Lower stress perfusion in patients with myocardial infarction with non-obstructive coronary arteries compared to controls in long-term follow-up with quantitative perfusion mapping

Introduction

Myocardial infarction with non-obstructive coronary arteries (MINOCA) constitutes a heterogenous condition with different coronary, cardiac and non-cardiac etiologies. Cardiovascular magnetic resonance imaging (CMR) has emerged as an important diagnostic tool in recent years and is now recommended in patients with MINOCA as a working diagnosis. However, despite early CMR following admission for MINOCA, no cause can be found in around 25% of all patients. A pathophysiological mechanism may be diffuse global coronary microvascular dysfunction (CMD) which has emerged as an important cause of myocardial ischemia. Quantitative adenosine stress CMR perfusion mapping allows for absolute quantification of myocardial perfusion, reflecting CMD in the absence of obstructive coronary disease in MINOCA patients.

Purpose

To study the presence of CMD in MINOCA patients with an initial normal CMR scan compared to healthy controls.

Methods

Patients from the multicenter myocardial infarction in our city with normal Coronaries 2 (SMINC-2) study, with a normal CMR scan 2–4 days after hospitalization, and healthy age- and sex-matched controls underwent stress perfusion at 1.5T (MAGNETOM Aera). Native rest T1 and T2 short-axis maps were acquired. Quantitative perfusion maps were acquired during adenosine stress (140 micrograms/kg/min) and at rest following an intravenous contrast bolus (0.05 mmol/kg of gadoteric acid, Gd-DOTA). Post contrast T1 maps were acquired after intravenous contrast (total dose 0.2 mmol/kg) rendering extracellular volume (ECV) maps. Global native T1, T2, ECV and rest and stress perfusion values were acquired by averaging segmental values per patient. Myocardial perfusion reserve (MPR) was calculated as perfusion in stress divided by rest. Values were presented as mean±standard deviation and compared with the independent t-test in normally distributed data, and with the Mann-Whitney U test in non-normally distributed data. Clinical data regarding cardiovascular risk factors, smoking and medications were presented as numbers (percentages) and compared with Fisher's exact test. Rate pressure product (RPP) was calculated as systolic blood pressure multiplied by heart rate in rest and stress.

Results

In total, 15 patients (59±16 years old, 60% female), and 15 healthy age- and sex-matched controls, were included. There was a trend towards higher incidence of hypertension in patients compared to controls, however no difference in other risk factors (Table 1). Compared to controls, MINOCA patients had lower perfusion in stress (Figure 1). There was no difference in global native T1, T2, ECV, rest perfusion, MPR or hemodynamic parameters between the MINOCA patients and the controls (p>0.05 for all, Table 1).

Conclusions

Myocardial stress perfusion is lower in MINOCA patients with a normal initial CMR scan compared to age- and sex-matched controls suggesting CMD as a possible pathophysiological mechanism in MINOCA.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Swedish Heart and Lung Foundation

Long-term survival in patients with univentricular heart: a nationwide, register-based cohort study

Background

Univentricular heart (UVH) is a broad term that covers various cardiac structural abnormalities in which one ventricle is severely underdeveloped, or a ventricular septal wall did not form, leading to a functional single-ventricle physiology. Patients with UVH have a very limited life expectancy if not surgically treated. While the outcome in children with UVH have been extensively studied, data regarding the long-term outcomes in an unselected, nationwide cohort is still lacking.

Purpose

The aim of the present study was to determine long-term survival in patients with UVH compared to an age- and sex-matched control population without congenital heart disease in Sweden.

Methods

We linked data from the Swedish Patient and Cause of Death Register to identify patients with UVH that were born between 1970 and 2017. Each patient with UVH was matched with ten individuals without congenital heart disease for year of birth and sex. The mortality risk in patients with UVH compared with matched controls was analyzed using Cox proportional regression models and Kaplan-Meier survival analysis.

Results

Of a total of 5,075 patients with UVH and 50,620 matched controls, 1,992 (37.9%) and 485 (1.0%) died, respectively. The mean follow-up (standard deviation) was 15.7 (± 14.2) years. A total of 758 patients (14.9%) of the UVH population were diagnosed with hypoplastic left heart syndrome (HLHS). The mortality risk was 53.01 (95% CI, 48.0–58.6) times higher in UVH and 163.5 (95% CI, 124.3–215.2) times higher in HLHS compared to controls. According to birth period, highest mortality was found at the earliest UVH cohort (1970–1981) 59.8%, and decreased by later birth periods. The lowest mortality was in the latest birth period, 2006–2017 (16.3%).

