COVID-19-induced postural orthostatic tachycardia syndrome treated with ivabradine.

A 22-year-old woman was referred with exertional dyspnoea and chest tightness 3 weeks following a diagnosis of COVID-19. Evaluation revealed a resting sinus tachycardia and criteria for postural orthostatic tachycardia syndrome were met. After non-pharmacological interventions failed to yield symptomatic improvement, ivabradine was commenced. This intervention was followed by a substantial improvement in the patient's exercise tolerance and energy levels and an objective reduction in supine and standing heart rate.

Inferolateral T wave inversion in athletes: phenotype-genotype correlation.

AIMS: Significant T wave inversion in young asymptomatic athletes is rare but poses a significant clinical challenge. Pre-participation sports screening programs identify such subjects. Clinical concern that such ECG changes represent an occult cardiomyopathy or forme fruste hypertrophic cardiomyopathy leads to diagnostic and therapeutic dilemma. We sought to genotype a cohort of such subjects with a normal cardiac phenotype identified in our unit over a 3-year period. METHODS: Ten athletes were referred from external screening. All exhibited deep T wave inversion inferolaterally. All had negative family history for sudden death and had a normal phenotype. A panel of 133 cardiac genes were screened. RESULTS: Ten male subjects with mean age of 39 years were screened. Seven had no evidence of mutations. Three subjects demonstrated variants of uncertain significance in 5 different genes: alpha-2-actinin (ACTN2), myopalladin (MYPN), the calcium channel genes CACNA1C and TRPM4 and potassium channel gene KCNQ1. The variants found have not been described in cardiomyopathies or channelopathies. At 3-year follow-up, one patient had undergone detraining, and his ECG showed complete resolution of all T wave changes. He did not have any demonstrated variants. CONCLUSIONS: The absence of mutations in target genes and heterogeneous sequence variations identified in this study suggest that inferolateral T wave inversion in athletes without a phenotype may potentially represent a benign repolarization syndrome related to athletic adaptation. This was the first study to assess a phenotype-genotype correlation in this population. Further genetic studies need to be undertaken in this area.

Randomized placebo controlled trial evaluating the safety and efficacy of single low-dose intracoronary insulin-like growth factor following percutaneous coronary intervention in acute myocardial infarction (RESUS-AMI).

BACKGROUND: Residual and significant postinfarction left ventricular (LV) dysfunction, despite technically successful percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI), remains an important clinical issue. In preclinical models, low-dose insulin-like growth factor 1 (IGF1) has potent cytoprotective and positive cardiac remodeling effects. We studied the safety and efficacy of immediate post-PCI low-dose intracoronary IGF1 infusion in STEMI patients. METHODS: Using a double-blind, placebo-controlled, multidose study design, we randomized 47 STEMI patients with significantly reduced (≤40%) LV ejection fraction (LVEF) after successful PCI to single intracoronary infusion of placebo (n = 15), 1.5 ng IGF1 (n = 16), or 15 ng IGF1 (n = 16). All received optimal medical therapy. Safety end points were freedom from hypoglycemia, hypotension, or significant arrhythmias within 1 hour of therapy. The primary efficacy end point was LVEF, and secondary end points were LV volumes, mass, stroke volume, and infarct size at 2-month follow-up, all assessed by magnetic resonance imaging. Treatment effects were estimated by analysis of covariance adjusted for baseline (24 hours) outcome. RESULTS: No significant differences in safety end points occurred between treatment groups out to 30 days (χ2 test, P value = .77). There were no statistically significant differences in baseline (24 hours post STEMI) clinical characteristics or LVEF among groups. LVEF at 2 months, compared to baseline, increased in all groups, with no statistically significant differences related to treatment assignment. However, compared with placebo or 1.5 ng IGF1, treatment with 15 ng IGF1 was associated with a significant improvement in indexed LV end-diastolic volume (P = .018), LV mass (P = .004), and stroke volume (P = .016). Late gadolinium enhancement (±SD) at 2 months was lower in 15 ng IGF1 (34.5 ± 29.6 g) compared to placebo (49.1 ± 19.3 g) or 1.5 ng IGF1 (47.4 ± 22.4 g) treated patients, although the result was not statistically significant (P = .095). CONCLUSIONS: In this pilot trial, low-dose IGF1, given after optimal mechanical reperfusion in STEMI, is safe but does not improve LVEF. However, there is a signal for a dose-dependent benefit on post-MI remodeling that may warrant further study.

