'Bushfire Season' in Australia: Determinants of Increases in Risk of Acute Coronary Syndromes and Takotsubo Syndrome

BACKGROUND

Climate change has resulted in an increase in ambient temperatures during the summer months as well as an increase in risk of associated air pollution and of potentially disastrous bushfires throughout much of the world. The increasingly frequent combination of elevated summer temperatures and bushfires may be associated with acute increases in risks of cardiovascular events, but this relationship remains unstudied. We evaluated the individual and cumulative impacts of daily fluctuations in temperature, fine particulate matter of less than 2.5 µm (PM_2.5) pollution and presence of bushfires on incidence of acute coronary syndromes and Takotsubo syndrome.

METHODS

From November 1, 2019, to February 28, 2020, all admissions with acute coronary syndromes or Takotsubo syndrome to South Australian tertiary public hospitals were evaluated. Univariate and combined associations were sought among each of 1) maximal daily temperature, 2) PM_2.5 concentrations, and 3) presence of active bushfires within 200 km of the hospitals concerned.

RESULTS

A total of 504 patients with acute coronary syndromes and 35 with Takotsubo syndrome were studied. In isolation, increasing temperature was associated (r_s = 0.26, P = .005) with increased incidence of acute coronary syndromes, while there were similar, but nonsignificant correlations for PM_2.5 and presence of bushfires. Combinations of all these risk factors were also associated with a doubling of risk of acute coronary syndromes. No significant associations were found for Takotsubo syndrome.

CONCLUSION

The combination of high temperatures, presence of bushfires and associated elevation of atmospheric PM_2.5 concentrations represents a substantially increased risk for precipitation of acute coronary syndromes; this risk should be factored into health care planning including public education and acute hospital preparedness.

Incidence and clinical/laboratory correlates of early hypotension in takotsubo syndrome

Aims

Takotsubo syndrome (TTS) is a form of acute myocardial inflammation, often triggered by catecholamine release surges, which accounts for approximately 10% of ‘myocardial infarctions’ in female patients above the age of 50. Its associated substantial risk of in‐hospital mortality is mainly driven by the development of hypotension and shock. While hypotension is induced largely by factors other than low cardiac output, its precise cause is unknown, and clinical parameters associated with hypotension have not been identified previously. We therefore sought to identify the incidence and clinical/laboratory correlates of early hypotension in TTS.

Methods and results

We analysed the in‐hospital data of patients recruited to the South Australian TTS Registry. Associations between the development of hypotension, patient demographics, severity of the acute TTS attack, and key biochemical markers were sought. One hundred thirteen out of 319 patients (35%) were hypotensive (median systolic blood pressure 80 mmHg) during their index hospitalization. Development of hypotension preceded all in‐hospital deaths (n = 8). On univariate analyses, patients who developed hypotension had lower left ventricular ejection fraction (P = 0.009), and higher plasma N‐terminal pro brain natriuretic peptide and troponin‐T concentrations (P = 0.046 and 0.008, respectively), all markers of severity of the TTS attack; hypotension also occurred less commonly in male than in female patients (P = 0.014). On multivariate linear regression analysis, female sex and lower left ventricular ejection fraction were independent correlates of the development of hypotension (P = 0.009 and 0.010, respectively).

Conclusions

Early development of hypotension is very common in TTS, and its presence is associated with a substantial risk of in‐hospital mortality. Hypotension is a marker of severe TTS attacks and occurs more commonly in female TTS patients.

Takotsubo Syndrome: Finally Emerging From the Shadows?

It is now 30 years since Japanese investigators first described Takotsubo Syndrome (TTS) as a disorder occurring mainly in ageing women, ascribing it to the impact of multivessel coronary artery spasm. During the intervening period, it has become clear that TTS involves relatively transient vascular injury, followed by prolonged myocardial inflammatory and eventually fibrotic changes. Hence symptomatic recovery is generally slow, currently an under-recognised issue. It appears that TTS is induced by aberrant post-β₂-adrenoceptor signalling in the setting of "surge" release of catecholamines. Resultant activation of nitric oxide synthases and increased inflammatory vascular permeation lead to prolonged myocardial infiltration with macrophages and associated oedema formation. Initially, the diagnosis of TTS was made via exclusion of relevant coronary artery stenoses, plus the presence of regional left ventricular hypokinesis. However, detection of extensive myocardial oedema on cardiac MRI imaging offers a specific basis for diagnosis. No adequate methods are yet available for definitive diagnosis of TTS at hospital presentation. Other major challenges remaining in this area include understanding of the recently demonstrated association between TTS and antecedent cancer, the development of effective treatments to reduce risk of short-term (generally due to shock) and long-term mortality, and also to accelerate symptomatic recovery.

