Cardiac arrest and sudden unexpected death in variant angina: complications of coronary spasm that can occur in the absence of severe organic coronary stenosis

Insights into the invasive diagnostic challenges of coronary artery vasospasm - A systematic review

Coronary provocation testing is an essential diagnostic procedure when evaluating vasospastic angina. Invasive methods using acetylcholine or ergonovine are considered the current gold standard. Despite efforts from global cardiovascular institutions, current protocols vary in dosage, administration time, and procedural approach. In addition, concerns over the specificity of findings and potential complications have limited routine uptake of this procedure in clinical practice. This systematic review evaluates current diagnostic protocols, focusing on invasive provocation testing. We included studies using intracoronary provocation testing with acetylcholine or ergonovine for the assessment of coronary artery vasospasm that detailed specific elements of the procedure (dosage, administration time, etc.) and included ≥50 patients. A total of 28 articles met strict inclusion criteria. Our review highlights the heterogeneity between current diagnostic protocols for invasive provocation testing. We believe standardization of a diagnostic protocol will encourage both current and future cardiologists to incorporate such procedures in the evaluation of variant angina.

Angina and Non-Obstructive Coronary Artery (ANOCA) Patients with Coronary Vasomotor Disorders

Angina and Non-Obstructive Coronary Artery (ANOCA) patients often lack a clear explanation for their symptoms, and are frequently discharged with the label of "unspecified chest pain", despite the availability of functional coronary angiography (provocative spasm and microvascular function testing) to identify potential underlying coronary vasomotor disorders. This study compared the outcomes of ANOCA patients with a coronary vasomotor disorder diagnosis post elective coronary angiography to patients discharged with unspecified chest pain. Using the CADOSA (Coronary Angiogram Database of South Australia) registry, consecutive symptomatic patients (n = 7555) from 2012 to 2018 underwent elective angiography; 30% had ANOCA (stenosis <50%). Of this cohort, 9% had documented coronary vasomotor disorders diagnosed, and 91% had unspecified chest pain. Patients with coronary vasomotor disorders were younger and had a similar female prevalence compared with those with unspecified chest pain. New prescriptions of calcium channel blockers and long-acting nitrates were more common for the coronary vasomotor cohort at discharge. In the 3 years following angiography, both groups had similar all-cause mortality rates. However, those with coronary vasomotor disorders had higher rates of emergency department visits for chest pain (39% vs. 15%, p < 0.001) and readmissions for chest pain (30% vs. 10%, p < 0.001) compared with those with unspecified chest pain. This real-world study emphasizes the importance of identifying high-risk ANOCA patients for personalized management to effectively address their symptoms.

Coronary Vasospastic Angina: A Review of the Pathogenesis, Diagnosis, and Management

Vasospastic angina (VSA) is an under-appreciated cause of chest pain. It is characterised by transient vasoconstriction of the coronary arteries and plays a significant role in the pathogenesis of stable angina and acute coronary syndromes. Complex mechanistic pathways characterised by endothelial dysfunction and smooth muscle hypercontractility lead to a broad spectrum of clinical manifestations ranging from recurrent angina to fatal arrhythmias. Invasive provocation testing using intracoronary acetylcholine or ergonovine is considered the current gold standard for diagnosis, but there is a wide variation in protocols amongst different institutions. Conventional pharmacological therapy relies on calcium channel blockers and nitrates; however, refractory VSA has limited options. This review evaluates the pathophysiology, diagnostic challenges, and management strategies for VSA. We believe global efforts to standardise diagnostic and therapeutic guidelines will improve the outcomes for affected patients.

