Hyperthyroidism and severe bradycardia: Report of three cases and review of the literature

Table 1 Features of 34 cases of hyperthyroidism and severe bradycardia

Number	Reference	Year	Age in yr	Sex	Bradycardia type
1	[6]	1970	22	F	Complete AVB
2	[7]	1980	55	F	2nd degree AVB
3	[8]	1985	55	F	Complete AVB
4	[9]	1985	54	F	Complete AVB
5	[10]	1990	29	M	Complete AVB
6	[11]	1998	16	F	Complete AVB
7	[12]	2001	60	F	Complete AVB
8	[12]	2001	30	F	Complete AVB
9	[13]	2005	50	M	Complete AVB
10	[13]	2005	68	F	Complete AVB
11	[14]	2006	67	M	Complete AVB
12	[15]	2007	40	M	Complete AVB
13	[16]	2008	59	M	Complete AVB
14	[17]	2009	28	F	Complete AVB
15	[18]	2011	55	F	Complete AVB
16	[19]	2012	37	F	Complete AVB
17	[20]	2012	71	F	2nd degree AVB
18	[21]	2014	75	F	2nd degree AVB
19	[22]	2015	30	M	2nd degree AVB
20	[23]	2017	10	F	2nd degree AVB
21	[24]	2020	28	F	Complete AVB
22	[25]	1972	21	F	SSS
23	[25]	1972	26	M	SSS
24	[25]	1972	63	F	SSS
25	[26]	1990	65	F	SSS
26	[27]	1995	50	F	SSS
27	[28]	1999	22	M	SSS
28	[29]	2006	36	M	SSS
29	[30]	2017	48	F	SSS
30	[30]	2017	63	F	SSS
31	[30]	2017	66	F	SSS
32	This report	2019	63	F	SSS
33	This report	2019	76	F	SSS
34	This report	2020	60	M	SSS

AVB: Atrioventricular block; F: Female, M: Male; SSS: Sick sinus syndrome.

Table 2 Clinical presentation of 34 cases of hyperthyroidism and severe bradycardia

Number	Symptoms of bradycardia	Sequence of occurrence of hyperthyroidism and bradycardia	Use of anti-arrhythmic drugs before onset of bradycardia	Accompanying conditions
1	-	Hyperthyroidism first	-	-
2	Syncope	Hyperthyroidism first	Propranolol	-
3	Syncope	Hyperthyroidism first	Digoxin and propranolol	-
4	Syncope	Hyperthyroidism first	-	-
5	-	-	-	Fever
6	-	-	-	Fever
7	Syncope	Hyperthyroidism first	-	-
8	Presyncope	Simultaneous	-	-
9	Syncope	Hyperthyroidism first	Propranolol	-
10	-	Bradycardia first	-	-
11	Near syncope	Bradycardia first	Carvedilol	-
12	Syncope	Bradycardia first	-	-
13	-	Simultaneous	-	Jaundice and febrile, creatinine 250 μmol/L
14	Syncope	Hyperthyroidism first	-	-
15	Syncope	Hyperthyroidism first	-	-
16	Syncope	Hyperthyroidism first	-	-
17	Syncope	Simultaneous	-	-
18	-	Simultaneous	-	-
19	-	Hyperthyroidism first	-	-
20	Dizziness	Hyperthyroidism first	Atenolol	-
21	Syncope	Bradycardia first	-	-
22	Syncope	Hyperthyroidism first	-	-
23	-	Simultaneous	-	Periodic paralysis
24	Syncope	Hyperthyroidism first	-	-
25	Syncope	Hyperthyroidism first	Propranolol, diltiazem	-
26	Fatigue	Bradycardia first	-	-
27	-	Simultaneous	-	-
28	Syncope	Simultaneous	-	Blood potassium 2.3 mmol/L
29	Palpitation	Hyperthyroidism first	Metoprolol	-
30	-	Simultaneous	-	-
31	-	Hyperthyroidism first	-	-
32	Syncope	Hyperthyroidism first	Cedilanide	-
33	Syncope	Hyperthyroidism first	-	-
34	Syncope	Simultaneous	-	-

-: No or information not available.

Table 3 Treatment and outcome of 34 cases of hyperthyroidism and severe bradycardia

Number	Hyperthyroidism treatment	Bradycardia drug treatment	Temporary pacemaker	ECG changes after treatment1	Bradycardia recovery time in d	Permanent pacemaker
1	Propylthiouracil	Isoproterenol, atropine, prednisone,	Yes	1st degree AVB	7	No
2	Methimazole	Atropine	Yes	1st degree AVB	8	No
3	Propylthiouracil, iodine-131	Atropine, isoprenaline	No	Returned to normal	-	No
4	Methimazole	Prednisolone	Yes	Returned to normal	1	No
5	-	-	-	Returned to normal	-	-
6	Carbimazole, intravenous iodide a	Dexamethasone	No	Returned to normal	-	No
7	Methimazole	-	No	No recovery	No recovery	Yes
8	-	Prednisone	No	No recovery	No recovery	Yes
9	Propylthiouracil	-	No	1st degree AVB	-	No
10	Propylthiouracil	-	No	Returned to normal	-	No
11	Methimazole	Atropine	Yes	No recovery	No recovery	Yes
12	Propylthiouracil	-	No	Returned to normal	3	No
13	Carbimazole	-	Yes	Returned to normal	21	No
14	Propylthiouracil	-	No	Returned to normal	8	No
15	Propylthiouracil, subtotal thyroidectomy	-	No	Returned to normal	7	No
16	Propylthiouracil	Steroid	No	1st degree AVB	7	No
17	Radioactive iodine	-	No	Returned to normal	-	No
18	-	-	No	Returned to normal	-	No
19	-	-	No	Returned to normal	2	No
20	Carbimazole	-	No	1st degree AVB	2	No
21	Propylthiouracil	-	Yes	Normal	8	No
22	Carbimazole	Atropine	Yes	Sinus bradycardia	2	No
23	-	-	No	Returned to normal	-	No
24	Carbimazole	Atropine	Yes	Returned to normal	4	No
25	Propylthiouracil and potassium iodine	-	No	Returned to normal	10	No
26	Methylmercaptoimidazole	Atropine	Yes	Returned to normal	2	No
27	Subtotal thyroidectomy	-	No	Returned to normal	-	No
28	Carbimazole	-	No	Returned to normal	2	No
29	Methimazole, surgical treatment	-	No	Returned to normal	-	No
30	Methimazole	-	No	No recovery	No recovery	Yes
31	Methimazole	-	No	Arrhythmias were fewer and shorter	-	No
32	Propylthiouracil	-	Yes	No recovery	No recovery	Yes
33	Methimazole	-	Yes	No recovery	No recovery	Yes
34	Propylthiouracil	-	No	/	/	Yes

¹Treatment included drugs or temporary pacemaker. -: Information not available; /: Did not occur. AVB: Atrioventricular block; ECG: Electrocardiogram.