A case of autosomal recessive hypercholesterolemia responsive to proprotein convertase subtilisin/kexin 9 inhibition.

We report the first case of hypercholesterolemia due to autosomal recessive hyperlipidemia caused by LDLRAP1 mutation responding favorably to PCSK9 inhibition.

Coronary artery anomalies: a practical approach to diagnosis and management.

The authors deal with common coronary anomalies, discuss their anatomy and some diagnostic and clinical aspects, and describe some of the principles of management.

Relation of different measures of low-density lipoprotein cholesterol to risk of coronary artery disease and death in a meta-regression analysis of large-scale trials of statin therapy.

Multiple randomized controlled trials (RCTs) have established the efficacy of statins for the prevention of cardiovascular disease. The benefits observed are often framed in terms of percentage reductions in low-density lipoprotein (LDL) cholesterol from baseline or percentage reductions between control and treatment groups, although epidemiologic data suggest that the absolute intergroup difference in LDL cholesterol (DeltaLDL(Control-Rx)) is the more informative measure. A systematic review of large-scale trials of statins versus placebo, usual care, or active (lower dose statin) control was conducted to calculate updated summary estimates of risk reduction in coronary artery disease and all-cause mortality. Meta-regression analysis was used to ascertain the relations of different LDL cholesterol metrics to outcomes. In 20 eligible RCTs, there were significant overall reductions for coronary artery disease (odds ratio 0.72, 95% confidence interval 0.67 to 0.78) and mortality (odds ratio 0.89, 95% confidence interval 0.84 to 0.94), but with substantial variability in trial results. DeltaLDL(Control-Rx) was the strongest determinant of coronary artery disease risk reduction, particularly after excluding active-comparator studies, and was independent of baseline LDL cholesterol. In contrast, baseline LDL cholesterol edged out DeltaLDL(Control-Rx) as the strongest determinant of mortality, but neither was significant after the exclusion of active-comparator studies. The exclusion of 3 RCTs involving distinct populations, however, rendered DeltaLDL(Control-Rx) the predominant determinant of mortality reduction. In conclusion, these findings underscore the primacy of absolute reductions in LDL cholesterol in the design and interpretation of RCTs of lipid-lowering therapies and in framing treatment recommendations on the basis of the proved coronary benefits of these drugs.

Comparative PRKAR1A genotype-phenotype analyses in humans with Carney complex and prkar1a haploinsufficient mice.

Carney complex (CNC) is a familial multiple neoplasia syndrome characterized by cardiac and extracardiac myxomas in the setting of spotty skin pigmentation and endocrinopathy. We previously identified PRKAR1A (regulatory subunit 1alpha of protein kinase A) mutations in CNC. Mutational analyses of the PRKAR1A gene in 51 unrelated CNC probands now detect mutations in 65%. All mutations, except for one unique missense mutation, lead to PRKAR1A haploinsufficiency. Therefore, we studied the consequences of prkar1a haploinsufficiency in mice. Although we did not observe cardiac myxomas or altered pigmentation in prkar1a(+/-) mice, we did observe some phenotypes similar to CNC, including altered heart rate variability. Moreover, prkar1a(+/-) mice exhibited a marked propensity for extracardiac tumorigenesis. They developed sarcomas and hepatocellular carcinomas. Sarcomas were frequently associated with myxomatous differentiation. Tumors from prkar1a(+/-) mice did not exhibit prkar1a loss of heterozygosity. Thus, we conclude that although PRKAR1A haploinsufficiency does predispose to tumorigenesis, distinct secondary genetic events are required for tumor formation.

Molecular genetic analysis of PRKAG2 in sporadic Wolff-Parkinson-White syndrome.