A Practical Approach to Invasive Testing in Ischemia with No Obstructive Coronary Arteries (INOCA)

Up to 65% of women and approximately 30% of men have ischemia with no obstructive coronary artery disease (CAD; commonly known as INOCA) on invasive coronary angiography performed for stable angina. INOCA can be due to coronary microvascular dysfunction or coronary vasospasm. Despite the absence of obstructive CAD, those with INOCA have an increased risk of all-cause mortality and adverse outcomes, including recurrent angina and cardiovascular events. These patients often undergo repeat testing, including cardiac catheterization, resulting in lifetime healthcare costs that rival those for obstructive CAD. Patients with INOCA often remain undiagnosed and untreated. This review discusses the symptoms and prognosis of INOCA, offers a systematic approach to the diagnostic evaluation of these patients, and summarizes therapeutic management, including tailored therapy according to underlying pathophysiological mechanisms.

Percutaneous coronary intervention in patients with documented coronary vasospasm during long-term follow-up

Objective

Although recurring coronary artery spasm (CAS) may lead to the development of fixed atherosclerotic coronary stenosis (FS), the relationship between coronary atherosclerosis and CAS is still speculative. We evaluated the incidence of FS requiring percutaneous coronary intervention (PCI) in patients with documented CAS during long-term follow-up and analysed their clinical features.

Methods

Clinical data of 3556 patients during a median follow-up of 9.4 years after non-invasive ergonovine spasm provocation testing with echocardiographic monitoring of left ventricular wall motion (erg echo) were analysed.

Results

Erg echo documented CAS in 830 (23.3%) patients, who had higher frequencies of coronary risk factors than those without CAS. Patients with documented CAS on erg echo showed significantly lower 10-year overall (90.5% vs 94.2%, p<0.001) and PCI-free (97.4% vs 98.4%, p=0.002) survival rates than those without CAS. Documented CAS was an independent factor associated with later PCI after adjustment by either Cox regression model or Fine-Gray competing risk model. There was no significant difference in baseline clinical characteristics between patients who needed later PCI and those who did not. Among 28 patients who needed later PCI after documentation of CAS, the original CAS and later PCI territory were concordant in 25 (89.3%), while 3 (10.7%) showed discordance.

Conclusions

CAS is a risk factor for the development of FS requiring PCI during long-term follow-up, and warrants physicians’ vigilance and careful follow-up of patients with documented CAS and insignificant stenosis of major epicardial coronary arteries at the time of initial diagnosis.

[Methergin pour le diagnostic de l'angor spastique : voie intraveineuse ou intracoronaire ?]

BACKGROUND

Vasospastic angina is an infrequent underlying cause of angina and is under-diagnosed. Ergonovine provocation tests can be performed via intravenous or intracoronary injections. Although the safety profile of intracoronary injection has been well documented, no study has yet compared the intracoronary and intravenous injections regarding the positivity rate of the test.

AIMS

This study sought to compare the positivity rate of intravenous versus intracoronary injection of ergonovine in the diagnosis of vasospastic angina.

METHODS

Between January 2010 and February 2018, 427 patients with suspected vasospastic angina underwent an ergonovine provocation test in 2 tertiary hospitals in France and were retrospectively included in this study. Injection was performed via the intravenous or the intracoronary route. The primary endpoint was the positivity rate of the test. Propensity score matching was used to account for confounding factors.

RESULTS

427 patients were included in the study. Mean age was 60.3 (+/- 12.4) years. There were 247 (58%) females and 97 (23%) smokers. The intracoronary route was used in 199 (47%) patients. The indication for the test was acute coronary syndrome for 121 (28%). No rhythmic complications or deaths were reported. After propensity-matching, the baseline characteristics of the 2 groups (148 patients in each) were comparable. The positivity rate was 24% in the intracoronary group and 9% in the intravenous group (OR [95%CI]: 3.2 [1.6, 6.4]).

CONCLUSIONS

Intracoronary injection of ergonovine is safe and associated with a positivity rate of the test three times higher compared to intravenous injection.