The N-AcetylCysteine and RAMipril in Takotsubo Syndrome Trial (NACRAM): Rationale and design of a randomised controlled trial of sequential N-Acetylcysteine and ramipril for the management of Takotsubo Syndrome

BACKGROUND

Takotsubo Syndrome(TTS), contrary to historical reports, is now increasingly recognised to be associated with substantial mortality and morbidity, both in the short- and long-term. Although TTS is often precipitated by a catecholamine "pulse", in-hospital hypotension is a common occurrence, increasing the risk of mortality. Furthermore, despite the transient catecholamine stimulus, there is increasing evidence that there are significant long term sequelae, including persistently impaired left ventricular(LV) systolic dysfunction, myocardial oedema with fibrosis, as well as persistent impairment of quality of life. A definitive therapeutic option to limit the extent of initial myocardial injury, and to accelerate recovery in TTS is therefore justified. However to date, there has been a lack of prospective studies in this area.

DESIGN AND RATIONALE

NACRAM is a multi-centre, randomised, placebo-controlled trial, sequentially testing early use of intravenous N-acetylcysteine(NAC), followed by/or oral ramipril for 12 weeks. The rationale for utilising these agents is related to their effects on limiting nitrosative stress and expression of the inflammasome activator thioredoxin interacting protein(TXNIP); both processes fundamental to the pathogenesis of TTS.

END POINTS

NACRAM is assessing resolution of myocardial oedema on cardiac magnetic resonance imaging(CMR), improvements in LV systolic function as measured by global longitudinal strain(GLS) on echocardiography, quality of life, and inflammatory markers.

DISCUSSION

To the best of our knowledge, NACRAM will be the first prospective study to help definitively evaluate a therapeutic option in acute attacks of TTS.

P813Iatrogenic takotsubo syndrome: incidence and impact

Background

Although Takotsubo syndrome (TTS) was once considered to be rare and largely benign, it is now recognised to represent a major cause of cardiac morbidity and mortality, especially in aging women. The biochemical precipitant of attacks of TTS is an increase in catecholamine concentrations within the myocardium, engendering inflammatory activation via biased post-receptor signalling at myocardial β2-adrenoceptor level. Cases of TTS have been reported in patients treated with catecholamines, and with antidepressants which limit catecholamine re-uptake. In the current investigation, we sought to delineate the extent and potential impact of this “iatrogenic” form of TTS.

Methods/Results

Patients' data from a regional registry of 272 consecutive cases of TTS were evaluated. After exclusion of patients (n=14) in whom TTS has occurred in association with life threatening extracardiac disease states, a total of 47 (18%) of patients were identified as having antecedent exposure to potentially “iatrogenic” agents (antidepressants in 29 cases, β2-adrenoceptor agonists in 14). Demographics, including proportion of male patients, did not differ significantly between patients with and without “iatrogenic” TTS, but plasma concentrations of the catecholamine metabolite normetanephrine tended to be greater (median 1160 vs. 950 pmol/L; p=0.07). Long-term survival (median follow-up 3.5 years) was marginally (p=0.09) worse for patients with “iatrogenic” TTS.

Conclusion

(1) A potentially iatrogenic component of precipitation (via iatrogenic elevation of catecholamine levels and β2-adrenoceptor stimulation) is present in a substantial proportion of patients.

(2) In such patients there is an implication of increased long-term mortality risk, potentially accentuated by continued administration of the precipitating agent(s).

Early rescreen/recall in the UK National Health Service breast screening programme: epidemiological data

OBJECTIVE

In the United Kingdom in 1994-95 about 16,500 women aged 50 to 64 were asked to come back earlier than the usual three yearly screening interval for further mammography (early rescreen (ES)) or for a range of further investigations at an assessment centre (early recall (ER)). This study aimed at providing epidemiological data on ES/ER, in particular, how often and why it is used, and what the outcome is of using it.

SETTING

National Health Service breast screening programme in the United Kingdom.

METHODS

All breast screening units were invited to complete a postal questionnaire. Two reminders were sent. The units were asked retrospectively to provide breast screening data about women aged 50 to 64 from their local computer systems. Women placed on ES/ER were followed up for at least one year.

RESULTS

The response rate was 71% (69/97), of which 14% (10/69) were unable to provide the required data, leaving 59 completed questionnaires (61%). The rate of placing women on ES/ER was above 1.0% for 26/54 (48%) responding breast screening units and above 2.0% for 13/54 (24%) units. Women were placed on ES/ER because of (a) previous breast cancer (21% of cases; cancer detection rate 2.4%), (b) diagnostic uncertainty (51%; cancer detection rate 3.0%), or (c) family history (27%; cancer detection rate 0.6%). Breast screening units with a high rate of placing women on ER were significantly more likely to have a high recall rate (rs = 0.63; n = 53; p < 0.0005) or a high benign surgical biopsy rate (rs = 0.33; n = 49; p < 0.05), or both. The cancer detection rate of ES/ER tended to decrease with increasing ES/ER rates (rs = -0.37; n = 51; p < 0.01).

CONCLUSIONS

A relatively large number of women were placed on ES or ER for a range of reasons. If the recommendations given are followed, the number of women placed on ER may be reduced while maintaining the cancer detection rate at the required level. The option of ES should not be used.