INTRODUCTION: Mutations in the PRKAG2 gene that encodes the gamma2 regulatory subunit of AMP-activated protein kinase have been shown to cause autosomal dominant Wolff-Parkinson-White (WPW) syndrome associated with hypertrophic cardiomyopathy. Prior studies focused on familial WPW syndrome associated with other heart disease such as hypertrophic cardiomyopathy. However, such disease accounts for only a small fraction of WPW cases, and the contribution of PRKAG2 mutations to sporadic isolated WPW syndrome is unknown. METHODS AND RESULTS: Subjects presented for clinical electrophysiologic evaluation of suspected WPW syndrome. WPW syndrome was diagnosed by ECG findings and/or by clinically indicated electrophysiologic study prior to enrollment. Echocardiography excluded hypertrophic cardiomyopathy. Denaturing high-performance liquid chromatography and automated sequencing were used to search for PRKAG2 mutations. Twenty-six patients without a family history of WPW syndrome were studied. No subject had cardiac hypertrophy, and only one patient had associated congenital heart disease. Accessory pathways were detected at diverse locations within the heart. Two polymorphisms in PRKAG2 were detected. [inv6+36insA] occurred in intron 6 in 4 WPW patients and [inv10+10delT] in intron 10 in 1 WPW patient. Both occurred in normal unrelated chromosomes. No PRKAG2 mutations were detected. CONCLUSION: This study shows that, unlike familial WPW syndrome, constitutional mutation of PRKAG2 is not commonly associated with sporadic WPW syndrome. Although polymorphisms within the PRKAG2 introns were identified, there is no evidence that these polymorphisms predispose to accessory pathway formation because their frequency is similarly high in both WPW patients and normal individuals. Further studies are warranted to identify the molecular basis of common sporadic WPW syndrome.

Prevention of stroke and dementia with statins: Effects beyond lipid lowering.

Stroke is a major cause of mortality and morbidity. The epidemiologic association between elevated serum cholesterol and stroke risk is controversial. However, recent secondary prevention studies with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have demonstrated a significant reduction in ischemic stroke without an increase in hemorrhagic stroke. Statins probably reduce stroke by a variety of mechanisms, including modulation of precerebral atherothrombosis in the aorta and the carotid artery, thus preventing plaque disruption and artery-to-artery thromboembolism. Statins also improve endothelial homeostasis by increasing the bioavailability of nitric oxide, which orchestrates the paracrine antiatherosclerotic functions of the endothelium. Studies in experimental models of ischemic stroke show that statin therapy reduces brain infarct size and improves neurologic outcome by directly upregulating brain endothelial nitric oxide synthase. Putative anti-inflammatory actions of statins may also contribute to neuroprotection and stroke prevention. Although the clinical benefit of statins largely depends on lowering low-density lipoprotein cholesterol, accumulating data indicate that many of the pleiotropic effects of statins are attributable to the cellular consequences of depletion of intermediates in the cholesterol biosynthetic pathway (isoprenoids). These molecules play fundamental roles in cell growth, signal transduction, and mitogenesis. In addition to reducing stroke risk, emerging data suggest that statins may reduce dementia. Further studies are needed to fully address the role of statins in the prevention of stroke in patients without established vascular disease and the role of cholesterol modulation in the treatment of dementia.

Statins in acute coronary syndromes.

The development of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors (statins) has been a very significant development in the management of coronary artery disease. Large prospective clinical trials have provided unequivocal evidence that cholesterol lowering therapy with statins reduces all-cause mortality in patients with coronary artery disease. There is now accumulating data indicating that statin treatment should be initiated early after an acute coronary syndrome. This body of evidence is based on large databases in which investigators compared outcomes among patients taking statins with those patients who were not prescribed cholesterol lowering therapy. Prospective, randomized, clinical trials also indicate that early statin therapy reduces recurrent ischemia. Finally, studies examining long-term compliance with statin therapy suggest increased adherence to therapy when statins are prescribed during the initial hospitalization for an acute coronary syndrome. In tandem with these clinical observations, there is a large body of scientific data that highlights many important cellular and molecular mechanisms through which statins may confer early benefit. These effects involve relatively rapid improvement in endothelial function, antiischemic, antithrombotic and antiinflammatory actions of statins.