Risk factor comparison in young patients presenting with acute coronary syndrome with atherosclerotic coronary artery disease vs. angiographically normal coronaries

Background: Acute myocardial infarction is a relatively rare phenomenon in the young population. The incidence has nevertheless increased from years past, likely due to the presence of multiple risk factors from an increasingly younger age. Regardless of whether they have atherosclerotic coronary artery disease or normal coronary angiogram, young patients with risk factors for coronary artery disease (CAD), chest pain, and positive troponin, are initially treated in a similar fashion. Our goal was to shed light on whether risk factors between these two groups differ to help guide physicians in clinically determining whether or not an atherosclerotic cardiovascular event has occurred, as well as to potentially identify young patients at risk of acute coronary syndrome (ACS) despite normal coronary arteries. Methods: A retrospective cross sectional study was undertaken over an 8 year period at Tawam Hospital. 576 patients aged 50 or under who underwent coronary angiography were selected for the study. Medical records were analyzed for the patient's demographics and CAD risk factor profile, including the following variables: family history of CAD, smoking status, Body Mass Index category, lipid profile, and diagnosis of hyperlipidemia, diabetes, or hypertension. Details of the coronary angiogram were also reviewed. Results: Statistically significant outcomes included a higher prevalence of diabetes, hyperlipidemia, and smoking history in patients with CAD compared to the patients with normal coronary angiogram. Diabetes was one of the strongest risk factors in CAD patients, with an odds ratio of 1.98 (p= 0.011), followed by hyperlipidemia at 1.85 (p= 0.021). Smoking history had an odds ratio of 2.93 (p <0.001). Conclusion: Risk factors were present in both groups, but significantly more in the CAD group. No particular risk factor stood out for the development of ACS in those with normal coronary arteries, other than mean BMI being slightly higher in this group. Based on our analysis, no single variable can accurately predict the risk for ACS in normal coronaries. To our knowledge, few studies have been done in the young population with angiographically normal coronary arteries to determine possible risk factors for development of ACS. Further research needs to be done to determine whether the risk factors that were common amongst both groups are coincidental, or a cause of ACS in those with normal coronary arteries.

Renal sympathetic denervation in patients with vasospastic angina

BACKGROUND

Sympathetic overactivity has been linked to vasospastic angina (VSA), although the exact pathophysiology of VSA is poorly understood. The purpose of this study is to assess if renal sympathetic denervation (RDN) reduces cardiac sympathetic nerve activity with a subsequent beneficial effect on angina relief in patients with refractory VSA.

METHODS AND RESULTS

Cardiac sympathetic nerve activity was assessed prior to procedure and at 6 months post-procedure using iodine-123 labeled meta-iodobenzylguanidine (123I-MIBG) imaging. The Seattle Angina questionnaire (SAQ) was used to assess the degree to which the disease impacts quality of life. No significant change was observed in early HMR (pre-RDN: 2.74 [2.10 to 3.21] vs 6 months post-RDN: 2.57 [2.20 to 3.00]; P = 0.76), and late HMR (pre-RDN: 2.56 [2.18 to 3.20] vs 6 months post-RDN: 2.36 [2.13 to 3.22]; P = 0.22). Additionally, no change was seen in WR (P = 0.22). SAQ results revealed significant improvements in perceived physical limitation, angina frequency, and quality of life at 6 months (P < 0.05 for all).

CONCLUSION

RDN resulted in improvements in angina class and quality of life at 6 months in patients with refractory VSA. RDN, however, did not result in significant changes in cardiac sympathetic nerve activity as measured using 123I-MIBG. The latter observation should be considered with caution given the small sample size of this study. Larger studies are needed to assess this further.

Diagnostic and Prognostic Value of Ergonovine Echocardiography for Noninvasive Diagnosis of Coronary Vasospasm

OBJECTIVES

This study sought to obtain large-scale evidence supporting the clinical usefulness of ergonovine echocardiography.

BACKGROUND

The role of noninvasive ergonovine provocation testing with echocardiographic monitoring of ventricular wall motion (ergonovine echocardiography) needs to be defined.