Conclusions

In this nationwide, register-based cohort study, the overall risk of mortality was more than 50 times higher in patients with UVH compared to matched controls. However, an increased survival was observed over time and by later birth periods. Quadragenarians with UVH is still a rare group but are expected to increase during the next decades.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Swedish heart lung foundation

Is impaired exercise capacity associated with higher risk of mortality in adults with congenital heart disease?

Background

Impaired exercise capacity is a common finding among adults with congenital heart disease (CHD) and it has previously been reported that impaired exercise capacity is associated with higher risk of mortality, hospitalisation and/or transplantation. However, previous reports have been single centre with small sample sizes and composite endpoints.

Purpose

The aim of present report was to analyse the association between mortality, as primary endpoint, and aerobic exercise capacity in adults with CHD.

Methods

Data on exercise capacity from all registered test assessed with bicycle ergometer were retrieved from the Swedish Registry of Congenital Heart Disease. Percent of predicted peak workload (%Wpred) was calculated according to sex, age and height and compared to a national reference material (n=1790, 58% men).

Results

2748 adults with CHD were included (41% women). Median age was 31.7 years (range 18–80.6 years) and mean %Wpred was 77±21.0%. At a median follow-up time of 5.3 years (range 0.02–36.5 years) 135 patients were deceased (4.9%). Moderately impaired exercise capacity (50–70% Wpred) (HR 3.0, p<0.001), severely impaired exercise capacity (<50% Wpred) (HR 9.7, p<0.001), NYHA class II (HR 4.4, p<0.001) and NYHA class III–IV (HR 12.6, p<0.001) was associated with increased risk of mortality in univariable cox regression. In multi-variable Cox regression exercise capacity <50% Wpred (HR 3.0, 95% CI [1.5–5.8], p<0.001), NYHA class II (HR 2.8, 95% CI [1.6–5-1], <0.001) and NYHA class III–IV (HR 8.0, 95% CI [4.2–15.1] p<0.001) was associated with higher mortality risk adjusted for sex and diagnosis.

Conclusions

Our findings show that exercise capacity <50% and NYHA class ≥II are both associated with increased risk of mortality, regardless of diagnosis.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): The Swedish Heart-Lung Foundation

No differences in native T1 of the renal cortex between Fabry patients and healthy volunteers in clinically acquired native T1 maps by cardiovascular magnetic resonance

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Karolinska Institutet Swedish Heart and Lung foundation

Introduction

Fabry disease (FD) is a lysosomal disease that causes accumulation of sphingolipids, which untreated may leadto hypertrophic cardiomyopathyand renal failure. Cardiovascular magnetic resonance imaging (CMR) can detect sphingolipid accumulationin the heart, using native T1 mapping. The kidneys are often visible in clinically acquired native T1 maps, however it is currently unknown if clinically acquired native T1 maps of the heart also can be used to detect sphingolipid accumulation in the kidneysin FD patients. 

Purpose

To evaluate if clinically acquired native T1 maps using CMR can be used to detect sphingolipid accumulation in the kidneysin FD patients. 

Methods

FD patients (n = 18, 41 ± 10 years, 44 % male) and healthy volunteers (n = 41, 26 ± 5 years, 49 % male) were retrospectively enrolled. Native T1 maps were acquired with a 1.5 T scanner (Magnetom Aera, Siemens Healthineers, Erlangen, Germany) usinga modified look locker inversion recovery (MOLLI) sequence with a 5s(3s)3s sampling scheme (Siemens WIP 1041). The native T1 maps were analysed using Segment (Medviso AB, Lund, Sweden). Native T1 values were measured by manually delineating regions of interest (ROI), conservatively placed with a minimum gap of 1 pixel between adjacent structures, in the renal cortex, renal medulla, myocardium, spleen, blood, and liver. Renal cortex ROIs were delineated in all slices where the renal cortex was visible and averaged across all slices. Renal medulla, spleen, and liver ROIs were drawn in the slice where most parenchyma was visible. Endo- and epicardial borders were delineated in all slices of the myocardium and averaged across all slices. Blood ROIs were placed in the midventricular slice, Figure 1.

Results

There were no differences in native T1 values between the patients and the healthy volunteers in the renal cortex (1034 ± 88 vs 1038 ± 51 ms, p = 0.89), blood (1632 ± 123 vs 1600 ± 104 ms, p = 0.94), spleen (1143 ± 45 vs 1134 ± 77 ms, p = 0.64) or liver (569 ± 49 vs 576 ± 45 ms, p = 0.57), and did not change when analysed with regards to sex, Figure 2. Native T1-values were lower in the myocardium of the patients compared to the healthy volunteers (937 ± 53 vs 1019 ± 35 ms, p = 0.01), and higher in the renal medulla (1635 ± 144 vs 1523 ± 70 ms, p = 0.01).

