Bidirectional ventricular tachycardia induced by respiratory alkalosis mediated hypokalemia in a patient with acute ischemic heart failure

Treating sleep disordered breathing for cardiovascular outcomes: observational and randomised trial evidence

Sleep disordered breathing (SDB) is considered a risk factor for cardiovascular disease (CVD). Obstructive sleep apnoea (OSA) can be treated with continuous positive airway pressure (CPAP), and central sleep apnoea (CSA), in patients with heart failure with reduced ejection fraction (HFrEF), by peak flow-triggered adaptive servo-ventilation. Presently, there is equipoise as to whether treating SDB prevents cardiovascular events. Some propose treatment for this indication, based on observational data, while others argue against because of the lack of randomised trial evidence. This review evaluates literature concerning the cardiovascular effects of treating SDB with PAP devices in individuals with and without CVDs. Nine observational studies report significantly lower cardiovascular event rates in those treated, than in those not treated, for SDB. Conversely, 12 randomised trials in which excessive daytime sleepiness was generally an exclusion criterion showed no reduction in cardiovascular event rates. The SERVE-HF trial showed an increase in mortality with use of minute ventilation-triggered adaptive servo-ventilation for CSA in patients with HFrEF. In the ADVENT-HF trial, treating HFrEF patients with coexisting OSA or CSA using peak flow-triggered adaptive servo-ventilation was safe and improved sleep structure and heart failure-related quality of life but did not reduce all-cause mortality or cardiovascular events. More evidence is required to determine whether treating CSA in patients with HFrEF prevents cardiovascular events and improves survival. Presently, the rationale for treating SDB with PAP remains improving sleep structure and quality of life, as well as relieving excessive daytime sleepiness, but not reducing cardiovascular events.

Bidirectional ventricular tachycardia due to digoxin-diuretic interaction in post-cardiac surgery patient: a case report

Bidirectional ventricular tachycardia (BVT) is a rare form of malignant ventricular arrhythmia characterized by beat-to-beat alternation in the QRS axis. BVT is a hallmark of digitalis toxicity, but digoxin-induced BVT secondary to digoxin-diuretic interaction in cardiac surgery patients is not widely reported. We present the case of a 62-year-old woman undergoing mitral valve replacement with tricuspid annuloplasty who developed postoperative congestive heart failure and vasoplegic syndrome requiring norepinephrine, vasopressin, and loop diuretics. During postoperative care, she presented atrial fibrillation with rapid ventricular response, achieving rate control with digoxin, but later displayed hemodynamically stable BVT associated with digitalis toxicity. The case highlights the importance of physicians monitoring digoxin toxicity when prescribing digoxin to patients with a diuretic regimen, particularly loop diuretics. During digoxin-induced-BVT, supportive treatment, including discontinuing digitalis coupled with potassium and magnesium supplements, can be considered as long as digoxin-specific antibodies are unavailable, and the patient is hemodynamically stable.

Adaptive servo-ventilation for sleep-disordered breathing in patients with heart failure with reduced ejection fraction (ADVENT-HF): a multicentre, multinational, parallel-group, open-label, phase 3 randomised controlled trial

BACKGROUND

In patients with heart failure and reduced ejection fraction, sleep-disordered breathing, comprising obstructive sleep apnoea (OSA) and central sleep apnoea (CSA), is associated with increased morbidity, mortality, and sleep disruption. We hypothesised that treating sleep-disordered breathing with a peak-flow triggered adaptive servo-ventilation (ASV) device would improve cardiovascular outcomes in patients with heart failure and reduced ejection fraction.