METHODS

Clinical data of patients who underwent ergonovine echocardiography in 3 tertiary referral hospitals in South Korea were analyzed.

RESULTS

Ergonovine echocardiography was performed in 14,012 patients (mean age 52.8 ± 11.1 years; 6,213 [44.3%] women) after exclusion of significant coronary arterial stenosis by functional (treadmill or perfusion scan, n = 9,824) or anatomic test (invasive or computerized tomographic coronary angiography, n = 4,188). Premature termination developed in 0.4% (n = 51), and a positive result was observed in 2,144 patients (15.3%), with variable frequencies according to the diagnosis (acute coronary syndrome [38.2%], variant angina [31.8%], effort angina [14.9%], aborted sudden cardiac death [17.6%], syncope [9.9%]). There was no mortality or development of myocardial infarction during the test. During median follow-up of 11.4 (interquartile range: 7.2 to 15.8) years, death of any cause and cardiovascular death occurred in 494 and 143 patients, respectively. The 10-year overall (96.7 ± 0.2% vs. 91.5 ± 0.6%; p < 0.0001) and cardiovascular mortality-free (99.2 ± 0.1% vs. 96.7 ± 0.4%; p < 0.0001) survival rates were lower in patients with positive ergonovine echocardiography. Regarding patients with positive test results, the functional test group and the anatomic test group did not show a significant difference in the survival rates. After adjustment of age and male sex, a positive test was an independent risk factor associated with all-cause mortality (hazard ratio: 1.879, 95% confidence interval: 1.548 to 2.280; p < 0.001) and cardiovascular death (hazard ratio: 2.903, 95% confidence interval: 2.061 to 4.089; p < 0.001).

CONCLUSIONS

Ergonovine echocardiography for coronary vasospasm diagnosis could be safely performed even without angiographic documentation of fixed coronary stenosis depending on the clinical presentation, and provided important prognostic implication. Ergonovine echocardiography can replace the invasive spasm provocation testing, which has been overlooked unfairly.

Role of coronary angiography for out-of-hospital cardiac arrest survivors according to postreturn of spontaneous circulation on an electrocardiogram

Survivors of out-of-hospital cardiac arrest (OHCA) have high mortality and morbidity. An acute coronary event is the most common cause of sudden cardiac death. For this reason, coronary angiography is an important diagnostic and treatment strategy for patients with postcardiac arrest. This study aimed to identify the correlation between postreturn of spontaneous circulation (ROSC) on an electrocardiogram (ECG) and results of coronary angiography of OHCA survivors.We collected data from our OHCA registry from January 2010 to November 2014. We categorized OHCA survivors into 2 groups according to post-ROSC ECG results. Emergent coronary artery angiography (CAG) (CAG performed within 12 hours after cardiac arrest) was performed in patients who showed ST segment elevation or new onset of left bundle branch block (LBBB) in post-ROSC ECG. For other patients, the decision for performing CAG was made according to agreement between the emergency physician and the cardiologist.During the study period, 472 OHCA victims visited our emergency department and underwent cardiopulmonary resuscitation. Among 198 OHCA survivors, 82 patients underwent coronary artery intervention. Thirty-one (70.4%) patients in the ST segment elevation or LBBB group and 10 (24.4%) patients in the nonspecific ECG group had coronary artery lesions (P < .01). Seven (18.4%) patients in the nonspecific ECG group showed coronary spasm.OHCA survivors without ST segment elevation or new onset LBBB still have significant coronary lesions in CAG. If there is no other obvious arrest cause in patients without significant changes in post ROSC ECG, CAG should be considered to rule out the possibility of coronary artery problems, including coronary spasm.