Conclusions

Compared to healthy volunteers, patients with FD and myocardial involvement have no differences in native T1 of the renal cortex. FD patients have higher native T1 in the renal medulla, which cannot be explained by differences in blood native T1. The findings suggest that clinically acquired native T1-maps cannot be used to detect sphingolipid accumulation in the renal cortex in FD patients.

Late cardiac interventions in adults with congenital ventricular septal defects

Introduction

Ventricular septal defect (VSD) is one of the most common congenital heart lesions. Shunts with hemodynamic significance are usually closed early in life whereas small shunts are left without intervention. The need for late cardiac interventions in these populations is essentially unknown. The aim was to study the late cardiac interventions in adults with VSD.

Methods

The national register on congenital heart disease was searched for patients with VSD with or without associated simple cardiac defects but without complex lesions. For these patients, the last 10 years (over the age of 18) in the national patient register was searched for cardiac interventions.

Results

774 patients (mean age 39.0±14.7 years, women =50.6%), 224 (28.9%) with previous closure of VSD, were identified. The total observed time was 6920 patient years. There were 43 interventions in 41 patients (5.3%) of whom 12 had a previous closure of VSD. Twelve patients had isolated closure of VSD, 18 closure of VSD together with other cardiac surgery (one of these had repeated cardiac surgery) and 8 had only other cardiac surgery. In 4 cases, a pacemaker was implanted, of whom one together with cardiac surgery.

Conclusion

The need for cardiac interventions is relatively common in adults with a VSD, also in those without previous closure of their shunt. Our data suggests that most patients with a VSD, closed or not, should be offered periodic follow-up as approximately one out of 20 patients may encounter a complication within 10 years.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): The Swedish Heart-Lung Foundation

P6599Upregulation of protein and gene expression of arginase-1 in patients with ST elevation myocardial infarction

Background

The mechanisms underlying rupture of a coronary atherosclerotic plaque and development of myocardial ischemia-reperfusion injury in ST-elevation myocardial infarction (STEMI) remain unknown. Increased arginase-1 activity leads to reduced nitric oxide production and increased formation of reactive oxygen species due to uncoupling of the endothelial nitric oxide synthase (eNOS). These events lead to endothelial dysfunction, plaque instability and increased susceptibility to ischemia-reperfusion injury in acute myocardial infarction. Experimental studies have shown that arginase-1 expression and activity are increased in atherosclerosis and during myocardial ischemia-reperfusion. Accordingly, inhibition of arginase-1 reduces atherosclerotic lesion development and limits the extent of infarct size during ischemia-reperfusion via an eNOS-dependent mechanism. Furthermore, arginase-1 inhibition improves endothelial function in patients with coronary artery disease but the potential role of arginase-1 in patients with STEMI is poorly understood.

Purpose

The purpose of the current study was to test the hypothesis that arginase-1 is upregulated and correlate to infarct size in STEMI patients.

Methods and results

Two independent cohorts of STEMI patients were included. In cohort 1, plasma and buffy coat leukocytes were collected from 53 STEMI patients at the time of arterial puncture for percutaneous coronary intervention, at 24–48 hours post STEMI and at 3 months post STEMI. Gene expression in leukocytes was determined in 51 patients with Affymetrix Human Transcriptome Array 2.0. In cohort 2, plasma was collected from 82 STEMI patients at admission and at 6 months for determination of plasma arginase-1. These patients underwent cardiac magnetic resonance imaging performed at day 4–7 and at 6 months post STEMI. Plasma arginase-1 levels were quantified with ELISA. Control blood samples were collected from 56 healthy age matched subjects. In cohort 1, ARG1 gene expression was four-fold higher in STEMI patients at admission compared to controls (Figure A). This expression returned to control levels within 3 months. Plasma arginase-1 levels were two times higher in STEMI patients at admission compared to controls, and remained elevated at 24–48 hours and at 3 months post STEMI (Figure B). The increase in plasma arginase-1 in STEMI patients was confirmed in cohort 2 (Figure C). Arginase-1 levels did not correlate with infarct size.

Conclusions

STEMI patients demonstrate increased gene expression and plasma levels of arginase-1 in the acute setting. In contrast to gene expression plasma arginase-1 levels remain significantly elevated over time. The markedly increased expression of arginase-1 already at admission may suggest a mechanistic role of arginase-1 in the development of STEMI. Further studies are needed to elucidate whether increased expression, induction and activity of arginase-1 are contributing factors for the development of STEMI.