Fabry disease pre-hypertrophy and pre-detectable storage

Background

Cardiac involvement in Fabry Disease (FD) occurs prior to left ventricular hypertrophy (LVH) and is characterized by low myocardial native T1 with storage reflected by cardiovascular magnetic resonance (CMR) and ECG changes.

Objectives

We hypothesize that a pre-storage myocardial phenotype might occur even earlier, prior to T1 lowering.

Methods

FD patients and age, sex and heart rate matched healthy controls underwent same-day ECG with advanced analysis and multiparametric CMR (cines, global longitudinal strain [GLS], T1 and T2 mapping, stress perfusion [myocardial blood flow, MBF] and late gadolinium enhancement [LGE]).

Results

114 Fabry patients (46±13 years, 61% female) and 76 controls (49±15 years, 50% female) were included. In pre-LVH FD (n=72, 63%), a low T1 (n=32/72, 44%) was associated with a constellation of ECG and functional abnormalities compared to normal T1 FD patients and controls. However, pre-LVH FD with normal T1 (n=40/72, 56%) also had abnormalities compared to controls: reduced GLS (−18±2 vs −20±2%, P<0.001), microvascular changes (lower MBF 2.5±0.7 vs 3.0±0.8mL/g/min, P=0.028), subtle T2 elevation (50±4 vs 48±2ms, p=0.027) and limited LGE (%LGE 0.3±1.1 vs 0%, P=0.004). ECG abnormalities included shorter P wave duration (88±12 vs 94±15ms, P=0.010) and T wave peak time (Tonset–Tpeak; 104±28 vs 115±20ms, P=0.015), resulting in a more symmetric T wave with lower T wave time ratio (Tonset–Tpeak)/(Tpeak–Tend) (1.5±0.4 vs 1.8±0.4, P<0.001) compared to controls.

Conclusions

FD has a measurable myocardial phenotype pre-LVH and pre-detectable myocyte storage with microvascular dysfunction, subtly impaired GLS and altered atrial depolarization and ventricular repolarization intervals.

Proposed stages of cardiac involvement

Funding Acknowledgement

Type of funding source: None

Metastatic small bowel neuroendocrine tumour with bilateral carcinoid heart disease

A 63-year-old woman was admitted with a year's history of exertional breathlessness, anxiety attacks, syncopal episodes, diarrhoea, fatigue, reduced appetite, 2 stones weight loss, and flushing affecting her face and trunk. Investigations revealed raised urine 5-hydroxy indole acetic acid (5-HIAA) and chromogranin A. CT scan demonstrated extensive soft tissue encasing the major vessels intra-abdominally, and a retroperitoneal mass. (111)In-octreotide single-photon emission CT (SPECT CT) showed increased focal activity in the mediastinum, retroperitoneum and mesenteric lymph nodes. Para aortic lymph node biopsy confirmed the diagnosis of metastatic well-differentiated grade 1 gastrointestinal neuroendocrine tumour (NET). Extensive cardiac investigations confirmed severe mitral regurgitation, moderate aortic and tricuspid regurgitation, and mild pulmonary regurgitation. The patient's symptoms of flushing and diarrhoea were controlled with octreotide LAR, and she underwent mechanical aortic and mitral valve replacement. Following discharge from surgery, she went on to develop hydronephrosis and urosepsis, followed by infective endocarditis, resulting in recurrent admissions, and eventually passed away in her sleep nearly 14 months after her initial diagnosis.

Analysis of promoter region polymorphism in the aldosterone synthase gene (CYP11B2) as a risk factor for myocardial infarction

Several polymorphisms in genes of the reninangiotensin-aldosterone system have been found to have pleiotropic effects on cardiovascular disorders. Recently, a polymorphism (-344 C/T) in the promoter region of the aldosterone synthase gene (CYP11B2), which may influence plasma aldosterone levels, has been reported to strongly influence left ventricular diameters and mass in young adults and arterial stiffness in essential hypertensives. We investigated any association with risk of myocardial infarction (MI). CYP11B2 -344 polymorphism genotypes were determined by polymerase chain reaction (PCR) in 542 acute MI cases and 500 control subjects without history of coronary disease. All subjects were white and <75 years old. There was no significant difference in either genotype distributions (cases CC 17%, CT 52%, TT 31%; controls CC 22%, CT 47%, TT 31%, P = .10) or allele frequencies (cases C/T 0.43/0.57, controls C/T 0.46/0.54, P = .39) between cases and controls. The odds ratio (OR) for MI associated with the CC genotype was 0.75 (0.54-1.05), and remained insignificant when analysis was restricted to the 129 (24%) cases and 193 (37%) controls < 55 years of age (OR 0.68 [0.36-1.27], P = .20). In further analyses, there was no interaction of the polymorphism with other cardiovascular risk factors (smoking, hypertension, diabetes, body mass index, or cholesterol level) in determining MI risk, and the polymorphism did not influence the frequency of these risk factors in either cases or controls. In the case cohort, age at MI was not significantly different in subjects with the three genotypes (CC 61.2 +/- 9.8 years, CT 61.8 +/- 9.1 years, TT 62.2 +/- 9.0 years, P = .69). We conclude that the aldosterone synthase -344 promoter region polymorphism does not significantly influence the risk of MI either directly or via interaction with other risk factors.

Distribution of tissue plasminogen activator insertion/deletion polymorphism in myocardial infarction and control subjects

An insertion (I)/deletion (D) polymorphism in the tissue plasminogen activator (TPA) gene locus has recently been reported to be associated with the risk of myocardial infarction (MI) with increased risk in II/ID subjects compared with DD subjects. To investigate this further, we analysed 529 acute MI cases and 525 population-based control subjects recruited in two centers (Leicester and Sheffield, UK). We found no difference between cases and controls in TPA I/D allele frequencies (cases I = 0.574, controls I = 0.582, p = 0.74) or genotype distribution (cases II 33%, ID 48%, DD 19%; controls II 34%, ID 49%, DD 17%, p = 0.88). Compared with the DD genotype, the age, sex and centre adjusted odds ratios for MI for II genotype was 0.95 (95% confidence interval, 0.64-1.40, p = 0.85) and that for ID genotype was 0.89 (0.62-1.27, p = 0.56). There was no significant effect modification by smoking status, body mass index or cholesterol level. There was no difference in the reported frequency of positive family history of coronary heart disease or mean age at MI in the different genotype groups. We conclude that in our populations the TPA I/D polymorphism is not a major independent risk factor for myocardial infarction.