Stress cardiomyopathy: Is it limited to Takotsubo syndrome? Problems of definition

In 2006, Takotsubo syndrome (TTC) was described as a distinct type of stress-induced cardiomyopathy (stress cardiomyopathy). However, when thinking about Takotsubo cardiomyopathy from the viewpoints of the AHA and ESC classifications, 2 possible problems may arise. The first potential problem is that a forecast of disease outcome is lacking in the ESC classification, whereas the AHA only states that 'outcome is favorable with appropriate medical therapy'. However, based on the literature data, one can make a general conclusion that occurrence of myocardial lesions in TTC (i.e., myocardial fibrosis and contraction-band necrosis) causes the same effects as in other diseases with similar levels of myocardial damage and should not be considered to have a lesser impact on mortality. To summarise, TTC can cause not only severe complications such as pulmonary oedema, cardiogenic shock, and dangerous ventricular arrhythmias, but also damage to the myocardium, which can result in the development of potentially fatal conditions even after the disappearance of LV apical ballooning. The second potential problem arises from the definition of TTC as a stress cardiomyopathy in the AHA classification. In fact, the main factors leading to TTC are stress and microvascular anginas, since, as has been already discussed, coronary spasm can cause myocardium stunning, resulting in persistent apical ballooning. Thus, based on this review, 3 distinct types of stress cardiomyopathies exist (variant angina, microvascular angina, and TTC), with poor prognosis. Adding these diseases to the classification of cardiomyopathies will facilitate diagnosis and preventive prolonged treatment, which should include intensive anti-stress therapy.

High susceptibility of atherosclerotic coronary arteries to the onset of vasospasm and angina pectoris-like symptoms due to coronary spasm in WHHLMI rabbits

We examined the relationship between atherosclerosis and the provocation of coronary spasm as well as the influence of coronary spasm on the onset of acute ischemic myocardial disease. Coronary spasm was provoked in anesthetized normal Japanese white (JW) rabbits and myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits, an animal model for coronary atherosclerosis and myocardial infarction, by injecting ergonovine during the infusion of norepinephrine through a marginal ear vein. A decrease in contrast flow in the left circumflex artery was observed on coronary angiograms. Ischemic changes were observed on the electrocardiograms of 29% (2/7) of JW and 79% (27/34, P=0.007) of WHHLMI rabbits. The frequency of coronary spasm was significantly high in rabbits with severe coronary plaques showing diffuse lesions. Left ventricle motility in vasospasm-positive rabbits, which was evaluated with echocardiograms, was decreased by 29% following the ergonovine injection (P<0.001), and every serum ischemic marker markedly increased 4 h after the provocation of vasospasm. These results demonstrate that atherosclerotic coronary arteries are positively related to the provocation of vasospasm, and vasospasm in severe atherosclerotic coronary segments evokes angina pectoris-like findings and/or non-fatal myocardial infarction. WHHLMI rabbits may be a novel animal model for angina pectoris and acute ischemic heart disease.

Serious cardiac complications in coronary spasm provocation tests using acetylcholine or ergonovine: analysis of 21 512 patients from the diagnosis procedure combination database in Japan

BACKGROUND

Previous studies on complications with coronary spasm provocation tests were based on small sample sizes or were limited to high-volume centers. The risk of provocation tests using acetylcholine (ACH) or ergonovine (ER) remains to be fully examined by a large-scale multicenter study.

HYPOTHESIS

ACH provocation tests are associated with a higher rate of serious cardiac complications than ER tests.

METHODS

Using the Diagnosis Procedure Combination database in Japan, we identified patients aged ≥20 years who underwent a pharmacological provocation test during coronary angiography. We assessed the composite outcome of cardiac complications requiring urgent procedures (defibrillation, chest compression, intra-aortic balloon pumping, or extracorporeal membrane oxygenation) or death on the day of the provocation test, and compared the outcome between ACH and ER tests.

