Three documents, three levels of detail
The US prescribing information gives one sentence: Victoza® had no adverse effect on blood pressure, but adults in trials had a mean heart rate increase of 2 to 3 beats per minute compared with placebo. [1] Palpitations do not appear in its Table 1 or its postmarketing list. [1] Europe goes a step further and places increased heart rate in its common class, meaning 1 in 100 to 1 in 10 people; its leaflet calls this an increased pulse. [2]
The Canadian product monograph is the most detailed. It has a cardiovascular warning covering heart rate, the PR interval on the ECG and fast heart rhythms, and it prints each trial’s events above 1%, which is where the word palpitations appears. [3]
| Source | What it reports | Comparison |
|---|---|---|
| US label, section 6.1 [1] | Mean heart rate increase of 2–3 bpm in adults | Placebo |
| EU SmPC, Table 1 [2] | Increased heart rate: common | Frequency class, no placebo rate |
| Canada, trial 1860, 26 weeks [3] | Palpitations: 1.2 mg 1.4%; 1.8 mg 0.0% | Sitagliptin 0.0% |
| Canada, healthy-volunteer ECG study [3] | Pulse above 90 bpm: 1.2 mg 20.0%; 1.8 mg 23.5% | Placebo 8.0% and 3.9% |
| Canada, pooled LEAD trials [3] | Fast-rhythm events 16.5 per 1,000 subject-years (0.7% of people) | Placebo 6.1 (0.2%); other drugs 15.3 (0.7%) |
| Canada, pooled LEAD trials [3] | First-degree AV block 2.6 per 1,000 subject-years | Placebo 0; other drugs 1.4 |
What the Canadian ECG findings mean
In a placebo-controlled study of 51 healthy volunteers wearing a 24-hour ECG monitor, liraglutide raised the time-averaged heart rate by 7 to 8 beats per minute. [3] It also lengthened the PR interval, the pause between the upper and lower chambers of the heart, by up to about 10 milliseconds. [3] In people with diabetes on long-term treatment, including the LEADER trial, the average rise was 2 to 4 beats per minute. [3]
In the pooled LEAD trials, the most commonly reported fast-rhythm events were extrasystoles, the extra or skipped beats many people describe as a flutter. [3] Atrial fibrillation, atrial flutter and similar rhythms together ran at 6.4 per 1,000 subject-years on liraglutide and 5.6 on active comparators, with none on placebo. [3] Serious rhythm events were 2.7 per 1,000 subject-years on liraglutide, 0 on placebo and 2.8 on comparators. [3] Canada says the clinical significance of the ECG changes is not fully known, and asks for caution in people who already have heart block or rhythm problems. [3]
LEADER: the long-term picture
Based on the LEADER trial, the US label adds a second use for Victoza®: cutting the chance of heart attack, stroke and cardiovascular death in adults with type 2 diabetes and established heart disease. [1] Europe and Canada both state that, in LEADER, the small rise in heart rate had no long-term effect on cardiovascular event risk. [2][3] Canada adds that the share of people with rhythm-related adverse events was similar on Victoza® and placebo in that trial. [3]
Smaller independent trials measured the same effect more closely. In a 12-plus-12-week crossover study of adults with newly diagnosed type 2 diabetes and stable coronary disease, liraglutide raised the 24-hour average heart rate by 8.1 beats per minute against placebo, including at night, and reduced heart rate variability. [5] In a 3-week crossover trial in people with type 2 diabetes and high blood pressure, office heart rate rose for up to 4 hours after a dose, with small increases over 24 hours and at night. [6]
That is reassuring at population level, but it does not mean an individual’s palpitations should be ignored. The rows above are averages across thousands of people; a new, persistent racing heart is still worth reporting.
Why the dose on the box matters
Saxenda® contains the same molecule at up to 3 mg a day for weight management, and its US label has a full heart rate warning. [4] It reports resting increases of more than 10 beats per minute at two visits in 34% of people against 19% on placebo, and asks patients to report palpitations or a racing heartbeat at rest. [4] Victoza® tops out at 1.8 mg and its US label carries no such warning, so the Saxenda® figures should not be read as Victoza® figures. [1][4]
Low blood sugar and other causes
The Victoza® Medication Guide lists a fast heartbeat among the signs of low blood sugar, together with sweating, shakiness, feeling jittery, hunger and dizziness. [1] The risk is higher when Victoza® is used with a sulfonylurea or insulin, and in patients aged 10 and older it was higher regardless of other medicines. [1] MedlinePlus counts blood sugar below 70 mg/dL as low. [8] If palpitations come with these signs, a meter reading at that moment is the quickest way to tell.
MedlinePlus lists common, often harmless triggers: anxiety and stress, caffeine, nicotine, alcohol, fever, exercise, decongestants and diet pills. [7] It also lists causes of a true rhythm problem: heart disease, valve problems, low potassium, an overactive thyroid and some asthma, blood pressure or heart medicines. [7] Vomiting and diarrhea, the most common early Victoza® effects, can upset fluids and salts; Canada lists dehydration among less common trial events. [3]
What the sources describe
- Cut back on caffeine, nicotine and other stimulants, which MedlinePlus says often reduces palpitations. [7]
- Breathing exercises, relaxation, yoga, meditation and regular exercise are the home measures MedlinePlus lists. [7]
- Tell your prescriber and pharmacist about decongestants or other medicines that speed the heart; Canada says the combination with Victoza® has not been studied. [3]
- Mention beta-blockers, calcium channel blockers or digoxin, which also affect the PR interval. [3]
- Write down when the palpitations start, how long they last, whether they feel fast, irregular or pounding, and your pulse and glucose at the time. MedlinePlus lists these as questions a provider may ask. [7]
Victoza® and Saxenda® are registered trademarks of Novo Nordisk A/S. PepLabo is not affiliated with or endorsed by Novo Nordisk A/S.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Palpitations with chest pain, shortness of breath, fainting, unusual sweating or dizziness | Emergency services (911 or local number) | Emergency | MedlinePlus [7] |
| A very rapid heartbeat together with a swollen face or throat, breathing problems or a severe rash | Stop Victoza® and get emergency help | Emergency | Medication Guide [1] |
| Palpitations, dizziness or fainting that suggest a rhythm problem | Get immediate medical attention | Emergency | Canadian Patient Medication Information [3] |
| Racing heart with sweating, shakiness or hunger while on insulin or a sulfonylurea | Check and treat per your plan; tell your prescriber | Today | Medication Guide [1] |
| A rapid or pounding heartbeat on liraglutide | Call your doctor | Today | MedlinePlus liraglutide [9] |
| Pulse above 100 at rest, frequent extra beats or new palpitations, especially with diabetes | Contact your provider promptly | Today | MedlinePlus [7] |
| A higher resting pulse than before that you notice on a watch or monitor | Raise it at your next visit | At your next appointment | US label section 6.1 [1] |
