16-86: Prevalence and prognosis role of wide QRS and of QRS “narrower than normal”

Introduction: Very narrow QRS has been described whose prevalence and clinical relevance in the normal adult population is unknown.

Methods: 546 healthy men between 50 and 60 yo (group 1) and 373 similar patients with coronary artery disease (368 men, EF < 50% in 40%, group 2) underwent signal averaged ECG allowing precise measurement of QRS duration. Patients and subjects with bundle branch block were excluded. All cause mortality was determined after 17 ± 3 years follow-up.

Results: Mean QRS duration was 97 ± 13 ms for group 1 (67-164) and 103 ± 16 ms (71-171) for group 2. 85/546 group 1 subjects (16%) had QRS < 85 ms and 23/546 (4%) had QRS > 120 ms. Tenth percentile was 84 ms and 90th percentile was 111 ms. 44/373 group 2 patients (12%) had QRS < 85 ms and 44/373 (12%) had QRS > 120 ms. QRS were larger in case of lower EF, lack of previous angioplasty and multivessel disease.

All cause mortality in group 1 was 10,4 % (57/546): 6/85 in case of QRS < 85 ms (7%) and 2/23 (9%) in case of QRS > 120 ms (p = ns compared to normal QRS duration). HR for all-cause mortality in case of QRS < 85 ms was 0,75 (95 % CI 0.32-1.76, p = 0,52) and 0,86 (95% CI 0.21-3.53, p = 0,84) for QRS > 120 ms.

All cause mortality in group 2 was 29 % (109/373): 7/44 in case of QRS < 85 ms (16%) and 22/44 (50%) in case of QRS > 120 ms (p = 0.002 when compared to normal QRS duration). Adjusted HR for all-cause mortality in case of QRS < 85 ms was 0,65 (95 % CI 0.29-1.45, p = 0,29) and 1.73 (95% CI 1.02-2.94, p = 0,05) for QRS > 120 ms.

Late potentials (LP) were considered present (2 positive of 3 criteria) in SA-ECG in 116/546 group 1 subjects (21%). LP were present in 100/373 group 2 patients (27%) and were significantly related to multivessel disease, altered EF, lack of revascularization or of angioplasty. LP were more frequently observed in case of QRS > 120 ms in both groups. LP were nor related to all-cause mortality in both groups.

Conclusion: QRS “narrower than normal” (< 85 ms) can be observed in a significant proportion of healthy males between 50 and 60 years old and in similar proportion of patients with ischemic heart disease. In opposition to QRS > 120 msec which are independantly related to a higher all-cause mortality in coronary artery disease patients, QRS < 85 ms were not linked to prognosis in any group.