RESULTS

Of 21 512 eligible patients in 602 hospitals, 10 628 (49.4%) underwent an ACH test and 10 884 (50.6%) underwent an ER test. The composite outcome occurred in 141 (0.7%) patients. The ACH group was significantly more likely to have the composite outcome than the ER group (0.9% vs 0.4%, P < 0.001). The propensity-score analyses showed consistent results (propensity score-matched, 0.9% vs 0.4%, P = 0.003; inverse probability-weighted, 0.8% vs 0.4%, P < 0.001). In a multivariable logistic regression analysis, ACH tests were significantly associated with a higher rate of the composite outcome than ER tests (odds ratio: 1.75, 95% confidence interval: 1.13-2.69, P = 0.011).

CONCLUSIONS

This retrospective cohort study suggested that ACH tests were associated with a higher rate of cardiac complications than ER tests.

Some observations on and controversies about coronary arterial spasm

The pathogenesis, clinical features, diagnosis, and treatment of spasm of epicardial coronary arteries are reviewed briefly, especially with regard to some issues that remain controversial. For diagnosis, emphasis is placed on the need for objective observations during an attack, even if that requires an attempt at pharmacologic provocation during coronary arteriography, or during echocardiography when prior arteriography has demonstrated the absence of severe coronary stenosis.

Provocative testing for coronary reactivity and spasm

Coronary spasm is an important and often overlooked etiology of chest pain. Although coronary spasm, or Prinzmetal's angina, has been thought of as benign, contemporary studies have shown serious associated adverse outcomes, including acute coronary syndrome, arrhythmia, and death. Definitive diagnosis of coronary spasm can at times be difficult, given the transience of symptoms. Numerous agents have been historically described for provocative testing. We provide a review of published data for the role of provocation testing in the diagnosis of coronary spasm.

Unusual Vasospastic Angina: A Documented Asymptomatic Spasm with Normal ECG-A Case Report and a Review of the Literature

We report the case of a 53-years-old patient, known to have coronary artery disease, presenting with typical angina at rest with normal ECG and laboratory findings. His angina is relieved by sublingual nitroglycerin. He had undergone a cardiac catheterisation two weeks prior to his presentation for the same complaints. It showed nonsignificant coronary lesions. Another catheterisation was performed during his current admission. He developed coronary spasm during the procedure, still with no ECG changes. The spasm was reversed by administration of 2 mg of intracoronary isosorbide dinitrate. Variant (Prinzmetal's) angina was diagnosed in the absence of electrical ECG changes during pain episodes.

Safety of coronary reactivity testing in women with no obstructive coronary artery disease: results from the NHLBI-sponsored WISE (Women's Ischemia Syndrome Evaluation) study

OBJECTIVES

This study evaluated the safety of coronary reactivity testing (CRT) in symptomatic women with evidence of myocardial ischemia and no obstructive coronary artery disease (CAD).

BACKGROUND

Microvascular coronary dysfunction (MCD) in women with no obstructive CAD portends an adverse prognosis of a 2.5% annual major adverse cardiovascular event (MACE) rate. The diagnosis of MCD is established by invasive CRT, yet the risk of CRT is unknown.

METHODS

The authors evaluated 293 symptomatic women with ischemia and no obstructive CAD, who underwent CRT at 3 experienced centers. Microvascular function was assessed using a Doppler wire and injections of adenosine, acetylcholine, and nitroglycerin into the left coronary artery. CRT-related serious adverse events (SAEs), adverse events (AEs), and follow-up MACE (death, nonfatal myocardial infarction [MI], nonfatal stroke, or hospitalization for heart failure) were recorded.

RESULTS

CRT-SAEs occurred in 2 women (0.7%) during the procedure: 1 had coronary artery dissection, and 1 developed MI associated with coronary spasm. CRT-AEs occurred in 2 women (0.7%) and included 1 transient air microembolism and 1 deep venous thrombosis. There was no CRT-related mortality. In the mean follow-up period of 5.4 years, the MACE rate was 8.2%, including 5 deaths (1.7%), 8 nonfatal MIs (2.7%), 8 nonfatal strokes (2.7%), and 11 hospitalizations for heart failure (3.8%).