METHODS

We conducted a multicentre, multinational, parallel-group, open-label, phase 3 randomised controlled trial of peak-flow triggered ASV in patients aged 18 years or older with heart failure and reduced ejection fraction (left ventricular ejection fraction ≤45%) who were stabilised on optimal medical therapy with co-existing sleep-disordered breathing (apnoea-hypopnoea index [AHI] ≥15 events/h of sleep), with concealed allocation and blinded outcome assessments. The trial was carried out at 49 hospitals in nine countries. Sleep-disordered breathing was stratified into predominantly OSA with an Epworth Sleepiness Scale score of 10 or lower or predominantly CSA. Participants were randomly assigned to standard optimal treatment alone or standard optimal treatment with the addition of ASV (1:1), stratified by study site and sleep apnoea type (ie, CSA or OSA), with permuted blocks of sizes 4 and 6 in random order. Clinical evaluations were performed and Minnesota Living with Heart Failure Questionnaire, Epworth Sleepiness Scale, and New York Heart Association class were assessed at months 1, 3, and 6 following randomisation and every 6 months thereafter to a maximum of 5 years. The primary endpoint was the cumulative incidence of the composite of all-cause mortality, first admission to hospital for a cardiovascular reason, new onset atrial fibrillation or flutter, and delivery of an appropriate cardioverter-defibrillator shock. All-cause mortality was a secondary endpoint. Analysis for the primary outcome was done in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT01128816) and the International Standard Randomised Controlled Trial Number Register (ISRCTN67500535), and the trial is complete.

FINDINGS

The first and last enrolments were Sept 22, 2010, and March 20, 2021. Enrolments terminated prematurely due to COVID-19-related restrictions. 1127 patients were screened, of whom 731 (65%) patients were randomly assigned to receive standard care (n=375; mean AHI 42·8 events per h of sleep [SD 20·9]) or standard care plus ASV (n=356; 43·3 events per h of sleep [20·5]). Follow-up of all patients ended at the latest on June 15, 2021, when the trial was terminated prematurely due to a recall of the ASV device due to potential disintegration of the motor sound-abatement material. Over the course of the trial, 41 (6%) of participants withdrew consent and 34 (5%) were lost to follow-up. In the ASV group, the mean AHI decreased to 2·8-3·7 events per h over the course of the trial, with associated improvements in sleep quality assessed 1 month following randomisation. Over a mean follow-up period of 3·6 years (SD 1·6), ASV had no effect on the primary composite outcome (180 events in the control group vs 166 in the ASV group; hazard ratio [HR] 0·95, 95% CI 0·77-1·18; p=0·67) or the secondary endpoint of all-cause mortality (88 deaths in the control group vs. 76 in the ASV group; 0·89, 0·66-1·21; p=0·47). For patients with OSA, the HR for all-cause mortality was 1·00 (0·68-1·46; p=0·98) and for CSA was 0·74 (0·44-1·23; p=0·25). No safety issue related to ASV use was identified.

INTERPRETATION

In patients with heart failure and reduced ejection fraction and sleep-disordered breathing, ASV had no effect on the primary composite outcome or mortality but eliminated sleep-disordered breathing safely.

FUNDING

Canadian Institutes of Health Research and Philips RS North America.

Severe Hypokalemia Causing Ventricular Tachycardia: A Case Report

Hypokalemia and hyperosmolar hyperglycemic syndrome (HHS) are two reversible but potentially fatal disorders that are important to identify and treat urgently. A 43-year-old patient presented to the ED with altered mental status and slurred speech, difficulty communicating, left-sided facial droop, and stool incontinence according to emergency medical services. This was preceded by 1.5 weeks of nausea, vomiting, polydipsia, and weight loss. On presentation, the patient was found tachycardic and tachypneic, with uncertain neurological deficits on physical exam, hyperglycemia, and electrocardiogram (EKG) abnormalities. Lab data were consistent with hyperosmolar hyperglycemic nonketotic coma. This case provides two important clinical scenarios in which cardiac EKG abnormalities and focal neurological deficits are the product of hyperosmolality and electrolyte abnormalities. Hypokalemia with EKG abnormalities consistent with a potential ischemic disease can progress into wide complex tachycardia and ventricular fibrillation. Hyperosmolar hyperglycemia may manifest with focal neurological deficits and without the classical presentation of a coma. Careful consideration of EKG and lab values in the context of clinical presentation may provide clues to resolvable etiologies. We report a case of a patient who presented to the ED with hypokalemia and HHS, both reversible but potentially fatal disorders that are important to identify and urgently treat.