Impact of the ISCHEMIA randomized clinical trial on the management of patients with chronic coronary syndrome

Background

In the ISCHEMIA trial, patients with chronic coronary syndromes (CCS) and moderate or severe ischemia had no significant difference in combined ischemic events with an initial invasive compared with a conservative strategy [1]. Coronary computed tomography angiography (CCTA) was part of the pre-randomization workup of ISCHEMIA and is gaining popularity over ischemia testing or initial invasive coronary angiography (ICA) as the initial diagnostic strategy for CCS [2].

Purpose

To analyse whether the results of the ISCHEMIA trial had a sizeable impact on the diagnostic algorithm for CCS by analysing trends in referral to ICA and/or revascularization.

Methods

ICAs performed in CCS patients between November 2019 and February 2022 at a high-volume centre were analysed. Two groups were defined based on procedure date: i) pre-ISCHEMIA, including ICAs performed before March 2020 (date of trial publication); ii) post-ISCHEMIA, including ICAs performed ≥3 months (i.e., blanking period) after trial publication. The primary outcome was the incidence of referral to ICA by CCTA. Secondary objectives included referral to ICA or revascularization by ischemia testing, referral to revascularization by CCTA, and referral by CCTA to ICA that did not require further intervention.

Results

A total of 2,365 patients qualified for the analysis, of which 487 (20.6%) and 1878 (79.4%) in the pre-ISCHEMIA and post-ISCHEMIA groups, respectively. There were no notable differences in baseline characteristics between groups. The primary outcome occurred more frequently in the post-ISCHEMIA group (73.5% vs 32.5%, p<0.01). Referral to ICA by ischemia testing was lower in the post-ISCHEMIA group (31.6%, vs 52.5% p<0.01), while referral for revascularization by CCTA was more frequent (8.3% vs 12.0% p<0.01). There were no significant differences in referral to revascularization by ischemia testing (3.4% vs 3.0%, p=0.73) and referral by CCTA to ICA that did not require further intervention (60.3% vs 60.8%, p=0.90).

Conclusions

At two years from publication, the ISCHEMIA trial seems to have impacted significantly on the decision-making algorithm for patients with CCS. The frequency of referral to ICA and revascularization by CCTA considerably increased, paralleled by decreased referral to ICA by ischemia testing.

Funding Acknowledgement

Type of funding sources: None.

A new mutation in the mitochondrial tRNA(Ala) gene in a patient with ophthalmoplegia and dysphagia

We describe a new mutation in the tRNA(Ala) gene, a T-->C transition at nucleotide position 5628, in a 62-year-old woman with late onset chronic progressive external ophthalmoplegia, dysphagia and mild proximal myopathy. The mutation is heteroplasmic and disrupts a highly conserved A-U base pair within the anticodon stem of the tRNA(Ala). Cytochrome c oxidase-negative fibers harbor a significantly higher level of mutated mtDNA than cytochrome c oxidase-positive fibers. This is the first mutation in the tRNA(Ala) gene which satisfies accepted criteria for pathogenicity.

T-cell anti-apoptotic mechanisms in inflammatory myopathies

Recent studies have shown an up-regulation of the Fas/Fas ligand system in inflammatory myopathies. In myositis, however, the major Fas-mediated cytotoxicity which activates caspases bypasses apoptosis. We therefore evaluated the expression of proteins promoting cell survival, such as bcl-2, bcl-x(l) and cyclin-dependent kinase inhibitors, on muscle biopsies from 14 patients with polymyositis, dermatomyositis, inclusion body myositis and HIV-associated myositis. Our data demonstrate that inflammatory cells are immunoreactive for bcl-x(l), p16 and p57, three apoptosis-preventing proteins. Hence, we assume that these proteins might protect T cells from apoptotic nuclear changes. Our results could explain the non-self-limiting nature of inflammatory myopathies.

Functional consequences of mutations in the human alpha1A calcium channel subunit linked to familial hemiplegic migraine

Mutations in alpha1A, the pore-forming subunit of P/Q-type calcium channels, are linked to several human diseases, including familial hemiplegic migraine (FHM). We introduced the four missense mutations linked to FHM into human alpha1A-2 subunits and investigated their functional consequences after expression in human embryonic kidney 293 cells. By combining single-channel and whole-cell patch-clamp recordings, we show that all four mutations affect both the biophysical properties and the density of functional channels. Mutation R192Q in the S4 segment of domain I increased the density of functional P/Q-type channels and their open probability. Mutation T666M in the pore loop of domain II decreased both the density of functional channels and their unitary conductance (from 20 to 11 pS). Mutations V714A and I1815L in the S6 segments of domains II and IV shifted the voltage range of activation toward more negative voltages, increased both the open probability and the rate of recovery from inactivation, and decreased the density of functional channels. Mutation V714A decreased the single-channel conductance to 16 pS. Strikingly, the reduction in single-channel conductance induced by mutations T666M and V714A was not observed in some patches or periods of activity, suggesting that the abnormal channel may switch on and off, perhaps depending on some unknown factor. Our data show that the FHM mutations can lead to both gain- and loss-of-function of human P/Q-type calcium channels.