CONCLUSIONS

In women undergoing CRT for suspected MCD, contemporary testing carries a relatively low risk compared with the MACE rate in these women. These results support the use of CRT by experienced operators for establishing definitive diagnosis and assessing prognosis in this at-risk population. (Women's Ischemia Syndrome Evaluation [WISE]; NCT00832702).

Prinzmetal angina in the differential diagnosis of syncope

Prinzmetal (variant) angina may be associated with cardiac arrhythmias that can deteriorate to fatal ventricular arrhythmias. We present 2 patients with syncope where vasospastic angina and severe ventricular arrhythmias were found to be responsible for the syncopal episodes.

Sudden cardiac arrest and syncope triggered by coronary spasm

BACKGROUND

Patients with coronary spasm generally have a good prognosis, although it can result in sudden cardiac arrest (SCA) and syncope. We hypothesized that the nature of coronary spasm triggering lethal arrhythmias may be different from that which induces angina-only.

METHODS

Clinical characteristics were examined in patients who had experienced SCA (n = 18) or syncope (n = 28) triggered by coronary spasm. These characteristics were compared to those of patients who had coronary spastic angina-only (n = 52).

RESULTS

SCA and syncope occurred frequently during daytime in 57% and 68%, respectively. Spontaneous ST-segment changes during daytime were recorded more often in patients with SCA (50%) and syncope (39%) than angina-only patients (4%, p < 0.01 for each). Nocturnal angina occurred less frequently in patients with SCA (33%) and syncope (32%) than angina-only patients (83%, p < 0.01 for each). Severe multivessel spasm, daytime ST-segment changes, and younger age were significant predictors of SCA. Daytime ST-segment changes and active smoking were related to syncope.

CONCLUSIONS

The circadian variance of coronary spasm triggering SCA or syncope may be different from that inducing typical coronary spastic angina. The coronary spasm should be evaluated for patients with aborted SCA or recurrent syncope of unknown cause, even though the patients have not experienced the typical nocturnal angina.

Expression of skeletal muscle sodium channel (Nav1.4) or connexin32 prevents reperfusion arrhythmias in murine heart

AIMS

acute myocardial ischaemia induces a decrease in resting membrane potential [which leads to reduction of action potential (AP) V(max)] and intracellular acidification (which closes gap junctions). Both contribute to conduction slowing. We hypothesized that ventricular expression of the skeletal muscle Na(+) channel, Nav1.4 (which activates fully at low membrane potentials), or connexin32 (Cx32, which is less pH-sensitive than connexin43) would support conduction and be antiarrhythmic. We tested this hypothesis in a murine model of ischaemia and reperfusion arrhythmias.

METHODS AND RESULTS

empty adenovirus (Sham) or adenoviral constructs expressing either SkM1 (gene encoding Nav1.4) or Cx32 genes were injected into the left ventricular wall. Four days later, ventricular tachycardia (VT) occurred during reperfusion following a 5 min coronary occlusion. In Nav1.4- and Cx32-expressing mice, VT incidence and duration were lower than in Sham (P < 0.05). In vitro multisite microelectrode mapping was performed in the superfused right ventricular wall. To simulate ischaemic conditions, [K(+)] in solution was increased to 10 mmol/L and/or pH was decreased to 6.0. Western blots revealed Cx32 and Nav1.4 expression in both ventricles. Nav1.4 APs showed higher V(max) and conduction velocity (CV) than Shams at normal and elevated [K(+)]. Exposure of tissue to acid solution reduced intracellular pH to 6.4. There was no difference in CV between Sham and Cx32 groups in control solution. Acid solution slowed CV in Sham (P < 0.05) but not in Cx32.

CONCLUSION

Nav1.4 or Cx32 expression preserved normal conduction in murine hearts and decreased the incidence of reperfusion VT.

