Covid 19 Drug Interactions

May 25, 2024 Andrew To

Covid 19 remains a problem. From the cardiology perspective, the main issue now is the use of anti-virals and drug interactions.

Paxlovid (nirmatrelvir/ritonavir) is the main drug of concern with respect to drug interactions. Unfortunately, there has been numerous incidents of drug interaction resulting in harm.

Commonly used cardiac drugs that are absolute contraindications to Paxlovid include (but not limited to)

Amiodarone, dronedarone
Flecainide
Propafenone
Ivabradine
Bosnian, Sildenafil, Tadalafil

Here are two great tools to check drug interactions. It is best to double check for each individual patient.

University of Liverpool Covid 19 Drug Interactions

University of Waterloo School of Pharmacy

AF - increasing role of rhythm control

February 18, 2024 Andrew To

There has been increasing evidence of rhythm control in AF. This is what we know in 2024 and my approach.

My approach to heart murmurs

February 17, 2024 Andrew To

3D echo image of mitral valve prolapse with flail of P2 scallop

Murmurs could be benign, up to 10% of adults, 30% of children, and could be exacerbated by conditions such as anaemia, pregnancy, fever, hyperthyroidism. Murmurs could also pathological, including valvular lesions and structural abnormalities.

Here is my approach.

My approach to palpitations

February 17, 2024 Andrew To

The two top reasons for patients seeking medical attention for palpitations are

Symptoms being bothersome
Is there something wrong? Is there a risk of sudden death?

The top priority for physician though is whether the murmur is benign or malignant.

Heart failure medications - dosages

February 17, 2024 Andrew To

Iris Iris Iris by Dane Mitchell @ Auckland Art Gallery 2019

Heart failure medications save lives.

Dosages are important though, and many patients may not be on sufficient dosages.

Here are a number of tables useful for references, adapted from ACC/AHA guidelines 2013.

Heart failure - Definitions

February 17, 2024 Andrew To

Twist, Bob, Spin by Jeff Thomson & Bev Goodwin @ Kaipara Coast Sculpture Gardens

Terminology can sometimes be confusing in heart failure care.

Here is a summary:

NYHA Class, HF stages, HFpEF vs. HFrEF

Frailty and Cardiovascular Disease

February 7, 2024 Andrew To

Clinical Frailty Scale from Dalhousie University

Frailty is relevant to cardiology because the disease process predispose to physical impairments that ultimate worsen the cardiovascular illness.

The phenomenon of increased vulnerability to stressors due to decreased physiological reserves leads to poor clinical outcomes after cardiovascular insults. Equally CVD worsens frailty due to hospitalisation, debilitation, immobility, systemic illness that underpins physiological deterioration in physical frailty. In cardiology, frailty is highly prevalent in patients with heart failure, valvular heart disease, but also myocardial infarction.

GLP-1 Agonists - FAQ

May 16, 2023 Andrew To

Effects of GLP-1 RA on CV risk factors/outcomes and practical aspects for the use of these agents; Marx et al. Circumflex 2022;146:1882-1894

GLP-1 agonist is a class of medications that are used in type 2 diabetes and obesity. This is what we need to know

Aspirin for Primary Prevention

May 6, 2022 Andrew To

Aspirin use in primary prevention is controversial, contrasting that of secondary prevention. It may offer benefit in some, but for most, risk-benefit analysis may argue against its use. Here is the discussion.

Our approach to CT calcium score

March 26, 2022 Andrew To

MESA calculator - probability of non-zero calcium score

In primary prevention, CT calcium scoring has been suggested to help decision making surrounding statin use.

Some of the underlying concepts are somewhat complex, but the screening paradigm remains that of matching the intensity of preventive efforts with the individual’s absolute risk.

The appropriateness of CT calcium scoring in an individual patient therefore depends

patient’s pretest probability of atherosclerotic cardiovascular risk
potential benefits of preventive therapies
negative aspects and risks of preventive therapies
patient preference

QT interval

February 12, 2022 Andrew To

We are often asked about how best to calculate the QT interval. This is the simplest way.

Use leads II, V5
Count the number of small boxes for the QT
Note heart rate

Use this website, and put in the two numbers, to get QTc

Arrhythmia in general practice

February 12, 2022 Andrew To

Most Patient would be asymptomatic when presented to the GP Practice. Hence ECG performed at the time would not normally demonstrate arrhythmia

Key is to identify high risk features on ECG

Chronic venous insufficiency

February 12, 2022 Andrew To

Venous disease affects all age groups, gender and racial groups. Interventional radiology approaches may improve patient outcome dramatically. Who are those?

C19 mRNA Vaccine Myocarditis

February 12, 2022 Andrew To

C19 mRNA vaccine myocarditis has been of concern for both the Pfizer and Moderna. Below, we have included some useful tables and resources that we could use in our practices.

My approach to heart murmur

October 30, 2019 Andrew To

Short axis view of aortic valve with significant stenosis

Murmur is common, but picking out the significant ones could be hard. Here is my approach.

Primary aldosteronism - the cardiologist's simplistic approach

September 7, 2019 Andrew To

Screening for secondary causes of hypertension is important, though often not thought of. Primary aldosteronism is the most common endocrine cause. The screening test is the aldosterone-renin ratio (ARR).

My approach to chest pain

September 7, 2019 Andrew To

Severe coronary non-calcified atherosclerosis with severe stenosis, on CT coronary angiography

Chest pain presentations are common, but management can be variable and difficult to understand. Here is my approach:

What should I do with heart failure with preserved ejection fraction?

September 7, 2019 Andrew To

HFpEF stands for heart failure with preserved ejection fraction. Commonly, it is defined as those with an LV ejection fraction of more than 50%, though varying definitions do exist.

This condition is poorly understood and is difficult to diagnose, because it is largely one of excluding other potential non cardiac causes of symptoms suggestive of HF.