Implantable cardioverter defibrillator (ICD) for polymorphic ventricular tachycardia (VT) due to coronary vasospasm

We report a case of a young woman who presented with atypical angina. During an episode of chest pain she had a documented run of sustained polymorphic ventricular tachycardia (VT). In addition to medical therapy, she received an ICD to prevent future episodes of sudden cardiac death.

Prinzmetal's variant angina

Although the prevalence of variant angina pectoris is unknown, it appears to be substantially less common than typical, exertional angina and unstable angina at rest. The patient with variant angina typically complains of a pressure-like, squeezing retrosternal chest discomfort of several minutes duration. The diagnosis is secured by the occurrence of transient ST-segment elevation in association with chest pain, both of which resolve spontaneously or with nitroglycerin. After the diagnosis is made, the patient usually becomes symptom-free on calcium-channel blockers with or without long-acting nitrates. Although the long-term survival of these patients is excellent, an occasional individual with variant angina sustains a complication, most often myocardial infarction, a life-threatening arrhythmia, or sudden cardiac death.

Low utilisation of cardiovascular risk reducing therapy in patients with acute coronary syndromes and non-obstructive coronary artery disease

BACKGROUND

Between 6-25% of patients undergoing coronary angiography for acute coronary syndrome (ACS) have non-obstructive coronary artery disease (NOCAD).

METHODS

One-hundred and eighty patients presenting with an ACS who were taking part in a risk factor modification study and had undergone coronary angiography were examined. We compared baseline characteristics, medical treatment and 12-month outcome in patients with NOCAD (<50% lumen diameter stenosis at coronary angiography) and obstructive CAD (> or = 50% lumen diameter stenosis at coronary angiography).

RESULTS

There were 29 (16%) patients with NOCAD and 151 (84%) with obstructive CAD (CAD). Patients with NOCAD were significantly younger, more likely to be female, had higher mean total cholesterol and LDL levels, and fewer received cardiac rehabilitation, treatment with statins, aspirin, ACE inhibitors, beta-blockers or clopidogrel. Over the next 12-months, there was no mortality or myocardial infarction in the NOCAD group compared to 2% in the CAD group, but 14% with NOCAD were readmitted for a cardiovascular cause including 2 patients (7%) who underwent percutaneous coronary intervention (PCI).

CONCLUSIONS

Patients presenting with ACS and NOCAD may not have a completely benign prognosis, and preventative strategies and therapies such as statins in this group of patients appear to be under-utilised.

Sudden cardiac death during Holter recording in a patient with vasospastic angina

Rest angina with transient ST segment elevation is the more frequent clinical presentation of coronary vasospasm. However, ventricular arrhythmias may be triggered by vasospasm episodes or reperfusion phenomenon, being vasospastic angina a rare but possible cause of sudden cardiac death in patients with structurally normal heart. We report of a patient admitted to the hospital presenting with recurrent nonexertional substernal chest pain who experienced an episode of sudden cardiac death due to malignant ventricular arrhythmias during a 24-hour Holter ECG.

Polymorphic ventricular tachycardia induced by coronary vasospasm: a malignant case of variant angina

Variant angina is generally a benign disease with self limiting symptoms. But in some cases serious ventricular arrhythmias which can lead to death can be seen. In this paper we present a case of variant angina who subsequently developed polymorphic ventricular tachycardia and was treated successfully with long acting nitrate and calcium channel blockade therapy.

Secondary prevention of sudden cardiac death in coronary artery spasm: is implantable cardioverter defibrillator always efficient?

Syncope and/or cardiac arrest in the setting of coronary artery spasm have been associated with atrioventricular block and asystole or ventricular tachyarrhythmias. Ventricular arrhythmias have been predominantly reported in cases of multivessel coronary artery spasm. The present report highlights the case of a young woman who suffered repeated episodes of multivessel coronary artery spasm in association with polymorphic ventricular tachycardia and cardiac arrest. The efficacy of implantable cardioverter defibrillator in secondary prevention of sudden cardiac death due to coronary artery spasm is discussed.